Jiwan
CCE
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Question Bank
(Based On NCERT Syllabus)
TEACHER RESOURCE
MANUAL
7
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Chapter- 1 : Nutrition in Plants
Objective Type Questions
A. Fill in the blanks.
1. Autotrophic
2. chloroplasts
3. Chemoautotroph
4. blue black colour
5. Parasitic plants
6. Saprophytic plants
7. dark reaction
8. Root, minerals
9. food web
10. Mushroom
11. host plant
12. A leaf
13. Nitrates or ammonia
14. Lichen on a rock
15. Mushroom
NCERT Questions
16. Autotrophs
17. Starch
18. Chlorophyll
19. Carbon-dioxide, Oxygen
B. Write whether the following statements are true or false.
1. False
2. True
3. True
4. False
5. True
NCERT Questions
6. True
7. False
8. True
9. True
C. Match the two columns to make correct pairs.
NCERT Questions
1. a. iv
b. i
c. v
d. ii
e. iii
2. a. iii
b. iv
c. i
d. v
e. ii
D. Multiple choice questions. Tick the correct option in each case.
1. b
2. c
3. a
4. d
5. d
6. b
7. b
8. b
9. c
10. c
11. a 12. c 13. c
NCERT Questions
14. b
15. c 16. b 17. b 18. b
19. a 20. a
21. c
22. a
23. d
24. b
E. Name them.
1. Nutrition
2. Autotrophs
3. Light Reaction
4. Phloem
5. Transpiration
6. Mycorriza
7. Cuscuta
8. Stomata
9. Pitcher plant
10. Tree, autotrophic
11. Fish, holozoic nutrition
12. Mosquito, parasitic
13. Mushroom, symbiotic
Descriptive Questions
F. Very short answer questions.
1. Nutrition is the process of breaking down food and substances taken in by the mouth to use for energy in
the body or it is the process of obtaining and consuming food.
2. Autotrophic and Heterotrophic.
3. The chlorophyll absorbs the sunlight.
4. The reaction which occurs as the first phase of photosynthesis, in which energy in the form of light is
absorbed and converted to chemical energy in the form of ATP.
5. Stomata are present on the underside of the leaf.
6. Transpiration is the process of water movement through a plant and its evaporation from aerial parts
especially from leaves but also from stems and flowers.
7. The xylem transports water from the roots to all parts of the plant whereas the phloem transports organic
nutrients. The xylem in a plant exists as non-living tissue at maturity whereas the phloem exists as living
cells. The xylem and phloem are both vascular tissues found in plants.
8. A slender projection from the root of a parasitic plant, such as a dodder, or from the hyphae of a parasitic
fungus, enabling the parasite to penetrate the tissues of its host and absorb nutrients from it.
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9. These are plants that have a mutually beneficial relationship with each other, without any negative
benefits to either partner.
10. Fertilizers are mainly made up of nitrogen, phosphorous and potassium compounds. They also contain
other secondary compounds of calcium, magnesium and sulphur, which are usually in smaller amounts.
Fertilizers are usually added to the soil to supplement soil nutrients.
11. The food necessary for growth, health, and good condition.
12. Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct
photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce
NADP to NADPH through a complex set of processes called photosynthesis.
13. The second stage of photosynthesis, which takes place in the stomata, can occur without the presence
of sunlight. In this stage, known as the Calvin Cycle, carbon molecules from Co2 are fixed into glucose
(C6H12O2).
NCERT Questions
14. Because organisms need carbohydrate, vitamins, minerals and other nutrients to gain energy and
proteins to live and to continue metabolism.
15.
16. Leaves of the plant.
17. Water, minerals, carbon dioxide, sunlight.
G. Short answer questions.
1. Nutrition is a process by which living organisms assimilate food and use it for growth and replacement of
tissues. Nutritional supplements include minerals, herbs, and meal supplements and are added to diet to
boost the immune system and support the overall health.
2. The process by which green plants and some other organisms use sunlight to synthesize nutrients from
carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and
generates oxygen as a by-product.
3. There are two main modes of nutrition1. Heterotrophic - organisms that feed on complex organic matter from the bodies of other organisms
for energy etc.
2. Autotrophic - organisms that are able to utilise carbon dioxide as its sole source of carbon dioxide
and use external energy sources to synthesis organic food materials.
4. The two stages of photosynthesis are called light dependent and light independent. Light dependent,
stage 1, requires light . Stage 2, the light independent stage, occurs either with or without light.
5. The function of stomata is to allow oxygen, carbon dioxide and water to move into and out of a leaf.
Stomata is found on the outer skin of a plant.
6. Each of a pair of curved cells that surround a stoma, becoming larger or smaller according to the
pressure within the cells.
7. Transpiration creates suction pressure which causes more water to be absorbed by the roots.
8. Phloem tubes carry sugar & other organic nutrients made by plant from the leaves to the rest of the plant.
9. Insectivorous plants grow in mineral poor soil or very wet areas where all the nutrients are washed from
the soil regularly. Without these minerals that the plants can pull from the soil, they struggle to survive.
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So, insectivorous plants supplement their meager food making skills by trapping insects and dissolving
them to absorb their essential minerals— like nitrogen.
10. In saprophytic nutrition, the main classes of matter that are broken down are proteins, fats, and starches.
Proteins are digested into amino acids. Fats are broken down into glycerol and fatty acids. Starches are
digested into simple sugars. All of the resulting substances are then of a small enough molecular size
that they can be transported across the cell membranes.
NCERT Questions
11. Saprophytes are organisms that feed on dead and decaying living beings by absorbing soluble organic
compounds. Example: Rhizopus
Parasite is an organism that is in a heterospecific relationship with another organism( commonly known
as "host") and obtains food from the latter and harms it. Example: Cuscuta
12. Stem makes the food for the plant.
13. a. PARASITE b. SAPROPHYTE c. AUTOTROPH d. SYMBIOSIS
14. The bacteria present in the root nodules of these plants convert atmospheric nitrogen into plant usable form.
15. Because bacteria present in the air start breeding and multiplying in the wheat flour kept outside.
16. a. Chlorophyll b. Water and minerals c. Carbon-dioxide d. Sunlight.
17. Observe the diagram as given in label the following terms given in the box.
Guard cells
Stomatal pore
Cholorplast
Stomatal opening
Guard cell
18. a. chlorophyll
b. energy
c. energy
d. photosynthesis
e. water
f. minerals
g. carbon dioxide
h. food
H. Long answer questions.
1 a. Autotrophs and Heterotrophs - An autotroph (from the Greek autos = self and trophe = nutrition) is an
organism that produces complex organic compounds from simple inorganic molecules and an
external source of energy, such as light or chemical reactions of inorganic compounds. Autotrophs
are producers in a food chain. Plants and other organisms that carry out photosynthesis are
phototrophs (or photoautotrophs). Bacteria that utilize the oxidation of inorganic compounds such as
hydrogen sulfide, ammonium or ferrous iron as an energy source are chemoautotrophs (some are
known as lithotrophs). A heterotroph (Greek heterone = (an) other and trophe = nutrition) is an
organism that requires organic substrates to get its carbon for growth and development. A
heterotroph is known as a consumer in the food chain. Contrast with autotrophs which use inorganic
carbon dioxide or bicarbonate as sole carbon source. All animals are heterotrophic, as well as fungi
and many bacteria. Some parasitic plants have also turned fully or partially heterotrophic, whereas
carnivorous plants use their flesh diet to augment their nitrogen supply, but are still autotrophic.
Heterotrophs are unable to synthesize organic, carbon based compounds independently from the
inorganic environment's sources (e.g. Animalia, unlike Plantae, cannot photosynthesize) and
therefore must obtain their nutrition from another heterotroph or an autotroph.
1. b. Saprophytic and Parasitic plants – Saprotrophs are decomposers and liberate energy for their own use
by breaking down complex organic matter from the dead bodies of other organisms. At the same time
this process releases vital chemical elements into the soil which are absorbed by autotrophs. Thus,
saprotrophs aid the recycling of materials from dead organisms to living ones. Fungal and bacterial
saprotrophs are referred to as saprophyte, while animal saprotrophs are called saprozoites.
Jiwan® Science CCE Question Bank Answer Key-7/3
Mucor hiemalis is a saprophyte and has their branched hyphae, providing a large absorptive
surface. These penetrate dead, decaying matter and secrete enzymes into it. The food is digested
extracellularly and is subsequently absorbed and transported to other parts of the fungal mycelium.
Parasites are organisms that live in or on other living organisms (called the host) generally receiving
shelter and deriving nutrients from it. The parasites cause harm to the host plant.
1. c. Symbiotic and Carnivorous plant – Symbiosis is a partnership between two organisms in which both
partner get benefitted from each other.
Carnivorous plants are plants that derive some or most of their nutrients (but not energy) from
trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous
plants have adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen,
such as acidic bogs and rock outcroppings.
2. a. Identify a healthy green leaf on a plant and cover a portion of it on both sides with two uniform pieces
of black paper, either in the morning before the sun rises or the previous evening so that the
experiment is performed with a starch-free leaf. Or, keep a healthy, green pot plant in a dark room for
1 or 2 days so that its leaves become starch-free, and then cover a portion of a leaf of this plant. Fix
the pieces of paper properly with clips. To make sure that there is no starch, collect a few
neighbouring leaves in the morning, decolourize them with alcohol and dip them into iodine solution.
Note that they do not turn black, thus all the leaves are starch-free. Now, let the plant be exposed to
light for some time, preferably till the evening and collect the leaf and decolourize it with alcohol.
Place the blanched leaf in iodine solution for a minute.
Observation:
The exposed portion turns blue or black, showing the presence of starch in it. The screened portion, on the
other hand, turns yellowish brown as no starch formed in it, the yellow color is due to the action of iodine solution
on protoplasm and cellulose. It is better to place the iodine-treated leaf in benzol for a few minutes as benzol
removes the brownish colour from the protoplasm and the cell-walls, and then the bluish-black colour of starch
becomes clear.
Inference:
The experiment shows that photosynthesis takes place only in the presence of sunlight and that starch is
formed in photosynthesis.
b. 1. Take a potted plant like croton whose leaves are partly green and partly white. The green part of
the leaf has chlorophyll but the white part of the leaf does not have chlorophyll.
2. Place this plant in a completely dark place for about three days to destarch its leaves.
3. Take out the potted plant from the dark place and keep it in bright sunshine for three to four days.
4. Pluck the variegated leaf from the plant, boil it in water for a few minutes and then remove its
green colour 'chlorophyll' by boiling it in alcohol. The green parts of the leaf get decolourised. So,
we get decolourised leaf.
5. Wash the decolourised leaf with hot water to soften it and remove any chlorophyll which may be
sticking to it.
6. Pour iodine solution over the colourless leaf and observe the change in colour of the leaf.
7. We will find that the outer part of leaf that was originally white (without chlorophyll) does not turn
blue-black on adding iodine solution showing that no starch is present in this outer part of the leaf.
From this observation we conclude that the photosynthesis to make starch does not take place
without chlorophyll.
8. The inner part of leaf which was originally green (contained chlorophyll) turns blue-black on adding
iodine solution showing that starch is present in this inner part of the leaf. From this observation we
conclude that the photosynthesis to make starch takes place in the presence of chlorophyll. In other
words, chlorophyll is necessary for the process of photosynthesis to take place.
3. Carnivorous plants are plants that derive some or most of their nutrients (but not energy) from trapping
and consuming animals, typically insects and other arthropods. Carnivorous plants have adapted to
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grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs and rock
outcroppings. Example – Venus fly trap and Pitcher plant.
4. Crop rotation is the practice of growing a series of dissimilar/different types of crops in the same area in
sequential seasons. Crop rotation gives various benefits to the soil. A traditional element of crop rotation
is the replenishment of nitrogen through the use of green manure in sequence with cereals and other
crops. Crop rotation also mitigates the build-up of pathogens and pests that often occurs when one
species is continuously cropped, and can also improve soil structure and fertility by alternating deeprooted and shallow-rooted plants. Crop rotation is one component of poly culture.
5. The iodine test for starch has following steps:
1. If the food to be tested is liquid, go to 2. If the food to be tested is solid, make an extract. Grind crush
or chop a small amount and put into a test tube to a depth of about 2 cm. Add a similar amount of
distilled water and stir with a glass rod. Allow to stand for a few minutes.
2. Draw up some of the clear liquid into a pipette and then either transfer it into another test tube or put
drops onto a white tile.
3. Add on drop of (brown) iodine solution on the tile and look for a colour change. A blue-black colour
indicates the presence of starch.
6. Leaves have a green pigment called chlorophyll. In presence of sunlight, they use carbon dioxide and
water to synthesize carbohydrate. During this process oxygen is released. The carbohydrates ultimately
get converted into starch.
Carbon dioxide from air is taken through stomata. Water and minerals are absorbed by roots and
transported to leaves.
NCERT Questions
7. Yes, they can survive without plants. Carnivores depend on the nutrients only found in animal flesh for
their survival. While they may consume small amounts of plant material, they lack the physiology
required for the efficient digestion of vegetable matter and, in fact, some carnivorous mammals eat
vegetation specifically as an emetic.
I. Give reasons.
1. Green plants are the ultimate source of energy on earth. Plants are able to undergo photosynthesis
which utilizes light energy to convert carbon dioxide or CO2 and water or H2O into sugar or C6H12O6 and
oxygen or O2. The ultimate energy source for plants is light.
2. Photosynthesis is a chemical process - It turns carbon dioxide and water into oxygen and carbohydrates,
therefore a chemical change occurs.
3. All plants cannot be called saprophytes. Because most plants make their food.
4. Due to the growth of fungus on it.
5. Plants need nitrogen for the formation of proteins that is used for their nutrition and subsequently for our
nutrition when we eat them. They cannot get nitrogen from the air as they are not able to take in nitrogen in
the gas state into their 'bodies'. They require nitrogen in the form of nitrates and nitrites in the soil which they
can diffuse in through the roots. It is for this reason that bacteria in the soil or symbiotic bacteria in
leguminous plants are responsible for the conversion of atmospheric nitrogen into nitrates and nitrites.
J. HOTS questions.
1. Plants produce oxygen as a byproduct which most animals need to survive. Also, they provide a large food
resource for the majority of animals on the planet. To elaborate, green plants contain chloroplasts, which
are like plant "lungs," that convert carbon dioxide, water, and light energy (photons) into energy (specifically
glucose or sugar, oxygen, and water) by a process known as photosynthesis. The waste product of this
process, oxygen, is an essential part of life. Without plants, the primary engine of the oxygen cycle would be
broken and not long after all life on the planet would soon wither. At the very least, without plants the food
chain would be severely disturbed, leading to catastrophic starvation of most animals.
2. If there is no coating on leaves of aquatic plants they rot in water, a oil coating prevents the leaf of a
aquatic plant. Oil coating over the leaf keep it safe from getting rot due to being wet in water.
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Chapter- 2 : Nutrition in Plants
Objective Type Questions
A. Fill in the blanks.
1. microscopic unicellular
2. Holozoic
3. Pseudopodia
4. food vacuole
5. cilia
6.
Water
7. Proboscis
8. Sweat, starch, sugar
9.
Gastric
10. fatty acids and glycerol
11. Wisdom tooth
12. Canines
13. Green plants
14. egestion
NCERT Questions
15. ingestion, digestion, absorption, assimilation and egestion
16. liver
17. gastric juices
18. Food vacuole
19. Mouth, rectum
20. socket, gum
21. Mouth, teeth
22. bile
23. Water, vitamins
24. root underside, tip (front part)
25. Pseudopodia, Vacuole
B. Write whether the following statements are true or false.
1. True
2. True
3. True
4. False
5. False
6. False
7. True
8. False
9. True
10. False
11. False
12. True
13. False
14. True
15. True
16. True
17. False
18. False
NCERT Questions
19. False
20. True
21. True
22. True
23. True
24. True
25. True
26. False
C. Match the two columns to make correct pairs.
NCERT Questions
1. a. iii
b. iv
c. i
d. ii
e. vi
f. v
2. a. iii
b. i
c. iv
d. ii
3. a. iv
b. v
c. i
d. iii
e. ii
D. Multiple choice questions. Tick the correct option in each case.
1. d
2. b
3. d
4. c
5. b
6. d
7. c
8. c
9. d
NCERT Questions
10. c
11. d 12. b 13. b 14. d
15. a 16. c
17. a
18. c
19. b
20. a 21. d 22. a
E. Name them.
1. Invertebrates
2. Pancreas
3. Paramecium
4. Liver
5. Water and vitamins
6. Anus
7. Digestion
Descriptive Questions
F. Very short answer questions.
1. The process of providing or obtaining the food necessary for health and growth.
2. A. Mode of nutrition in plant
Autotrophic Nutrition - Auto means ‘self’ and trophos means ‘nourishment’. Plants are called
autotrophs because they make their food themselves. The making of food for themselves is called
the autotrophic nutrition. Autotrophic nutrition is found in green plants.
B. Heterotrophic Nutrition - The word Heterotrophic is the combination of two words i.e. Hetero +
Trophos. Hetero means 'others' and 'trophos' means nourishment. If organisms depend on others
for their food, it is called the Heterotrophic nutrition
Animals cannot make their
Jiwan® Science CCE Question Bank Answer Key-7/6
food themselves. They depend for food upon plants. Therefore, nutrition in animals is called
Heterotrophic nutrition. Animals are known as heterotrophs.
C. Saprotrophic Nutrition - The taking of nutrients by organism from dead and decaying matter in the
form of solution is called the saprotrophic nutrition. The organisms which use saprotrophic mode of
nutrition are called saprotrophs. Example: fungi.
3. Parasitic.
4. Vultures eat the carcasses of dead animals.
5. Egestion.
6. Nutrition in amoeba is holozoic. Thus, solid food particles are ingested which are then acted upon by
enzymes and digested. It is an omnivore, feeding on both plants and animals. Its diet includes bacteria,
microscopic plants like the diatoms, minute algae, microscopic animals like other protozoa, nematodes
and even dead organic matter.
7. Phagocytosis is the process cells use to engulf and ingest nutrient and bacteria particles.
8. The enzyme, salivary amylase will act on starch but not on protein.
9. Molars and premolars help in grinding food.
10. A ruminant is an animal with a stomach that has multiple compartments, allowing it to extract nutrition
from grasses, hay, and other cellulose-rich foods which other animals usually find indigestible.
11. Protein is digested in the stomach.
12. The role of bile in digestion is for digestion and absorption of fats and fat-soluble vitamins. Waste
products like bilirubin are also eliminated from the body by secretion into bile. Bile acts as a surfactant
that helps to emulsify fats in food.
13. Partly digested food returned from the first stomach of ruminants to the mouth for further chewing.
NCERT Questions
14. Glucose is the simplest form of sugar. It can directly be absorbed by intestine and can easily be
transported by blood to various cells of the body. Cells directly act on glucose along with oxygen to given
energy. While carbohydrates are complex forms of sugars and they need to be further broken down into
simpler substances like glucose before absorption. Hence, it requires extra time as compared to glucose
which provides instant energy.
15. a. Absorption of glucose-villi in small intestine.
b. Chewing of food-mouth (buccal cavity).
c. Killing of bacteria-stomach.
d. Complete digestion of food small intestine.
e. Formation of faeces-large intestine.
G. Short answer questions.
1. The primary function of the large intestine is the transportation of waste and re-absorption of water from it
before it is excreted. When proper metabolism has taken place the waste is usually in solid form.
2. Nutrition of an animal by absorption of dissolved salts and simple organic nutrients from surrounding
medium; also, refers to feeding on decaying organic matter.
3. Symbiosis refers to a situation in which two different organisms subsist together in close association. In a
symbiotic relationship, at least one member of the pair profits from the relationship and the other may be
injured or relatively unaffected.
4. When we eat, the saliva breaks down the chemicals in the food a bit, this helps in making the food mushy
and easy to swallow. Our tongue helps out, pushing the food around while we chew with our teeth. When
we're ready to swallow, the tongue pushes a tiny bit of mushed-up food called a bolus toward the back of
our throat and into the opening of our esophagus, the second part of the digestive tract.
5. Taking care of your teeth helps prevent plaque, which is a clear film of bacteria that sticks to your teeth.
After you eat, bacteria go crazy over the sugar on your teeth, like ants at a picnic. The bacteria break it
down into acids that eat away tooth enamel, causing holes called cavities. Plaque also causes gingivitis ,
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which is gum disease that can make your gums red, swollen, and sore. Your gums are those soft pink
tissues in your mouth that hold your teeth in place.
6. Gastric acid is one of the main secretions of the stomach. It consists mainly of hydrochloric acid and
acidifies the stomach content to a pH of 1 to 2. Chloride (Cl−) and hydrogen (H+) ions are secreted
separately in the stomach fundus region at the top of the stomach by parietal cells of the gastric mucosa
into a secretory network called canaliculi before it enters the stomach lumen.
Gastric acid acts as a barrier against microorganisms to prevent infections and is important for the
digestion of food. It's low pH denatures proteins and thereby makes them susceptible to degradation by
digestive enzymes such as pepsin. The low pH also activates the enzyme precursor pepsinogen into the
active enzyme pepsin by self-cleavage. After leaving the stomach, the hydrochloric acid of the chyme is
neutralized in the duodenum by sodium bicarbonate.
The stomach itself is protected from the strong acid by the secretion of a thick, protective mucus layer,
and by secretin induced buffering with sodium bicarbonate. Heartburn or peptic ulcers can develop when
these mechanisms fail. Drugs of the antihistaminic and proton pump inhibitor classes can inhibit the
production of acid in the stomach, and antacids are used to neutralize existing acid.
7. When we swallow food moves down into the stomach from the mouth this is peristalsis, by the rhythmic
contraction of smooth muscles.
8. Ruminants have four large stomachs that mash up all the food and help them to digest very quickly.
When they have eaten, ruminants lie down to allow this process to take place. They bring any bits of food
that are not mashing easily back up to their mouths and re-chew them. This is called chewing the cud.
NCERT Questions
9. The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi. The
villi increase the surface area for absorption of the digested food. Each villus has a network of thin and
small blood vessels close to its surface. The surface of the villi absorbs the digested food materials. The
absorbed food is then transported to various organs via blood vessels.
10. Liver secretes bile juice that is stored in a sac called the gall bladder. The bile plays an important role in
the digestion of fats.
11. Cellulose, a type of carbohydrate present in grass and it can be digested by ruminants but not by
humans. Ruminants have a large sac-like structure between the small intestine and large intestine called
caecum. The cellulose of the food is digested here by the action of certain bacteria which are not present
in humans.
12. Similarity: The basic process of digestion of food and release of energy is the same in amoeba as well as
in human beings. In amoeba, digestive juices are secreted into the food vacuole. They act on the food
and break it down into simpler substances. Gradually the digested food is absorbed. Similarly, in human
beings various digestive juices (mouth, stomach, intestine etc.) act on food and break it down to simpler
substances.
Difference: The digestion process in amoeba is simple while in human beings it is a complex process.
The process of ingestion and egestion are also quite different. Amoeba engulfs its food by surrounding
the food particle with its pseudopodia. The undigested food which is largely carbon dioxide gas is
expelled outside by the vacuole. While in human beings, the food (which is complex substance) is taken
inside the mouth and undergoes a complex process of digestion and absorption. Finally the undigested
food it expelled in the form of faeces.
13. Test tube A the colour of boiled rice changed to blue black due to the presence of starch. But the test tube
B rice remains same there is no colour change because saliva contains the enzyme amylase, also called
ptyalin, which is capable of breaking down starch into simpler sugars. So, the food in test tube B turned
into sugar after being chewed and that is why no colour change in test tube B.
14. Food items containing fats, The gall bladder works to store the excess bile that the liver produces and
releases it when digestion is occurring. Breaking down fat is necessary because this fat cannot be
properly utilized by the body unless it is in a simpler form. The toxins that people encounter everyday can
Jiwan® Science CCE Question Bank Answer Key-7/8
be muted by the bile and then carried out of the body as waste. Stones in the gall bladder can end up
causing serious probelm when they plug the pathway for these products to move where needed.
The gall bladder function, unknown to many of us is an important part of our body's daily operation. In
addition to storing the excessive bile from the liver, it helps the body neutralize the acids which the stomach
produces by releasing the correct amount of bile when needed. Post gall bladder removal, bile simply runs in
a continuous stream from the liver into the intestines. It's not as concentrated as bile from a gall bladder, but is
more dilute. The body gradually adjusts and one can eat normally again in a few weeks.
15. Grass eating animals quickly swallow the grass and store it in a separate part of the stomach called
rumen, here the food gets partially digested and is called cud, but later the cud is brought back to the
mouth in small lumps and the animal chews it. This process is called rumination and the animals are
called ruminants.
16. He is coughing because his food has gone into the respiratory tract near the food pipe and his body is
coughing to throw out the hurriedly eaten food.
H. Long answer questions.
1. Amoeba obtains its nutrition in a heterotrophic mode. Both the anabolic and catabolic functions are
carried out in the same cell. Amoeba feeds on plankton and diatoms present in water. It can form arm-like
structures called pseudopodia, extending from any part of its body as it is shapeless. When it senses food
in its surroundings it extends its pseudopodia in that direction and moves towards it. Then it engulfs the
food with its pseudopodia. When the food enters its body the amoeba forms a food vacuole around it
which contains certain enzymes to digest the food. When the food is digested the unwanted waste is
released through its body surface.
Amoeba engulfing its prey
2. A. Autotrophic Nutrition – Autotrophs synthesize organic materials from inorganic materials. Some
organisms derive their energy for this process from sunlight and are called photoautotrophs.
Example: Green plants other, organisms use chemical energy and are called chemoautotrophs.
Example: Nitrifying bacteria. Photoautotrophs are the primary producers in food chain.
B. Heterotrophic Nutrition - Heterotrophs eat ready - made complex organic food. From this they obtain
energy for metabolism, atoms and molecules to build new protoplasm or repair worn - out parts, and
ions, co-enzymes and vitamins vital for chemical processes. There are four types of heterotrophic
nutrition-saprophytic, parasitic, symbiotic and insectivorous.
C. Saprohytic Nutrition - Saprotrophs are decomposers and liberate energy for their own use by
breaking down complex organic matter from the dead bodies of other organisms. At the same time
this process releases vital chemical elements into the soil which are absorbed by autotrophs. Thus
saprotrophs aid the recycling of materials from dead organisms to living ones. Fungal and bacterial
saprotrophs are referred to as saprophyte, while animal saprotrophs are called saprozoites.
Mucor hiemalis is a saprophyte and has their branched hyphae, providing a large absorptive surface.
These penetrate dead, decaying matter and secrete enzymes into it. The food is digested
extracellularly and is subsequently absorbed and transported to other parts of the fungal mycelium.
D. Parasitic Nutrition- Parasites are organisms that live in or on other living organisms (called the host)
generally receiving shelter and deriving nutrients from it. The parasites may cause harm to the host
plant.
3. Holozoic nutrition is a method of nutrition that involves the ingestion of liquid or solid organic material,
digestion, absorption and assimilation of it to utilize it.
Jiwan® Science CCE Question Bank Answer Key-7/9
In this mode of nutrition, the food may be a small bacterium, a plant or an animal. Here, the food is first
taken into the body through an opening called a mouth (ingestion), then it is converted into a simple and
soluble form by various enzymes (digestion); simplified products thus formed are then absorbed
(absorption); the conversion of nutrient into the fluid or solid substance of the body (Assimilation); and
finally the undigested part of food is removed from the body (egestion).
4. Mastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of
digestion and it increases the surface area of foods to allow more efficient break down by enzymes.
During the mastication process, the food is positioned between the teeth for grinding by the cheek and
tongue. As chewing continues, the food is made softer and warmer, and the enzymes in saliva begin to
break down carbohydrates in the food. After chewing, the food (now called a bolus) is swallowed. It enters
the esophagus and via peristalsis continues on to the stomach, where the next step of digestion occurs.
a. Crushing by teeth .
b. Enzyme called amylase acts on food.
c. Tongue movement turns food into bolus.
d. Swallowing of bolus by mixing with the saliva.
5. The dilated portion of the alimentary canal situated between the oesophagus and the beginning of the
small intestine is called the stomach. It is a muscular distensible organ and its shape and size varies. It is
about 30 cms long and 15 cms wide. There are four regions in the stomach. These are the cardiac region,
fundus, body and the pyloric region. The cardiac region is situated at the upper end of the stomach. The
oesophagus opens into this and this opening is called the cardiac orifice.
This is guarded by the cardiac sphincter muscles which prevent the regurgitation (moving back) of the
food into the oesophagus. The fundus is the dome like upper part of the stomach and it projects above
the cardiac orifice.
The main part of the stomach is called the body and at its lower ends it narrows into the pyloric region.
The pyloric region connects itself to the small intestine through the pyloric aperture and is guarded by a
valve called the pyloric sphincter. This regulates the movement of the food into the intestine.
Structurally the wall of the stomach is made up of four layers of tissue. These are:
1. An outer covering of the serous membrane (the peritoneum).
2. A muscle layer which in turn is made up of three layers of visceral muscle fibres namely longitudinal,
circular and oblique.
3. A sub mucous layer consisting of loose areolar tissue carrying blood vessels, lymphatics and nerves.
4. The mucous membrane constituting the innermost layers is thick and smooth having a velvety
surface when the stomach is full.
The mucous membrane of the stomach contains a number of minute depressions called gastric pits.
Embedded in these gastric pits are found a number of glands which secret the gastric juice. There
are three types of gastric glands. These are:
1. The peptic cells that produce zymogen
2. The oxyntic cells that secret HCL, and
3. Mucous cells which add mucous.
The three secretions together form an acidic gastric juice with a pH of 2. The gastric juice is
discharged into the stomach. It contains water, salts, mucin, hydrochloric acid, pepsin, rennin and
gastric lipase. It has been estimated that on an average about two to three litres of gastric juice is
secreted per day.
6. Absorption is the taking of one thing into the area of another. A good example of this is a sponge which will
absorb or take in the water from another area and put it inside of itself.
Villi (singular: villus) are small, finger-like projections from a mucus membrane (e.g. small intestine/ileum
wall or chorion). Villi do not have any significant role in the process of digestion. Perhaps you mean their
role in the process of absorption in the digestive system.
Jiwan® Science CCE Question Bank Answer Key-7/10
Villi increase the surface area of the ileum for efficient absorption of products of digestion (e.g. glucose,
amino acids, fatty acids and glycerol). They also have a one-cell thick villus wall that reduces the
distance needed for substances to diffuse for easier and faster diffusion, a capillary network with a lymph
vessel/lacteal that maintains the concentration gradient of products of digestion to absorb those
substances efficiently, can move and have microvilli (smaller finger-like projections for the same
function). The capillary network absorbs glucose and amino acids by diffusion or active transport,
whereas the lymph vessel absorbs fatty acids and glycerol by diffusion.
7. Ruminants are mammals that are able to acquire nutrients from plant-based food by fermenting it in a
specialized stomach prior to digestion, principally through bacterial actions. The process typically
requires regurgitation of fermented ingesta or cud, and chewing it again. The process of re-chewing the
cud to further break down plant matter and stimulate digestion is called "Rumination". The word
"ruminant" comes from the Latin ruminare, which means "to chew over again".
8.
Mouth
Salivary Gland
Oesophagus
Liver
Stomach
Gall Bladder
Pancreas
Small Intestine
Large Intestine
Rectum
Anus
Digestive System and Organs
NCERT Questions
9. We know that including all animals, fungi, many bacteria, non-green plants and human being do not
possess the ability to synthesize their own food. Therefore depend upon autotrophs for their food supply
either directly or indirectly. The green plants (leafy vegetables / grass) trap solar energy and
manufacture their food in the form of glucose. So, leafy vegetables and grass can provide sufficient
energy required for the survival of human being.
10. a. The cutting and biting teeth as A.
b. The piercing and tearing teeth as B.
c. The grinding and chewing teeth as C.
d. The grinding teeth resent only in adult as D.
Molar
Premolar
Canine
Incisor
arrangement of teeth and different
types of teeth
Jiwan® Science CCE Question Bank Answer Key-7/11
11. a. Bile is produced in liver and is stored in a sac called the gall bladder.
b. Fats are one of the hardest things for our body to digest as they do not dissolve in water
c. Fats are hard to digest--primarily because they do not dissolve in water. The liver manufactures a
chemical called bile that works with enzymes to break down fats. Your gall bladder--located just under
the liver and just above the duodenum--stores bile until you ingest a high fat meal. Eating a meal-especially a high fat meal--releases a hormone (cholecystokinin) that causes the gall bladder to
release bile into the duodenum (small intestine).
d. The digestion of fats is completed in small Intestine.
e. Yes, bile helps in digestion of fats in small intestine.
12.
Mouth
Salivary Gland
Oesophagus
Liver
Stomach
Gall Bladder
Pancreas
Small Intestine
Large Intestine
Rectum
Anus
Digestive System and Organs
a. The largest gland in our body. ___________ Liver
b. The organ where protein digestion starts. ___________ Stomach
c. The organ where bile juice gets stored. ___________ Gall bladder
13. a. 20 teeth would be there in your mouth.
b. An adult would have 32 teeth.
I. Give reasons.
1. The enzymes found in saliva are essential in beginning the process of digestion of dietary starches and
fats. These enzymes also play a role in breaking down food particles entrapped within dental crevices,
protecting teeth from bacterial decay.
2. The pancreas contains exocrine glands that produce enzymes important for digestion. When food
enters the stomach, these pancreatic juices are released into a system of ducts that culminate in the
main pancreatic duct. The pancreatic juices and bile that are released into the duodenum help the body
to digest fats, carbohydrates, and proteins.
3. Ruminants are mammals that can break down cellulose. Humans have one stomach that fills with
hydrochloric acid and enzymes to help break down food. Ruminants, such as cows, have a stomach with
several compartments.
Cows, like all herbivores, eat grasses and other plant material. Plants contain cellulose, which is very
hard to digest (even for an herbivore). So, when a cow swallows some grass, the chewed grass first
enters the compartment of the stomach called the rumen. The rumen contains a salty solution and
bacteria that helps to break down the cellulose.
Cows then regurgitate (spit up) the material from the rumen, called cud, back into their mouths. They
“chew their cud” to help break down the cellulose even further. The cud is swallowed again, and it reenters the rumen. This cycle repeats as necessary until the material is broken down far enough to be
Jiwan® Science CCE Question Bank Answer Key-7/12
churned up and passed into the true stomach. From there, digestion continues through the intestines
and excretory system of the cow.
4. The abomasum is the fourth and final stomach in a cow's digestive system. The abomasum secretes
rennin, which works to curdle the milk they ingest. A cow is a ruminant animal, which means it partially
digests food, regurgitates it, and chews it again.
5. The surface area of the inner lining of the small intestine is around 4,500 square meters. That's about the
size of a football field! Finger-like protrusions on the surface of the intestinal lining called villi make this
massive surface area possible. Because the proteins, carbohydrates, lipids as well as many vitamins and
minerals are absorbed through the small intestine, nutrient uptake would be greatly inhibited without villi.
J. HOTS questions.
1. Cholera bacteria produce toxins which increase secretion of chloride ions into the lumen of the intestine.
This results in severe diarrhoea. The use of oral rehydration solutions(ORS) in the treatment of diarrheal
diseases have the following benefits:
1. Cholera produces a toxin which causes Na and Cl ions to be released into the lumen, lowering water
potential.
2. Water diffuses by osmosis across the epithelial cells into the lumen to even water potential but does
not get reabsorbed and causes diarrhoea.
4. ORS is given containing salts and water to replace the fluid lost.
2. Glucose is the end product of carbohydrates which is one of the complex organic substance provide
maximum energy to our body when digested i.e., broken down in simpler form accepted by the blood for
transporting it to each and every cell where it combines with O2 (respiration) to release energy, hence we
get instant energy from glucose.
3. In order to kill harmful bacteria and for digestion by the enzymes in our stomach to work, the stomach has
a very low pH and highly concentrated hydrochloric acid in it (HCl). Our tissues are protected from the
acid because we have a layer of mucus surrounding the stomach to protect from the very strong acid.
Sometimes the acid goes up and irritates our esophagus which doesn't have the protective coating and I
think this is called heartburn or acidity.
NCERT Questions
4. Goat's milk is a good source of high quality protein and has about the same amount of protein as cow's
milk. The protein in goat's milk reacts with the stomach acids forming a soft curd that is easier to digest.
As a result, the milk is processed quicker and may not stay in the stomach as long, which may decrease
reflux. There is also less casein in goat's milk, which may make it less allergenic.
Goat's milk contains a little more fat than cow's whole milk. However, goat's milk contains short-chain
and medium-chain fatty acids that are easier to digest. Because goat's milk does not contain agglutinin,
a protein found in cow's milk, it does not need to be homogenized. The fat globules in goat's milk do not
cluster together like they do in cow's milk, making it easier for the body to digest.
Jiwan® Science CCE Question Bank Answer Key-7/13
Chapter- 3 : Matter
Objective Type Questions
A. Fill in the blanks.
1. Atom
2.
Mixtures
3.
®
4.
reactants
5. Atomicity
6.
Nacl
7.
2
8.
1 atom
10.
Latin
9. Gold, Silver
B. Write whether the following statements are true or false.
1. True
2. False
6. False
7. False
3. True
4.
True
5.
True
C. Match the two columns to make correct pairs.
1. a. ii
b. iii
c.
iv
d.
v
e.
i
D. Multiple choice questions. Tick the correct option in each case.
1. d
2. c
3. a
4. a
5. c
6. c
7. a
8. d
9.
d
10.
a
E. Name them.
1. Matter
2.
Galvanization
5. Reactants
6.
Atomicity
3.
Atom
4.
No of electron
Descriptive Questions
F. Very short answer questions.
1. The smallest unit of any element is known as an atom. The atom is made up of 3 smaller subatomic
particles known as protons, electrons, and neutrons.
2. O2, H2, Cl2
3. 25
4. Mercury
5. Bromine(Br) and Mercury(Hg)
6. Co-Cobalt,Na-Sodium
7. O2 represents the stable form of oxygen gas. The oxygen in the air is the diatomic molecule. Atomic
oxygen may appear in chemical equations, usually as an unstable intermediate.
As in ... 4Na(s) + O2 ® 2Na2O
8. Copper is derived from Cuprum. Hence, its symbol Cu is short for Cuprum.
9. A mixture consists of two or more compounds simply mixed together. It does not involve formation of any
new molecules.
10. Milk is a mixture of water, cream, minerals, vitamins, etc.
11. Alchemy is referred to as the transformation of substances mainly of all elements into gold and silver.
12. These symbols are used so that it could be understood by the whole world.
G. Short answer questions.
1. Atomicity is the total number of atoms present in one molecule of an element or a compound. For
example: one molecule of hydrogen (H2) contains two atoms of hydrogen. Therefore, atomicity of
hydrogen is 2. Similarly, 1 molecule of O3 contains 3 atoms. Therefore, its atomicity is 3.Molecule of
Argon exist as Ar and hence it's a monoatomic compound.
2. The smallest particle that makes up matter.For examples H, C, O, N is atoms. Molecule is combination of
atoms with bond. Molecule is created by bonded atoms For example H2, CO2, N2
3. Mixture of pulses can be separated by hand picking.
Jiwan® Science CCE Question Bank Answer Key-7/14
4. Chemical formulas are short-hand representations of compounds using chemical symbols and
oxidation numbers.
5. Most elements have partly filled orbital and they try to gain or lose or share electrons so as to satisfy
octate rule.
6. A symbol is a short form of an element that has a universal recognition, the need using symbols was felt
in order to reduce the inconvenience of writing names of the elements.
H. Long answer questions.
1. An atom is the smallest particle in an element while a combination of two or more atoms forms a
molecule. Whereas molecules can be broken down to individual atoms, atoms cannot hence retain the
properties of the element. Both the molecule and atom are microscopic hence cannot be viewed by the
naked eye.
Example – Molecules are a group of atoms covalently bonded to each other (which can be considered a
'direct connection'). The molecule can consist of atoms of the same element, or atoms of different
elements. Example – A gold molecule will be same as gold atom.
I. Give reasons.
1. Atoms are so small that they cannot be seen by the most powerful microscope. Approximately, 4 million
gold atom, placed end to end form a line of only 1 mm length.
2. Because not all compounds and element react with each other.
3. Most elements have partly filled orbital and they try to gain or lose or share electrons so as to satisfy
octate rule.
4. Helium doesn't form any compounds because its outer electron shell is full, so it won't react with any
other elements, along with the other Noble Gases.
5. We balance chemical equations because they have to obey law of conservation of mass. Law of
conservation of mass states that mass can neither created, lost nor destroyed. Therefore, we use
coefficient in front of reactants and products in order to make sure there are equal number of molecules
or atoms on both sides.
J. HOTS questions.
1. An energy of the order of 20 electron-volts would be enough to break down a water molecule into its
constituent atoms, and this is easily done in an electrical discharge where many ionized components
reach energies of many tonnes of electron volts, and these energetic species can easily break apart the
water molecules. This is done very often in the field of plasma chemistry. A plasma torch at atmospheric
pressure, for example, can reach temperatures of 60,000 degrees.
2. Sodium metal is a soft, light-weight, silvery white, reactive metal. Owing to its extreme reactivity, it occurs
in nature only combined in compounds, never as a pure elemental metal. Sodium metal floats on water
and reacts with it violently, releasing heat and flammable hydrogen gas, and forming a solution of the
strong base sodium hydroxide.
Sodium's powdered form is highly explosive in water and is a poison when uncombined or combined
with many other elements. This metal should be handled carefully at all times. Sodium must be stored
either in an inert atmosphere, or under a liquid hydrocarbon such as mineral oil or kerosene.
Jiwan® Science CCE Question Bank Answer Key-7/15
Chapter- 4 : Fibres
Objective Type Questions
A. Fill in the blanks.
1. shearing
2. Sericulture
3. Hair of the animals
4. silkworms
5. animals
6. pashmina
7. merino
8. pupa
9. Anthrax bacteria
10. Nylon
11. winter
NCERT Questions
12. Wool, silk
13. Cocoon, worm
14. Thick fur
15. air, conductor
B. Write whether the following statements are true or false.
1. True
2. False
3. False
4. True
5. False
6. False
7. True
8. False
9. False
10. False
NCERT Questions
11. False
12. True
13. True
14. True
15. False
C. Match the two columns to make correct pairs.
1. a. iv
b. iii
c. ii
d. i
2. a. iii
b. iv
c. ii
d. i
D. Multiple choice questions. Tick the correct option in each case.
1. b
2. a
3. c
4. c
5. b
6. b
7. d
8. d
9. a
10. b 11. a
NCERT Questions
12. c
13. d 14. c 15. d 16. a
17. c 18. d
19. d
20. a
21. b 22. d 23. c
E. Name them.
1. Alpaca, Ilama
2. Shearing, scouring
3. Tassar, Muga
4. Cashmere, Pashmina
5. Jammu & Kashmir, Himachal Pradesh
6. Nylon, Rayon
7. Cotton, Jute
Descriptive Questions
F. Very short answer questions.
1. Seed fibre: Fibres collected from seeds or seed cases. e.g. cotton and kapok.
Leaf fibre: Fibres collected from leaves. e.g. sisal and agave.
Bast fibre or skin fibre: Fibres are collected from the skin or bast surrounding the stem of their respective
plant. These fibres have higher tensile strength than other fibres. Therefore, these fibres are used for
durable yarn, fabric, packaging, and paper. Some examples are flax, jute, kenaf, industrial hemp, ramie,
rattan, soybean fibres, and even vine fibres and banana fibres.
Fruit fibre: Fibres are collected from the fruit of the plant, e.g. coconut (coir) fibres.
Stalk fibre: Fibres are actually the stalks of the plant. E.g. straws of wheat, rice, barley, and other crops
including bamboo and grass. Tree wood is also such a fibre.
2. Lamas, sheep, goat, camels, rabbits, Musk oxen.
3. Jute and cotton.
4. Mohair wool is a special type of fibre shorn from the Angora goat. This fibre called Mohair is quite warm,
durable, and is not characterised by itchy feel. It is different from normal wool in that it is from goats not
sheep.
5. Angora Goat.
6. Yarn is made from many different fibres -- animal, plant and vegetable. Animal fibres' include wool,
mohair, angora, silk, cashmere, llama, alpaca and qiviut (musk ox) and are made of mostly protein.
Jiwan® Science CCE Question Bank Answer Key-7/16
Cotton, linen and ramie are vegetable fibres. Synthetic (man-made) fibres include acrylic, nylon,
polyester, metallic and micro fibres. Each fibre has its own qualities, and they are often blended to take
advantage of the best properties of each.
7. Wool is obtained from the hair of the animals. The animals living in cold areas, like hills, have thick hair
on their body. These hair trap a lot of air and keep the animal warm. Similarly the wool fibres trap air and
protect the body from cold.
8.
1 Natural fibers are fibers that are found in These firbers are man made or simoly
prepared in lab. Ex: Nylon, Teflon etc.
nature. Ex: Wool, silk, and cotton etc.
2 They are good absorbents and so able to They do not have such pores as they are made
assorb heat, temperature, cold, sweat etc. up of chemicals and so do not act as good
adsorbents.
depending on conditions and nature of fibres.
3 No spinning process is required for filament Melting, wet or dry spinning processes are
used for filament production.
production.
Not as comfortable as natural fibres.
4 Comfortable in use.
5 Their length is naturally obtained and it is nor Their lengths can be controlled by man and the
fibres can easily be changed to different
possible to change the fibre structure.
structures.
9. Cloth produced by weaving or knitting textile fibres.
10. The yarn is made by twisting the fibres together. Fibres are very delicate and when twisted together they
gain more strength.
11. a. Merino wool - Merino Sheep
b. Mohair
- Angora goat
c. Pashmina - Pashmina Goat
12. It is the process of removing fleece through shearing machines or razors.
13. The fleece from the sheep has a lot of grease and dirt, so it is cleaned in warm soapy water. This grease is
called lanolin and is used for making cosmetics and soap.
14. Andhra Pradesh and Karnataka.
15. The wool is sorted into groups according to their softness, length, weight, colour and ease of dyeing. The
longer fibres are woven into yarns to be used for knitting sweaters and the shorter fibres are spun and
woven into woollen cloth.
NCERT Questions
16. Rearing -The domestication of animals for wool.
Shearing. It is the process of removing fleece through shearing machines or razors.
Sericulture - The process of rearing silkworm for the production of silk.
17. Shearing, Scouring, Sorting, Colouring, Spinning.
18.(a) Sericulture and
(b) Moriculture are related to silk production.
G. Short answer questions.
1. The wool is sorted into groups according to their softness, length, weight, colour and ease of dyeing. The
longer fibres are woven into yarns to be used for knitting sweaters and the shorter fibres are spun and
woven into woollen cloth.
2. It is done in summers so that the fleece grows back by winters.
3. Selective breeding is the process of breeding plants and animals for particular genetic traits. Bred
animals are referred to as breeds while bred plants are known as varieties, cultivars or cultigens.
Crossbred plants are called hybrids while the cross of animals results in what is called a crossbreed.
4. Cashmere wool, usually simply known as cashmere, is a fibre obtained from Cashmere goats and other
types of goat. Common usage defines the fibre as a wool but in fact it is a hair, and this is what gives it its
Jiwan® Science CCE Question Bank Answer Key-7/17
E
unique characteristics as compared to sheep's wool. The word cashmere derives from an old spelling of
Kashmir. Cashmere is fine in texture, strong, light, and soft. Garments made from it provide excellent
insulation.
5. Alpaca and llama fibre is hollow, making it lightweight and quite warm. Alpaca fibre is generally finer and
softer than llama wool, although llamas are being bred now specifically for finer fibre and many llama
fleeces rival some alpaca for softness and quality.
6. In order to provide a safe place to the caterpillars for making cocoons branches of trees or shrubs are
placed in their rearing houses.
7. The process of drawing the silk filament from the cocoon.
8. Jute, hemp, cotton coir is obtained from plant.
NCERT Questions
9. a. The black sheep in the poem seems to have wool on almost all the parts as it in the poem it offers
wool, enough to fill three bags full.
b. Here the white fleece of the lamb refers to pure white woollen coat that it wears.
10. a. Picking out the burr b. Shearing c. Scouring d. Sorting e. Dyeing of various colours.
11. The hair traps a lot of air and keeps the animal warm.
12. a. Sericulture b. Silkworm c. Mulberry d. Reeling
13.
E
H
T
T
E
A
E
P
E
P
H
O
S
K
L
Y
H
S
P
P
L
H
14. 1. Cocoon
2. Pupa
3. Eggs
4. Caterpillar
15. d, a, c, b
H. Long answer questions.
1. Selective breeding helps to rule out weaknesses and disability in animals and helps make farming more
lucrative for farmers by providing robust animals for sale.
2. 1. Pashmina wool- Pashmina is a type of cashmere wool and the textiles that are made from it. The
name comes from Pashmineh, made from Persian word pashm or wool. This wool comes from a
special breed of goat indigenous to the Himalayan mountains. The special goat's fleece has been
used for thousands of years to make high-quality shawls that also bear the same name. Throughout
history, kings, queens and other nobility were the only ones who could afford to have shawls and
blankets made from this ultra luxurious fabric. Ancient texts make reference to the fine textiles made
from Pashmina and mentions of Pashmina have been found all the way back to the times of
Mahabharat.
The Himalayan Mountain goat, Capra hircus, sheds its winter coat every spring and the fleece is
caught on thorn bushes. The soft undercoat of the goat is what makes Pashmina so soft, warm and
light. One goat sheds approximately 3-8 ounces of the fiber. The soft underbelly fur of approximately
twenty goats is needed to make one Pashmina shawl. Entire villages support themselves by
scouring the mountainside for the finest fleece to be used. Now, with the popularity of Pashmina all
over the world, cottage industries have sprung up and there are many goat farms where the soft
underbelly wool of the goats can be more easily harvested.
Jiwan® Science CCE Question Bank Answer Key-7/18
2. Merino wool - The Merino is an economically benefic breed of sheep prized for its wool. The breed is
originally from Turkey and central Spain, and its wool was highly valued already in the Middle Ages.
Merino wool is finely crimped and soft. Merino need to be sheared at least once a year because their
wool does not stop growing. If the coat is allowed to grow, it can cause heat stress, mobility issues,
and blindness. Merino wool is common in high-end, performance athletic wear. Typically meant for
use in running, hiking, skiing, mountain climbing, cycling, and in other types of outdoor aerobic
exercise, these clothes command a premium over synthetic fabrics.
3. Angora wool- Angora is a smooth, luxurious fabric and yarn which is used commonly for knitting,
crocheting and clothing. It is made from the fur of Angora rabbits and is woven together sing other
soft materials such as cashmere. The wool is a mixture of Angora fibres', cashmere, and lambs wool.
Pure Angora wool is impossible to make as the fibres are too fine to hold together.
3. There are eight steps in the process of wool manufacturing,
1. The first step is obtaining the wool from the sheep for wool manufacturing,
2. When wool for wool manufacturing comes to the factory, it is quite dirty. Raw wool comes to the
factory fresh off the sheep, and the wool manufacturing team must sort and grade the raw wool
before it is cleaned. Since sheep are sheared once a year, a variety of sheep age and quality are
used for wool manufacturing. Grade depends on breed of sheep mostly as well as how well the
sheep was raised. The attributes of wool quality are crimp, length, strength, color, and the fineness of
the fibre. Fleece is picked through and sorted by people who are a great asset to the wool
manufacturing industry.
3. The next step to the wool manufacturing process is called scouring. This is basically the process of
cleaning wool. There are machines that are used for this process, and then the wool is soaked,
bathed twice, and rinsed. The scoured wool is then dried and baled for further wool manufacturing
processes.
4. The next step in wool manufacturing is the removal of lanolin. Lanolin is grease that is in the water
where the wool was scoured.
5. Next, the wool is often dyed. Some wool manufacturing requires dyeing at a later stage, but for most
higher-end wool fabrics, the dyeing process takes place immediately after baling.
6. Carding is the stage before wool becomes yarn.
7. The spinning stage of wool manufacturing forms yarn by twisting up the roving taut. This is a quick
process done on a spinning frame. After it's spun, the wool manufacturers steam it and store the
bobbins while they wait for it to be woven into fabric.
8. The final stage to wool manufacturing is finishing the fabric. Unfinished fabric looks shoddy right off
the loom, so it is fulled.
4. Silk moths are insects of the order Lepidoptera, which includes butterflies and moths. The life cycle of the
silk moth has several stages from egg to adult moth over a period of about six to eight weeks. The egg
hatches into a caterpillar that sheds its skin several times before enclosing itself in a cocoon made of silk
filament. Inside the cocoon, it transforms from caterpillar to moth, a process known as metamorphosis.
5. Extracting silk from the cocoon:
• The first step is to separate the silk fibre from the cocoon. For this, they need to be exposed to
warmth.
• Piles of cocoons are kept under the sun, boiled or exposed to steam. The warmth causes the silk
fibre to separate from the rest of the cocoon.
• The next step is called reeling the silk, which is the process of delicately unwinding the fibre from the
cocoon. These silk filaments are soft, and 300 to 900 metres long.
• Reeling is also done in special machines.
Jiwan® Science CCE Question Bank Answer Key-7/19
• The silk thread is then bleached and dyed into many shades.
• The silk fibre is now spun into silk thread, which is then woven into silk cloth by weavers.
6. A working condition that can lead to illness or death. Often, people in jobs which pose a high level of risk
are paid more than similar but less risky jobs to compensate for the danger involved. Example- Fire
fighters experience an occupational hazard of fighting fire on a daily basis because they are working in
conditions that could lead to injury or death.
I. Give reasons.
1. Sheep rearing is done in summers so that the hair can grow back by winter.
2. Inhalation of vapours emanating from the boiling of cocoon causes risk of asthma. Handling of dead
worms before reeling requires constant contact with boiling water leaving skin raw and blistered.
3. In hot weather, white or light coloured clothes suit better, because they reflect the heat and keep the body
cool, whereas black clothes retain heat. During summer, clothes made of cotton are more comfortable.
Cotton clothes allow the body heat to escape. People wear loose clothes to keep cool. Loose clothes
allow air to circulate below the fabric. Thus, loose clothes are more suited during summer than tight fitting
clothes. Hence, summer wear should be breathable, light-coloured and loose fitting rather than dark and
tight fitting.
In cold weather, warm and thick clothes should be worn. A wool base layer helps maintain body
temperature at a comfortable level in either cool or warm conditions. So, woollen garments are suitable
for cold weather. As wool is a very good insulator and a poor conductor of heat, it can absorb moisture
without becoming wet. Woollen clothes keep the body warm and protect from the cold winds. Also, the air
trapped between the woollen fibres prevents the flow of heat from the body to the cold surrounding. It
also prevents the cold air from coming in contact with the body. Woollen garments have excellent shape
retention because of the crimp in the fibres.
4. Wool is a bad conductor of heat and its fibres' can trap air in between themselves. Air is also bad
conductor of heat but wool is even more so our body doesn't radiate much heat. That is why we feel
warmth when we wear woollen clothes.
J. HOTS questions.
1. Silk is woven from the cocoons of silkworms, which requires killing the silkworm. Animal rights activists
are against the killing of any animal.
2. Shahtoosh Shawl is obtained from the endangered animal Chiru,so the Government has banned
Shahtoosh for the protection and conservation of the animal.
3. Silk is woven from the cocoons of silkworms, which requires killing the silkworm. Animal rights activists
are against the killing of any animal.
Jiwan® Science CCE Question Bank Answer Key-7/20
Chapter- 5 : Physical and Chemical Changes
Objective Type Questions
A. Fill in the blanks.
1. galvanization
5. plasma
9. oxidation
NCERT Questions
11. CaCo3
2.
6.
10.
endothermic
caramel
same
3.
7.
12.
sodium bicarbonate 13.
oxygen, hydrogen
atoms
paint, apply oil
4.
8.
14.
chemical
galvanizing
physical, physical
15. chemical
16. chemical
17. reversible
18.
physical change
19. rusted, chemical, substance
B. Write whether the following statements are true or false.
1. False
2. True
3. False
4. True
5. True
6. True
7. False
8. False
NCERT Questions
9. False
10. False
11. True
12. False
13. True
14. True
15. True
16. True
17. False
C.Match the two columns to make correct pairs.
1. a. v
b. iii
c. iv
d. ii
e. i
NCERT Questions
2. a. iv
b. vi
c. v
d. i
e. iii
f. ii
D.Multiple choice questions. Tick the correct option in each case.
1. c
2. d
3. d
4. a
5. c
6. b
7. c
8. d
NCERT Questions
9. b
10. c
11. d 12. b 13. d
14. c 15. d
16. d
17. a
18. a
19. a 20. b
E. Name them.
1. Corrosion
2. Chemical change
3. Endothermic reactions
4. Reactivity series
5. Enzymatic browning
Descriptive Questions
F. Very short answer questions.
1. The difference between physical change and chemical change is that while physical change basically
involves a change in state of matter and energy, chemical change occurs at the molecular level.
Chemical change brings about the creation of a new substance different from the original and is not
reversible while in physical change, the substance remains the same though there may be a change in
state of matter. Melting of ice is a physical change while resting of iron is a chemical change.
2. Physical change.
3. Presence of oxygen and moisture.
4. Coating a piece of iron with a layer of zinc to prevent rusting is called galvanizing.
5. Rust is a reddish brown layer formed on iron objects when exposed to moisture and air.
6. Rust = 2 Fe2o2. H2O.
7. Ice melting in water, a piece of chalk powdered.
8. A chemical reaction which absorbs heat is endothermic.
9. Burning of hair is a chemical change. During this process, a distinct smell can be experienced. Food
which has turned stale smells bad. It is because of a chemical change that has taken place.
Jiwan® Science CCE Question Bank Answer Key-7/21
10. a. Mix a teaspoon of vinegar with sodium bicarbonate baking soda. Bubbles will rise up to show carbon
dioxide being produced.
b. Addition of water to chuna or quicklime leaves makes the water very hot, almost boiling. Here the
heat is given out. So it is exothermic.
c. Leave an iron nail in a solution of copper sulphate and observe the next day. Iron will have a reddish
coating. Copper from copper sulphate is displaced by iron.
11. Soot is fine particles of unburnt carbon which deposit when a flame burns with fuel like coal, candle
kerosene etc.
12. Mg-.Magnesium, Fe-Iron, Al-Aluminium, Pb-Lead, Cu-copper, Na-Sodium, P-phosphorus.
13. Na, Mg, Fe, Ag.
NCERT Questions
14. a. Chemical change
b. Physical change
c. Chemical change
d. Physical change
e. Physical change
f. Chemical change
15. vinegar + baking soda = carbon dioxide + sodium acetate Copper sulphate + iron = ferrous sulphate +
copper
16. Melting of ice into water.
17. Physical change.
G. Short answer questions.
1. Water can exist in three states: Solid, liquid and gaseous. In all the three states its chemical composition
is the same and its chemical properties do not change, only the physical state changes. So,
interchanging states of water from ice to water vapour is only a physical change.
2. In a chemical change, (a) A new substance is formed, (b) The new substance has new properties, (c)
Mostly, the change is irreversible by ordinary methods, (d) The reaction involves gain or loss of heat.
3. Rust is conversion of iron into iron oxide which will lose the properties of iron. Gradually all the iron
converts to rust and the metal is completely destroyed.
4. Stainless steel is made by combining iron with a metal called chromium and it gains non-rusting
property. So, it will safeguard against rusting.
5. Enzymatic browning is the reaction of phenol compounds present in some fruits and vegetables, with air
in the presence of enzymes to produce a brown coloured pigment called melanin. It causes browning of
cut fruits and vegetables.
6. A burning candle produces flame due to burning of wax produces light and heat besides some CO2. So it
is a chemical change.
7 In an exothermic reaction, heat is produced as one of the end products. An example of this is when a
candle burns. An endothermic reaction is one in which heat is absorbed--heat is needed to finish the
reaction.
An exothermic reaction releases energy; in exothermic reactions, heat is a product. Example: When a
liquid turns into a solid, such as liquid water turning into ice, it must release energy in order for the water
to solidify. That is why ice is colder than regular water, is has less energy, seeing as the liquid released
energy to turn into ice.
B + C ® BC + 100 joules
An endothermic reaction absorbs energy; in endothermic reactions, heat is a reactant. Example: When
a liquid turns into a gas, it must absorb sufficient energy to overcome the intermolecular forces in order
for the particles to escape into the gas phase. Consider this reaction:
H2O (L) + 2260 joules ® H2O (g) the notations represented as (L) and (g) show the state of water as
liquid or gas.
[Note: joules is the measurement of heat energy.]
Jiwan® Science CCE Question Bank Answer Key-7/22
8. When fruits and vegetables rot, microbes grow on them and cause chemical decomposition. It is
accompanied by evolution of some gases which are responsible for the foul smell. The decomposition
results in change in texture too.
9. Alloys are uniform mixtures of different metals, which give new properties to the metal formed. For E.g.,
when iron is mixed with chromium, carbon and a small quantity of other metals, stainless steel is formed.
It is rust proof and corrosion free.
10. The setting of milk into curd is an example of chemical change as new substance are formed which have
different taste , form, properties and can not be converted back to milk. Also apart from solid pieces
cheese, resulting left behind liquid called milk plasma has chemical properties different from milk.
H. Long answer questions.
1. 1. When physical change occurs in a substance, you will not be able to create a new substance. The
substance will remain in its original state. In contrast, when chemical change occurs in the
substance, you will be able to produce a different kind of substance. This means you will lose the
original substance and a new one will form.
2. Physical change is superficial and can possibly be reversed; a chemical change is complete and
permanent. For example, water can freeze so liquid can turn to solid but the substance is still water.
You can unfreeze ice to revert to the liquid state of water. But if you burn paper, you will get a new
substance called ash. You can not 'un-burn' ash to transform it back to paper.
3. Another big difference between physical and chemical change is the speed of transformation.
Physical change occurs faster and sometimes instantaneously. Most chemical changes, on the
other hand, take longer time to become discernible. You can crumple a tin can and you will
immediately see physical changes. But corrosion of tin can occurs very slowly; it will take a long time
before you see the appearance of rust on the can.
4. There is a wide difference between physical and chemical changes. With physical change, you are
not transforming the original molecular composition of the substance. But with chemical change, the
molecular structure is being transformed thus you will get a new substance.
5. A chemical change may also cause a physical change; a physical change alone cannot lead to a
chemical change.
6. Physical reactions can or cannot be initiated but chemical reactions start only after they are initiated.
7. Energy changes are small in a physical reaction when compared to a chemical reaction.
8. Chemical changes take place on the molecular level but Physical changes are concerned with
energy and states of matter.
9. Chemical reactions are reactions that alter an object chemically. It may not change on the outside
but its changed on the inside. Physical changes are changes you can see, feel, somtimes smell
"most of the time when the smell changes it chemical though as well.
10. In digestion, the physical changes include breaking down of particles by chewing and the mixing by
peristalsis chemical changes include the enzyme reactions and the acid reactions in the stomach.
11. Physical: Does not change the composition and is between the states of matter. This means tearing,
cutting, melting, freezing.
Chemical: Changes composition. This includes burning, rusting, change in colour, change in odour,
formation of a precipitate (solid) .
12. Chemical reactions give out light and heat while the physical reactions do not.
13. In short.....physical reactions are simple and chemical reactions are complex.
2. Rust is caused by oxygen reacting with water. It's a form of corrosion. It can be prevented through
covering in plastic coating, paint, galvinising, or bringing into contact with magnesium. The last is done
by the magnesium reacting before the iron or steel does and was often used on ships. However, it
became inefficient due to the fact that it had to be replaced every once in a while.
Jiwan® Science CCE Question Bank Answer Key-7/23
3. The four general types of chemical reactions are synthesis, decomposition, single-displacement and
double-displacement.
Synthesis reactions involve two simple substances combining together to make more complex
substances. For example:
2Na + Cl2 ® 2NaCl
Decompositions involve complex compounds breaking down into simpler substances, by means of
heat, electricity or catalysts to speed up the reaction.
2KClO3 ® 2KCl + 3O2
(KClO3, or potassium chlorate, was heated)
Single-displacement reactions involve a more reactive element displacing a less active element in a
compound. That less reactive element becomes displaced at the end of the reaction.
Zn + 2HCl ® ZnCl2 + 2H2
(Zn, the more active element, replaces H in HCl to combine with Cl2. ZnCl2 is formed and H2 was
displaced)
Double-displacement reactions involve two elements displacing each other to form new compounds. It's
like the two elements "exchanged partners", unlike in the single-displacement reaction, where only one
"exchanged partners".
HCl + NaOH ® NaCl + H2O
H displaces Na in NaOH to form water. As a consequence, Na is displaced so it combines with Cl to form
NaCl.
4. Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive
element from its compound. Both metals and non-metals take part in displacement reaction. Reaction of
iron nails with copper sulphate solution.
5. A synthesis reaction is two or more elements or compounds reacting to form ONE product ex:
2H3(g) + O2(g) ® 2H2O(l)
A single displacement reaction occurs when one element replaces another element from a compound in
aqueous solution. For this to occur the element that is DISPLACED must be less active then the element
replacing it (refer to the activity series below)
Ex: 2K(s) + 2H2O(l) ® 2KOH(aq) + H2(g)
NCERT Questions
6. When baking soda is mixed with lemon juice, bubbles formed because of evolution of carbon dioxide
gas. This is a chemical change, because in this reaction new substances are formed.
7. In burning of candle some of the wax melts, which is physical change, while most of the wax burnt, which
is a chemical change.
In the burning of wood, water present in wood changes into vapour, this is physical change, while burning
of wood is a chemical change.
8. In burning of wood, new substances are formed and hence is a chemical change. While cutting the wood
into small pieces no new substance is formed, thus it is a physical change.
9. Process:
·
Water is taken in a beaker.
·
Few drops of sulphuric acid is added to the water.
·
Water is let to boil.
·
When water starts boiling, copper sulphate powder is added to the water with continuous stirring the
solution.
Jiwan® Science CCE Question Bank Answer Key-7/24
·
When copper sulphate starts deposited into bottom of the beaker, then solution is filtered and left for
cooling.
· After cooling, the crystals of copper sulphate is prepared.
10. Iron get rusted because of reaction with oxygen present in moist air. By painting iron gate, iron is
prevented to come into contact with oxygen present in moist air, which prevent it be getting rusted.
11. Iron get rusted because of reaction with oxygen present in moist air. In coastal areas, air contains more
moisture because of sea or ocean, while in deserts air is dry and hot. Thus because of getting more moist
air iron objects getting rusted faster in coastal areas than in deserts.
12. a. Examples of reversible change include the meltiing of ice, dissolving sugar in water, freezing juice into
an ice pop or popsicle, folding paper, melting wax, melting chocolate, boiling a kettle in which the steam
can be changed back into water, evaporating salt out of salt water, and writing on paper with a pencil.
b. The burning of the fuel in the vehicles and in the factories is an irreversible process, hydrocarbon
combustion like the burning of wood or oil, radioactive decay .
c. rusting of iron, combustion (burning) of wood.
13. Give an example of a chemical reaction for each of the following situations:
a. Take a piece of magnesium ribbon and rub it with sand paper to remove dirt from its surface.
b. CaCo3(s) + 2HCl(aq) ® CaCl2(aq) + H2O(l) + CO2(g) Here Co2 is evolved.
c. The ignition of hydrogen with a burning splint. The hydrogen ignites and burns with a distinct "pop".
the equation for this reaction is: 2H2O + O2 ® 2H2O.
14.a.
b.
c.
d.
Rust is formed when iron combines with oxygen to become iron oxide.
Yes, it can be turned back through reduction reaction.
Yes, Metal oxides can be used in redox reactions if matched with the right secondary metal.
When oxidation occurs in copper, on the other hand, the result is a greenish coating called copper
oxide and the spolling of fresh fruit.
15. a. The iron nail will be covered brownish colour.
b. Yes these changes are chemical changes.
c. Fe + CuSo4 = Cu + FeSo4
I. Give reasons.
NCERT Questions
1. Lime water is a saturated solution of calcium hydroxide. When CO2 is passed through it a precipitate of
calcium carbonate is formed.
Ca(OH)2(aq) + CO2(g) ® CaCO3(s) + H2O(l)
2. Baking soda is sodium hydrogen carbonate. Vinegar is ethanoic acid. The two react to form water and
sodium acetate, releasing carbon dioxide in the process.
J. HOTS questions.
1. Physical Changes in Burning Candle: On heating, candle wax melts is a physical change. Since it again
turns into solid wax on cooling. The change is reversible.
Chemical Changes in Burning Candle: The wax near to flame burns and gives new substances like
Carbon Dioxide, Carbon soot, water vapours, heat and light.
Cooking of food, hard-boiling of egg are examples where both physical and chemical changes occurs. In
both cases the physical appearance of the substances change and new substances are formed.
2. We should not put a stainless steel spoon in a pickle jar because it reacts with the ACIDS.
3. The gas that is released is most commonly Carbon Dioxide (CO2). The CO2 is already dissolved inside
the soda bottle. When you open the cap, the pressure inside is released and the CO2 escapes.
Jiwan® Science CCE Question Bank Answer Key-7/25
Chapter- 6 : Acids, Bases and Salts
Objective Type Questions
A. Fill in the blanks.
1. organic
2. Citric acid
3. Alkalies
4. Robert Boyle
5. blue, red
6. red, blue
7. Litmus paper
8. Ammonia
9. pH
10. Calcium hydroxide
11. Acetic acid
12. base
13. Sulphuric
14. Turmeric, China rose
15. red
16. basicity
17. slaked lime
NCERT Questions
18. sour, acetic acid
19. natural
20. pink
21. react, salt
B. Write whether the following statements are true or false.
1. False
2. True
3. False
4. False
5. True
NCERT Questions
6. False
7. False
8. True
9. True
10. True
11. False
12. False
13. True
14. False
15. False
16. False
C. Match the two columns to make correct pairs.
1. a. iv
b. vi
c. vii
d. viii
e. iii
f. v
g. i
h. ii
NCERT Questions
2. a iii
b. v
c. iv
d. i
e. ii
D. Multiple choice questions. Tick the correct option in each case.
1. a
2. b
3. d
4. b
5. d
6. b
7. d
8. c
NCERT Questions
9. c
10. b 11. c 12. b 13. c
14. b 15. c
16. d
17. a
18. d 19. c 20. c
E. Name them.
1. Alkalis
2. Neutralization
3. Turmeric
4. Phenolphthalein
5. Sulphuric acid
6. Calcium Hydroxide
Descriptive Questions
F. Very short answer questions.
1. citric acid
2. Sodium hydroxide, ammonia
3. A material used to find whether a given substance is acidic or basic.
4. A reaction in which a substance is made neither acidic nor basic.
5. They react with metals to produce salts which can be toxic or harmful.
6. Hydrochloric acid
7. Sulphuric acid
8. It shows no reaction.
9. Nitric acid
10. Bases that dissolve in water are alkalies.
NCERT Questions
11. As Ammonia turns red litmus blue. It is basic in nature.
12. If we were to evaporate the water from the solution after this neutralization reaction, we would be left
with solid sodium chloride, commonly known as table salt.
13. Oranges can calm stomach as they contain a variety of natural acids, particularly citric and ascorbic
acids. Eating an orange or drinking freshly squeezed orange juice can improve digestion capacity.
Jiwan® Science CCE Question Bank Answer Key-7/26
G. Short answer questions.
1. Acids are sour, corrosive, mostly water soluble and turn blue litmus red.
2. Acids react with bases to produce salt and water.
3. Organic acids are mild, naturally occurring in plant and animal products. E.g, lactic and citric acid.
mineral acids are chemically synthesized. They are strong, corrosive and are laboratory product. e.g.
hydrochloric acid and sulphuric acid.
4. Concentrated acid is slowly added to water while constantly stirring the water, otherwise, it might splash
due to a large amount of heat produced.
5. In acidic medium, a blue litmus strip changes to red and in a basic medium a red litmus changes to blue.
6. Neutral substances are neither acidic nor basic. They show no reaction with litmus paper. e.g, water.
7. Hydrochloric acid is produced in the human stomach to aid in digestion. When excess of it is secreted it
causes discomfort and burning sensation which is termed as heart burn.
8. Ant sting releases formic acid which is neutralized with a baselike baking soda. It will reduce the pain
and swelling.
9. Industrial wastes are either acidic or basic and they change the nature of river water on mixing with it and
pose a threat to aquatic life.
10. Phenolphthalein and methyl orange are synthetic indicators. They show change in colour on mixing with
acidic or basic substances. EG., Phenolphthalein is colourless and changes to pink when added to
base.
NCERT Questions
11. Acids
1. Acids are sour in taste.
2. The chemical nature of such substances is acidic.
3. Acid turns blue litmus red.
4. Acids are generally found in vinegar, curd, spinach, amla, citrus fruits, tamarind, grapes, unripe
mangoes, Citrus fruits such as oranges, lemons, etc.
Bases
1. Bases are bitter in taste and soapy to touch.
2. The nature of such substances is said to be basic.
3. Bases turn red litmus blue.
4. Bases are generally found in lime water, soap, window cleaner, Milk of Magnesia.
12. Litmus is extracted from lichens . It is most commonly used as an indicator to determine the chemical
nature of substance. It has a mauve (purple) colour in distilled water. When added to an acidic solution, it
turns red and when added to a basic solution, it turns blue. It is available in the form of a solution, or in the
form of strips of paper, known as litmus paper. Generally, it is available as red and blue litmus paper. To
test a substance for an acid or a base or a neutral, litmus test is performed in which the acid turns blue
litmus red, bases turn red litmus blue and has no effect on neutral substance.
13. The distilled water is neutral. First, it is neither sour (Acidic) nor bitter (Basic), secondly to very its
chemical nature, we can perform litmus test. It neither turns blue litmus red nor red litmus blue hence we
can say, distilled water is neutral substance.
14. An acidic drink will have sour taste and will turn blue litmus red. A basic drink will turn red litmus blue. A
neutral drink will not change the colour of red or blue litmus. He can also use turmeric solution for
checking the drinks.
15. Turmeric which is yellow in colour, when exposed to neutral (Sugar Solution) or acidic substances
(Hydrochloric Acid) it will retain its yellow colouration. However, if turmeric is exposed to more alkaline
substances (sodium hydroxide) it becomes a dark pink/red. So, first we detect sodium hydroxide -a
basic substance by a colour change from yellow to dark or red. Then will test for an acid or neutral
substance with indication of no colour change. Now out of these two, we will mix one with already tested
solution for basic substance -sodium hydroxide with dark or red colour, if on mixing the colour reverses
back to yellow, the liquid is an acid and the remaining third liquid is neutral.
16. Blue litmus paper when dipped in a solution, if It remains blue. The nature of the solution is neutral.
Jiwan® Science CCE Question Bank Answer Key-7/27
17. A. Remains red , B. Blue, C. Remains red , D. Remains red
18. If a wasp stungs you, apply vinegar to the sting to neutralize the toxins.
The effect of ant bite can be neutralized by applying baking soda.
19. The effect of antbite can be neutralized by rubbing moist baking soda on it.
H. Long answer questions.
1. Acid changes China rose extract to dark pink and base changes it to green. The extract of China rose is
made by using hibiscus flower by boiling a few petals in distilled water for five minutes and distilling it. It is
light mauve in colour when extracted.
2. Acids1. Sour in taste.
2. Turns blue litmus red.
3. Turmeric shows no change.
4. Acids are non-metallic compounds.
5. Example- H2SO4,HNO3,HCl.
Bases1. Bitter in taste.
2. Turn red litmus blue.
3. Turmeric turns red.
4. Bases are metallic compounds.
5. Examples- Na2CO3,NaOH.
3. Antacids are basic in nature and they are helpful in neutralizing stomach acids. Eg., milk of magnesia.
stomach acids cause heartburn, when produced in excess and are treated with antacids.
4. 1. The sting of an ant contains formic acid. When an ant bites, it injects the acidic liquid into the skin.
The effect of the sting can be neutralised by rubbing some moist solution of a basic substance such
as baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.
2. The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the
acids will kill fish and other organisms. The factory wastes are, therefore, neutralised by adding basic
substances.
3. An antacid tablet is taken when we suffer from acidity, as it neutralise it effect.
4. In the morning first, we brush our teeth. Toothpastes are basic in nature and they help to neutralize
the acids produced in the mouth by bacterial action. That is why brushing teeth twice with a good
toothpaste is necessary.
5. Acids- Acids are used in the manufacture of fertilizers. Some acids like sulfuric acid are used as
electrolytes in a wet cell battery. Dilute sulfuric acid or hydrochloric acid is used in construction to
treat steel before it is painted.
Bases
1. Sodium hydroxide (caustic soda) is used in the manufacture of soap. It is used in petroleum-refining,
in making medicines, paper, pulp, etc. It is used in making rayon.
2. Calcium hydroxide is also known as slaked lime. It is used to neutralize acid in water supplies; in the
manufacture of bleaching powder; as a dressing material for acid burns; as an antidote for food
poisoning; in the preparation of fungicides and in the mixture of whitewash. It is mixed with sand and
water to make mortar which is used in the construction of buildings. It is also used by farmers on the
fields to neutralize the harmful effects of acid rain.
3. Ammonium hydroxide is used to remove ink spots from clothes and to remove grease from windowpanes. It is used in the cosmetic industry.
4. Alkalis are used in alkaline batteries. Generally, potassium hydroxide is used in such batteries.
Salts - Salts occur naturally in many parts of the world and it evaporates from water bodies and
mineral halite. Common salts include sodium chloride, calcium chloride and potassium dichromate.
Sodium chloride also known as table salt is used for the seasoning of food while calcium chloride is
used to remove dampness from rooms and as a de-icer. Potassium dichromate is used to make
bleach for photographic uses.
Jiwan® Science CCE Question Bank Answer Key-7/28
NCERT Questions
6. Neutralisation is a process in which an acid solution when mixed with base solution, react with each
other to produce a salt and water along with generation of heat. Salt so produced, may be acidic, basic or
neutral in nature. In this process the acidic nature of the acid and the basic nature of the base are
destroyed.
7. China rose extract is mauve in colour. Acid changes to dark pink and base changes to green.
8. Soil should be neutral for healthy growth of plants. Excess use of fertilizers can turn the soil acidic. It is
corrected by adding either quicklime (CaO) or slaked lime (CaOH2)If the soil is basic vegetable matter
and fertilizers are added to neutralize it.
9. Label the test tubes as A, B and C.
Dip the turmeric indicator in test tube A. If the turmeric paper changes to red then the liquid in the test
tube is sodium hydroxide; which is a base. Otherwise, it is either hydrochloric acid or sugar solution;
which is neutral.
If the liquid in the test tube A is not sodium hydroxide then keep it aside and repeat the above procedure
with the test tube B. If it is not sodium hydroxide then the liquid in test tube C must be sodium hydroxide.
Take aside the test tube with sodium hydroxide and pour sodium hydroxide in remaining two test tubes.
The test tube which becomes warm contains acid. When acid and base neutralize each other, heat is
released in the process.
10. a. Tartaric acid turns blue litmus red, and no change with phenolphthalein.
b. Soap solution turns red litmus blue and give pink colour with phenolphthalein.
c. Pure water is neutral and colourless with phenolphthalein.
11. Fishes are dying in pond because of problems like the water chemistry, oxygen levels in the water and
supply of food for the fish. The wastes of factory contain acids. If they are allowed to flow into the water
bodies, the acids will kill fish and other organisms. The factory wastes are, therefore, neutralised by
adding basic substances.
I. Give reasons.
1. In many cases, it is unsafe to store acid in metal containers because some acids can damage the
containers, in ways such as dissolving or corroding them.
2. The simple answer is that a base is any substance which reacts with acids according to the general
equation
Acid + Base ® Salt + Water. This definition includes alkalis. But also means that all metal oxides are
bases even those which do not dissolve in water to form alkalis. Alkalis are bases which dissolve in water
to form solutions with a pH above 7. This is not restricted to metal oxides but also includes compounds
like ammonia. Copper oxide is a base ( it reacts with dilute acids to give a copper salt + water) but it is
insoluble in water and can never be an alkali.
NCERT Questions
3. An antacid tablet is taken when we suffer from acidity, as it neutralise it effect.
4. The sting of an ant contains formic acid. When an ant bites, it injects the acidic liquid into the skin. The
effect of the sting can be neutralised by rubbing some moist solution of a basic substance such as baking
soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.
5. The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids
will kill fish and other organisms. The factory wastes are, therefore, neutralised by adding basic
substances.
J. HOTS questions.
1. A wasp sting is alkali so you need to put something acid like vinegar on it. Wasps rarely leave the sting
behind. A bee sting is acid, so needs an alkali like bicarbonate of soda. A bee can leave its sting behind.
This must not be pulled out on case it's pushed in deeper. The best way to get it out is to scrape with a
fingernail.
2. Tamarind has an acid called tartaric acid. The silver tarnishes by forming silver sulphide. The acid in
tamarind helps to dissolve the salt and expose the metal.
Jiwan® Science CCE Question Bank Answer Key-7/29
Chapter- 7 : Heat
Objective Type Questions
A. Fill in the blanks.
1. energy
2. Conductors, insulators 3. hotter, cooler
4. conductors
5. 0 degree
6. 212 degree F
7. Laboratory
8. Laboratory
9. Mercury
10. Conduction
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11. temperature
12. clinical
13. Celsius
14. radiation
15. conduction
16. black
B. Write whether the following statements are true or false.
1. True
2. False
3. True
4. True
5. False
C. Match the two columns to make correct pairs.
1. a. iii
b. iii
c. i
d. iii
e. ii
f. i
g. iii
h. i
NCERT Questions
2. a. iv
b. iii
c. i
d. ii
D. Multiple choice questions. Tick the correct option in each case.
1. a
2. c
3. d
4. c
5. d
6. c
7. a
8. b
9. a
10. b
NCERT Questions
11. d
12. b 13. d 14. c
E. Name them.
1. Heat energy
2. Conduction
3. Insulators
4. Mercury
5. Green House
6. Radiation
Descriptive Questions
F. Very short answer questions.
1. Moist winds that blow in from the sea are called a sea breeze and dry winds that blow towards the sea are
called a land breeze. The main differences between a land breeze and a sea breeze are that one is a dry
flow of air that moves from the inland towards the water and the other is a moist air flow, sometimes
mixed with rain, that comes from the sea and blows inland. A sea breeze is typically stronger than a land
breeze and, although always flowing in the same manner each day, their roles reverse on a constant.
2. Radiation is energy that comes from a source and travels through some material or through space. Light,
heat and sound are types of radiation.
3. Because they don't attract as much sun light. The sun actually reflects off bright colours. Darker colours
absorb sunlight and heat. That's why darker/heavier colours are worn in the winter or cooler seasons.
4. The metal tyre is heated by turning it in a fire using tongs until it has expanded enough to fit over the
wooden wheel. They fit around the wooden wheel when they become cool.
NCERT Questions
5. Conductors-copper and iron, Insulators-wood and plastic.
6. It provides insulation to the ice kept in it.
7. The thermometer B heats up faster as it gets heat from the candle.
8. A blanket traps the air and works as an insulator.
9. Due to expansion on heating there is rise in the level of mercury.
G. Short answer questions.
1. Conduction is the process of transferring something such as heat from one point to another through a
solid medium. This transfer does not involve movement of the material carrying out the process.
2. Conductor: Those objects which allow electricity to pass through them are known as conductors. The
conductors can pass electricity through them due to free electrons present in them. for example: iron,
copper, aluminium etc.
Jiwan® Science CCE Question Bank Answer Key-7/30
Insulator: Those objects which do not allow electricity to pass through them are called insulators. The
insulators can't pass electricity due to less or absence of free electrons. for example paper, wood,
rubber etc.
3. A temperature is a numerical measure of hot and cold in a body that is in its own state of internal thermal
equilibrium. Its measurement is by detection of heat radiation or particle velocity or kinetic energy, or by
the bulk behavior of a thermometric material. It may be calibrated in any of various temperature scales Celsius, Fahrenheit, Kelvin, etc. The fundamental physical definition of temperature is provided by
thermodynamics.
4. Both scales are based on the freezing conditions of water, a very common and available liquid. Since
water freezes and boils at temperatures that are rather easy to generate (even before modern
refrigeration), it is the most likely substance on which to base a temperature scale. On the Fahrenheit
scale, the freezing point of water is 32 degrees and the boiling point is 212 degrees. Zero Fahrenheit was
the coldest temperature that the Germany-born scientist Gabriel Daniel Fahrenheit could create with a
mixture of ice and ordinary salt. He invented the mercury thermometer and introduced it and his scale in
1714 in Holland, where he lived most of his life.
Anders Celsius, a Swedish astronomer, introduced his scale is 1742. For it, he used the freezing point of
water as zero and the boiling point as 100. For a long time, the Celsius scale was called "centigrade." The
Greek prefix "centi" means one-hundredth and each degree Celsius is one-hundredth of the way
between the temperatures of freezing and boiling for water. The Celsius temperature scale is part of the
"metric system" of measurement (SI) and is used throughout the world, though not yet embraced by the
American public.
5. Convection refers to the movement of molecules within fluids. It is not possible in solids because the
molecules in solids are tightly packed. Convection in the atmosphere occurs when energy is transferred
by the movement of air.
6. The reason why we need to shake the clinical thermometer before use is in order to ensure that there is
accurate reading. Shaking the thermometer causes it to go back to the reservoir point ready for taking
the next maximum reading. The maximum temperature obtained is sometimes affected by the
environment.
7. Heat energy is the energy transferred among particles in a system or body by means of kinetic energy
and it is measured in joules or calories. A substance's heat energy is determined by how active its
molecules and atoms are.
8. Conduction- the transfer of heat from matter to matter.
Convection- the transfer of heat from matter to air.
Radiation- the transfer of heat from one point to another, such as boiling water.
9. Gas have almost no interior atom bonds, and contain the most energy.
NCERT Questions
10. Similarities: They are used to measure the temperature. Both type of thermometers uses calibrated
glass tubes with a fine passage inside, along the length of tube for mercury expansion . They have glass
tube with a closed end on one side. Both type have a bulb for containing Mercury at other end. Both
types measure temperature in degree Celsius.
Differences : A clinical thermometer is used for measuring the temperature of human body where as a
laboratory thermometer is used for measuring the temperature of other substances other than human
being. A clinical thermometer reads temperature from 35°C to 42°C as he normal temperature of human
body is 37°C. The range of a laboratory thermometer is generally from –10°C to 110°C. A clinical
thermometer has a kink to prevent mercury from being fallen back on of its own where as a laboratory
thermometer does not have one. A laboratory thermometer should be kept upright not tilted for taking
temperature reading.
11. a. O to P,O to R, b. P,R and then Q.
12. In case B. It is because the conduction of heat starts from point P and then it reaches Q. In the rod which
is solid, the particles are vibrating around a fixed position. As the molecules at one end get heated, they
Jiwan® Science CCE Question Bank Answer Key-7/31
get more energy and can vibrate more rapidly. They collide with their neighbours and pass on this extra
energy to them. These in turn vibrate faster and pass on energy to their neighbours. Thus without moving
from their positions the heat energy is transferred from molecule to molecule through the whole length of
the rod. In other words, even though the rod is heated only at one end, heat travels through the whole rod.
This method by which heat is transferred from one of a solid to another is called conduction.
13. Cover the lid of the warm milk added with a small amount of curd and put it in like warm water.
H. Long answer questions.
1. Mercury is used in thermometers as opposed to water because of a few simple reasons.
a. While mercury is a liquid, it doesn't have the same properties as water, therefore it won't condensate
at the top of the thermometer, making the reading of temperature more accurate.
b. It relies on thermal expansion meaning the molecular bonds will expand with heat and contract with
cold. This is why the mercury fluctuates according to temperature.
c. It's melting point is −38.83 °C (water is only 0 °C) and doesn't boil until 356.73 °C (water boils at 100
°C) which made mercury a better candidate to read temperature since it's liquid stage goes a lot
farther than water.
d. Mercury's silver appearance, makes it easy to read temperatures at just a glance. Mercury is still
used in some thermometers but because of its toxicity levels, it is gradually being replaced by alcohol
or electronic thermometers.
2. Using a Clinical Thermometer
1. Wash the thermometer preferably with an antiseptic solution.
2. Hold it firmly and give it a few jerks. Make sure that the level of mercury, which is the shining thread
falls below 350C.
3. Place the bulb of the thermometer under your tongue.
The precautions to be observed while reading a laboratory thermometer:
1. The thermometer should be kept upright not tilted.
2. The bulb of the thermometer should be surrounded from all sides by the substance of which the
temperature is to be measured.
3. The bulb should not touch the surface of the container.
3. Heat conduction is the transfer of heat from one molecule to another or between neighbourly molecules.
It can occur in solids, air, liquids and between masses.
4. Take a glass of boiling water and drop a cold metal spoon in it. After five minutes check the spoon and you
will find it is warm/hot. It is because the heat got transferred from the hot water to the spoon.
5. Along the seashore, as the air above the land is heated up during the day, it rises and cool air from over
the sea flows in to take its place. This is sea breeze. At night the land cools down much faster in
comparison to the sea. The cooler air over land flows out to take the place of hot air that rises above the
sea, setting up the land breeze.
o
o
6. (i) Laboratory Thermometer: It ranges from -10 C to 110 C.
(ii) Clinical Thermometer: It is used to measure body temperature. It ranges from 35oC to 42oC and 94oF
to 108oF. Mercury thermometer can measure temperature from -35oC to 357oC.
o
o
(iii) Alcohol Thermometer used to measure temperature. from -125 C to 50 C.
7. Expansion on heating can be disadvantageous since metal frames of doors and windows expand in
summer and get jammed. Railway tracks will bend on expansion if care is not taken. Thick glasses can
break on touching hot surfaces due to uneven expansion. Electric cables may sag in summer due to
expansion.
NCERT Questions
8. Wearing more layers of clothing during winter keeps us warmer because in between the layers there is
trapped air. As air is bad conductor of heat so the outside low temperature does not get transferred to
body as well as prevent our body heat to get transferred to colder surrounding outside. Hence more
layers of cloths keep us warmer during cold winter.
Jiwan® Science CCE Question Bank Answer Key-7/32
9. Water inside the pan is getting heat through convection.
Heat is being transferred through steel body of pan by conduction.
Steel pan is getting heat from burner through radiation.
10. Houses should be like in olden times which had very high roofs with ventilators provided high up on the
walls. The warm air being light rose and escaped from the ventilators. The cool air from outside being
heavy settled at the base of the room.
11. Light coloured tents would be preferred in hot summer afternoon as light colour reflects the heat. But the
same tent may not be good in winters as we need a dark coloured tent, which can keep us warm. Dark
colour trap the sun's heat and keep us warm.
12. Position P is warmer as the warm air rises up.
13. Pin in figure A will fall first as the distance between the pin and the flame is shorter than the figure B.
14. All matter is made of molecules. When an object is heated, it causes the molecules to vibrate. The
molecules closer to the heat source vibrate faster and slowly transfer the vibrations to the molecules
away from the flame. In this way all molecules begin to vibrate and conduction of heat take place across
the solids.
15.1. Cooking utensils are made from good conductors of heat. Such utensils get heated up quickly. Food
can be cooked efficiently in shorter time. The utensils are generally made of copper, brass, steel,
aluminium etc.
2. The handles of kettles and utensils are made of bad conductors of heat such as wood, plastic,
ebonite, etc. They help in holding them comfortably.
3. Woollen clothes are bad conductors. Woollen clothes are not actually warm. They do not allow heat
to conduct away or to escape out and thus keep our body warm.
4. Building materials like brick, asbestos, mud, grass, etc., are bad conductors of heat. They do not
permit heat and cold to pass through the walls of bricks. They keep the houses warm in winter and
cool in summer. Roof sheds are made of asbestos for the same reason.
5. Hair and the fur of animals are bad conductors of heat. They protect them from cold.
6. Vehicles carrying inflammable materials such as petrol are covered with materials of bad conductors
of heat. Otherwise, the petrol can get heated up and catch fire.
16. Convection is the (circular) movement of heat through a fluid such as air or water. The movement occurs
because the heat energy causes the fluid molecules to "spread out" with an excited state of energy. This
"spreading out" causes the heated fluid to become less dense than the surrounding fluid, so it rises. As
the energy dissipates, it gains density again and starts to settle back down. So, in your example, the
flame at the bottom of the oven heats the surrounding air which circulates (convects) inside the oven and
transfers energy to the potato.
17. A sea-breeze (or onshore breeze) is a wind from the sea that develops over land near coasts. It is
formed by increasing temperature differences between the land and water which create a pressure
minimum over the land due to its relative warmth and forces higher pressure, cooler air from the sea to
move inland. Generally, air temperature gets cooler relative to nearby locations as one moves closer to a
large body of water.
SEA
BREEZE
FRONT
COOL
WARM
At night, the land cools off quicker than the ocean due to differences in their specific heat values, which
forces the dying of the daytime sea breeze. If the land cools below that of the adjacent sea surface
Jiwan® Science CCE Question Bank Answer Key-7/33
temperature , the pressure over the water will be lower than that of the land, setting up a land breeze as
long as the environmental surface wind pattern is not strong enough to oppose it. If there is sufficient
moisture and instability available, the land breeze can cause showers or even thunderstorms, over the
water. Overnight thunderstorm development offshore due to the land breeze can be a good predictor for
the activity on land the following day, as long as there are no expected changes to the weather pattern
over the following 12–24 hours. This is mainly because the strength of the land breeze is weaker than the
sea breeze. The land breeze will die once the land warms up again the next morning.
18. The beaker which is heated from the bottom heats up faster than the beaker with heat from the mouth.
I. Give reasons.
1. Convection is the name for a means of heat transfer, as distinguished from conduction and radiation. It is
also a term that describes processes affecting the atmosphere, waters, and solid earth. In the
atmosphere, hot air rises on convection currents, circulating and creating clouds and winds. Likewise,
convection in the hydrosphere circulates water, keeping the temperature gradients of the oceans stable.
The term convection generally refers to the movement of fluids, meaning liquids and gases, but in the
earth sciences, convection also can be used to describe processes that occur in the solid earth.
2. When you have a cloudy night, the clouds prevent heat from escaping through the atmosphere and into
space. This process is called radiation. Cooling can only happen on a clear night or a night with a very
small amount of clouds present. The clouds act like a blanket and trap the heat it, and that is why every
time you have a cloudy night, it is always warmer than a clear night.
3. It's because of the gases we get by burning such as carbon mono-oxide are lighter than air ,so they rise up.
Thus to exhaust those gases chimneys are on top of the roof. Hot air is lighter so it rises up and flows out.
4. Black is a lack of colour - absorbs all colours in the spectrum of light, then that energy stores up as and
alongside heat, effectively radiating it. White, on the other hand, is every colour in the light spectrum reflects all light, and the heat along with it, effectively not radiating heat.
NCERT Questions
5. In places of hot climate it is advised that the outer walls of houses be painted white because a light colour
absorbs very less heat radiation so a less amount of heat is absorbed by the wall and transferred inside
the house. And we feel comfortable inside such houses due to lower temperature.
6. The jerks will bring the level of mercury down. Ensure that it falls below 35°.
7. The bulb of the thermometer has mercury in it which when expands gives us the reading of the
temperature in our body so it is advisable not to hold it with the bulb.
8. Heat is transmitted through three processes which are; conduction, convection, and radiation. The heat
that reaches earth from the Sun does so through infrared radiation, and travels at the speed of light. As
such, it takes about eight minutes for it to reach Earth from the Sun.
9. Houses in olden times had very high roofs with ventilators provided high up on the walls. The warm air
being light, rose and escaped from the ventilators. The cool air from outside being heavy settled at the
base of the room.
10. Wool is cheaper and usually thicker, woven with yarn. The wool is laden with dead air pockets that heat
up from body heat loses and feels warmer while serving as a good insulator to prevent rapid loss of the
body heat.
11. The main reason is to make it stay at the maximum point so you get an accurate reading. Without the
constriction the mercury which would drop as soon as it is taken out and couldn't show the temperature
where it was just taken.
12. Heavy bottoms make the pan durable, the pan appears colourful, dark base is a better conductor of heat,
and it is easier to clean the pan.
13. Small gaps are usually left between railway tracks so as to create an allowance for expansion of the rails
whenever temperatures rise. Without these gaps, the rails may buckle in hot weather. Such gaps are
known as expansion joints.
14. Materials expand when heated and contract when cooled. When the hot liquid hits the cold glass the
inside of the glass gets hot faster than the outside of the glass. So, the inside expands and the outside
Jiwan® Science CCE Question Bank Answer Key-7/34
does not expand. Since glass is rigid it does not flex but cracks or breaks. This can also break a car
windshield if you try and defrost it with hot water. The larger the temperature difference the more likely
the glass is to break. If the glass was hot when the hot liquid was poured in it would not break.
15. A clinical thermometer measures the max temp of the human body due to the expansion of the mercury
in the bulb, which flows past a kink in the column and rises in the graduated stem, to read the highest
body-temp. Once it is removed from the body, the mercury stays at that level, and does not fall because
it cannot flow back into the bulb -- the kink prevents the back flow. It has to be shaken vigorously, as you
know, for us to get the mercury back; then it is ready to take the temp again. Also, the temp cannot rise
further on its own from the max reading because the mercury does not expand the moment the
thermometer is taken out of the body.
J. HOTS questions.
1. There are two reasons.
a. Silver is expensive than copper, aluminium and iron.
b. Pure silver is a soft metal. So pots and pans will soon lose shape. There will be greater wear and
tear. It will reduce life of the pans and pots so frequent replacement and repairs will be needed.
2. Heat rises up, so placing the air conditioner high allows the unit to cool the hottest air that is at the top of
the room.
3. A black or low reflectivity surface on a food container or the inside of a solar cooker improves the
effectiveness of turning light into heat. Light absorption converts the sun's visible light into heat,
substantially improving the effectiveness of the cooker.
4. Hot air rises up. So air from room heater kept on floor rises up and heats complete room. But cold air
settles down and hence air conditioner is installed near ceiling.
5. Birds have many physical and behavioural adaptations to keep warm, no matter what the low
temperature of their surroundings.
Physical Adaptations
Feathers: Birds' feathers provide remarkable insulation against the cold, and many bird species grow extra
feathers as part of a late fall molt to give them thicker protection in the winter. The oil that coats birds'
feathers also provides insulation as well as waterproofing.
Legs and Feet: Birds' legs and feet are covered with specialized scales that minimize heat loss. Birds can
also control the temperature of their legs and feet separately from their bodies by constricting blood flow to
their extremities, thereby reducing heat loss even further.
Fat Reserves: Even small birds can build up fat reserves to serve as insulation and extra energy for
generating body heat. Many birds will gorge during the fall when food sources are abundant, giving them an
extra fatty layer before winter arrives.
Fluffing: Birds will fluff out their feathers to create air pockets for additional insulation in cold temperatures.
Tucking: It is not unusual to see a bird standing on one leg or crouched to cover both legs with its feathers to
shield them from the cold. Birds can also tuck their bills into their shoulder feathers for protection.
Sunning: On sunny winter days, many birds will take advantage of solar heat by turning their backs to the
sun (therefore exposing the largest surface of their bodies to the heat) and raising their feathers slightly.
This allows the sun to heat the skin and feathers more efficiently. Wings may also be drooped or spread
while sunning, and the tail may be spread as well.
Shivering: Birds will shiver to raise their metabolic rate and generate more body heat as a short term
solution to extreme cold. While shivering does require more calories, it is an effective way to stay warm.
Roosting: Many small birds, including bluebirds, chickadees and titmice, will gather in large flocks at night
and crowd together in a small, tight space to share body heat.
6. Energy can be transferred from one object to another. The heat transferred from one object must be
equal, but opposite in sign, to the heat taken in from the other object.
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Chapter- 8 : Climate and Adaptation
Objective Type Questions
A. Fill in the blanks.
1. inclination of earth on its axis
2. equator
3. Tropic of Cancer
4. -37 degree C
5. extreme heat, scarcity of water 6. insulation
7. hibernation, aestivation 8. Camouflage
9. adaptation
10. Constant fusion of hydrogen atom, helium
11. direct
NCERT Questions
12. Climate
13. hot, dry
14. the polar region, tropical region
B. Write whether the following statements are true or false.
1. True
2. True
3. True
4. False
5. False
NCERT Questions
6. False
7. False
8. True
9. False
C. Match the two columns to make correct pairs.
1. a. ii
b. iii
c. iii
d. ii
e. iii
f. i
g. iii
h. i
NCERT Questions
2. a. iv
b. ii
c. i
d. iii
D. Multiple choice questions. Tick the correct option in each case.
1. a
2. d
3. c
4. b
5. c
6. c
7. a
8. d
9. d
NCERT Questions
10. d
11. a 12. a 13. a 14. b
15. c 16. b
17. d
18. b
19. c
20. a
21. c
E. Name them.
1. Blubber
2. Meteorologist
3. Camouflage
4. Rain gauge
5. Climate
Descriptive Questions.
F. Very short answer questions.
1. a. Meteorology can be defined as the branch of science that is concerned with the processes as well as
phenomena of the atmosphere. It is mostly used to determine the weather prediction.
b. Weather is the condition of air in a place at specific times. Types of weather could be defined as: wet
or dry, clear or cloudy, dry or wet and stormy or calm.
c. An instrument for measuring the humidity of the air or a gas.
2. Day to day condition of a wind which determine the temperature of a place.
3. Weather forecast is done with the help of satellites which click and send images of atmosphere from the
space which are analysed by millions of computers and observers.
4. Weather of a place refers to the conditions like rainfall, humidity etc, at a given place at a certain time.
5. A rain gauge is an instrument used by meteorologists and hydrologists to measure precipitation (e.g.
rain) in a certain amount of time. It usually measures in millimetre. Rain gauge is an meteorological
instrument for determining the depth of precipitation (usually in mm) that occurs over a unit area (usually
one metre squared) and thus measuring rainfall amount.
6. The areas around the poles of the earth are known as polar regions.
7. Blubber is the thick fat under the skin that helps to insulate seals from severe cold.
8. Desert animals are mostly nocturnal to escape from the intense heat of the day.
9. The long winter sleep which some animals resort to during severe winter is called hibernation.
10. Desert reptiles excrete wastes in the form of uric acid, an insoluble white compound to conserve water.
11. The elephant fans itself with its long ears to cool itself in hot and humid climate.
12. Toucans have beaks which help them to crack open the hard shells of fruits and nuts and pluck fruits from
weak branches from far off distance.
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NCERT Questions
13. Temperature, humidity, time of sunset and sunrise, rainfall and wind conditions are elements of weather.
14. The maximum temperature of the day occurs generally in the afternoon while the minimum temperature
occurs in the early morning.
15. (a) Jammu and Kashmir : moderately hot and wet climate for a part of the year
(b) Kerala
: very hot and wet
(c) Rajasthan
: hot and dry
(d) North-east India
: wet
16. The weather at a place changes frequently as it is the day to day condition of the atmosphere at a place
with respect to the temperature, humidity, rainfall, wind speed, any of these elements, can vary over very
short periods of time.
17.We find animals of certain kind living in particular climatic conditions because animals are adapted to
survive in the conditions in which they live. Animals living in very cold and hot climate must possess
special features to protect themselves against the extreme cold or heat. Fish has gills to survive in water
but a lizard don't have gill so live in water.
18. Crocodile.
19. Polar region-Polar bear and penguins.
Tropical rainforests-Jaguar and Toucan.
20. Polar bears are adapted to the extremely cold climate by having some special characteristics such as white
fur, strong sense of smell, a layer of fat under the skin, wide and large paws for swimming and walking, etc.
Polar bears have white fur so that they are not easily visible in the snowy white background. It protects
them from their predators. It also helps them in catching their prey. To protect them from extreme cold,
they have two thick layers of fur. They also have a layer of fat under their skin. In fact, they are so wellinsulated that they have to move slowly and rest often to avoid getting overheated. Physical activities on
warm days necessitate cooling. So, the polar bear goes for swimming. It is a good swimmer. Its paws are
wide and large, which help it not only to swim well but also walk with ease in the snow. While swimming
under water, it can close its nostrils and can remain under water for long durations. It has a strong sense
of smell so that it can catch its prey for food.
21. Penguins have thick skin for insulation, they huddle together to keep themselves warm, they shelter their
young ones between their furry feet to keep them warm, their streamlined body, webbed feet and flippers
make them excellent swimmers.
G. Short answer questions.
1. Weather describes the condition of the atmosphere. It might be sunny, hot, windy or cloudy, raining or
snowing. The weather depends on the temperature, precipitation, humidity and atmospheric pressure of the
part of atmosphere (air) closest to the surface of the earth. The weather is constantly changing as
temperature and humidity change in the atmosphere from time to time.
Climate is the average weather condition - temperature, pressure, precipitation and humidity - expected for
a certain place or region. Climate is based on the average weather experienced over 30 years or more.
2. High humidity makes the weather sticky and when humidity reaches 95% rainfall occurs. Relative
humidity has an influence on the amount of precipitation that can form. Precipitation often forms as a
result of raising a parcel of air from the surface and above the lifting condensation level. The more
moisture there is, the more precipitation there can be. Relative humidity also controls the amount of
evaporation that can be done. Less evaporation occurs at higher relative humidity values because there
is less space available. When the temperature is very warm outside, the combined effect of that and the
high relative humidity makes for a very unpleasant environment. There now exists an "apparent
temperature" known as heat index.
3. The core of the sun is so hot and there is so much pressure, nuclear fusion takes place: hydrogen is
changed to helium. Nuclear fusion creates heat and photons (light).The sun's surface is about 6,000
Jiwan® Science CCE Question Bank Answer Key-7/37
Kelvin, which is 10,340 degrees Fahrenheit (5,726 degrees Celsius). The amount of solar heat and light
is enough to light up Earth's days and keep our planet warm enough to support life.
4. An adaptation is trait of an organism that has been favoured by natural selection.
5. Aestivation is prolonged summer sleep in desert organisms, like ground squirrel, hedgehog ,and frog.
6. Camouflage is the built-in protection in the animals which increase their chances of survival by tricking
predators. Ex-stick insect, lion and tigers.
7. Penguins protect the egg and keep it warm in harsh weather conditions. Female penguin hunt for fish till
the eggs hatch then males go for hunting. Parents switch between taking care of the babies and
gathering food. Penguins take care of their babies include chasing for food, adult penguin engulfing the
food and saving it for its babies. It can moderately digest the fish or other food inside their stomachs; later
it coughs it after several hours and also vomiting the caught food after digesting and holding it for a while.
8. Migration refers to the movement of people from one region to another. Different forms of migration
include emigration which is movement out of a region and immigration which is movement into the
region. The number of people in a country increases if immigration exceeds emigration.
9. Extremely dry area of land with sparse vegetation. It is one of the Earth's major types of ecosystems,
supporting a community of distinctive plants and animals specially adapted to the harsh environment.
NCERT Questions
10. Following are some of the characteristics of animals:
(i) tropical rainforests
(ii) polar region
(iii)
polar region
(iv) tropical rainforests
(v) tropical rainforests (vi)
polar region
(vii) polar region
(viii) tropical rainforests (ix)
tropical rainforests
(x) tropical rainforests
11. An elephant living in the tropical rainforest has adapted to the conditions of rainforests in many
remarkable ways. Look at its trunk. It uses it as a nose because of which it has a strong sense of smell.
The trunk is also used by it for picking up food. Moreover, its tusks are modified teeth. These can tear the
bark of trees that elephant loves to eat. So, the elephant is able to handle the competition for food rather
well. Large ears of the elephant help it to hear even very soft sounds. They also help the elephant to keep
cool in the hot and humid climate of the rainforests.
12. a. Weather is the day-to-day state of the atmosphere in a region, and its short-term (minutes to weeks)
variation whereas Climate is defined as statistical weather information that describes the variation of
weather at a given place for a specified interval. They are both used interchangeably sometimes but
differ in their measure of time, and trends that affect them.
Weather is the combination of temperature, humidity, precipitation, cloudiness, visibility, and wind. In
popular usage, climate represents the synthesis of weather; more formally it is the weather of a
locality averaged over some period (usually 30 years) plus statistics of weather extremes.
b. Humidity is defined as amount of water vapour in air. The effect of high humidity indicates the
likelihood of fog or precipitation. Also, if the humidity is high, we sweat more but our sweat is not
evaporated much. As a result we feel hot. This is commonly seen in coastal areas like Mumbai,
Kolkata etc.
Precipitation or rainfall When air becomes saturated with water vapour, then water condenses from gaseous state, to liquid
state, and falls down to Earth in the form of drizzle, rain, hail, snow (water solidifies to ice). Precipitation is
a caused by the presence of humidity in the air.
c. Polar regions-They are the areas around the pole. The sun is visible only for about six months of the
year. Sun rays are not very strong. Region is covered with ice throughout the year. Winter
temperature may drop to as low as -37 degree C.
Tropical rainforests- this region is located between the Tropic of Cancer and Tropic of Capricorn.
They have hot climate with temperature ranging from 15 degree C to 40 degree C. They get heavy
rainfall and therefore have high humidity.
Jiwan® Science CCE Question Bank Answer Key-7/38
d. The maximum temperature of the day occurs generally in the afternoon while the minimum
temperature occurs in the early morning.
H. Long answer questions.
1. The tilt of the earth is, in fact, responsible for the seasons of the year. When one hemisphere is tilted more
toward the sun, it is summer in that hemisphere. When it is tilted away, that hemisphere experiences
winter. Autumn and spring are the times in between summer and winter when the tilt is facing neither
directly toward or away from the sun.
2. To overcome the competition for food and shelter, some animals are adapted to get food which is not
easily reachable. Example, red-eyed frog has developed sticky pads on its feet to help to climb tress on
which it lives. Another example is of the Toucan bird, which possesses a long, large beak. This helps a
toucan to reach the fruits on branches which are otherwise too weak to support its weight.
3. a. Polar Bear - A polar bear lives in the cold, snowy Arctic lands. They are the largest land carnivores.
animals in the polar region like polar bears are adapted to the extremely cold climate by having some
special characteristics such as white fur, strong sense of smell, a layer of fat under the skin, wide and
large paws for swimming and walking, etc.
Polar bears have white fur so that they are not easily visible in the snowy white background. It
protects them from their predators. It also helps them in catching their prey. To protect them from
extreme cold, they have two thick layers of fur. They also have a layer of fat under their skin. In fact,
they are so well-insulated that they have to move slowly and rest often to avoid getting overheated.
Physical activities on warm days necessitate cooling. So, the polar bear goes for swimming. It is a
good swimmer. Its paws are wide and large, which help it not only to swim well but also walk with
ease in the snow. While swimming under water, it can close its nostrils and can remain under water
for long durations. It has a strong sense of smell so that it can catch its prey for food.
b. Penguins- Penguins have white fronts and black backs. This colouration acts as a form of
camouflage when they are in the water - the dark backs make it difficult for predators such as
Leopard seals, to see penguins from above against the dark sea floor while the light coloured fronts
make them hard to see from below against the bright sky. Penguins have a special system of
feathers with the parts of the feather close to the body trapping a lot of air and so making for good
insulation against the cold, while the outer tips interlock with one another to provide a waterproof
outer layer. Penguins also have special adaptations to allow them to drink sea water and excrete the
salt from a special gland near their eyes. They also have adaptations that allow them to dive to great
depths and stay submerged for long periods without the need to breathe. Some species of penguin
(those that live in the coldest climates) also have adaptations of their circulatory systems that allow
them to keep their main organs warm, but let other parts of their body operate at lower temperatures.
c. Camel - Camels are adapted to their habitat by having a hump which stores food and water. They
have long legs which keep their bodies away from the heat of the sand, and their feet have 3 large
toes which help them walk on the sand. They have long, thick eyelashes which protect their eyes
from the sun and the sand, and their fur protects them from the heat of the sun while also keeping
them warm during cold desert nights.
4. The tropical rainforest has a large population of animals because it experience continuous warmth and
rain through out the year. Such climatic conditions in rainforests are highly suitable for supporting an
enormous number and variety of plants and animals.
5. We find animals of certain kind living in particular climatic conditions because animals are adapted to
survive in the conditions in which they live. Animals living in very cold and hot climate must possess
special features to protect themselves against the extreme cold or heat.
For Example , animals in the polar region like polar bears are adapted to the extremely cold climate by
having some special characteristics such as white fur, strong sense of smell, a layer of fat under the skin,
wide and large paws for swimming and walking, etc.
6. a. atmosphere b. temperature c. Humidity d. Pressure e. Precipitation f. Average
7. Tropical rainforest1. Hot and humid.
2. Monkey.
3. Gorilla.
Jiwan® Science CCE Question Bank Answer Key-7/39
4. Assam.
5. Western Ghats.
6. Winter temperature around 37 degree C.
7. Hot and humid climate.
Polar Region1. Sun does not rise for six months. 2. Days and nights are almost equal in length throughout the year.
3. Reindeer.
4. Penguin.
5. Greenland.
I. Give reasons.
1. Different parts of Earth receive different amounts of sunlight, depending on their latitude. Regions near
the equator receive more direct sunlight than the poles, so Earth is generally warmer near the equator
and colder toward the poles.
2. I think it because weather has to be measured on a very large scale. Everything has to be taken into account
i.e, temperature, wind, humidity, solar radiation, topography of the land etc. If one small thing changes,
whether it be that the system come to a small building or a large mountain, and the wind is slightly different, it
will completely change the outcome and they will have to run all the models again and it will change it. Every
little thing, weather man-made or natural will completely change how the whether system behaves.
3. Moisture in the air plays an important part in drying the clothes. If moisture is less, the clothes dry faster.
In dry weather moisture is very less so clothes dry faster.
4. The climatic conditions in rainforests are highly suitable for supporting an enormous number and variety
of animals. Tropical rainforests lie near to the Equator. This region receives rainfall distributed regularly
throughout the year, about 6-33 feet a year. It remains frost free and warm all year long, with
temperatures between 70° and 85°F with very little daily fluctuation. Because of continuous warmth and
rain, this region supports wide variety of plants and animals. The major types of animals living in the
rainforests are monkeys, apes, gorillas, lions, tigers, elephants, leopards, lizards, snakes, birds and
insects. Tropical rainforests are found in Western Ghats and Assam in India, Southeast Asia, Central
America and Central Africa.
5. The arctic region is sparsely populated because of extreme climatic conditions. The climate of the Arctic,
classified as polar, is characterized by long, cold winters and short, cool summers. The Arctic Ocean
stays frozen throughout the year. Great seasonal changes in the length of days and nights are
experienced north of the Arctic Circle, ranging from 24 hours of constant daylight ("midnight sun") or
darkness at the Arctic Circle to 6 months of daylight or darkness at the North Pole.
J. HOTS questions.
1. Many tropical animals have sensitive hearing, sharp eyesight, thick skin and a skin colour which helps
them to camouflage by blending with the surroundings. This helps them to protect themselves from
predators. Example, big cats like lions and tigers have thick skin and sensitive hearing.
2. Community helps in survival so the animals of polar region lives in community to support each other in
taking care of their young ones-as in penguins a few penguins are responsible for taking care of the
young ones when the rest of them are away hunting fish and to survive the harsh weather conditionpenguins huddle against each other and every penguin gets a chance to come in the centre.
3. The southwestern summer monsoons occur from June through September. The Thar desert and
adjoining areas of the northern and central Indian subcontinent heats up considerably during the hot
summers. This causes a low pressure area over the northern and central Indian subcontinent. To fill this
void, the moisture-laden winds from the Indian Ocean rush into the subcontinent. These winds, rich in
moisture, are drawn towards the Himalayas. The Himalayas act like a high wall, blocking the winds from
passing into Central Asia, and forcing them to rise. As the clouds rise their temperature drops and
precipitation occurs. Some areas of the subcontinent receive up to 10,000 mm (390 in) of rain annually.
4. The shortest day of the year is winter solstice, which happens either the 21st or 22nd of December. The
sun shines directly over the tropic of Capricorn, causing winter in the northern hemisphere, and the sun
appears at the lowest point in the sky. Therefore, it sets faster, causing a very short day and long night.
The longest day of the year is summer solstice, which happens either June 20th or 21st. In this case, the
sun directly strikes the Tropic of Cancer, causing summer in the northern hemisphere. The sun is at the
highest point in the sky, which means it sets much slower, causing a long day and short night.
Jiwan® Science CCE Question Bank Answer Key-7/40
Chapter- 9 : Soil
Objective Type Questions
A. Fill in the blanks.
1. natural
2. Earthworm and micro
3. contamination
4. Clayey
5. planting trees, making embankments
6. Loamy soil
7. lopsoil
B. Write whether the following statements are true or false.
1. False
2. True
3. True
4. False
5. True
6. False
7. True
8. True
9. False
10. False
11. True
12. True
13. False
14. True
15. True
C. Match the two columns to make correct pairs.
1. a. v
b. iii
c. iv
d. i
e. ii
NCERT Questions
2. a. v
b. iii
c. i
d. ii
e. iv
f. vi
D. Multiple choice questions. Tick the correct option in each case.
1. b
2. c
3. a
4. c
5. a
6. c
7. c
8. c
9. a
10. a
NCERT Questions
11. b
12. a 13. b 14. a
E. Name them.
1. Groundwater
2. Loam
3. Natural gas
NCERT Questions
4. Weathering
5. Soil erosion
6. Eutrophication
7. Infiltration
Descriptive Questions.
F. Very short answer questions.
1. Clayey soil.
2. Loamy soil.
3. Sandy soil.
4. Loamy soil.
5. Clayey soil.
6. Rocks make up the inorganic component of the soil.
7. Colour, size of particles and the texture are different in different horizon of the soil.
8. The presence of humus makes soil darker. The more the humus, the darker the soil.
9. Minerals are found in Horizon B.
10. The texture means the feel of the soil. The size of particles in the soil gives its characteristic texture.
11. Xerophytic plants survive in sandy soil.
12. Loamy soil is gritty in texture.
NCERT Questions
13. Clay<Silt<Sand<Gravel <Rock.
14. a---HUMUS b—SOIL PROFILE c---HORIZON d---LOAM e---WEATHERING f ---PERCOLATION.
G. Short answer questions.
1. When plant residues are returned to the soil, various organic compounds undergo decomposition.
Decomposition is a biological process that includes the physical breakdown and biochemical
transformation of complex organic molecules of dead material into simpler organic and inorganic
molecules.
Jiwan® Science CCE Question Bank Answer Key-7/41
The continual addition of decaying plant residues to the soil surface contributes to the biological activity
and the carbon cycling process in the soil. Breakdown of soil organic matter and root growth and decay
also contribute to these processes. Carbon cycling is the continuous transformation of organic and
inorganic carbon compounds by plants and micro and macro-organisms between the soil, plants and the
atmosphere.
2. Soil profile is the top layer of soil, on this layer animals live. It's made mostly of sand, it has a decomposed
organic matter, it has layers of weathered bedrock.
3. It is also known as A-horizon is generally dark in colour and fertile as it is rich in humus and minerals. This
layer is generally soft, porous and can retain more water. This provides shelter for many living organisms
such as worms, rodents, moles and beetles. The roots of small plants are embedded entirely in the
topsoil.
4. Clayey soil has water logging. Due to this air can't pass through clayey soil.
5. Water flowing down the mountains in northern India carry a large amount of soil particles into the plains
where they are deposited along the bank, making the northern plains fertile.
6. Loamy soil is rich in humus and can support plants very well.
7. The amount of water that can pass through the soil is known as percolation rate.
8. The collection of ground water between lumps of rocks and crevices makes the water table.
NCERT Questions
9. Percolation is highest in the sandy soil. The rain water also gets percolated so no streams are seen for
long time even in rainy days.
10.Labelling the diagram
a. Topsoil
b. Subsoil
c. C-horizon
d. Bedrock
11. He could not dig any further as the lower layer is of bedrock.
12.It is not good to remove grass and small plants from an open unused field as in the absence of plants the
soil become loose so it can be removed by wind and flowing water.
13.Limestone neutralises acidic soil by reacting with the acid to produce neutral carbon dioxide and
compounds. The effect of acid rain on the environment entirely depends on the ability of soils to be able
to neutralise the acid.
14. B—is advantageous for absorption of water and minerals.
H. Long answer questions.
1. The earth was once covered with huge pieces of rocks which broke down gradually over a period of
thousands of years. The breaking down was brought about by natural forces like the wind, rain, heat and
cold, plant roots, etc. This process is known as weathering. Weathering is a continuous process and soil
formation continues to take place. The remains of dead plants and animals are decomposed by
microbes in the soil and the organic matter provides the nutrients for plants.
Jiwan® Science CCE Question Bank Answer Key-7/42
2. A vertical section of soil from the ground surface of the bedrock showing the different layers of soil is
called soil profile. Each different layer of the soil is called a horizon. The colour of the soil, the size of the
rocks and the texture is different in different horizons.
3. Soil can be classified into three types based on the particle.
Size and texture:
(a) Sandy Soil :
• This type of soil contains more sand.
• It has the biggest particle size.
• It is very porous and water drains out quickly, keeping the soil mostly dry.
• Mainly found in desert areas.
• Only xerophytic plants that can survive on less water can thrive in such soil.
(b) Clayey Soil :
• It contains finer particles of soil.
• It is very smooth to touch.
• The particles pack together and provide for very little air spaces.
• It is heavier than sandy soil.
• It can retain water for a long time and remain wet.
• It becomes sticky when wet, and hard when dry.
• Since it gets waterlogged easily, it does not allow air required for plant roots to breathe.
• This type of soil is most suitable for making pots and toys.
(c) Loamy Soil :
• It is a mixture of sand, clay and silt.
• It has a gritty texture.
• It is porous and also holds moisture.
• It also contains humus.
• It supports a rich variety of soil organisms which keep the soil fertile.
4. Soil is considered to be the most important natural resource since it is the home for many animals like
earthworms, many microbes, decomposing bacteria, etc.
Soil is rich in nutrients which support plants, which are primary source of food on earth. Plants also a
provide materials for commercial products like timber, textiles, paper, medicines rubber, etc. So, it is very
essential for supporting all forms of life on earth.
5. They take support in the soil and grow. The roots of trees absorb the nutrients and water from the soil and
make their food. The roots spread into the soil, bind it and protect it from soil erosion. They draw the
water from the deeper layers to surface, thus holding the soil together. So, we can say that trees protect
the soil. The roots of trees penetrate into the crevices of rocks, and cause breaking of rocks leading to
weathering. The leaves, flowers and various parts of trees decompose in the soil and turn into humus,
enriching the soil and providing organic components to it. So, we can say that trees help in formation of
the soil.
NCERT Questions
6. Water logging affects a number of biological and chemical processes in plants and soils that can affect
crop growth in the short and long term.
7. In dense forests the soil is bind by the roots of the trees but the barren land is open to destruction by wind
and water so easily the top soil is eroded.
Jiwan® Science CCE Question Bank Answer Key-7/43
I. Give reasons.
1. Earthworm are called friends of farmer because they move through the soil that loosens and aerates the
soil. This also helps the water to reach the roots quickly. Earthworm's excreta increases the fertility of the
soil. After their death, they get decomposed and add humus to the soil.
2. 1. Topsoil has a higher humus content than subsoil. It tends to be the layer of the soil food web where
above and below ground organisms such as bacteria, beetles, and earthworms live and die.
2. The death and the resulting decay of these organisms contribute to the build-up of organic matter.
3. Another word for humus is organic material.
3. Soil is defined as a covering over most of the earth's land surface. It is made of particles of rock and
minerals, living things and the remains of living things. It takes thousands of years for soil to form just a
few inches. So, it is the most important natural resource.
4. It has higher permeability (airflow) for more vigorous roots but loses some nutrient and water retention.
NCERT Questions
5. Due to rapid urbanization, infiltration of rain water into the sub-soil has decreased drastically and
recharging of ground water has diminished.
6. To keep the roots of the plant well aerated.
J. HOTS questions.
1. Reduction in quantity of soil due to erosion will affect the percolation rate since too little water will be
soaked and water will flow away causing further erosion and flooding of low lying areas. So, larger the
quantity of soil, higher will be the percolation rate.
2. Urbanization results in concentration of people in cities increasing the demand on available water
sources. It leads to indiscriminate use of ground water. The ground water is often used faster than its rate
of replenishment. Thus, the water table goes down.
3. The construction of buildings and roads are gradually covering the open part of the soil with concretes. As
a result the rain water run offs fail to percolate (movement of water) through the soil. Water table is the
upper level of an underground surface beneath which rocks and soil are completely emerged under
water. The runoff water percolates through the soil and reaches the layer of ground water. As a result the
water level of the water table rises up.
4. Soil erosion means that the soil is carried away, by water or wind. And if the soil goes from a field, the
farmer can't grow stuff there anymore. If disappears from the ground the foundation of the house may
also collapse.
5. Clay is preferred for making toys because it contains finer particles of soil. It is very smooth to touch. It
becomes sticky when wet and hard when dry.
Jiwan® Science CCE Question Bank Answer Key-7/44
Chapter- 10 : Respiration
Objective Type Questions
A. Fill in the blanks.
1. mucus
2. bronchi
3. alveoli
4. RBCs
5. Cell wall
6. broken
NCERT Questions
7. Air spaces, soil
8. floor
9. stomata
10. spiracles
B. Write whether the following statements are true or false.
1. True
2. False
NCERT Questions
3. False
4. True
5. True
6. False
7. True
8. False
9. False
10. True
C. Match the two columns to make correct pairs.
1. a. v
b. iv c. ii
d. iii
e. i
NCERT Questions
2. a. iii b. vi
c. i
d. v e. ii
f. iv
3. a. iii b. iv
c. i
d. ii
D.Multiple choice questions. Tick the correct option in each case.
1. c
2. a
3. c
4. c
5. d
6. a
7. b
8. b
NCERT Questions
9. c
10. b 11. b 12. b 13. b
14. c 15. c
16. b
17. b
18. d
E. Name them.
1. Respiration
2. Epiglottis
3. Diaphragm
4. Aerobic respiration
5. Stomata
Descriptive Questions.
F. Very short answer questions.
1. Trace the path of travel of oxygen in humans during respiration, using arrows.
2. a. The oxidative process occurring within living cells by which the chemical energy of organic molecules
is released in a series of metabolic steps involving the consumption of oxygen and the liberation of
carbon dioxide and water.
b. Oxidation reaction is any chemical reaction that involves the moving of electrons. When iron reacts
with oxygen it forms a chemical called rust. The iron is oxidized and the oxygen is reduced.
c. A trachea is a large membranous tube reinforced by rings of cartilage and conveying air to and from
the lungs. The trachea extends from the larynx to the bronchial tubes and it is a vital organ in the
respiratory system.
3. Name the breathing organs in the following:
a. Earthworm-Moist skin
b. Cockroach-Spiracles
c. Fish-gills
4. Alcohol and carbon dioxide.
5. Guard cells help in closing and opening of the stomata.
6. Lactic acid.
7. Oxygen is transported via blood.
Jiwan® Science CCE Question Bank Answer Key-7/45
8. Breathing, that is, inhalation of air and exhalation of CO2 is known as external respiration.
9. Number of breaths per minute is called breathing rate.
10. An elastic cartilage placed below the lungs in the chest cavity is called the diaphragm.
11. Unicellular organisms respire by the process of diffusion.
12. Fermentation is production of alcohol and carbon dioxide when respiration takes place anaerobically.
13. Aerobic Respiration
C6 H12O6+ 6O2 ® 6H2O + 6CO2 + Energy
(sugar) (oxygen)
(water) (carbondioxide)
G. Short answer questions.
1.
S.No.
Aerobic Respiration
Anaerobic Respiration
(i)
Takes place in the presence of oxygen.
(i)
Takes place in the absence of oxygen.
(ii)
The end products are CO2 , water and energy.
(ii)
The end products are alcohol, CO2 and
small amount of energy.
2. A cramp is a muscle pull and immobility caused by accumulation of lactic acid in muscle cells, during
strenuous exercise.
3. The plants require CO2 for photosynthesis and O2 for breathing. These are obtained from air through
small openings called stomata present in the leaves and the stem. The stomata are controlled by two
bean shaped cells. Contraction, of the guard cells causes opening and closing, the stomata. Gases enter
and leave the cells through these stomata.
4. During inhalation, the diaphragm contracts and helps to expand the lungs. During exhalation the
diaphragm relaxes helping the lungs to contract and expel the air out.
5. Release of energy from food in the presence of oxygen is called oxidation.
6. Cellular respiration refers to the oxidation of food in the cells to release energy.
7. Insects use breathing tubes called trachea to breathe.
8. Gills are respiratory organs in fishes.
9. In human beings, alveoli are places where exchange of gases takes place in lungs.
10. Breathing rate is affected by physical exercise, altitude, age and anxiety.
11. The stomatal pore, guard cell, the subsidiary and epidermal cell are all together known as stomatal
apparatus.
12. C6H12O6 ® 2C2H5OH + 2CO2 ® glucose ® ethanol + carbon dioxide
NCERT Questions
13. The food has stored energy, which is released during respiration. Therefore, all living organisms respire
to get energy from food by breathing the air. During heavy exercise, fast running , cycling, walking for
many hours or heavy weightlifting, the demand for energy is high. Therefore, to meet the extra demand
of energy, an athlete breathes faster and deeper than usual after finishing the race.
14. Aerobic and Anaerobic Respiration
Similarities
1. Both are necessary for the survival of living organisms.
2. In both type of respiration, the food is broken and energy is released for the functioning of an organism.
3. In both type of respiration, carbon dioxide, water and energy is produced finally.
Differences
1. An aerobic respiration takes place using oxygen, inhaled in breathing, where as an anaerobic
respiration requires no oxygen.
2. In aerobic respiration, breakdown of glucose results in production of carbondioxide, water and
energy where as in anaerobic respiration, the breakdown of glucose first results in lactic acid and
energy then lactic acid break down into carbon dioxide and water.
Jiwan® Science CCE Question Bank Answer Key-7/46
3. An aerobic respiration uses respiratory organs such as lungs or gills where as anaerobic respiration
take place at cellular or muscular level.
15. When we inhale a lot of dust-laden air, the dust particles get trapped in the hair present in our nasal
cavity. However, sometimes these particles may get past the hair in the nasal cavity. Then they irritate the
lining of the cavity, as a result of which we sneeze. Sneezing expels these foreign particles from the
inhaled air and a dust free, clean air enters our body.
16. d
17. Oxygen. Oxygen serves as the end of the electron transport chain during aerobic respiration. By gaining
additional electrons, oxygen atoms are able to ionize and bind with hydrogen ions to form water.
18. Sleeping < watching Television < Cycling < Brisk Walk.
19. Stomata are tiny plant structures found on the outer skin layer, also known as the epidermis, of plants.
They consist of two specialized cells, called guard cells that surround a tiny pore called a stoma. The
word stomata means "mouth" in Greek because they allow communication between the internal and
external environments of the plant. Their main function is to allow gases such as carbondioxide, water
vapour and oxygen to move rapidly into and out of the leaf. Stomata are found on all above ground parts
of plants including the petals of flowers, petioles, soft herbaceous stems and leaves. They are formed
during the initial stages of the development of these various plant organs and therefore reflect the
environmental conditions under which they grew.
Breathing holes located along the sides of insects. The spiracles are connected to the air tubes, or
trachea, and allow the insect to exchange gases. The insect can open or close the spiracles by
contracting muscles along its side. Some spiders also have spiracles. Sharks and rays have a spiracle
behind each eye. When the shark is not moving, the spiracle helps the shark to breathe.
H. Long answer questions.
1. Cells of living beings carry out all the basic processes of life and energy for these cells is obtained from
food. In cellular respiration, the glucose obtained as the end product of digestion is oxidized to release
water and carbondioxide. These end products are eliminated through lungs. The cellular respiration
goes on all through the day. The respiration can either take place in the presence of oxygen— AEROBIC,
or in the absence of oxygen— ANAEROBIC. In humans, under strenuous physical activity, energy is
released under anaerobic conditions, and the end product can be lactic acid. These are removed as the
supply of oxygen is restored.
2. We know that plants are the source of oxygen on earth. They produce oxygen by a process called
photosynthesis. But like all living organisms plants also carry out respiration. The exchange of gases in
plants takes place at stomata present in the leaves and stem. The stomata are made of two guard cells.
The expansion and contraction of the guard cell causes the opening and closing of the stomata.
Plants do not need much oxygen for respiration, hence the rate of respiration in plants is much slow than
that in animals. Like animals, plants also release carbon dioxide, water and energy as by-products.
3. Animals have different modes of carrying out exchange of gases.
(a) Cockroaches: Cockroaches have spiracles on the body and a network of tubes called trachea. The
oxygen rich air is taken in by the spiracles and transported by the trachea. In a similar way, carbon
dioxide is expelled from the body.
(b) Earthworm: It uses its moist skin as a respiratory organ. The gases are transported in and out of its
body through a system of capillaries.
(c) Fishes: Fishes have gills which are made of a large number of filaments richly supplied with
capillaries to carry out exchange of gases.
(d) Birds and Mammals: They have highly developed lungs and respiratory system to carry out
exchange of gases.
4. Respiration in human beings is carried out in two steps, namely: (i) Breathing (ii) Oxidation of food
Breathing: It is a physical phenomenon of taking in oxygen and giving out carbon dioxide.
Jiwan® Science CCE Question Bank Answer Key-7/47
Oxidation of food: It is a chemical process of breakdown of food to release energy, carbondioxide and
water. Breathing takes places in the nostrils and the air passes into the lungs through the trachea and
bronchi. The nostrils have hair which filter the air by trapping dirt, dust and germs. The lining of the
nostrils secrete mucous which also helps in this purification. The purified air passes through trachea. The
trachea branches into two smaller tubes called bronchi. Each bronchus (singular) enters a lung. A pair of
lungs is present in the chest cavity. Each bronchus is divided into fine airtubes called the bronchioles . At
the end of each bronchiole, is an air sac called alveoli. Blood vessels surround the alveoli and oxygen
from the air that enters it. The CO2 produced during respiration is passed into the alveoli from the blood
and during exhalation, it leaves the body.
Oxidation: The oxygen absorbed by the blood reaches cells where the glucose is also transported by the
blood. Oxidation takes place inside the cell and the energy released is used up for cell activities.
5. During strenuous physical activity, the cellular respiration takes place rapidly and it can proceed even
when oxygen is not available sufficiently. So, respiration is taking place under anaerobic conditions and
results in production of lactic acid. This accumulates in the cells causing muscle pull and immobility. This
is what is called as a cramp. When oxygen supply is restored, the lactic acid is converted into CO2 and
H2O and the normal aerobic respiration is restored.
6. Attached to all the little alveoli in your lungs are blood capillaries. The oxygen in your lungs enters the
bloodstream, and our red blood cells attach themselves to the oxygen, carrying it around to the rest of our
body. Also in the alveoli, the deoxygenated blood (with CO2 in it) enters from the blood into the lungs to
be expelled (when you breathe out).
7. Similarity: Both involve the oxidation of a material to release energy. Difference: The energy released
from combustion is solely in the form of heat, whereas in cellular respiration it is released as heat and
chemical energy (in the form of ATP).
8. The air you exhale generally has a greater partial pressure of CO2. I show that with my class by having a
student blow into a beaker of water with bromthymol blue indicator. The pH is initially adjusted to 7. When
they blow into the liquid through a straw, the solution will become yellow as the CO2 reacts with water to
make H+ and HCO3-. CO2 is a product of the oxidation of hydrocarbons, but the process is more complex
than the "combustion" reactions we often write. Another source of exhaled CO2 comes from other
reactions in the body. Consider the lactic acid which is produced in muscles which increases the
hydrogen ion concentration in the blood. Consider this equilibrium in the blood.
CO2(aq) + H2O(l) Û H+ + HCO3–
As H+ concentration increases, the equilibrium shifts to the left to produce more CO2. The excess CO2 is
eliminated through the lungs as you exhale.
If it weren't for green plants taking in CO2, then there might be a net build up of CO2 based on exhalation.
In confined spaces, like the space shuttle, "scrubbers" have to be used to remove the excess CO2.
NCERT Questions
9. a) The cramps occur when muscle cell respire anaerobically. The partial breakdown of glucose
produces lactic acid. The accumulation of lactic acid causes muscle cramps.
b) The accumulation of lactic acid causes muscle cramps. We get relief from cramps after a hot water
bath or a massage. Hot water bath or massage improves circulation of blood. As a result, the supply
of oxygen to the muscle cells increases. The increase in the supply of oxygen results in the complete
breakdown of lactic acid into carbondioxide and water.
10. a) Carbondioxide is highest in jar C as the leaves are broken away from the plant.
b) Carbondioxide is lowest in the jar-A where all the carbon dioxide is used up by the plants and
converted into oxygen.
11. a) Testing carbondioxide is released during respiration.
b) Limewater turns milky due to CO2(g) bubbled through colourless limewater [(Ca(OH)2(aq)].
Jiwan® Science CCE Question Bank Answer Key-7/48
12. a) The dough rise because of yeast which is present in the dough. Yeast burn food in a much slower
process called fermentation. Fermentation gives off two byproducts, carbon dioxide, and ethanol.
This carbondioxide forms pockets inside the dough. As these pockets of gas multiply and get larger,
the bread dough blows up like thousands of tiny balloons. This causes it to rise.
b) Bread dough will often smell like alcohol. When yeast cells consume sugar they produce alcohol and
carbondioxide as by product.
c) Adding sugar to the dough mixture can speed up the action of the yeast.
d) The yeast will not fermentation reaction so the dough will not rise.
13. a) A shows inhalation and B shows exhalation.
b)
(i)
(i)
(iii)
(iii)
(ii)
A
(iii)
(iii)
B
)ii(
I. Give reasons.
1. Overwatering plants can rot the roots and soon the plants will not be able to absorb water and die.
2. During exercising the demand for energy is high but the supply of oxygen to produce the energy is
limited. So, anaerobic respiration takes place in the muscles to fulfil the demand of energy.
3. A yawn is a reflex that occurs when the level of oxygen in the blood drops. By yawning, which is actually a
huge breath, more oxygen is introduced into our system.
4. Mountain climbers use oxygen tanks because the air is a lot thinner at high altitudes. Oxygen tanks
ensure that they get enough oxygen no matter how high they climb. Otherwise, they could die.
J. HOTS questions.
1. Lung capacity refers to the ability of lungs to expand and hold air. The higher the lung capacity, the better
will be the oxygen intake. It can be measured by how much the chest expanded on deep inhalation.
2. Pranayam is a breathing technique. There are many ways in which one can practice pranayam. It helps
us to practice breathing in the right manner to maximize the benefits of breathing and minimize
occurrence of illnesses due to faulty breathing.
3. Plants are carrying out two different processes simultaneously, namely, respiration and photosynthesis.
During photosynthesis, they take in CO2 from air and release O which is used up during respiration. So,
the oxygen they take up from the environment is a smaller amount as compared to the oxygen they
release into the environment as a result of photosynthesis.
4. At night trees go for respiration, which uses oxygen in the atmosphere and gives out carbondioxide. So, if
you sleep under a tree at night, you will have lack of oxygen to breathe.
5. During exercising oxygen is needed for the aerobic respiration to start and to speed up the breakdown of
food and to release more energy.
NCERT Questions
6. Test tube A will have high concentration of carbondioxide. This experiment shows relationship between
plants and animals. During breathing snail inhales dissolved oxygen in water and exhaled carbondioxide.
Test tube B and C will have less carbon dioxide as the plants photosynthesize and release oxygen.
7. Anaerobic respiration occurs in muscle cells when they do not have access to enough oxygen to
complete aerobic respiration to generate all the ATP they need. In human muscle cells, the end product is
lactate/lactic acid.
Jiwan® Science CCE Question Bank Answer Key-7/49
Chapter- 11 : Transport of Materials in Plants and Animals
Objective Type Questions
A. Fill in the blanks.
1. antibodies
2. Sap
3. Digested food, oxygen
4. Carbon dioxide, liquid waste
5. Blood
6. suction
7. 4 to 5 litres
8. Food, enzymes, waste
9. Pulmonary vein, carbondioxide rich 10. Stethoscope
11. Sweating
12. Auricles
13. Red blood corpuscles
14. Left auricle
NCERT Questions
15. blood
16. Red Blood
17. blood vessels
18. heartbeat
19. Carbondioxide
20. salts
21. urine
22. transpiration
B. Write whether the following statements are true or false.
1. False
2. True
3. True
4. True
5. False
6. False
C. Match the two columns to make correct pairs.
NCERT Questions
1. a. ii
b. iv
c. i
d. iii
2. a. i
b. iv
c. vi
d. ii
e. v
f. iii
D.Multiple choice questions. Tick the correct option in each case.
1. c
2. d
3. b
4. a
5. c
6. c
7. c
8. c
NCERT Questions
9. a
10. a
E. Name them.
1. Xylem
2. Transportation
3. Plasma
4. Ventricles
5. Transpiration
6. Osmosis
7. Nephron
Descriptive Questions.
F. Very short answer questions.
1. Transportation of water from the roots to the leaves.
2. Transportation of food from the leaves to other parts.
3. Regular periodic contraction and relaxation of heart muscles to push the blood through the body is
known as heart beat.
4. WBC — White Blood Cell. RBC — Red Blood Cell.
5. The elimination of wastes from the body through excretory organs, is known as excretion.
6. Sweat consists of salts like sodium and urea in a soluble form.
7. Nephrons are filtering units of kidneys. When blood passes through nephrons, it takes out a lot of waste
products and helps in reabsorbing salt, water and other useful substances from the blood. The filtered
waste is excreted as urine.
8. It pumps blood to the lungs. Exchange of gases takes place at the lungs.
9. Nephron
10. Blood
NCERT Questions
11. Valve
12. Heart
G. Short answer questions.
1. Human body is very complex. It needs an efficient transportation system to :
(a) transfer the digested nutrients to all cells for oxidation.
(b) transfer medicine and antibodies to sites of injury and infection.
Jiwan® Science CCE Question Bank Answer Key-7/50
2. Materials transported in the human body are digested food, oxygen and carbondioxide, enzymes and
hormones, metabolic wastes, medicines and antibodies.
3. Transpiration is a process whereby water vapour escapes from the stomata and creates a suction pull in
the plants. Due to this pull, there is ascent of sap, i.e., movement of water and minerals from the roots to
the shoot tips of the plants. It helps to cool the plants.
4. Valves in the heart open in one direction and thus prevent the back flow of blood.
5. Beating sound of the heart is due to contraction and expansion of the heart muscles.
6. Human excretory system comprises of two kidneys, ureter and urinary bladder.
7. Dialysis is a method of filtering the blood using an external apparatus. It is carried out on a person whose
kidneys fail to function. When kidneys fail, wastes accumulate in blood and create toxic conditions of
blood. Such people have to be kept on dialysis.
8. a.
1) Arteries carry blood away from the heart while veins carry blood to the heart.
2) Arteries have thick and muscular walls (as they have to endure higher pressure) whereas veins have thin
and slightly muscular walls.
3) Arteries have no valves, while veins have valves.
4) Arteries (in the post-fetal human) carry oxygenated blood except for the pulmonary arteries. Veins (in the
post-fetal human) carry de-oxygenated blood except for the pulmonary veins.
b. Both the atria and ventricles are chambers found on the heart with the top and smaller one being the atria
that functions to collect blood from the veins that are connected to it. The bottom and larger chamber is
the ventricles which use pressure action of powerful muscles to push blood out of the ventricles and into
the arteries connected above them. In addition, the walls of the ventricles are thicker, while that of the
atria are thinner.
c. RBCs, also called erythrocytes, have a protein called hemoglobin. The blood gets its color when
hemoglobin absorbs oxygen from the lungs. As the blood travels through the body, the hemoglobin
releases the oxygen in the tissues. RBCs have a life cycle of 4 months and they appear in the form of flat
indented discs.
The WBCs, also called leukocytes, handle more complex functions. They are the defense mechanism of
the human body for fighting infections. There are different types of WBCs with varied life cycles and
distinct functions. White blood cells also produce a special protein called antibody which recognize and
fight the presence of foreign elements in the body.
9. Transpiration is the evaporation of water / loss of water from plants, especially leaves. It is a type of
translocation. The amount of water lost by a plant depends on its size, the surrounding light intensity,
temperature, humidity, wind speed, and soil water supply.
10.The main reason why plants wilt is because of diseases. The wilting of plants may also be caused by
plant dehydration, over watering, too much sunlight and the use of excess fertilizer on the plants. It is
characterized by the loss of rigidity of non-woody plants.
11. a) Transpiration generates a suction pull which can pull water to great heights in tall trees.
b) Transpiration also cools the plant.
12.A semi-permeable membrane is a membrane which will allow certain molecules or ions to pass through it
by diffusion and occasionally specialised "facilitated diffusion". The rate of passage depends on the
pressure, concentration and temperature of the molecules or solutes on either side, as well as the
permeability of the membrane to each solute.
13.A urine glucose test determines whether or not glucose (sugar) is present in the urine.
NCERT Questions
14.The platelets are another type of cells in blood, which are responsible for formation of clot in blood when it
comes in contact with air. So, this prevents excess bleeding from the injury as it plugs the skin opening
by clout formation on it. If there are no platelets in the blood,then we may die from a small injury due to
excess blooding as there will be no clotting to plug it.
Jiwan® Science CCE Question Bank Answer Key-7/51
15. Stomata are tiny pores present on the surface of the leaves. These pores are surrounded by 'guard cells'
The two functions of Stomata are follows:
Function 1 : We know that photosynthesis is an important process in plants, in which plants, in the
presence of sun light with help of chlorophyll, make use of simple chemical substances like carbon
dioxide, water and minerals for the production of food for themselves. The carbondioxide required in
this process is made available by stomata, through direct absorption from the air.
Function 2 : Stomata helps in plants absorb mineral nutrients and water from the soil. Not all the water
absorbed is utilised by the plant. The water evaporates through the stomata present on the surface of the
leaves by the process of transpiration. The evaporation of water from leaves generates a suction pull
(the same that you produce when you suck water through a straw) which can pull water to great heights
in the tall trees. Transpiration also cools the plant.
16. It is necessary to excrete the metabolic waste products because they are toxic to our body and can
disrupt our physiology if not eliminated. On the other hand the undigested food if not eliminated for a long
time may produce toxicity in the body. Hence, excretion is an important physiological function.
17. Blood only flows through arteries in one direction due to the pressure being exerted by the heart. Veins
have small valves along their length that prevent backwards flow.
18. The level of sugar solution will increase. For very short distances water can move from one cell to
another, in the same way water reaches xylem vessels of the root from the soil.
19. a----4, b----3, c---5, d----1, e----2
20. a) The pulmonary artery b) Since pulmonary artery carry blood from the heart it is called an artery.
21. a) Dialysis is the artificial process of eliminating waste (diffusion) and unwanted water (ultra filtration)
from the blood. Our kidneys do this naturally.
b) Some people, who have failed or damaged kidneys which cannot carry out the function properly
need dialysis.
22. a) Lungs
b) The organ that stores undigested food is the large intestine. The large intestine takes in any food
that, it cannot take any nutrients or goods From. It from there it goes out of the anus as is faeces.
c) The urine is filtered out of the blood in the kidneys, goes through the ureter to the bladder and then is
expelled through the urethra and finally the urinary meatus.
d) Skin through sweat glands.
23. a) Stethoscope, b) A. The ear piece B. The tube C. The chest piece.
24. The evaporation of water from leaves generates a suction pull which can pull water to great heights in the
tall trees.
H. Long answer questions.
1. Transportation of water in plants is facilitated by the vascular system of plants consisting of xylem and
phloem. These tubes extend from root tip to shoot tip covering every cell of the plant. Xylem transports water
while phloem transports food throughout the plant body. The medium of transportation in plant cells is a
whitish fluid called sap. The roots absorb water and minerals from the soil. Continuous absorption of water
by the roots creates an upward push. Evaporation of water from leaves creates a pull in the leaves. As a
result of the push from the roots and pull from the leaves, the transportation takes place.
2. Blood is a mixture of a liquid portion called plasma in which the various blood cells like the red blood cells,
white blood cells and platelets are suspended.
Plasma: The liquid portion of the blood carries dissolved food, wastes, enzymes, etc., along with the
blood cells. It has 90% water and is yellowish in colour.
3. Red Blood Cells: Get the name because of the colour they carry. The red colour is due to a pigment called
haemoglobin. They are disc shaped cells and primarily responsible for transporting oxygen.
White Blood Cells: They are colourless and are spherical in shape. They are larger than RBCs and are
fewer in number. They are very important for protecting us against infections. They can be called the
soldiers of the body.
Jiwan® Science CCE Question Bank Answer Key-7/52
Platelets: Platelets are very tiny fragments of cells. They play an important role in blood clotting at the site
of injury. So, they are very useful in preventing excessive loss of blood.
4. Heart is the pumping organ of a living body. In humans, it is as big as our fist. It consists of four chambers —
the two upper chambers are called auricles and the two lower chambers are called the ventricles. The left
side of the heart is separated from the right side by a thick wall called septum. This keeps the oxygenated
blood away from the deoxygenated blood. Valves are present between the auricles and ventricles to stop
the backflow of blood. The muscles of the heart are capable of working timelessly, all our lives producing
rhythmic contraction and relaxation. This is what we call as heart beat. The contraction pumps the blood
out of the heart and relaxation allows flow of blood into the heart.
5. Human body has two kidneys placed on either side of the backbone just above the waist. They consist of
a large number of filtering units called nephrons supplied with a very intricate network of capillaries.
Blood passes through these nephrons which remove the various wastes and also reabsorb the useful
substances along with water. The wastes get collected and are drained out of the kidney through pipes
called the ureters and collect in the urinary bladder. Periodically the bladder empties itself and the wastes
are eliminated as urine.
6. To study the ascent of sap in plants.
Materials: White carnation, green food colour, a vase, water.
Procedure:
(i) Fill the vase with water and add a few drops of food colour.
(ii) Place the carnation in the vase.
(iii) Observe after eight to ten hours.
Observation: You will see flecks of colour on the petals of the carnation. If you take out the stem and look
at its centre, it would have been coloured green.
NCERT Questions
7. Transport of materials is necessary in plant or in animals as all organisms need food, nutrition, water and
oxygen for survival. The food is the source of energy and every cell of an organism gets energy by the
breakdown of glucose. The cells use this energy to carry out vital activities of life. Therefore food must be
made available to every cell of an organism. They need to transport all these to various parts of their
body. Further, animals need to transport wastes to parts from where they can be removed.
8. Plants absorb mineral nutrients and water from the soil. Not all the water absorbed is utilised by the plant.
The water evaporates through the stomata present on the surface of the leaves by the process of
transpiration. The evaporation of water from leaves generates a suction pull (the same that you produce
when you suck water through a straw) which can pull water to great heights in the tall trees. Transpiration
also cools the plant.
9. The diagram of human excretory system.
Kidney
Ureter
Urinary bladder
Urethra
Urinary opening
Human Excretory System
Jiwan® Science CCE Question Bank Answer Key-7/53
10.a.
b.
c.
11. a.
12. a.
b.
c.
Circulatory system of animals— Arteries, Capillaries, Atria ,Veins, Heart.
Excretory system in humans— Ureter, kidneys, Urethra, Urinary Bladder.
Transport of substances in plants-Root hair, Xylem, Phloem.
Arteries b. veins c. veins d. arteries
e. arteries f. veins g. valves h. veins.
A wound stops bleeding due to the process of clot formation called coagulation.
The wound colour is red.
The main function of platelets, or thrombocytes, is to stop the loss of blood from wounds
(hematostasis). To this purpose, they aggregate and release factors which promote the blood
coagulation. Among them, there are the serotonins which reduces the diameter of lesioned vessels
and slows down the haematic flux, the fibrin which trap cells and forms the clotting. Even if platelets
appear roundish in shape, they are not real cells.
I. Give reasons.
1. Because they fight against the diseases and also prevent the germs that may enter our body.
2. During exercise, the heart rate increases to supply more oxygenated blood to the muscles, since they
need more oxygen when they are moving. It also increases to quickly move the waste to the lungs and
kidneys. Although we pant when running, it's the heart's inability to get the oxygen to the muscles, rather
than the lungs ability to gather oxygen.
3. Excretion is the removal of waste products from the chemical reactions that occur inside all living things
(organisms). The Chemical reactions of a human are called cell metabolism. The normal waste product
from mammals is urea. It is released in urine and sweat. Carbon dioxide is also something that is
excreted from mammals when breathing out. Excretion is important for living things because a build up of
the waste products from these chemical reactions is very dangerous for the body because it can, in
excess, be poisonous.
NCERT Questions
4. Transplant the rose bush as quickly as possible. The longer the roots are out of the ground, the higher the
odds of killing the plant.
J. HOTS questions.
1. A hole in the heart refers to an opening in the septum which separates left side from the right side of the heart.
This causes mixing up of oxygenated blood with deoxygenated blood and therefore, the oxygen content of
the blood reaching the cells reduces. That is why Ali has been advised to avoid physical activity.
2. Phloem conducts the food in the plant from the leaves to the other parts. If we remove a portion of the
phloem, downward transportation of food gets blocked and so the portion above gets swollen.
3. The thick wall septum divides the left and right side of the heart preventing mixing of pure and impure blood.
4. The xylem transports water from the roots to all parts of the plant whereas the phloem transports organic
nutrients. The xylem in a plant exists as non-living tissue at maturity whereas the phloem exists as living
cells. The xylem and phloem are both vascular tissues found in plants.
5. The walls of the ventricles are thicker and contain more cardiac muscle than the walls of the atria. This
enables the ventricles to pump blood out to the lungs and the rest of the body.
Jiwan® Science CCE Question Bank Answer Key-7/54
Chapter- 12 : Reproduction in Plants
Objective Type Questions
A. Fill in the blanks.
1. asexual, sexual
2. spore
NCERT Questions
3. vegetative propagation
4. unisexual flower
5. pollination
6. Fertilization
7. Wind, water and animals.
B. Write whether the following statements are true or false.
1. True
2. True
3. True
4. False
5. True
6. False
7. True
8. True
9. True
10. True
11. True
12. True
13. True
14. False
15. False
16. True
17. True
C.Match the two columns to make correct pairs.
1. a. vi
b. v
c. iv
d. ii
e. i
f. iii
NCERT Questions
2. a. iii
b. v
c. ii
d. i
e. iv
D.Multiple choice questions. Tick the correct option in each case.
1. a
2. b
3. d
4. c
5. b
6. b
7. a
8. d
9. a
10. a
NCERT Questions
11. d
12. a 13. d 14. b 15. b
16. a 17. c
18. a
19. c
20. c
21. a
22. c
E. Name them.
1. Asexual reproduction
2. Fertilization
3. Dandelion
4. Pea
Descriptive Questions.
F. Very short answer questions.
1. Vegetative parts of a plant are its leaves, stem, roots, etc.
2. Flowers can be either unisexual or bisexual. Some flowers carry both male and the female part on them.
They are called bisexual or hermaphrodites or complete flowers.
3. The stem tuber of the potato gives rise to a new plant.
4. Strawberry develops side shoots which have buds that develop into new plants.
5. A hybrid variety is a plant which is a cross between two different varieties of a species. It carries the
characteristics of both the varieties.
6. For producing a new plant by tissue culture, a small piece of tissue is extracted from the parent plant. This
is called explant.
7. The end product of fertilisation is a zygote.
8. Wind dispersal allows the seeds to be spread in a wide area. Dandelion seeds have wings which help
them to be easily carried by wind.
9. Seed dispersal is a method of carrying seeds from one place to another over a wide area to help them
find favourable conditions for growth.
10. Germination is the process of a new plant growing out of a seed, when conditions are favourable.
11. 1. Reproduction: The ability of living organisms to produce their own kind is called reproduction.
2. Asexual Reproduction: It is the kind of reproduction in which only one parent is involved.
3. Vegetative Propagation: When a new plant arises from one of the vegetative parts of the plant like
stem, leaf or root, it is known as vegetative propagation.
4. Adventitious Buds: The leaves of some plants like Bryophyllum have buds along their margin which
give rise to new plants. These are called adventitious buds.
5. Corm: A corm is an underground stem that gives rise to daughter plants as in colocasia or gladioli.
Jiwan® Science CCE Question Bank Answer Key-7/55
NCERT Questions
12. Spore formation.
13. Rice-grows from a seed.
14. A branch and a bud.
15. Self pollination.
16. These plants are called weeds. Their seeds are dispersed by wind and grows wherever they find
favourable conditions.
G. Short answer questions.
1. Pollen tube is a long tube which develops from the pollen to the stigma down below to the ovule. This
tube helps to transfer the male gamete to the ovule.
2. Reproduction is important as it helps in the survival of species and continues the genetic characteristics
of the mother species.
3. The two types of flowers are unisexual and bisexual flowers. Unisexual flowers have only one of the
reproductive organs either male or female. Bisexual flowers carry both the male and female reproductive
organs.
4. The method of producing a new plant from one of the vegetative parts of the plant is called vegetative
propagation. It can be roots, stem, or leaves.
5. The buds that develop along the margin of some plants like the byophyllum, develop into new plants.
They are called adventitious buds.
6. Grafting helps to produce new varieties with superior qualities. It helps in producing disease resistant
and high yielding varieties.
7. Budding is a method of reproduction in microbes like yeast. A bud like cellular outgrowth develops from
the parent plant, grows till it reaches the maximum size and then separates from the parent plant.
8. Flowers pollinated by insects are: (a) Sweet smelling (b) Brightly coloured (c) Produce nectar (d) Have
sticky stigma and pollen grains.
9. When pollens fall on the stigma of the right flower, a pollen tube grows from the pollen to the ovule
through the stigma and the pollen is transferred to the ovule through this tube which then fuses with the
egg in the ovule and the zygote is formed.
10. After fertilization, the petals, stamens and the sepals wither away. The style and the stigma also fall off.
The zygote obtains nutrition from the ovule and starts growing by the process of cell division. The zygote
thus develops into an embryo. The embryo is embedded in the seed leaves which are rich in stored food.
The ovule also develops hard layers which forms a protective coat to the seed.
11. Seed dormancy is the state of rest of seeds. The seeds generally remain inactive until they get the
favourable conditions of growth like moisture, warmth and air.
Seed hibernation, also called seed dormancy, is the ability of a seed to remain in hibernation when there
is a lack of things essential to their development (water, sunlight, nutrients, etc.) or in harsh conditions
(extreme cold, extreme heat, hard ground, etc.). There is not a specific time limit in which a seed may
hibernate; some seeds found in the arctic grew after an estimated 10,000 years. When conditions are
right for the particular type of seed, they can come out of hibernation and grow.
12. In asexual reproduction plants can give rise to new plants without seeds, whereas in sexual
reproduction, new plants are obtained from seeds.
13. A seed start germinating when it gets light, soil, water, air, the basic requirement for the process of
germination.
14. Cutting, grafting, layering and tissue culture.
15. a) Pollen grain
b) Pollen tube c) Zygote formation
16. a) Fungus
b) Spores of fungus cover germinate when they get favourable conditions for growth.
17. a. ii
b. i
c. iii
Jiwan® Science CCE Question Bank Answer Key-7/56
18. The coconut palm tree is a widely-dispersed species due to special adaptations developed by its seed.
The seed floats due to an internal air cavity. The coconut's external husk protects the internal seed from
predators and the salt of the ocean. The coconut palm is one of the most successful of the ocean drifter
species.
H. Long answer questions.
1. Tissue Culture: In this method, used for plants such as chrysanthemum, orchids and asparagus, a small
piece of tissue is extracted from the parent plant. This is called explant and is kept in a nutrient rich
medium to promote cell division. The cells divide into a loosely arranged mass called callus, which slowly
multiply giving rise to shoot and root.
2. Agents of Pollination :
Insects: They are attracted to the colour and fragrance of petals. They also visit the flowers to collect the
sweet juice called nectar. Nectar is obtained from the base of the flowers and as the insect sits on the
flower, the pollen grains stick to the body of the insects. As the insect visits another flower, these pollens
are dropped at the stigma of that flower. Insect pollinated flowers are:
• Sweet smelling and brightly coloured.
• Produce nectar.
• Have sticky stigma and pollen grains.
Wind: Strong winds blow away pollens from the anther of one flower to the stigma of another flower. Such
flowers are:
• Not brightly coloured, no nectar.
• Have light pollen grains.
Have large anthers, loosely attached.
• Stigma hang out to trap pollen grains.
Water: This is responsible for pollination in most aquatic plants like sea grass. The pollens fall in water
and are carried by the water current.
Mammals: Bats and rodents are attracted to flower which:
• Have a strong odour.
• Often brown or white.
• Huge in size to bear their weight.
Birds: Sun birds and humming birds have long beaks to reach the nectarines. They are attracted to
brightly coloured flowers which may not usually be scented.
3. A seed can germinate or give rise to a new plant only if the conditions are favourable, or else it stays in a
dormant state. Seed dormancy is a state of rest of the seeds. As the seed takes in water and oxygen the
enzymes in the seed begin to function to change the stored food into soluble form. This provides the
energy for growth and cell division. The radicle gives rise to the root and then the plumule begins to push
up into shoot and leaves after which the plant begins to make its own food.
Seed Germination Stages
4. Grafting is a common method used for developing hybrid varieties of fruits and flowers. In this method
two varieties of a species with the most desirable characteristics are chosen. One of it is rooted in the soil
and only its stump is retained. This is called the STOCK. The other plant's stem with several buds is bent
Jiwan® Science CCE Question Bank Answer Key-7/57
and placed over the stock and two are finely tied together as one plant. The two plants continue to grow
and from the point where they are tied together, a new plant starts developing. This plant will carry the
cells of both the varieties and hence will have the characteristics of both.
5. Tissue Culture: In this method, used for plants such as chrysanthemum, orchids and asparagus, a small
piece of tissue is extracted from the parent plant. This is called explant and is kept in a nutrient rich
medium to promote cell division. The cells divide into a loosely arranged mass called callus, which slowly
multiply giving rise to shoot and root.
6. A complete flower has four whorls:
Sepals: These are modified leaves that protect the petals in the bud and are usually green in colour.
Petals: They are brightly coloured leaf like structures, that function to attract insects.
Stamens: They bear the anther that contains the pollen grains. Pollen grains have male gametes in
them. Stamen is thus the male part.
Pistil: It is the female organ that is divided into — stigma, style and ovary. The female gametes called the
ovules are contained in the ovary.
NCERT Questions
7. a) stamens
b) pistil
c) stigma
d) petal
8. a) zygote
b) fertilization
c) embryo
d) seeds
e) fruit
9. a) wind
b) birds and animals
c) animals and humans
10. a) Petal
b) Sepal
c) Stamen
11. There are different methods by which plants reproduce asexually. They are vegetative propagation,
budding, fragmentation and spore formation. The vegetative parts of a plant are the roots, stems and
leaves. When new plants are produced from these parts, the process is called vegetative propagation.
1. Budding- A bulb like projection grows on the parent organism. It grows and may eventually break
away from the parent. E.g. yeast, hydra, corals, sponges.
2. Fragmentation- The organism breaks up into two or more fragments after maturation. These
fragments grow into new individuals. E.g. spirogyra, hydra.
3. Spore formation- A spore is a tiny, spherical and unicellular body protected by a thick wall. Under
favourable conditions, a spore germinates and develops into a new individual. E.g. mosses, ferns,
moulds.
12. In sexual reproduction, new plants are obtained from seeds. The flowers are the reproductive parts of a
plant. The stamens are the male reproductive part and the pistil is the female reproductive part. A pistil
consists of stigma, style and ovary. The ovary contains one or more ovules. The transfer of pollen from the
anther to the stigma of a flower is called pollination. The female gamete or the egg is formed in an ovule. In
sexual reproduction a male and a female gamete fuse to form a zygote. The process of fusion of male and
female gametes (to form a zygote) is called fertilisation. The zygote develops into an embryo. After
fertilisation, the ovary grows into a fruit and other parts of the flower fall off. The fruit is the ripened ovary. The
seeds develop from the ovules. The seed contains an embryo enclosed in a protective seed coat. Seeds
and fruits of plants are carried away by wind, water and animals and reproduced again on the grounds.
13.
Anther
Stigma
Filament
Filament
(a) Stamen
Ovary
(b) Pistil
Reproductive parts of a Flower
Jiwan Science CCE Question Bank Answer Key-7/58
®
14. Pollination is of two types, self-pollination and cross-pollination. In self-pollination, pollen grains are
transferred from the anther to the stigma of the same flower. In cross-pollination, pollen grains are
transferred from the anther of one flower to the stigma of another flower of the same kind.
Pollens
Stigma
Anther
(a) Self-Pollination
(b) Cross-Pollination
Self Pollination and Cross Pollination
15. The flowers are the reproductive parts of a plant. The stamens are the male reproductive part and the
pistil is the female reproductive part. A pistil consists of stigma, style and ovary. The ovary contains one
or more ovules. The transfer of pollen from the anther to the stigma of a flower is called pollination. The
female gamete or the egg is formed in an ovule the process of fusion of male and female gametes (to
form a zygote) in flowers is called fertilisation. The zygote develops into an embryo. After fertilisation, the
ovary grows into a fruit and other parts of the flower fall off. The fruit is the ripened ovary. The seeds
develop from the ovules. The seed contains an embryo enclosed in a protective seed coat. Seeds and
fruits of plants are carried away by wind, water and animals and reproduced again on the grounds.
16. Seed are dispersed by wind, water and animals.Winged seeds such as those of drumstick and maple,
light seeds of grasses or hairy seeds of aak (Madar) and hairy fruit of sunflower, get blown off with the
wind to faraway places. Some seeds are dispersed by water. These fruits or seeds usually develop
floating ability in the form of spongy or fibrous outer coat as in coconut. Some seeds are dispersed by
animals, especially spiny seeds with hooks which get attached to the bodies of animals and are carried
to distant places. Examples are Xanthium and Urena. Some seeds are dispersed when the fruits burst
with sudden jerks. The seeds are scattered far from the parent plant. This happens in the case of castor
and balsam.
I. Give reasons.
1. Asparagus grows from a 1 year old plant or roots.
2. Explant is kept in nutrient rich medium so that it can be induced to rapidly produce new shoots.
3. Grafting is used in agriculture often because it can create numerous advantages for both the plant and
the farmer. For example, apple trees are often grafted because they can be made shorter and therefore
easier to cultivate. Other crops are grafted so that they have disease-resistant roots or so that they can
increase the quantity of fruit or vegetable product they produce.
J. HOTS questions.
1. Insect pollinated flowers are generally small in size to help insects to collect nectar easily. The insects
are attracted to the flowers for nectar and in that process they transfer the pollen from one flower to the
other.
2. Since seeds remain dormant for a long period, the hard outer coat helps in protecting the seeds from
absorbing moisture and being damaged by outside agents. The embryo inside the seed has life and
needs protection from chemical and physical damage.
3. Spring season is the flowering season. All the flowers are in full bloom and so, the air is carrying a lot of
pollen grains. So, people who have allergic tendencies and breathing problems find it tough since their
condition worsens due to pollens present in air.
Jiwan® Science CCE Question Bank Answer Key-7/59
Chapter- 13 : Time and Motion
Objective Type Questions
A. Fill in the blanks.
1. Quantum process
2. odometer
3. curved
4. Footsteps, handspan
5. Quarty
6. Extreme position
7. speedometer
B. Write whether the following statements are true or false.
1. True
2. False
3. False
4. False
5. False
6. False
NCERT Questions
7. True
8. False
9. True
10. False
11. False
C. Match the two columns to make correct pairs.
1. a. iv
b. i
c. ii
d. v
e. iii
D.Multiple choice questions. Tick the correct option in each case.
1. c
2. d
3. c
4. a
5. a
6. c
NCERT Questions
7. d
8. b
9. d 10. c
11. a
12. b 13. d
14. a
15. d
16. a
17. b
E. Name them.
1. Speed
2. Pendulum
3. Oscillation
4. Motion
Descriptive Questions.
F. Very short answer questions.
1. Sundial and Hourglass.
2. CGS system of units the unit for Mass was Gram, Length was Centimeter and Time was Sec. In FPS,
pound was the measure for Mass, Feet was the measure of Length, and sec is for time.
3. The steady rise and fall of water level in a vessel with markings on the inside surface were used to
measure the passage of time.
4. An odometer is an instrument attached to the steering panel of vehicles to record the distance travelled
by a vehicle.
5. Quantities like weight, time, length, etc., that can be measured, are called physical quantities.
6. SI stands of Systems International de Unites.
7. An oscillation is the time taken for one to and fro movement about the mean position of a pendulum.
8. Sundials can be fairly accurate. The largest sundial is in Jaipur and could measure time upto an accuracy
of two seconds. But they can't be used when the sun is away.
9. The speed of an object is the distance travelled divided by the time taken. Speed = distance/time.
10. The motion of the planets around the sun is an example of uniform motion.
3
11. The SI base unit of length is the meter (m). The SI base unit for volume is the cubic meter m . The SI base
unit for mass is kilogram (kg). The SI base unit for temperature is kelvin (K).
12. The SI unit of speed is metre/second (m/s).
13. The time increases with the increase in length.
14. A graph that is steadily rising straight line depicts uniform motion.
15. Uniform motion
16. Oscillation
17. Crystal of quartz
18. Stopwatch
19. Uniform motion
Jiwan® Science CCE Question Bank Answer Key-7/60
NCERT Questions
20. (a) oscillatory motion
(b) straight line motion
(c) straight line motion
(d) oscillatory motion
(e) oscillatory motion
(f) straight line motion
21.Time taken to complete 20 oscillations = 32 s
Time period of the pendulum
= Nos of oscillations/ Total Time taken
= 32/20 s = 1.6s
22.The distance between two stations
= 240 km
Time taken by the train to cover that distance = 4 hours
Speed of the train
= 240/4 Km/h = 60 km/h
23.Uniform motion
24.Boojho's speed is more than Paheli's.
25.Periodic motion
G. Short answer questions.
1. Measurement is the comparison of an unknown quantity with some fixed quantity of the same kind. The
humidity, temperature, length, weight, time, etc., can be measured.
2. The time taken by the pendulum to complete one oscillation is time period.
3. Crystals of quartz send pulses or vibrations at a very precise rate and so measure time very accurately.
They don't get affected by weather conditions.
4. The distance travelled = 50 km = 50 × 1000 m = 5000 m
The time = 1 hr = 60 mintues × 60 Seconds = 3600 seconds
Speed =
Distance
Time
=
5000 m
3600 sec
=
50 m/s
36
Ans. Speed of the car 13.9 m/s.
5. The distance = 6 m
Time = 10 sec
Distance
6m
=
\Speed =
= 0.6 m/s
10 seconds
Time
Ans. Speed of the ant = 0.6m/s.
6. Motion in which a body covers unequal distance in equal intervals of time is called non-uniform motion.
7. Distance for going forward and backward = 120 × 2 = 240 km.
Speed of the car = 60 km/hr.
Distance
240 km
=
60 km/hr
Time
Ans. 4 hrs.
8. CGS system
FPS system
Unit of length — Centimeter
Foot
Unit weight — Gram
Pound
Unit of time — Second
Second
9. An object is said to be moving with uniform speed if it covers equal distances in equal intervals of time.
10. The modern electronic watches are based on the principle of quartz.
\ Time =
Jiwan® Science CCE Question Bank Answer Key-7/61
NCERT Questions
11. A is moving faster.
12. C diagrams shows that the truck is moving with a speed which is not constant.
13. Distance-8, 16. Time-6
14. 386208000seconds
15. 10 km/s
16. Non uniform motion
17. Graph shown:
Time (sec)
x
15
30
45
60
Distance (cm)
y
16
32
48
64
Distance (cm)
16
16
16
16
15
30
45
Time (sec)
60
H. Long answer questions.
1. A simple pendulum is made by suspending a weight on a string. The characteristic of a pendulum is that
irrespective of the weight of the suspended object, or the nature of its material, for a given length, the
pendulum always completes its oscillation at the same time. So, this property is used in construction of
pendulum clocks. Each oscillation moves the second hand. So, 60 oscillations will result in the
movement of the minute hand, through one division and so on. In 1665,Christian Huygens, a Dutch
physician made the first pendulum clock.
2. The various systems of measurements are CGS System where the units of length, weight and time are
centimeter, gram and second. FPS system where the units of length, weight and time are foot, pound and
second, and SI system where units of length, weight and time are metre, kilogram and second.
3.
y
D
8
Distance (m)
6
C
4
B
A
2
0
9.00
9.05
9.10
9.15
9.20
x
Time (min)
Distance-Time Graph for Non-Uniform Motion
4. Solution
speed after 2 second =15/2 = 7.5 m/s
speed after 4 second = 30/4 = 7.5 m/s
speed after 6 second = 45/6 = 7.5 m/s
Jiwan® Science CCE Question Bank Answer Key-7/62
speed after 8 second = 60/8 = 7.5 m/s
speed after 10 second = 75/10 = 7.5 m/s
The motion is uniform
y
Scale
X axis = 1 am = 1 sec
y axis = 1 am = 10 in
80
70
Distance (m)
60
50
40
30
20
10
O
1
2
3
4
5
6
7
8
9
10 x
Time (sec)
Distance (in Km)
5. Uniform motion
An object moving along a straight line with a constant speed is said to be in uniform motion.
In this case, the average speed is the same as the actual speed.
Non-uniform motion
If the speed of an object moving along a straight line keeps changing, its motion is said to be non-uniform.
In this case, the average speed is different fron the actual speed.
NCERT Questions
6. Initial reading of car odometer
= 57321.0 km
Final reading of car odometer
= 57336.0 km
Time at the time of initial reading = 08:30 AM
Time at the time of initial reading = 08:50 AM
Distance travelled by the car
= 57336.0 km - 57321.0 km
= 15 Km
Time taken by the car to cover distance = 08:50 AM - 08:30 AM
= 20 m
Speed of the car (in Km/m)
= 15 km/20m
= .75 Km/m
Speed of the car (in Km/h)
= 15 km/20m X 60
= 45 Km/h.
7. Solution
Speed of bicycle
= 2 m/s
Time taken by Salma to reach school = 15 minutes = 15 × 60 Seconds
Distance between her house and the school = Speed of bicycle × Time taken
= 2 m/s × 15 × 60 s
= 1800 m or 1.8 Km.
8. a.
100
90
80
70
60
50
40
30
20
10
0
0 10 20 30 40 50 60
Time (in minutes)
Distance– Time Graph for A car moving with a constant speed
Jiwan® Science CCE Question Bank Answer Key-7/63
Distance (in Km)
8. b.
100
90
80
70
60
50
40
30
20
10
0
0 10 20 30 40 50 60
Time (in minutes)
Distance– Time Graph for a car parked on side road
9. a. 8m from the point of origin b. 6m
c. 2.15m/s
10. speed for second part of journey = 3.33m/s
Average speed for entire journey = 2.77m/s
11. a. Bhoojho stopped in between points B and C i.e. no motion
b. Non-uniform
c. 0.270m/s
I. Give reasons.
1. In olden times there was a need to have instruments that could give better precision of time.
2. Quartz crystals emit vibrations are fixed frequency. These vibrations (pulses) are counted and are used
to measure time. It can measure time up to milliseconds and has high accuracy i.e., a normal quartz
wristwatch may lose or gain less than a fraction of a second in a day. While the mechanical clocks used
earlier were based on weights and spring which rotate the gears. The lowest time interval these
mechanical clocks are up to minute. Hence accuracy of quartz clocks is more accurate than the clocks of
earlier times.
3. Long ago, people used footsteps, handspan or arm length to measure length, but these units of
measurement proved unreliable as these lengths varied from person to person. there was thus a need
for units of measurement that were uniform and gave the exact measurement. Such units are called
standard units. The system of SI units or System of International deUnites(French) has been adopted for
uniformity in measurement.
J. HOTS questions.
1. Bullet train uses electromagnetic force to propel trains down the track. It runs on special magnetic tracks.
It can gain a speed of 300 km/hr using overhead power supply of 25,000 volts.
2. The speed of the bus = 64 km/hr =
64 × 100
60 × 60
= 640/18=160/9 =17.78m/s.
The speed of the car = 12.5 m/s.
\ The bus is moving at a greater speed.
3. Length and mass were the earliest measurements made by mankind. Time measurement was done in
terms of length as distance and mass. For example position of sun, moon and stars give idea of days,
months and years. Later mechanical clocks based on weights and spring can measure time accurately
up to minutes. Today atomic clocks measure time accurately upto nano-seconds by measuring waves
emitted by Cesium clock in terms of speed of light and frequency. Over the time improvements in
accuracy in measuring length and mass help in measuring time with more accuracy and precision.
Jiwan® Science CCE Question Bank Answer Key-7/64
Chapter- 14 : Electric Current and its Effects
Objective Type Questions
A. Fill in the blanks.
1. circuit diagram
2. low
3.
a soft iron core
4. break in circuit
5. reverses
6.
alloy of tin and lead
7. Mini Circuit Breaker
8. resistance
9.
insulators like air
11. good conductor
12. electrolyte
13.
safety device
14. negative
15. battery
16.
becomes red hot and gives out heat
10. elements
NCERT Questions
17. fuse
B. Write whether the following statements are true or false.
1. True
2. False
3. False
4. True
8. False
9. True
5. False
NCERT Questions
6. False
7. True
C. Match the two columns to make correct pairs.
1. a. iii
b. iv
c. i
d.
ii
e.
v
D. Multiple choice questions. Tick the correct option in each case.
1. c
2. b
3. c
4. d
5. b
11. c
12. b
13. c
6. d
7. c
8. a
NCERT Questions
9. c
10. a
E. Name them.
1. Voltage
2. Electromagnet
3. Solenoid
4. Voltaic pile
5. Connecting points
Descriptive Questions.
F. Very short answer questions.
1. Electricity is energy on account of flow of electrons.
2. Electric iron, electric oven, electric toaster, electric water heater.
3. An electromagnet is a coil of insulted wire wound round a piece of magnetic substance that behaves like
a magnet as long as the current is flowing through it.
4. An electric circuit consists of a battery, a key, wires and an object which works on electricity.
5. a. Water Geyser — Heating effect of electricity,
b. Electric Bell — Magnetic effect of electricity.
6. Magnetic effect of electric current is used in electromagnetic cranes used for lifting heavy scraps.
7. A conductor heats up on passing electricity due to the resistance offered by the conducting material. The
higher the resistance, the more will be the heat produced.
8. Two main effects of current are heating effect and magnetic effect.
9. The core of an electromagnet is made of soft iron.
NCERT Questions
10. a. BATTERY
b. FUSE
c. TORCH
d. SWITCH
11. Fuse is a metal wire or strip that melts when too much current flows, which interrupts the circuiting which
it is connected. Short circuit, overloading, mismatched loads or device failure are the prime reasons for
excessive current. Fuses are a simple, economical, and low-maintenance alternative to circuit breakers.
Jiwan® Science CCE Question Bank Answer Key-7/65
12. MCBs or Miniature Circuit Breakers (MCBs) are electric safety devices being used in place of fuses.
These are a kind of switch which turns off (breaks electric circuit) automatically when excessive current
flows due to short circuit.
13. No. She has not done the right thing. A lighted bulb is already hot so it might break.
14. A CFL has a higher purchase price than an incandescent lamp, but can save over five times its purchase
price in electricity costs over the lamp's lifetime.
G.Short answer questions.
1. Diagram of an open electric circuit with a cell and bulb.
Cell
Switch
+
-
Bulb
2. An electric fuse is a thin wire made of an alloy of tin and lead, with a low melting point. When excess
current flows, it gets heated and melts thus breaking the circuit.
3. The strength of the electromagnet depends on the number of turns in the coil and the strength of the current.
4. The deflection of needle in a magnetic compass will depend on (a) strength of the current (b) The
direction of flow of current.
5. MCB stands for miniature circuit breaker, a device used for monitoring the main supply of electricity when
it exceeds the specified maximum limit. The MCB automatically stops the current and protects the
buildings or homes.
6. Copper is an excellent conductor with low resistance and does not get heated. It has high melting point
and so it is well suited for electrical wires.
7. Electromagnets are used in a. Electric Bells and b. Electromagnetic cranes.
NCERT Questions
8. No, as the wattage of both electrical appliances are different.
9. a. Hair dryer and microwave used heating effect of current b. an electric bell and a magnetic crane
uses magnetic effect.
10. An electromagnet cannot be used for separating plastic bags from a garbage heap as it attracts only iron
pieces and will not attract plastic bags.
11. There is a maximum limit on the current which can safely flow through a circuit. If by accident the current
exceeds this safe limit, the wires may become overheated and may cause fire. To prevent this, In all
buildings fuses are inserted in all electrical circuits. If a proper fuse is there in the circuit, it will blow off and
break the circuit. A fuse is thus a safety device which prevents damages to electrical circuits and possible
fires. So, we will not agree with an electrician, who is using a wire in place of fuse of proper rating as if by
accident the current exceeds safe limit, the wires may become overheated and may cause fire.
12. Following can be the possible reasons:
1. The bulb may be fused due to broken element.
2. Cells are not connected properly i.e. +ve terminal of first cell should connect to -ve terminal of the
second one.
3. There may be loose connections. e.g. wire is not connected properly to switch or to the bulb.
4. The switch is not functioning well.
5. The cells are dried up. The power of the cell i.e, chemical inside the cell which produces electric
current has been exhausted.
Jiwan® Science CCE Question Bank Answer Key-7/66
13. a. None of the bulb will glow when the switch is in the 'OFF' position as there will be no electric current
in the circuit. b. The Bulb A, B and C will glow when they are connected as shown in the figure given
below and the switch is moved to 'ON' position.
H. Long answer questions.
1. a. Heating effect of current
Materials Required: Key, battery, a piece of cardboard drawing pins, nichrome wire.
Procedure: Use the elements given above to form a circuit as shown. Touch the wire and feel the
temperature. Switch on the circuit for 3-4 minutes and feel the air above it. You’ll feel the heat
emanating from it. It proves that current can produce heating effect.
2. a. Magnetic effect of current
Materials Required : A cardboard tray of a matchbox, an electric wire, a small compass needle, an
electric cell, a switch.
Procedure : First wrap an electric wire a few time around the cardboard tray, Place the small
compass needle inside the tray. Now, connect the free ends of the wire to an electric cell through a
switch. First note the direction of the compass needle and bring a bar magnet close to it. Now move
the switch to the ‘ON’ position and carefully observe the deflection of compass needle. Move the
switch to the ‘OFF’ position and observe the needle's position. Normally the compass needle points
in the N-S direction. It gets deflected when a magnet is brought close to it. The compass needle also
deflects when the current flow in to the wire. This experiment proves that the current also produces
magnetic effect.
3. a. After switching the current what happens, Do the pins cling to the tip of the nail? b. Switch off the
current, are the pins still clinging to the end of the nail?
c. What make the pins to cling to the nail?
4. The amount of heat produced in a wire depends on a)its length – as length increases heat produced
increases; e.g. elements are coiled in heaters to increase length and thickness – as thickness increases
heat produced decreases; e.g. lead wires of iron, heater etc., are thicker than normal connecting wire so
that they don't get heated up easily. a. No, heat produced will not be same b. Again it will not be
same. Heat produced will be more in case of less thick wire.
5. An electric bell works when an electrical current flows through an electromagnetic coil. This causes a
piece of iron inside the bell, called a striker, to be attracted to the electromagnet and when it is, it strikes
the side of the bell housing. The contact is broken as the striker moves toward the bell so it moves back to
its original place, makes contact with electric again, and the cycle repeats.
Battery
Switch
Spring
Soft iron armature
Gong
Electromagnet
Hammer
Jiwan® Science CCE Question Bank Answer Key-7/67
6.
Symbols of electric components
Electric components
a.
Electric cell
b.
Switch in OFF position
c.
Electric bulb
d.
Battery
Symbol
I. Give reasons.
1. There is a maximum limit on the current which can safely flow through a circuit. If by accident the current
limit exceeds this safe limit, the wires may become overheated and may cause fire. If proper fuse is there
in the circuit, it will blow off and break the circuit. A fuse is thus a safety device which prevents damages to
electrical circuits and possible fires.
2. We cover it with a plastic so that kids do not get an electric shock and plastics are bad conductor of heat
and electricity they stop the current flow.
NCERT Questions
3. Therefore, Paheli's electromagnet will attract more pins because it has more winding of wire, thus will
generate greater force of attraction in comparison to the Boojho's electromagnet having less number of
windings.
J. HOTS questions.
1. Every room of an apartment has wiring done in parallel. Each route of the wire is connecting to MCB so
that any appliance used in that circuit should be protected against damage. In addition we have lines of
different ratings used for different purposes. Therefore, many MCBs are installed for independently
protecting them.
2. Fuse wire melts because it has a very low melting point. Other wires are made of metals with high melting
points so they don't melt.
NCERT Questions
3. The magnetic field strength is proportional to the number of turns of the winding. for a given current
increasing the number of turns will increase the strength of the field, up to the point where the core
saturates.
Jiwan® Science CCE Question Bank Answer Key-7/68
Chapter- 15 : Water
Objective Type Questions
A. Fill in the blanks.
1. lithosphere
2. Coal, gas, oil
3. Plastic, aluminium and glass
4. 97.41
5. 1.984
NCERT Questions
6. digging wells and tube wells. 7. ice, water and water vapour 8. aquifer
9. infiltration
B. Write whether the following statements are true or false.
1. False
2. False
3. False
4. False
5. False
6. False
7. False
8. False
9. True
NCERT Question
10. False
11. False
12. False
13. True
14. True
15. True
16. True
17. True
18. False
19. False
20. False
21. False
22. False
23. True
24. False
C.Match the two columns to make correct pairs.
1. a. iv
b. i
c. ii
d. iii
D.Multiple choice questions. Tick the correct option in each case.
1. b
2. b
3. d
4. c
5. c
NCERT Questions
6. c
7. d
8. c
9. a 10. a
11. b 12. c
13. a
14. d
15. c
16. d
17. a
E. Name them.
1. Natural resources
2. Water table
3. Glacier
4. Rainwater harvesting
5. Water cycle
Descriptive Questions.
F. Very short answer questions.
1. Soil and water.
2. Resources which are not easily replenished in short intervals of time and take a very long time to get
renewed are called non-renewable resources.
3. Surface run off refers to that part of precipitation which seeps into the ground and becomes a part of the
ground water.
4. Large scale deforestation has reduced the amount of rainfall and it can be considered as the major cause
of depleting water table.
5. Rain water harvesting is the method of collecting the rainwater falling on roof tops of buildings and on
ground and channellizing those to enrich the subsoil water or collection of rain water in tanks for daily
needs.
6. a. Aquifer is ground water stored between layers of hard rock below th water table .
b. The process of seeping of water in the ground is called infiltration.
c. The evaporation of water from oceans and its arrival back into oceans is called water cycle.
G. Short answer questions.
1. Soil is considered a renewable resource since the formation of soil has been an ongoing process brought
about by natural forces. But due to indiscriminate use of soil, the top soil has eroded in so many places
that it will take thousands of years to replenish itself.
Jiwan® Science CCE Question Bank Answer Key-7/69
2. The various sources from which water vapour is formed are oceans, rivers, lakes, snow and ice plants
also help in formation of water vapour through transpiration.
3. Various forms of precipitation are snow, rain, sleet, hail and dew.
4. Aquifer is the space where ground water is stored and moves slowly.
5. Urbanization has led to the construction of many houses leading to land scarcity and increased land
covered in concrete so the renewal of the ground water table is diminishing.
6. Forests play a very important role in the water cycle. Rain water is soaked by the trees of the forests and it
promotes underground percolation of water. The plants help to a great extent in formation of water
vapour in the atmosphere through transpiration. So, cloud formation and precipitation is possible where
there is thick forest cover.
NCERT Questions
7. Water drawn from under the ground gets replenished by seepage of rainwater. The water table does not get
affected as long as we draw as much water as is replenished by natural processes. However, water table
may go down if the water is not sufficiently replenished. As stated, there are ten tube wells in a lane of fifty
houses, so the quantity of water being pumped out by 10 tube wells can not be replenished by the available
sources like rain, drainage to recharge the ground water table. As a result of this, in long term the water table
will be get depleted and after some years there will be no water for 10 tube wells to pump out.
8. For maintaining the garden, we can take following steps to minimise the use of water :
We can employ drip irrigation to water the garden. Drip irrigation is a technique of watering plants by
making use of narrow tubings which deliver water directly at the base of the plant.
We should water the plants in garden in early morning hours. If you are unable to water early in the
morning, late afternoon is the next best; this is after the sun's heat has lost its harshness but before the
chill in the air begins to set in. We should avoid using a sprinkler during windy weather, as the water will
blow away and evaporate, wasting the water.
H. Long answer questions.
1. Underground water refers to the rainwater that percolates into the lower layers of the soil. It collects
between the layers of soil and rocks. This forms the water table. The space where the groundwater is
stored and through which it moves slowly is known as aquifer. The groundwater passing through layers
of soil gets filtered and is almost free of suspended impurities. But it can contain salts and germs.
2. It is our responsibility to take care of water conservation at household level. The following measures
should be taken for it:
a. Do not allow the water to leak out of pipes and taps. Any leaking joint should be immediately fixed.
b. Water wastage should be avoided at all costs.
(i) Do not keep the tap water running when you brush, or clean utensils.
(ii) Use water sparingly and judiciously while washing clothes, mopping, etc.
(iii) Waste water obtained by washing grains, vegetables fruits etc., can be collected and used for
watering plants.
(iv) The waste water from RO filters should be reused in various areas like mopping floors, flushing
toilets, washing clothes, stairways, cars, etc.
(v) Take care not to throw away filtered, treated water. Serve only a small quantity at a time so that
we don't have to throw away the left over.
3. Water cycle: Water is one of the few substances that can exist in all the three states. Water from the
surface of the earth turns into water vapour by evaporation from the surface of oceans, rivers, lakes and
ponds. The water vapour can also be formed from green plants during transpiration and from ice as
sublimation. All the vapour rises up and condenses to form tiny droplets. These water droplets form
clouds. The clouds get heavier with more and more water droplets collecting in them. Eventually, they
Jiwan® Science CCE Question Bank Answer Key-7/70
become too heavy and fall down as rain, snow, sleet or hail. As the water returns to the ground, a lot of the
water returns, to oceans, rivers, lakes and ponds. Some of the snow and ice stay as glaciers. Some
percolate into the ground and become a part of ground water. This process of water leaving the earth and
returning to the earth is known as water cycle. It is essential to replenish used water and purify it.
Diagram of Water cycle
4. Factors that affect the water table of an area are:
(a) Increase in population: Due to rapid increase in population, there is more demand for drinking
cooking and washing needs.
(b) Urbanization: Urbanization leading to increased construction activities, concretization of the surface
of the ground, reduction in cultivable land area, etc., leads to reduction in ground water and increase
in demand.
(c) Failure of monsoon: Since monsoons fail frequently water table has been diminishing. It is due to the
overuse of ground water and very slow rate of replenishment.
(d) Deforestation: Rapid deforestation for building towns and factories. Forests aid in ground water
enrichment and lack of them will result in reduction of ground water.
NCERT Questions
5. The rainwater and water from other sources such as rivers and ponds seeps through the soil and fills the
empty spaces and cracks deep below the ground. The process of seeping of water into the ground is
called infiltration. The groundwater thus gets recharged by this process. At places the groundwater is
stored between layers of hard rock below the water table. This is known as an aquifer. Water in the
aquifers can be usually pumped out with the help of tube wells or hand pumps.
6. The factors responsible for the depletion of water table:
1. Increasing population
Increasing population creates demand for construction of houses, shops, offices, roads and
pavements. This decreases the open areas like parks, and playgrounds. This, in turn, decreases the
seepage of rainwater into the ground. What could be the consequence? A cemented floor does not
allow water to seep in easily, while in a grass lawn water seeps through it in no time. Moreover a huge
amount of water is required for construction work. Often groundwater is used for this purpose. So, on
the one hand we are consuming more groundwater, and on the other we are allowing lesser water to
seep into the ground. This results in depletion of water table. In fact, the water table in some parts of
many cities has gone down to alarmingly low levels.
2. Increasing industries
Water is used by all the industries. Almost everything that we use needs water somewhere in its
production process. The number of industries is increasing continuously. Water used by most of the
industries is drawn from the ground.
Jiwan® Science CCE Question Bank Answer Key-7/71
3. Agricultural activities
A majority of farmers in India depend upon rains for irrigating their crops. Irrigation systems such as
canals are there only in a few places. Even these systems may suffer from lack of water due to erratic
rainfall. Therefore, farmers have to use groundwater for irrigation. Population pressure on
agriculture forces increasing use of groundwater day by day. This results in depletion of water table.
7.
Clouds
Rains
Hand Pump
Recharge
Water Body
Water Table
Aquifer
Ground Water
I. HOTS Questions.
1. Though Cherrapunji is world's rainiest place, there is still acute water shortage because of widespread
destruction of coniferous forests that protected soil. The ground does not absorb the rain water. The city
of Cherrapunji is 1290 meter above sea level and much of the torrential rains run off the mountain to the
valley below. So, people there frequently have to travel on foot for several kilometers to get drinking
water.
2. A renewable resource is a natural resource that can replaces through biological or other natural
processes and get replenished after some time. They are an intergal part of natural environment but they
are endangered by industrial developments and growth. Solar radiation, biomass , tides, geothermal,
and winds are examples of renewable resources.
3. We need to conserve natural resources because these natural resources are the sources of our daily
needs. And if these resources are abused and harmed, we will have short quantity of sources for food
and living. Come to think of it, we can also be harmed if natural resources are abused. Because when
illegal loggers log trees endlessly in mountains, the rain that drops on mountain will not be absorbed by
the trees and if it's not absorbed by the trees, the water can cause mudslide that can affect those who live
on mountainside. Like that. so we have to conserve natural resources.
Jiwan® Science CCE Question Bank Answer Key-7/72
Chapter- 16 : Wind and Storm
Objective Type Questions
A. Fill in the blanks.
1. less dense
2. wind
3. convection current
4. Anemometer, wind vane
5. less
6. low pressure centre
NCERT Questions
7. flowing
8. uneven
9. warm, cooler
10. high, low
11. pressure
12. low
B. Write whether the following statements are true or false.
1. False
2. False
3. False
4. False
5. False
6. False
7. False
NCERT Questions
8. True
9. False
10. False
11. False
12. False
13. False
14. False
15. True
C. Match the two columns to make correct pairs.
1. a. v
b. iv
c. ii
d. i
e. iii
2. a. ii, iv b. i, iii
D. Multiple choice questions. Tick the correct option in each case.
1. d
2. b
3. b
4. d
5. d
6. b
NCERT Questions
7. c
8. d
9. c 10. d
11. b
12. b 13. c
E. Name them.
1. Monsoon
2. Tornadoes
3. Atmosphere
4. Atmospheric pressure
5. Anemometer
Descriptive Questions.
F. Very short answer questions.
1. The atmosphere is a layer of gases which surrounds the entire Earth. It consists mainly of Nitrogen,
Oxygen, as well as a few other gaseous elements.
2. Atmospheric pressure is defined as the force per unit area exerted against a surface by the weight of the
air above that surface.
3. Mountain climbers use oxygen tanks because the air is a lot thinner at high altitudes. Oxygen tanks
ensure that they get enough oxygen no matter how high they climb. Otherwise, they could die.
4. It is due to altitude sickness. Altitude sickness occurs when you cannot get enough oxygen from the air at
high altitudes.
5. Sudden changes in nature that bring large scale destruction to life and property are termed as natural
disaster.
6. Lift is the reduction in air pressure due to high wind speed.
7. Wind vane is used to know the direction of wind.
8. a. Central USA b. Equatorial area c. Coastal areas
9. A warning that informs people to prepare for an upcoming cyclone.
10. The centre.
NCERT Questions
11. Indian ocean
12. Sea is towards B side as wind from oceans towards the land as monsoon winds.
13. Afternoon
G. Short answer questions.
1. The thinning of air at high altitudes results in lower atmospheric pressure. The pressure exerted by fluids in
the body comparatively increases and that causes blood capillaries to break and causes nose bleeding.
Jiwan® Science CCE Question Bank Answer Key-7/73
2. The movement of air from a high pressure area to a low pressure area causes wind currents.
3. Convection currents are formed as a result of rising of warm air leading to a low pressure area causing
convection currents.
4. Lightning is caused by the rapid up and down movement of the water droplets within the clouds
producing electric charges.
5. Tornados mostly take place in the central part of United States of America.
6. Thunderstorms are a common occurrence in the tropical climate.
7. Air expands on heating and becomes lighter and lower in density. The air inside the balloon gets heated
up and so becomes lighter and exerts less pressure. This makes the balloon rise up.
8. A funnel cloud is a rotating cone shaped column of air extending downward from the base of a
thunderstorm, but not touching the ground. When it reaches the ground, it is called a tornado.
NCERT Questions
9. Method 1: We can find the wind direction using a Wind Vane or Weather Vane or Weather Cock. It
consists of a flat metallic sheet generally cut into shape of a cock or arrow which is mounted on disk and
free to move around an axial shaft and point in the direction of wind . They are typically used as an
architectural ornament to the highest point of a building.
Method 2: We can find the direction of light wind using smoke from aggarbatties. The direction of smoke
will indicate the wind direction.
10. 1. Filling air in a football: A football filled tight with air, take a shape of a sphere which is very difficult to
press and can even support the weight of a player.
2. Pumping the air : We use air pump to fill the air into cycle tires and sometimes football. In pumping, air
inside the pump cylinder get pressed by the moving the piston down and subsequently forced inside
the cycle tire tube or football through a valve. If we just close the outlet of pump with a finger, then it is
very difficult to move the piston rod further down to other end as pressed air has no where to go and
exert pressure on the piston thus preventing its further down movement.
11. If a bottle is capped and then left in the cold, the air inside the bottle cools faster than the air outside the
bottle. This means the air outside the bottle is exerting more pressure than the air inside the bottle, and
the bottle collapses.
12. The umbrella upturns due to the pressure of the wind.
13. Avoid a low pitched roof, use a hip roof or a high pitched gable roof.
H. Long answer questions.
1. Thunderstorms: Thunderstorm is a severe atmospheric disturbance that causes high speed storms
accompanied with lightning. Thunderstorms are most frequently an occurrence in the tropical climate. The
air near the surface heats up taking along with it a lot of moisture and is carried to great heights. In the higher
regions of the atmosphere, the vapour cools forming thunderclouds, rapidly falling as rain and hail. The rapid
up and down movement of the water droplets within the clouds produces electric charge that causes
lightning. Lightning heats the air in its path so quickly that a loud sound is produced that we hear as thunder.
2. a.
S.No.
Cyclone
Tornado
(i)
(ii)
(iii)
Any large scale atomospheric low
pressure system which often brings in
rain, thunder storms, etc.
Bigger, larger scale storms
Less violent as compared to tornadoes,
Some cyclones produce tornadoes but
most do not.
Are violent rotating column of air extending
from the base of a thunderstorm to the ground.
Relatively smaller
More violent
Jiwan® Science CCE Question Bank Answer Key-7/74
b.
c.
S.No.
Thunderstorm
Cyclone
(i)
A severe atmospheric disturbance
causing high speed storms with lightning.
Are powerful storms that can wipe out a whole
city.
(ii)
Phenomenon seen over land.
Do not develop over land. Occur over seas.
(iii)
Frequent occurrence in the tropical
climate
Frequent occurence over warm seas over the
equator.
S.No.
Tornado
Thunderstrom
(i)
Tornadoes are violent rotating columns
of air extending from the base of a
thunderstorm to the ground.
Thunderstorm are a serve atmospheric
disturbance causing high speed stroms with
frequent flash of lighting.
(ii)
Covers relatively small areas.
Covers relatively a large area.
(iii)
More violent and dest-ructive in nature.
It's effect in disastrous on the land area.
(iv)
Often form along the southern astal
belts of the U.S.A.
Occurs frequently in the tropical climate.
3. When a tornado strikes:
(a) One should listen to warnings on TV, radio and be alert.
(b) Avoid being on road, driving or moving.
(c) Take to a tornado shelter which is an underground room with no windows.
4. During a cyclone:
(a) Being in the sea or near a sea coast should be avoided.
(b) Food and water sources should be kept in safe storage locations to safeguard against food shortage
and water contamination.
(c) It is advisable to take shelter in cyclone shelters when the warning is issued.
NCERT Questions
5. We would not buy a house having windows but no ventilators, as there will be no cross ventilation of air
inside the room. Fresh cool air entering the room through window, gets heated through human and other
household activities like breathing, cooking and become lighter. This warm air rises up inside the room. If
there is no ventilator near the roof, the warm air will have no passage to leave as the level of window is
quite low from the level of warm air. This will increase the room temperature as well as humidity inside
leading to human discomfort.
6. Air exerts pressure in all directions. If banners and hoardings do not have holes, pressure exerted by
wind may tear them off or make them fall. Holes let the air pass through and reduce the air pressure on
banners and hoardings.
7. In case cyclone approaches our village or town, we can help our neighbours in following way :
• We should not ignore instread must listen to the warnings issued by the meteorological department
through TV, radio, or newspapers.
• We should make necessary arrangements to shift the essential household goods, domestic animals
and vehicles, etc., to safer places.
• Avoid driving on roads through standing water, as floods may have damaged the roads; and keep
ready the phone numbers of all emergency services like police, fire brigade, and medical centres.
• If you are staying in a cyclone hit area —
• Do not drink water that could be contaminated. Always store drinking water for emergencies.
• Do not touch wet switches and fallen power lines.
Jiwan® Science CCE Question Bank Answer Key-7/75
•
•
•
8.
Do not go out just for the sake of fun.
Do not pressurise the rescue force by making undue demands.
Cooperate and help your neighbours and friends.
With the help of satellites and radars, cyclone alert or cyclone watch is issued 48 hours in advance of
any expected storm and a cyclone warning is issued 24 hrs in advance. The message is broadcast
every hour or half hour when a cyclone is nearer the coast. We should not ignore the warnings
issued by the meteorological department through TV, radio, or newspapers. We should make
necessary arrangements to shift the essential household goods, domestic animals and vehicles,
etc., to safer places.
9. To expel air exhaust should be fitted near the ceiling because hot air being lighter rises up.
10. The clothes will move away from the balcony towards the sea because the hot air from the land rises
up and moves towards the sea is cooler than the land and so the air above it flows towards the land.
11. 1. Take two paper bags of the same size. Hang the two bags in an inverted position on the two ends
of a metal or a wooden stick.
2. Tie a piece of thread in the middle of the stick. Hold the stick by the thread as in a balance.
3. Put a burning candle below one of the bags.
4. The balance gets disturbed, the bag with candle below it rising up. As the warm air is lighter than
cold air, it rises up, pushing the bag above.
12. The trees bent towards the sea as the hot air from the land rises up and moves towards the sea.
I. Give reasons.
1. The hot air weighs less than cold air or hot air is less dense is a better expression. The heavier air moves
less and rests while the quicker moving less dense air rises.
2. Because storms draw their power and strength from the water they form over. Most hurricanes lose
intensity rapidly after making landfall because landforms, buildings and other obstacles "slow it down" by
removing the things it loves (low pressures, open spaces, light winds and warm water. So, the storm has
less chance to regenerate on land. As a result it loses power and energy.
3. Yes, the strongest winds occur at the eye of the cyclone became here the wind speed is sustained by the
steady flow of worm moist winds from the sea.
NCERT Questions
4. As Chandigarh is not near a coastline it is unlikely to be effected by cyclone. The whole coastline of India
is vulnerable to cyclones, particularly the east coast.
5. No. All of the doors and windows should be closed (and shuttered). So, that the pressure differences
between inside your house and outside in the storm do not build.
J. HOTS Questions.
1. The regions close to the equator receive the maximum heat of the sun and areas around the poles
receive minimum heat. This uneven heating of the earth gives rise to air currents. The warm air above the
equator rises and the cold air from the poles take its place. This creates wind currents that flow from the
poles to the equator on land.
Jiwan® Science CCE Question Bank Answer Key-7/76
Chapter- 17 : Light
Objective Type Questions
A. Fill in the blanks.
1. rectilinear propagation
2. image
3.
4. concave
5. VIBGYOR
6.
7. convex
8. convex
9.
NCERT Questions
10. concave mirror
11. mirror
12.
13. plane
14. real
15.
16. concave mirror
17. plane
18.
B. Write whether the following statements are true or false.
1. False
2. True
3. False
4. True
NCERT Questions
5. False
6. True
7. True
8. False
10. False
11. False
C. Match the two columns to make correct pairs.
1. a. v
b. ii
c. i, iv d. iii
e. vi
D. Multiple choice questions. Tick the correct option in each case.
1. b
2. b
3. a
4. a
5. c
6. d
NCERT Questions
7. c
8. b
9. b 10. d
11. b
12. b 13. c
14.
E. Name them.
1. Luminous
2. Virtual image
3. Concave
plane
convex
convex mirror
virtual image
lens
convex
9. False
b
4. Dispersion
5. Spectrum
Descriptive Questions.
F. Very short answer questions.
1. The curved concave surface.
2. The rebounding of light rays falling on a solid opaque surface.
3. No, light always travels in a straight line.
4. When light strikes a rough irregular surface, diffused reflection takes place.
5. A smooth, polished, regular surface will give a clear image.
6. When white light passes through a prism it splits into its constituent colours.
7. An image which cannot be caught on a screen is a virtual image.
8. Concave and Convex.
9. Concave mirrors concentrate light. They are used for the same purpose in making solar heating panels.
10. On metro stations convex mirrors are used to get a view of passenger or customer activity.
NCERT Questions
11. Concave lens.
G. Short answer questions.
1. Spherical mirrors are those whose reflecting surfaces are curved.
2. When the rays of a parallel beam of light move towards one another and meet at a point, we call it as
converging light. When the rays of a parallel beam of light move away from one another, we call it
diverging light.
3. In an ambulance, the word is written in a laterally inverted manner so that when viewed through the rear
view mirror of a vehicle on road, it can be read and will appear like normal alphabets.
4. A lens is a transparent glass or plastic with a curved surface. The two types of lenses are convex lens and
concave lens.
Jiwan® Science CCE Question Bank Answer Key-7/77
5. Converging Light
(i) When the rays of a beam of light passing through a medium bend inwards and move towards one
another to meet at a point, the light can be called as converging.
(ii) Convex lens converges light.
Diverging Light
(i) When the rays of beam of light passing through a medium bend outwards and move away from it one
can call it diverging light.
(ii) Concave lens diverges the light.
NCERT Questions
6. 1. Image is virtual.
2. It is behind the mirror.
3. Image is erect (means not inverted).
4. Image is of same size as the object.
5. Image is at same distance from the mirror as the object is from the mirror.
7. The alphabets A, H, I, M, O, T, U, V, W, X, Y will have images in plane mirror exactly the letter itself. The
reason for this is such letters are vertically symmetric i.e., vertical plane divides into identical halves.
Even if image interchanges, it appears same as the letter.
8. A convex mirror is used as a car/scooter rear side view mirror to view a wider angle behind the car.
9. A is a converging lens or convex lens and B is a diverging lens or concave lens.
10. No. Dispersion will take place as LASER light is always monochromatic: all particles have exactly the
same wavelength (colour) so they do not break into seven colours.
11. When the prism is turned upside down, the angle of refractions will change to the other direction, hence
the order of colors will also change correspondingly. Prism A will have VIBGYOR and prism B will have
ROYGBIV.
12. The driver will not be able to see the traffic behind him.
13. The torch will produce a diffused reflection.
14. Concave mirrors can produce real images.
15. Try to look at your image formed in both the mirrors. A concave forms an enlarged image of letters of the
newspaper but a convex mirror forms a real and inverted image of letters of the newspaper.
16. Convex mirror can be used as it can give a wide view of his shop.
17. The object is moving away from it.
H. Long answer questions.
1. Concave Mirrors:
(i) The image formed by a concave mirror is magnified and erect when the object is very close to the
mirror. So, it can be used as a magnifying mirror in beauty parlors, as shavring mirrors, by doctors to
check ear, nose, throat, etc., by dentists to see the tooth clearly, etc.
(ii) The light falling on concave mirror converges at its focus. So it can be made use of in solar panels, in
head lights of vehicles and search lights.
(iii) It is useful in reflecting telescopes and microscopes.
(iv) As fun mirrors where one can see oneself inverted because concave mirrors produce real inverted
images when the object is away from the mirror.
Convex Mirrors:
(i) These always produce an erect small size image. So, it is useful as rear view mirrors in vehicles
since it gives a wider view of the field behind.
(ii) For the same reason, it is used in shopping malls, metro stations public places to monitor movement
of people and their activities.
2. Lenses can be concave or convex.
Convex lens: Rays of light passing through convex lens converge and can produce a real image which
Jiwan® Science CCE Question Bank Answer Key-7/78
can be caught on a screen. So, it is useful in making cameras, microscopes and telescopes. When the
object is very close to the lens, it can produce a magnified, erect and virtual image. So, it is used as a
magnifying glass.
Concave lens: Rays of light passing through concave lens diverge and always give a small, erect, virtual
image. So, it is useful as spectacle lens to correct myopia.
3. Aim: To demonstrate the rectilinear propagation of light or that light travels in a straight line.
Materials: 3 index cards, a candle.
Given a picutre
Procedure:
(i) Punch a hole exactly in the centre of the cards.
(ii) Place the cards in a straight line parallel to each other. You can place them between books to keep
them erect.
(iii) Light a candle at the end of the last card, at the level of the holes.
(iv) Observe from the hole of the first card.
(v) Now move the card in the center, a little left and observe.
4. Newton's disc is a round cardboard piece on which all the seven colours of the white light are painted in
the right proportion. When rotated at great speed the disc appears white proving that white light is made
up of seven component colours. Sir Isaac Newton devised it.
NCERT Questions
5. A concave mirror can form a real and inverted image. When the object is placed very close to the mirror,
the image formed is virtual, erect and magnified.
6. Concave mirror- The image depends on the position of the object in front of the mirror. If the object is very
close to the mirror the image is virtual, erect & magnified. As the distance increases image becomes real,
inverted & its size keeps changing on the screen.
7. The three types of mirrors are concave, convex and plane mirror. In the plane mirror, our image will be
seen as same size of us and erect. In case of concave mirror, our image will be inverted. This is because
concave mirror forms real, inverted image when object is placed behind the focus of the mirror. In case of
convex mirror, the size of the image will be diminished or smaller than us and the image will be erect too.
This is because the image formed is virtual and erect.
I. Give reasons.
1. Convex mirrors are used as rear view mirrors because they offer a wider view. So, the driver is able to see
the whole wide rear. But plane mirrors do not diminish the image and are therefore inappropriate for use
as rear view mirrors.
2. A convex lens is said to have a real focus and concave lens a vitual. A convex lens converges light on its
focus whereas a concave lens diverges the light rays that seem to come from the focus therefore it is virtual.
3. The reason behind this is that the mirror which we usually use to see our image is a plane mirror, which
forms a image laterally inverted (means the objects right appears to be left in its image and vice versa),
but it doesn't forms the image inverted due to which our upper and lower portion remains unchanged.
4. Rainbows are optical and meteorological phenomena that cause a spectrum of light to appear in the sky
when the Sun shines onto droplets of moisture in the Earth's atmosphere. They take the form of a
multicoloured arc, with red on the outer part of the arch and violet on the inner section of the arch.
5. We cannot obtain the image because the image is formed behind the mirror.
J. HOTS questions.
1. A convex lens can be used for concentrating sunlight to cause a paper to burn. It is because it converges
the light falling on it and focuses it at one point, producing the heat high enough to burn the paper.
2. A rear view image in a vehicle produces a virtual, erect and smaller image of what is behind. It helps the
driver to know what is behind him on the road. But since convex mirrors produce smaller images, the
distance between two vehicles is not visible as in reality. The vehicle behind always appears to be farther
than it really is. Hence the warning is printed so that the driver makes the right decisions.
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Chapter- 18 : The Forest Reserves
Objective Type Questions
A. Fill in the blanks.
1. understorey
2. canopy
3. replenish
4. chain
5. water vapour
6. Hyena, vulture
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7. pollination
8. air and water
9. lowest
10. soil
B. Write whether the following statements are true or false.
1. True
2. False
3. False
4. True
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5. True
6. False
7. True
8. True
C. Match the two columns to make correct pairs.
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1. a. iii
b. v
c. iv
d. i
e. iii
D. Multiple choice questions. Tick the correct option in each case.
1. d
2. d
3. c
4. a
5. c
6. c
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7. d
8. b
9. c
E. Name them.
1. Primary producers
2. Biodiversity
3. Renewable resources
4. Ecosystem
Descriptive Questions.
F. Very short answer questions.
1. a) Forest- An area rich in diverse forms of flora and fauna providing a rich biodiversity to our homeland.
b) Understorey- The herbs and shrubs that grow under the canopy are known as understorey.
c) Foliage- The leaves of trees, shrubs and herbs are known as foliage.
2. The upper branched part of each tree forms its crown.
3. The branches of tall trees forming a thick cover over the forest are called the canopy.
4. Teak, sal, mahogany and rosewood are good for timber.
5. The carnivores are dependent on what herbivores have consumed as food. So, they are called
secondary consumers.
6. Mushroom works as a decomposer, though it is not a microorganism.
NCERT Questions
7. Noise pollution is less in the forest because the forest absorbs the noise of the nearby highway.
8. Grass → insects → frog → snake → eagle.
G. Short answer questions.
1. The roots of the plants bind the soil and prevent soil erosion. They also increase water absorbency of the
soil and help to enrich subsoil water. They support soil organisms and porosity.
2. The forests work to purify air by taking in all the CO2 and giving out O2 . This is how the oxygen is recycled
in our atmosphere. So, they can be called the green lungs.
3. India is considered to be a mega diverse country since Indian subcontinent is believed to be the home of
45,000 flora and 81,000 fauna species.
4. The scavengers in the forest like the hyena, vulture, jackal etc., feed on the dead carcasses of animals
and clean the environment.
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5. Causes of deforestation:
(a) Increase in population has given rise to increase in demand for space, timber, firewood and other
forest resources.
(b) Technological advancement: Building road, railways, bridges, etc., has resulted in encroachment of
forest areas.
(c) Urbanization: Movements of people from villages to cities in search of jobs has increased the space
requirement for making houses and industries. So, deforestation has been resorted to.
6. Forest fires are caused by atmospheric rise in temperature and friction caused between dry stems,
leaves and branches of trees. Lightning can also start a forest fire.
NCERT Questions
7. Microorganisms are the bacteria and fungi that grow on dead matter and the left over carcasses to break them
down to simple organic matter which goes back to the environment. So, they are known as decomposers.
8. Fruits and vegetables, wood and timber, turpentine and latex, spices, resin and gum, medicines.
9. Woodpecker, golden eagle, wild pigeon, parrots, cuckoo, barn owl.
10. No, they would have not seen the same type of plants and animals as the the trees and forest varies with
the place, altitude, biotic and abiotic components.
11. Animal manure has been used in vegetables gardens for centuries. It adds nutrients and organic matter
to the soil and aids in the development of a healthy, living soil.
H. Long answer questions.
1. Forests are very important, precious wealth of our country. They are very important for recycling oxygen,
to regulate the climate of an area, for soil conservation, for maintaining ecological balance, for obtaining
industrial raw materials and so on. The government of India has over a long period established 597
protected areas comprising 500 wildlife sanctuaries and 95 national parks. There are also legislation
against poaching, deforestation, etc. The government has also been trying to create awareness
amongst people, the need to conserve forests, its flora and fauna.
2. Forest — A great wealth:
Forests are an integral part of every nation. They are very essential to keep our environment fit for living
besides providing innumerable, valuable substances that we use. The most important contribution of
forests is recycling of oxygen and intake of CO2. This helps to control global warming too. The forests are
homes for a huge variety of animals which help to keep the ecological balance. Forests play a key role in
binding the soil and enriching it too. The forests help in precipitation, bringing about rainfalls and it helps
to increase the subsoil water. Forests provide us with rare and valuable medicinal plants, trees that
provide us timber, resins, gums and rubber, spices and many more useful products. It is the responsibility
of each one of us to help in conserving our forests and thus make the earth a better place to live on.
3. The food chain shows the interrelationship between plants and various animals in a habitat. The green
plants are the primary food producers on earth. These plants are directly consumed by the herbivores
which are called primary consumers. The carnivores and omnivores which feed on herbivores are called
the secondary consumers. The carnivores feed on other carnivores and are the tertiary consumers. The
following example shows the line of energy flow.
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4. Food Web: A food web shows the interlink that exists between several food chains. Most ecosystems
consist of several food chains. Because several animals eat more than one type of food, several food
chains are interlinked.
NCERT Questions
5. The wide variety of animals help the forest to regenerate and grow. In forest, plants produce food. All
animals, whether herbivores or carnivores, depend ultimately on plants for food. Organisms which feed
on plants often get eaten by other organisms, and so on. For example, grass is eaten by insects, which in
turn, is taken by the frog. The frog is consumed by snakes. This is said to form a food chain:
Grass → insects → frog → snake → eagle.
6.
7.
8.
9.
Many food chains can be found in the forest. All food chains are linked. If anyone food chain is disturbed,
it affects other food chains. These food chains produces a lot of supplementary products which are vital
for the plants growth. The micro-organisms which convert the dead plants and animals to humus are
known as decomposers. Decomposers help in maintaining the supply of nutrients to the growing plants
in the forest. Decaying heap of animal dropping are good source of nutrition for plants in the forest. The
decaying animal dung also provides nutrients to the seedlings to grow. The animals also disperse the
seeds of certain plants and help the forest to grow.
The forests prevent floods in many ways. The forest acts as a natural absorber of rainwater and allows it
to seep. In deep forest, during heavy rain, the raindrops do not hit the forest floor directly. The uppermost
layer of the forest canopy intercept the flow of raindrops, makes its impact slow. On the ground it is
absorbed by heaps of decaying leaves etc. In the absence of trees in the forest, rain may hit the ground
directly and may flood the area around it. Heavy rain may also damage the soil. Roots of trees normally
bind the soil together, but in their absence the soil is washed away or eroded.
The forests are perfect recycling factories of nature. Here nothing goes waste. Forest is a system
comprising of various plants, animals and micro-organisms.The various components of the forest are
interdependent on one another. All animals, whether herbivores or carnivores, depend ultimately on
plants for food. Organisms which feed on plants often get eaten by other organisms, and so on. For
example, grass is eaten by insects, which in turn, is taken by the frog. The frog is consumed by
snakes. This is said to form a food chain. Many food chains can be found in the forest. All food chains
are linked.
The micro-organisms called decomposers play an important role in the forest. The presence of
humus ensures that the nutrients of the dead plants and animals are released into the soil. From
there, these nutrients are again absorbed by the roots of the living plants.The dead animals become
food for vultures, crows, jackals and insects. In this way, the nutrients are cycled. So, nothing goes
waste in a forest.
The conditions and issues we have to face when forests disappears are:
(a) Soil erosion: Trees in a forest hold soil with their roots. If trees are gone, soil will be washed away.
(b) Landslides: Without trees, land will be very unstable and easily down the slope.
(c) Water pollution: Without tree roots holding the soil in a forest, soil will run into the river.
(d) Temperature increase.
(e) Loss of biodiversity: Plants and animals will lose their food and shelter.
(f) Floods: Bald hills and mountains can no longer hold back sudden flows of water, which cause floods.
(g) Increase in carbon dioxide: Depletion of forests results in increase in carbon dioxide, which will
cause global warming.
Animals and plants in a forest are dependent on the other for food. So, there is a need of variety of
animals and plants in a forest. Many food chains can be found in the forest like
Grass → insects → frog → snake → eagle.
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10.
Atmosphere
Clouds
Rain
Plants
Oxygen
Carbon dioxide
Animals
Plants
Soil
Roots
Water Table
11. 1. Forests provide us with oxygen.
2. They protect soil and provide habitat to a large number of animals. Forests help in bringing good
rainfall in neighboring areas.
3. They are a source of medicinal plants, timber and many other useful products.
12. Dams, deforestation, mining, and industrial development are all responsible for degradation of forests.
13. Drawing of a forest.
14. The forest plays an important role in maintaining the balance between oxygen and carbondioxide in the
atmosphere. As we know plants for their food nutrition requirement make use of process of
photosynthesis, in which they consume carbon dioxide, released by the living organism from the
environment. As a result of photosynthesis, plants release oxygen which is again consumed by living
beings for respiration and this cycle goes on.
I. Give reasons.
1. The forests prevent floods in many ways. The forest acts as a natural absorber of rainwater and allows it
to seep. In deep forest, during heavy rain, the raindrops do not hit the forest floor directly. The uppermost
layer of the forest canopy intercept the flow of raindrops, makes it's impact slow. On the ground it is
absorbed by heaps of decaying leaves etc. In the absence of trees in the forest, rain may hit the ground
directly and may flood the area around it. Heavy rain may also damages the soil. Roots of trees normally
bind the soil together, but in their absence the soil is washed away or eroded.
2. The sunlight cannot pass through the canopy of trees on the top making it dark inside.
3. An ecosystem is basically an entire self-sufficient biological system. It consists of all sorts of living things
that feed off each other i.e., Plant absorbs sunlight, deer eats plant, tiger eats deer, etc., and the cycle
continues. This was a very simple example, though an ecosystem is more complex and made up of many
different types of living things, but you get the gist. An ecosystem basically needs no help from the
outside of its boundary to continuously sustain itself. A 'balance in nature' therefore, is the continuous
balance between all these living things as well as environmental factors. For example, if the only
carnivore (meat-eater) in a specific ecosystem is the tiger, and for some reason it is going extinct (maybe
man has killed most of them for their fur), then that means the deer will be allowed to flourish and plants
will also start to diminish. This is how an imbalance in nature could come about. Another example could
be global warming (maybe caused by air pollution from our vehicles), which would cause the ice caps in
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the mountains to melt, hence causing flooded rivers, which in turn would kill much plant and animal life,
and again cause an imbalance in nature. The disruption of the balance of nature can caused by a number
of things, but more often than not, it is attributed to something us humans are involved in. Either we're
cutting down too many trees and causing deforestation, or we're hunting too many animals of a specific
species for sport or trade, etc. We must be careful and respect nature and the precious balance it tries to
maintain.
4. Scavengers are important to the ecosystem by cleaning up the mess. Scavangers are the ones that look
for dead bodies/organic matters. These are important as they decompose dead organic matters (such
as leaves, trees, dead animals etc).This allows nutrients back into cycle. For example, decomposed
matter is taken up by tree, which then helps to grow.
J. HOTS questions.
1. If all the snakes are destroyed then there will be a dent in the food chain which will leave the tertiary
consumers like the eagle (which feeds on snake) starved. When the eagles starve, they will perish and
this in turn will result in reduction in eagle population. On the other hand the primary consumers like the
frogs, rats, mice, etc., which are consumed by the snakes will increase in number and so will their
dependence on, green plants. The green plants will reduce on earth. So, there will be an imbalance
created in the environment even if one species will be destroyed.
2. Deforestation will cause failure of monsoons and reduction in rainfall. The clouds pass away due to lack
of precipitation and dryness will prevail because of it.
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Chapter- 19 : Waste Management
Objective Type Questions
A. Fill in the blanks.
1. dump
2. contaminants
3. vertical bars
4. PVC
5. UV(ultraviolet)
6. Oil and grease
7. low
8. cholera
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9. pollutants
10. sewage
11. sludge
12. cooking oil and fats
B. Write whether the following statements are true or false.
1. False
2. True
3. True
4. True
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5. True
6. True
7. True
8. True
C. Match the two columns to make correct pairs.
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a. ii
b. iv
c. i
d. iii
D. Multiple choice questions. Tick the correct option in each case.
1. c
2. c
3. d
4. b
5. b
6. d
7. c
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8. b
9. c 10. a 11. c
12. d
13. c 14. a
15. b
16. c 17. c 18. a
E. Name them.
1. Sewage
2. Sludge
3. Contaminants
4. Aerator (also called bioreactor)
Descriptive Questions.
F. Very short answer questions.
1. Wastes can be (a) household waste like the sewage, kitchen waste, water used for washing clothes and
bathing, (b) Biomedical wastes like used syringes, cotton, bandages, vials, etc.
2. Waste water is generated from house hold and so on, from farms carrying pesticides, fertilizers, etc., as a
result of mining operations and from industries.
3. Manholes are openings in the sewage pipes which help in clearing blockages, if any.
4. The treatments plants help to remove the waste and unwanted material from water and make it clean for
reuse. It involves physical, chemical and biological treatment of the waste.
5. The waste water, after treatment can be sent for agricultural or industrial reuse or can also be converted
to potable water.
6. Dumps are places where waste is left in one spot on the ground or under the ground.
7. E-wastes are wastes generated by the electronic industry — like TV, refrigerators, air conditioners, cell
phones, computers, etc.
8. (a) E-waste-mobile, telephone, refrigerator.
(b) Hazardous waste-paints, aerosols, pesticides.
9. (a) Dump- a site for depositing rubbish.
(b) Trenches- a long, narrow, deep depression in the ocean bed, typically one running parallel to a plate
boundary and marking a subduction zone.
10. Improper way of dumping wastes can cause floods because it makes the sewer clog. It can also pollute
bodies of water and can cause the death of marine life that resides in water ecosystem.
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11. Chlorine and ozone.
12. An open drain is a breeding ground for mosquito and flies which can cause many diseases.
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G. Short answer questions.
1. The organic matter that settles down at the base of the sewage treatment tank is known as sludge.
2. Water borne diseases spread due to contaminants getting mixed with water due to (a) Water logging
after a heavy spell of rain (b) Leakage in the sewer system (c) Flooding of storm water pipelines (d)
Leakage in the drinking water pipelines (e) Unhygienic and poor sanitary conditions.
3. Water is a very important, essential natural resource without which we can't go through a single day of
our life. Due to enormous amount of human activities, the amount of waste water generated is in excess
of the amount of clean water available for use. This has led to a state of water crises. To avoid any serious
consequences of water shortage, we should adopt measures like waste water management along with
other water conservation techniques. Much of the waste water generated at homes, farms, industries,
marketplace, mines and construction sites can easily by treated and reused. Sewage treatment plants
convert the sewage to useful manure and the liquid part can be reused in agricultural sector.
4. Septic tank is a covered concrete tank which is built under ground. It is sealed from outside air. The faecal
matter is allowed to pass into it where it is decomposed into odourless sludge which is periodically taken out.
5. The sewer system is a network of underground pipes which collect sewage from various sources and
transport it to a place where the liquid waste can be treated.
6. During floods, especially in places where there is lack of good drainage system, the flood water
overflows carrying the sewage waste also. This poses a great risk of drinking water pipelines getting
contaminated. The sewage that gets mixed carries microbes which are disease causing and so, we see
breakout of epidemics like cholera.
7. The major source of water contamination is faeces which keep lying in the open due to the practice of
open defecation in our country. Lack of good, clean toilets forces people to resort to open defecation and
this needs to be taken care of.
8. The bioreactor is the aeration tank in the sewage treatment plant where aerobic bacteria consume the
organic matter and settle down as sludge.
NCERT Questions
9. Sewage is wastewater released by homes, industries, hospitals, offices and other users. It also includes
rainwater that has run down the street during a storm or heavy rain. The water that washes off roads and
rooftops carries harmful substances with it. Sewage is a liquid waste which has dissolved and
suspended impurities as contaminants or pollutants . If this untreated sewage is discharged into rivers or
seas. It may cause water pollution and soil pollution in which both the surface water and groundwater get
polluted. Groundwater is a source of water for wells, tubewells, springs and many rivers. Therefore if it
gets polluted, it becomes the most common route for water borne diseases. They include cholera,
typhoid, polio, meningitis, hepatitis and dysentery.
10. This process of removing pollutants from wastewater is commonly known as wastewater treatment” or
“Sewage Treatment” . It takes place in several stages. Sludge is one of the By-products of wastewater
treatment along with biogas. During the “Sewage Treatment”, after filterations of floating solid objects
through bar screen, the speed of wastewater is decreased to allow sand, grit and pebbles to settledown .
The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like faeces
settle at the bottom and are removed with a scraper. This is the sludge. The sludge is transferred to a
separate tank where it is decomposed by the anaerobic bacteria. The biogas produced in the process
can be used as fuel or can be used to produce electricity. Air is pumped into the clarified water to help
aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted
matter still remaining in clarified water. After several hours, the suspended microbes settle at the bottom
of the tank as activated sludge. The water is then removed from the top. Dried sludge is used as manure,
returning organic matter and nutrients to the soil.
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11. The function of bar screens in a wastewater treatment plant is to remove coarse solids and other large
materials often found in raw wastewater. Removal of these materials is necessary to enhance the operation
and maintenance of subsequent treatment units. Preminary treatment operations typically include coarse
screening, grit removal and, in some cases, communication of large objects. Wastewater is passed through
bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed.
12. There is a direct relationship between sanitation and disease. Poor sanitation and contaminated
drinking water is the cause of a large number of diseases. Under poor sanitation people may resort to
defecate in the open, on dry riverbeds, on railway tracks, near fields and many a time directly in water. It
may cause water pollution and soil pollution. Both the surface water and groundwater get polluted.
Groundwater is a source of water for wells, tubewells, springs and many rivers due to this, it becomes
the most common carrier for water borne diseases. They include cholera, typhoid, polio, meningitis,
hepatitis and dysentery.
13. Inorganic impurities include phosphates, nitrates and metals.
14. Organic impurities in sewage include animal waste, urine, oil, vegetable and fruit waste, faeces,
pesticides and herbicides.
15. Septic tanks can be used if there is no sewerage.
16. Waste can be segregated and collected in bins as wet waste and dry waste so that the dry waste can be
recycled or reused and the organic waste can go into the composting bins.
17. c, e, b, d, a.
18. a- i, b- iii, c- ii
19. Sludge - a) Nutrients are the organic impurities and b) Disease causing bacteria and other microbes are
the inorganic impurities.
H. Long answer questions.
1. Sanitation in Public Place: Public places like railway stations, bus stations, market areas, places of
worship, tourist spots, etc., are places where a large number of people frequently urinate, and even
defecate. Lack of proper public toilets in these places poses a very serious sanitation issue. People
resort to urination and defecation in the open, which results in soil contamination, which in turn causes
contamination of subsoil water, ponds, lakes, rivers, etc. The contamination of drinking water sources
causes breakout of epidemics of water borne diseases like cholera, jaundice, diarrhoea, etc. If attention
is not paid to building and maintaining public toilets poor health and poor hygiene will prevail at all times.
2. Waste water management refers to treatment of water generated due to various human activities to
make it safe and reusable. At domestic level, the water used in cleaning vessels, washing clothes,
kitchen use, bathing, brushing, flushing, etc., are collected in sewage pipes and are transported to an
area where they can be treated or disposed off into water sources. At industrial level, it is very essential to
detoxify the waste water first since they carry many harmful chemicals and toxins. The water thus treated
should be allowed to flow into the nearby water sources. Waste water treatment plants try to remove
solid impurities and treat the water biologically and chemically and filter it and then send it to appropriate
areas for reuse. Judicious use of waste water will save a lot of water which otherwise goes waste and will
help us to end our water woes.
NCERT Questions
3. The steps involved in getting clarified water from wastewater involves physical, chemical, and biological
processes, which remove physical, chemical and biological matter that contaminates the wastewater.
1. Wastewater is passed through bar screens. Large objects like rags, sticks, cans, plastic packets,
napkins are removed.
2. Water then goes to a grit and sand removal tank. The speed of the incoming wastewater is
decreased to allow sand, grit and pebbles to settle down through sedimentation .
3. The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like
faeces settle at the bottom by sedimentation and are removed with a scraper. This is the sludge. A
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skimmer removes the floatable solids like oil and grease. Water so cleared is called clarified water.
The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The
biogas produced in the process can be used as fuel or can be used to produce electricity.
4. Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human
waste, food waste, soaps and other unwanted matter still remaining in clarified water. After several
hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then
removed from the top. The activated sludge is about 97% water. The water is removed by sand
drying beds or machines. Dried sludge is used as manure, returning organic matter and nutrients to
the soil. The treated water has a very low level of organic material and suspended matter. It is
discharged into a sea, a river or into the ground. Nature cleans it up further.
4. Untreated human excreta is a health hazard because as this will result in poor sanitation. A very large
fraction of our people defecates in the open, on dry riverbeds, on railway tracks, near fields and many a
time directly in water. It may cause water pollution and soil pollution. Both the surface water and
groundwater get polluted. Groundwater is a source of water for wells, tubewells, springs and many rivers
due to this, it becomes the most common carrier for water borne diseases. They include cholera,
typhoid, polio, meningitis, hepatitis and dysentery.
5. We can contribute in maintaining sanitation at public places.
We should not scatter litter anywhere. If there is no dustbin in sight, we should carry the litter home and
throw it in the dustbin. We must realise our responsibility in maintaining the water sources in a healthy
state. We should adopt good sanitation practices as way of life. A small initiative as an agent of change
on our part will make a great difference.
6. Organic impurities in sewage include animal waste, urine, oil, vegetable and fruit waste, faeces,
pesticides and herbicides. Inorganic impurities include phosphates, nitrates and metals.
7. Sewerage is the removal of waste water and refuse by means of sewers. Sewage treatment is the process
of removing contaminants from wastewater and household sewage, both runoff (effluents), domestic,
commercial and institutional. It includes physical, chemical, and biological processes to remove physical,
chemical and biological contaminants. It's objective is to produce an environmentally safe fluid waste
stream (or treated effluent) and a solid waste (or treated sludge) suitable for disposal or reuse (usually as
farm fertilizer). Using advanced technology it is now possible to re-use sewage effluent for drinking water.
I. Give reasons.
NCERT Questions
1. Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes. In an
open drain the fats clog the soil pores reducing its effectiveness in filtering water. Also they may kill
microbes that help purify water. Therefore oil and fats should always be discharged after taking due care
in the dustbin or if possible in some suitable dumping place.
2. Avoid putting tea leaves down the sink drain. Tea leaves accumulate in the drain and clog at the S-bend.
It won't take long before things are getting stuck if you do this continuously. Besides which, tea leaves are
better in your compost or on the garden.
J. HOTS questions.
1. The storm water drains should be separate from sewers because sewers carry a lot of contaminants in
the form of chemical or biological impurities. If sewer water gets mixed with storm water, the
contaminants will pollute the soil, sub soil water and the water sources nearby, resulting in the out breaks
of epidemics of water borne diseases.
2. The vertical bars in the sewage treatment plants help to separate out the bigger sediments that are used
in landfills. On removing large solid particles, the liquid portion can be separated and treated to make it
less impure.
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