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A COMPLETE SOLUTION OF TEXT-BOOKS
Science Server - 4
1.
FOOD MAKING IN PLANTS
Exercise
A. Answer the following questions :
1. Why are green plants called producers?
Ans. Green plants are called producers as only they can prepare their own
food.
2. Define photosynthesis.
Ans. Photosynthesis is a process by which green plants make their food
using water, carbon dioxide, sunlight and chlorophyll.
3. How do we use the food made of plants?
Ans. Leaves need water, carbon dioxide, sunlight and chlorophyll to
produce food.
4. How is the food made by plants used by us?
Ans. Leaves make use of carbon dioxide, water, sunlight and chlorophyll to
prepare food for plants. The food prepared by green plants is glucose
(a kind of sugar). Oxygen is given out by leaves as a by product of the
reaction. The reaction that actually describes the process of
photosynthesis is as :
Sunlight
Carbon dioxide + Water
Glucose(food) + Oxygen
Chlorophyll
Oxygen this produced mixes with air and is used by us for breathing.
Oxygen is given out by leaves through stomata. During the process of
photosynthesis food is prepared in the form of sugar. Plants use this
food to produce energy, for the growth of plant, for the repair of
damaged parts of the plant and to conserve the food to be used by
animals and human beings.
5. What is stomata? What is its use in a leaf ?
Ans. Stomata are tiny pores on the lower surface of a leaf. Stomata works as
windows. They take in carbon dioxide and give out oxygen to the air.
Stomata also releases extra water from the plants.
B. Choose the correct word from the box and fill in the blanks :
1. Leaves are known as kitchen of a plant.
oxygen
2. Iodine is used to test the presence of starch.
iodine
3. Leaves are green due to the presence of chlorophyll.
sugar
4. Oxygen is a by product of photosynthesis.
kitchen
5. Plants produce food in the form of sugar.
chlorophyll
C. Write :
1. Two roots that we eat :
(a) raddish
(b) turnip
2. Two leaves that we eat :
(a) cabbage
(b) spinach
3. Two gases involved in photosynthesis : (a) carbon dioxide (b) oxygen
4. Two fruits that we eat :
(a) mango
(b) apple
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D. Write True or False against the following statements :
1. Food is prepared in roots of a plant.
2. Carbon dioxide is used in photosynthesis.
3. Animals can survive alone.
4. The flat part of leaf is called stomata.
5. Iodine gives blue colour with starch.
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
1
Across :
2. a gas given out by plants
4. food factories of plants
6. Food is prepared in plants in this form.
7. an element needed for photosynthesis
Down :
1. process of food making in plants
3. Chlorophyll gives green colour to plants.
5. tiny pores in leaves
2
False
True
False
False
True
P
H
3
O X Y G E N
T
R
O
E
5
S 4 L E A V E S
N
Y
T
N
O
T
M
6 S U G A R
H
E
T
S
A
I
S U N L I G H T
7
Fun Time Activity
1. Collect different kinds of leaves and paste them in your scrapbook.
Write their names also.
Ans. Do yourself.
2. Use iodine to test the presence of starch in potato, egg albumin, boiled
rice, etc.
Ans. Do yourself.
2.
ADAPTATIONS IN PLANTS
Exercise
A. Answer the following questions :
1. What do you understand by adaptation?
Ans. The natural environment in which a plant grows is called its habitat.
Plants develop certain features which enable them to survive
successfully in a particular habitat. Such features are called adaptations.
2. What are terrestrial plants? Name any three terrestrial plants.
Ans. Plants that grow on land are called terrestrial plants. Mango, pine and
banyan are three terrestrial plants.
3. How do xerophytes adapt themselves in desert conditions?
Ans. Xerophytes are desert plants. The grow in a relatively dry habitat. In
such plants, the stem is profusely branched usually stunted, roody, dry
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and hard. Leaves are reduced to spines. This helps in preventing the
loss of water from the leaves. Photosynthesis takes place in its green
stem. The roots are long and spread wide and go deep into the ground.
This helps them to draw water from deep places inside the ground.
4. What are floating plants? How are they adapted to suit their habitat?
Ans. Floating plants float freely on the surface of water. Their roots, stem
and body are light in weight and are spongy. Their stem is reduced and
roots are poorly developed. Their leaves have a thin waxy coating so
that water may not wet the surface and block the stomata. Some
common floating plants are lemna, pistia, jussieu, water hyacinth.
5. What are insectivorous plants? Give two examples.
Ans. Some plants are insect-eaters. They are known as insectivorous plants.
The common insectivorous plants are pitcher plant, sundew and venus
fly trap. Pitcher plant traps insects and absorbs nutrients from their
bodies and venus fly trap may snap and shut when any insect sits on it.
B. Choose the correct word from side box and fill in the blanks :
1. The leaves of desert plants are reduced to spines.
mangroves
2. Hydrilla is a submerged aquatic plant.
plains
3. Plants that grow on marshy areas are called mangroves.
spines
4. The mesophyte are the plants growing in plains.
hilly
5. Plants of hilly areas have needle-like leaves.
submerged
C. Write :
1. Two fixed aquatic plants :
(a) lotus
(b) water-lily
2. Two floating aquatic plants :
(a) lemna
(b) water hyacinth
3. Two submerged aquatic plants : (a) hydrilla (b) vallisneria
4. Two insectivorous plants :
(a) sundew (b) pitcher plant
5. Two plant growing in hilly areas : (a) pine tree (b) spruce tree
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
1
C
M A N G O
C
4
L O T U S
U
U
5
N
M
S
6 D E O D A R
E
R
7 S P
W
H
Y
Across :
2. a mesophyte
3. a fixed aquatic plant
6. a tree of hilly areas
7. In xerophytes leaves are
reduced to spines.
2
3
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N
E
S
Down :
1. a xerophyte
4. an insectivorous plant
5. Mangroves are the plants
of marshy areas.
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Fun Time Activity
Collect the pictures of any 10 kinds of plants around you, and paste them in
your scrapbook.
Ans. Do yourself.
3.
ADAPTATIONS IN ANIMALS
Exercise
A. Answer the following questions :
1. What is a habitat?
Ans. The natural environment in which an animal or a plant lives, is called its
habitat.
2. What is meant by adaptation?
Ans. All animals adjust themselves according to the changing conditions of
environment. This is called adaptation.
3. How do the fish adapt to live in water?
Ans. Fish breathe the air dissolved in water through special organs called
gills. They have fins to help them swim and balance in water. Dolphins
and whales do not have gills. They have to come up to the water surface
to breathe.
4. What are arboreal animals? Name any three of them.
Ans. Animals that spend most of the time on trees are called arboreal
animals. Monkey, squirrel and chameleon are arboreal animals.
5. How does a camel adapt to live in desert?
Ans. The camel is known as 'the ship of the desert'. It has thick skin and can
live for 10-12 days without water. Its hump is a reservoir of fat. So
when the camel does not get water or food, it can still survive because
feet keep it from sinking into the sand desert.
6. How are birds adapted for flying?
Ans. Birds have wings to fly. Their bones are hollow, which make them light
in weight. Their body shape also help them to fly easily in air.
7. What do you understand by camouflage?
Ans. Some animals have special feature of changing their colours to merge
with their surroundings. It then becomes difficult to see these animals.
This adaption is known as camouflage.
8. Why did dinosaurs vanish from the earth?
Ans. Dinosaurs vanish from the earth. This is because they failed to adapt
themselves according to the changing conditions of climate, food and
surroundings. So they all died and were lost forever.
B. Choose the correct word from the box and fill in the blanks :
1. A long winter sleep is known as hibernation.
migration
2. Dolphins and whales do not have gills.
gills
3. The camel is known as the ship of the desert.
hibernation
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4. Movement of animals from one region to another in
search of better living conditions is called migration.
ship
5. Webbed feet help ducks to swim in water.
webbed feet
C. Write True or False against the following statements :
1. Monkey is an arboreal animal.
True
2. Carnivores have long, sharp tearing teeth.
True
3. Human beings are herbivores.
False
4. Parasites do not have teeth.
True
5. Whales breathe through gills.
False
D. Match the following :
1. squirrel
(a) aquatic animal
2. bat
(b) arboreal animal
3. salamander
(c) aerial animal
4. dolphin
(d) terrestrial animal
5. lion
(e) amphibian
Let us Enjoy
Search the names of two animals of each category from this maze. Write
the names in the space given :
Amphibians :
(a) frog
E V M E R B U G N I M A L H A
(b) newt
S F R O G T U O P R O C T E C
Terrestrial :
T I F S N N E T L F B A T F R
(a) tiger
O L M I T K E S T E N M I M I
(b) camel
E E S A N D E W S E U E R R O
Aerial :
U
E N D I N T Y T G R L S I T
(a) bat
(b) butterfly I C L E R R I U Q S S F I S H
V H E R Y I G M P O R O L T A
Aquatic :
(a) crab
N E T F O R E A N A N M I Y M
(b) fish
A S L T O C R A B P R O I T S
Arboreal : M R O W E P A T E U E I V E R
(a) squirrel
(b) monkey
Parasites :
(a) bug
(b) leech
Fun Time Activity
1. Collect the pictures of any three endangered animals (e.g. gharial, great
Indian bustard, turtle, etc.) and paste them in your scrapbook.
Ans. Do yourself.
2. Make a list of amphibians and search their pictures on net.
Ans. Do yourself.
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4.
REPRODUCTION IN ANIMALS
Exercise
A. Answer the following questions :
1. What is reproduction?
Ans. All living beings have a special ability to produce more of their own
kind. This unique feature is called reproduction.
2. What are mammals? Name two mammals.
Ans. Animal that directly give birth to their young ones are called mammals.
They carry their babies within their baby till they are fully developed.
The produce milk to feed their babies. Cat and cow are two mammals.
3. Describe the structure of a bird's egg
with a diagram.
Ans. A bird's egg has hard outer shall. Inside the
shell there is a sticky liquid called
albumen. Inside it, there is yellow liquid
called yolk. Inside the yolk is growing
chick called embryo.
4. How does a fish reproduce?
Ans. A fish lay eggs at a safe place
in water. The mother fish
hatches the egg into fry. The
fry grows to be an adult fish.
A fish lay thousands of eggs at
a time. Out of these only a few
hundreds grow into baby fish.
Some are eaten by big fish
and many are crushed by fast
water current.
5. How do birds take care of their babies?
Ans. The baby birds that hatch out of the eggs are not capable of flying. The
mother and father birds feed the babies. Nests are prepared to keep the
babies safe from heat, cold, rain and enemies.
6. Describe the stages in the life cycle of a frog.
Ans. A frog lays its eggs in water. The
cluster of frogs egg is called
'spawn'. The young one of a frog
that comes out of the egg is called a
tadpole. It has a tail. The hind legs
of the tadpole appear first. Then
the front legs appear. Slowly the
tail disappears and it becomes an
adult.
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B. Choose the correct word from the box and fill in the blanks :
1. The cluster of frog's egg is called spawn.
tadpole
2. The shedding of old skin in insects is known as moulting.
fry
3. The young one of a frog is known as tadpole.
yolk
4. The yellow liquid in an egg is known as yolk.
moulting
5. A baby fish is called fry.
spawn
C. Write True or False against the following statements :
1. A dog lays eggs.
False
2. Babies are exact copies of their parents.
False
3. Lizard is a mammal.
False
4. A fish lays thousands of eggs at a time.
True
5. The baby of the frog is called a larva.
False
D. Match the following :
1. nymph
(a) fish
2. fry
(b) frog
3. chick
(c) cockroach
4. tadpole
(d) cat
5. kitten
(e) hen
Let us Enjoy
Draw a diagram to show the life cycle of a frog in your note book.
Ans. Do yourself.
Fun Time Activity
Visit a poultry farm and observe the mother hen sitting on her eggs.
Observe and note in your notebook, how the mother hen looks after her
chicks.
Ans. Do yourself.
5.
FOOD AND ITS DIGESTION
Exercise
A. Answer the following questions :
1. What do you mean by nutrients?
Ans. The food we eat contains several different types of substances that play
their own roles in keeping our body healthy and working. These
substances are called nutrients.
2. Name the various nutrients present in our food.
Ans. The various nutrients that our food contains are carbohydrates,
proteins, fats, vitamins and minerals.
3. What is the role of roughage and water in our diet?
Ans. Roughage is an important part of our diet because it helps in easy
digestion of food and smooth removal of waste material out of our body.
Water makes up 60-70% of the human body. It also forms an important
part of our diet as it maintains our body temperature and help the body to
function properly. We should drink 8-10 glasses of water everyday.
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4. What is a balanced diet?
Ans. The food we eat daily is called our diet. A diet that contains the proper
amount of all the nutrients, roughage and water required for good
health is called a balanced diet.
5. Write any four good eating habits.
Ans. (i) Eat your food at fixed times.
(ii) Chew your food properly before swallowing it.
(iii) Do not talk while eating.
(iv) Rinse your mouth throughly after eating.
B. Choose the correct word from the box and fill in the blanks :
1. Vitamins and minerals are known as protective foods.
diet
vitamins
2. Roughage and water helps to remove waste material
proteins
out of our body.
fats
3. Fats and carbohydrates give energy to our body.
roughage
minerals
4. Proteins are body-building foods.
carbohydrates
5. The food we eat daily is called our diet.
water
C. Write one use of each of the following :
1. Carbohydrates : Carbohydrates provide us energy to do our work.
2. Proteins
: Proteins make new tissues in our body.
3. Fats
: Fats give us more heat and energy than carbohydrates.
4. Vitamins
: Vitamins give us protection from many diseases.
5. Minerals
: Minerals are necessary for growth and development
of bones, teeth and new blood cells.
6. Roughage
: Roughage helps in easy digestion of food.
D. Match the following :
1. Carbohydrates
(a) fibres
2. fats
(b) fish, egg, beans
3. proteins
(c) potato, rice, sugar
4. vitamins
(d) butter, ghee, oil, nuts
5. roughage
(e) egg, chicken, fruits
Let us Enjoy
Label the diagram and put these parts of the digestive system in the correct
order :
stomach, anus, food pipe, large intestine, mouth,
small intestine
1. mouth
2. food pipe
3. stomach
4. small intestine
5. large intestine
6. anus
digestive system
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Fun Time Activity
1. Note your diet for 10 days and make a chart. Do you think you are
taking a balanced diet? How?
Ans. Do yourself.
2. Make a time table for your tiffin box including variety of foods that
provide you a balanced diet.
Ans. Do yourself.
6.
TEETH : STRUCTURE AND CARE
Exercise
A. Answer the following questions :
1. What are the main functions of teeth in our body?
Ans. There are three important functions of teeth :
(i) Teeth help us to eat our food.
(ii) Teeth help us to speak well.
(iii) They help us look handsome and young.
2. What are premolars? Where are they located in our mouth?
Ans. Premolars are broad and flat teeth. These teeth help us in cracking food.
Hence, these are also known as cracking teeth. There are four
premolars in each jaw. They are next to canines.
3. How does a tooth decay?
Ans. When the teeth are not properly cleaned, some food particles get stuck in
or between the teeth. Micro-organisms in the mouth activate and feed on
these food particles and begin to produce acids. These acids act on the
enamel. Slowly, they make holes in the tooth. These holes are called
cavities. These cavities cause pain and further destruction of tooth.
4. What is the differents between incisors and canines?
Ans.
Incisors
Canines
(i) There are four incisors in
(i) There are two canines in
the front in each jaw.
each jaw.
(ii) They help us to cut or bite
(ii) These teeth are used for
our food.
tearing food.
(iii) Incisors have sharp straight
(iii) These are very sharp and
edges.
pointed teeth.
5. Write any three points which you can take care of your teeth.
Ans. (i) Brush your teeth well twice a day.
(ii) Eat a well balanced diet including calcium rich foods to give
strength to your teeth.
(iii) Do not eat too hot or too cold food.
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B. Write True or False against the following statements :
1. Milk teeth are permanent.
False
2. Canines are also called the tearing teeth.
True
3. The tooth is covered with enamel.
True
4. Incisors are the grinding teeth.
False
5. We have two molars in each jaw.
False
C. Choose the correct word from side box and fill in the blanks :
1. Our first set of teeth are called the milk teeth.
incisors
2. Our second set of teeth are called the permanent teeth.
nerves
3. There are four types of teeth :
milk
(i) incisors
(ii) canines
canines
(iii) premolars (iv) molars
permanent
4. Nerves connect the gums to the teeth.
molars
5. The portion between the crown and the root of our tooth
neck
is neck.
premolars
Let us Enjoy
molars
Here is a picture
of the lower
molars
premolars
jaw. Label
premolars
the teeth :
canines
Ans. Do yourself.
incisors
Fun Time Activity
Try to speak letters A to Z without letting your tongue touch your teeth.
What do you notice? Write down here ten letters :
(i) Which you can speak properly?
__________________________
(ii) Which you cannot speak properly? __________________________
Ans. Do yourself.
7.
MICRO-ORGANISMS
Exercise
A. Answer the following questions :
1. What are micro-organisms? Where are they found?
Ans. Micro-organisms are very small living beings. They are so small that
they cannot be seen through naked eyes. We need microscope to see
them. Micro-organisms are found every where around us. They are
present in air, water, soil and even inside our bodies.
2. Name different types of micro-organisms.
Ans. Bacteria, virus, protozoa and fungi are the four main types of microorganisms found in and around us.
3. Write about two useful of micro-organisms.
Ans. (i) Some fungi like Penicillium are useful in making medicines and
vaccines.
(ii) Bacteria is needed to convert milk into curd.
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4. Write two ways to prevent harmful micro-organisms from entering
our body.
Ans. (i) Always eat clean and fresh food. Don't by uncovered food from the
market. It may contain disease causing micro-organisms in it.
(ii) Drink pure and filtered water. Most of the disease causing microorganisms enter our body through impure water.
5. Explain two methods of food preservation.
Ans. (i) Freezing : Things kept in refrigerator remain fresh for long as
micro-organisms cannot grow in cold conditions.
(ii) Boiling : Boiling of milk, water, etc prevent them from spoiling.
B. Choose the correct word from the box and fill in the blanks :
1. Disease causing micro-organisms are called germs.
yeast
2. We need a microscope to see the micro-organisms.
mushroom
3. Yeast is used to make bread and flour fluffy.
germs
4. Boiling prevents milk from getting spoiled.
boiling
5. Mushroom we eat is actually a fungi.
microscope
C. Write :
1. Two diseases caused by bacteria : (a) diptheria
(b) typhoid
2. Two diseases caused by virus :
(a) polio
(b) measel
3. Two diseases caused by protozoa : (a) malaria
(b) dysentery
4. Two diseases caused by fungi :
(a) ringworm (b) athlete's foot
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
1
Across :
Y
2.
a disease caused by virus
E
4. the type of micro-organism
A
2
M E A S E L S
that causes malaria
I
T
3
5.
micro-organisms that cause
C
B
4 P R O T O Z O A
diseases
O
6
I
7.
a disease caused by bacteria
5 G E R M S
L
8. a fungi that we eat
I
C 7 D I P T H E R I A
N
N
O
Down :
P
G
G
1. This fungi is used to make
W
E
O
bread fluffy.
R
2.
an instrument needed to see
8 M U S H R O O M
the micro-organisms
3. Milk can be preserved by
boiling.
6. a disease caused by fungi
Fun Time Activity
1. Make a beautiful chart to show how germs enter our body and hang it in
school corridor.
Ans. Do yourself.
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8.
AIR
Exercise
A. Answer the following questions :
1. What happens when air is heated?
Ans. Air expands on heating and hot air rises up.
2. What is the composition of air?
Ans. Air mainly consists of nitrogen and oxygen. Air
contains about 76% nitrogen and 21% oxygen.
The remaining 1% of air is made up of many
other gases and a small amount of water vapour.
0.3% of air is made up of carbon dioxide.
3. What is the difference between the sea breeze and the land breeze?
Ans. Sea breeze : During the daytime the
land gets heated up faster than the sea
water. Therefore, the air above the land
is heated up earlier to the air above the
sea. The warm air from the land rises up
and the cooler air of the sea occupies its
space on the land. Thus the cool air from
the sea blows towards the land during
daytime
.
Land breeze : During the night, the land
cools down quickly, so the air above it
also cools down. But the water in the sea
is still warmer than the land. As a result
the air above sea rises up and the cooler
air from the land reaches the sea and
occupies the space of warm air of the
sea. Thus, the cool air from the land
blow towards the sea during night time.
4. What is air pollution?
Ans. Mixing of harmful substances into air is called air pollution. These
harmful substances are called pollutants.
5. Write two effects of air pollution.
Ans. (i) Polluted air causes many respiratory disorders like bronchitis,
asthma and throat infections.
(ii) Polluted air causes irritation in our eyes and skin.
B. Choose the correct word from the box and fill in the blanks :
1. Air is a mixture of gases.
breeze
mixture
2. Air has 0.3% carbon dioxide.
warm
3. Air is used by human beings for breathing.
breathing
4. Gently moving air is called breeze.
cold
5. Warm air is lighter than cold air.
carbon dioxide
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C. Write True or False against the following statements :
1. Air is necessary for breathing and burning.
2. The main component of air is oxygen.
3. Air is needed to hear sound.
4. Air is weightless and spaceless.
5. Polluted air produces acid rain.
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
1
Across :
A
4. 78% of air is nitrogen.
C
2
5. Gently moving air is
I
C
3
called breeze.
E
O
D
7. Air is a mixture of gas.
4 N
I T R O G E N
E
V
A
Down :
5 B R E
E
I
1. Polluted air causes acid
G
N
C
rain.
Y
T
7
M
I
X
T U R
E
True
False
True
False
True
6
E Z
X
P
A
N
D
S
E
O
2. Movement of air on heating
N
causes convection currents.
3. Burning of food releases energy in our body.
6. Air expands on heating.
Fun Time Activity
1. Draw a diagram in your notebook, showing composition of air.
Ans. Do yourself.
2. Draw a chart on 'Air Pollution' and hang it in your school corridor.
Ans. Do yourself.
9.
WATER
Exercise
A. Answer the following questions :
1. Write some natural sources of water.
Ans. The natural sources of water are rivers, seas, oceans and lakes.
2. How will you purify water by filtration?
Ans. In this method, the insoluble impurities
are removed by using a filter paper.
Impure water is poured over the filter
paper. The impurities remain on the
paper while clean water collects in the
beaker.
3. How can germs present in water be killed?
Ans. By boiling water, germs present in it are killed.
4. List any two ways by which we can avoid wastage of water.
Ans. (i) Get the leaking taps repaired, timely.
(ii) Do not keep tap water running while brushing.
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5. Write any two ways by which we can reuse the water.
Ans. (i) Water used for washing clothes can be collected and reused for
mapping the floor.
(ii) Water used for washing fruits and vegetables can be collected and
used for watering plants.
6. Explain water cycle.
Ans. The sun's heat warms up the water
of rivers, seas and other water
bodies. It gets converted into water
vapours by the process called
evaporation. Water vapour rises in
water cycle
the higher cooler layers of the
atmosphere and changes into water drops by the process called
condensation. Water droplets join together to form clouds. Heavy clouds
burst giving rain. Rainwater falls back on the land and water bodies. The
process cycle goes on repeating air nature. This is called water cycle.
B. Choose the correct word from the box and fill in the blanks :
1. Nearly three quarters of the earth is covered with water.
precious
2. Boiling the water kills the germs present in it.
water
3. Water is very precious.
universal
4. We should repair leaking water taps.
germs
5. Water is called universal solvent.
repair
C. Write :
1. Two ways of water purification :
(a) by adding chlorine
(b) boiling
2. Two ways of reusing water :
(a) water used for washing hands and face can be used to flush out the
toilets.
(b) water used for washing clothes can be collected and reused for
mapping the floor.
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
1
2
Across :
G
F
3. Water is a universal solvent.
E
I
4. Underground water may be drawn
3 U N
I V E R S A L
through wells.
M
T
4
5. Addition of chlorine kills germs
R
4 W E L L S
present in water.
A
A
Down :
T
T
I
E
1. soluble impurity present in water
O
5 C H L O R
I N E
2. a method of removing
N
insoluble impurities from water
4. liquid of life
Fun Time Activity
Visit with your teacher or parents a nearby well/river/pond and make
people aware about keeping the water bodies clean.
Ans. Do yourself.
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10.
WEATHER
Exercise
A. Answer the following questions :
1. Define the following terms :
(a) Weather (b) Humidity (c) Evaporation (d) Condensation
Ans. (a) Weather : Weather is the state of the atmosphere surrounding us. It
depends upon the conditions of sun, wind and rain at a particular place.
(b) Humidity : Humidity means the amount of water vapour present in
air. When too much water vapour is already present in air, our sweat
does not get dry easily, we feel sticky and call it weather as humid.
(c) Evaporation : The process of changing of water into water vapour
on heating is called evaporation.
(d) Condensation : The process in which water vapours cool down to
form water again is called condensation.
2. In India, how many seasons do we experience?
Ans. There are four seasons enjoyed in India. These are winter, spring,
summer and autumn. We have rains in the monsoon. Monsoons are
seasonal (usually end of summers).
3. How does the sun cause wind to blow?
Ans. The heat energy of the sun heats the air near the earth. The hot air
spreads and become lighter. The light, hot air rises up. At the same time
cooler air flows down to take its place. Thus the sun causes the wind to
blow.
4. Which types of earth's movement cause :
(a) day and night
(b) seasons
Ans. (a) Day and night : The earth's rotation on its axis causes day and night.
(b) Seasons : The revolution of earth around the sun causes seasons on
earth.
B. Choose the correct word from side box and fill in the blanks :
1. Warm air becomes lighter and rises up.
fog
2. We have rains in the monsoons.
condensation
3. The earth's rotation on its axis causes day and night.
lighter
4. The blanket of water droplets and cold air above the land
or water surface is called fog.
rotation
5. During condensation, water vapour change into
water again.
monsoons
C. Write True or False against the following statements :
1. The weather can change very quicky.
True
2. The sun does not effect the state of weather.
False
3. The sun causes winds to blow.
True
4. Water droplets evaporate to form water vapours.
True
5. We feel comfortable on a humid day.
False
Let us Enjoy
Enjoy to fill the following crossword puzzle using the given clues :
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2
1 H U M I D I T Y
Across :
E
3
1. amount of water vapour in air
3 S N O W 5
4
3. freezed water vapours
W
P
F
6. process of changing water into
6 E V A P O R A T I O N
water vapour
G
I
A
7. earth's movement on its axis
N
T
Down :
G
H
E
2. water droplets present outside
7 R O T A T I O N
of the cold surface
3. a season in India
4. conditions of atmosphere of a place
5. while blanket of cold air and water drops
Fun Time Activity
1. Make a chart on seasons. Hang this season chart in your classroom.
Ans. Do yourself.
2. Cut and paste different types of clothes and eatables used in different
seasons.
Ans. Do yourself.
11.
MATTER AND MATERIALS
Exercise
A. Answer the following questions :
1. What do you mean by matter?
Ans. Anything that has weight and occupies space is called matter. Matter is
made up of tiny particles called molecules. Molecules of different
substances are of different types.
2. Give two differences between solid, liquid and gas.
Ans.
Solid
Liquid
Gas
(i) Solid have a definite (i) Liquids do not have (i) Gases do not have a
a definite shape but
definite shape and
shape and volume.
their volume is
volume.
definite.
(ii)Liquids
flow from (ii)Gases flow in all
(ii)Solids do not flow.
higher level to
directions.
lower level.
3. Differentiate between transparent and opaque substances giving
examples.
Ans. If the light rays pass through a material, it is called a transparent
material, like glass. The materials which do not allow the light rays to
pass through them are called opaque materials, like wooden board,
cardboard, etc.
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4. What is a solution?
Ans. The mixture of solute and solvent is called a solution.
5. Which substances are called inflammable?
Ans. The substances that catch fire easily are called inflammable substances.
B. Choose the correct word from the box and fill in the blanks :
1. Liquids flow from higher level to lower level.
gases
2. Iron is the good conductor of heat.
liquids
3. Water is used to extinguish fire.
solids
4. Molecules of solids have strong force of attraction.
water
5. Gases neither have definite shape not definite volume.
good
C. Write :
1. Two solids that are hard
:
(a) wood
(b) stone
2. Two transparent objects
:
(a) glass
(b) water
3. Two solids soluble in water :
(a) salt
(b) sugar
4. Two solids that conduct heat :
(a) iron
(b) copper
5. Two solids that are brittle
:
(a) stone
(b) salt
D. Write True or False against the following statements :
1. In gases, molecules are less and distant.
True
2. Sand is insoluble in water.
True
3. Glass is opaque.
False
4. Water is highly inflammable.
False
5. The colour of mustard oil is red.
False
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
2
Across :
1 S O L I D S
1. substances having fixed shape
P
3. It occupies space and has weight.
3 M A T T E R
4
7. Matter is made up of these.
Q
G
6
5
8. a bad conductor of heat
U
S
G
A
7 M O L E C U L E S
Down :
L
A
2. substance through which light
U
S
cannot pass
S
T
4. It spreads in all directions.
I
5. Salt mixes with water to form
8 W O O D
a solution.
N
6. a transparent and brittle substance
Fun Time Activity
1. Take various substances from your home such as soil, sand, sugar, salt,
chalk powder and check their solubility in water.
Ans. Do yourself.
2. Make a list of various solids from your surroundings and classify them
as hard, salt, transparent, opaque, good conductors or bad conductors of
heat.
Ans. Do yourself.
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12.
SOIL : EROSION AND CONSERVATION
Exercise
A. Answer the following questions :
1. How is soil formed?
Ans. Soil is formed by the action of wind, water and rain.
2. Explain the layers of soil.
Ans. There are three main layers of the soil :
(i) Topsoil : It is the uppermost layer of earth. It is a few inches thick, in
which the roots of the plant grow. It is also called the humus layer as
it consists of dead and remains of plants and animals. This layer is
dark in colour.
(ii) Subsoil : This layer is below the topsoil. It is lighter in colour, with
more sand and a few stones. It is hard and contains no humus. It is
not good for plants growth as it contains very little organic matter.
Roots of some trees may reach to subsoil.
(iii) Bedrock : This layer is found below the subsoil. It is mainly made
up of rocks. The upper rocks are soft and porous, while the rocks
present below are hard and now-porous.
3. What is soil erosion?
Ans. The carrying away of the topsoil by wind, water and other factors is
called soil erosion.
4. How do plants help in preserving soil?
Ans. Trees, other plants and grasses prevent soil erosion. Roots of plants
hold the soil together. The stormy winds or floods cannot do much harm
to the topsoil, if the soil is covered by trees or small plants.
5. What do you understand by soil conservation?
Ans. The protection of soil from being blown or washed away is called soil
conservation. We can protect the soil by afforestation, by terrace
farming and building bunds, embankments and dams.
B. Choose the correct word from side box and fill in the blanks :
1. Bedrock contains mainly rocks and stones.
natural
2. Cutting down of trees indiscriminately is called
topsoil
deforestation.
deforestation
3. Erosion disturbs the balance between topsoil and
conservation
subsoil.
subsoil
4. Soil erosion is undesirable and natural phenomenon.
undesirable
5. Soil conservation means protection of soil from erosion.
bedrock
C. Write True or False against the following statements :
1. The uppermost layer of the soil is subsoil.
False
2. The topsoil is soft, loose and fertile.
True
3. Overgrazing is a method of soil conservation.
False
4. Soil erosion reduces the fertility of soil.
True
5. Embankments and dams further increase the soil erosion.
False
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D. Match the following :
1. afforestation
(a) protecting the soil
2. deforestation
(b) steps on hill sides
3. soil erosion
(c) cutting down trees
4. soil conservation
(d) planting trees
5. terrace farming
(e) moving the top soil
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
1
Across :
D A M S
2
1. Dams can be built on rivers to
3
E
B
prevent soil erosions.
F
E
T
4
4. carrying away of soil
D
E R O S I O N
R
R
P
5. middle layer of soil
5 S U B S O I
E
L
6. remains of dead plants 6
H U M U S
C
O
and animals in soil
I
T
K
I
7. an agent of soil erosion L
A
L
L
Down :
T
7 W I
S
N D
1. cutting down of trees
O
2. lowest layer of soil
N
3. most fertile layer of soil
6. Terrace farming is done on hills.
Fun Time Activity
1. Draw any two figures to show soil erosion in your science notebook.
Ans. Do yourself.
2. Collect some pictures showing the different methods of soil
conservation and paste them in your scrapbook.
Ans. Do yourself.
13.
FORCE, WORK AND ENERGY
Exercise
A. Answer the following questions :
1. Define the following terms - (a) force (b) work (c) energy (d) simple
machine.
Ans. (a) Force : The effort we make to push or pull a body is known as force.
(b) Work : In science, the work is said to be done only when a
force(pull or push) moves a body through a distance.
(c) Energy : Energy can be defined as an ability to do work.
(d) Simple machines : The small tools which make our work easy are
known as simple machines.
2. Write the effects produced by force.
Ans. Force can produce the following effects :
· It can move a stationary object.
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· It can stop a moving object.
· It can change the speed of a moving object.
· It can change the direction of a moving object.
· It can change the shape of an object.
3. What do you mean by gravitational force?
Ans. The force by which the earth pulls the objects towards itself is called
gravitational force.
4. Name four appliances that work on electrical energy.
Ans. Television, fan, air cooler and electric iron are for appliances that work
on electrical energy.
5. Name any four types of energies.
Ans. Heat energy, electrical energy, light energy and wind energy are four
types of energies.
B. Choose the correct word from the box and fill in the blanks :
1. Push or pull is called force.
magnetic
2. We need energy to apply force to do any work.
solar
3. Sunlight contains solar energy.
force
4. Magnet attracts iron nails because of magnetic force.
gravitational
5. Earth attracts everything towards itself due to
gravitational force.
energy
C. Name the type of force applied in each of these actions :
1. While catching a ball :
gravitational force
2. While stretching a rubber band :
elastic force
3. While using a scissors :
mechanical force
4. While using a magnet :
magnetic force
D. Identify the situations where work is actually done :
1. Kicking a ball and ball moves away
Yes
2. Trying to lift a heavy bag but cannot lift it
No
3. Pushing the door and the door shuts
Yes
4. Riding a bicycle and going to school
Yes
5. Standing on the ground carrying suitcase on head
No
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
Across :
1
2. a push or a pull
W
3
2 F O R C E
5. Animals use muscular force for work.
4
S
R
L
6. force applied by magnet
O
K
A
Down :
5 M U S C U L A R
1. Energy is the ability to do work.
T
A
3. force applied by a stretched
I
R
rubber band
6 M A G N E T I C
4. energy of sun
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Fun Time Activity
1. Collect pictures of various simple machines. Paste them in your
scrapbook.
Ans. Do yourself.
2. Try to make a small wind wheel using paper and broom sticks.
Ans. Do yourself.
14.
SOLAR SYSTEM
Exercise
A. Answer the following questions :
1. Why don't we see the stars during the day?
Ans. We do not see the stars during the day. It is because the light coming
from the sun to the earth is too bright.
2. When did the sun begin to shine?
Ans. The sun began to shine about five billion years ago.
3. What is meant by the solar system?
Ans. The sun has eight planets moving around it in their own orbits. These
planets are of different sizes. The sun and its family of eight planets is
together known as the solar system.
4. Name the eight planets according to the distance from the sun.
Ans. The eight planets according to the distance from the sun are Mercury,
Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
5. Name a few man-made satellites launched by India.
Ans. Aryabhatta, Bhaskara, Rohini, Inset IA, Inset IB, Inset 2A, Inset 2B and
Inset 3E are some man-made satellites launched by India.
B. Choose the correct word from the box and fill in the blanks :
1. The sun is the nearest star to the earth.
earth
2. Saturn has a spectacular ring system around it.
saturn
3. A satellite is a heavenly body that revolves around a planet. artificial
4. The earth is the only planet known to have life.
sun
5. Man-made satellites are called artificial satellites.
satellite
C. Write :
1. Two characteristics of sun :
Ans. (a) Sun is a hot ball of burning gases.
(b) Temperature at sun's surface is about 6000 °C.
2. Two characteristics of earth :
:
Ans. (a) The earth is the only planet known to have water and oxygen.
(b) It is neither too hot nor too cold.
3. Two characteristics of moon :
Ans. (a) Moon is earth's natural satellite.
(b) Its diameter is about one-sixth of the diameter of the earth.
4. Two uses of artificial satellites :
Ans. (a) They help in weather monitoring.
(b) They help in telecommunications and space exploration.
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D. Match the following :
1. Mercury
(a) coldest planet
2. Neptune
(b) brightest planet
3. Jupiter
(c) red planet
4. mars
(d) biggest planet
5. venus
(e) hottest planet
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
2
Across :
1 M
A R
4
1. red planet
N
R
5. hottest planet
5 M
E R C U R Y
6. Indian satellite
7. centre of solar system
P
A
8. blue planet
T
B
U
6
R
O
H
I
3
S
A
T
U
R
N
I
Down :
U N
A
7 S
2. first Indian satellite
E
T
3. planet with 60 moons
E
R
T H
A
8
4. coldest planet
A
Fun Time Activity
1. Make a model of the solar system on a cardboard sheet, by pasting
pictures of the planets around the sun.
Ans. Do yourself.
2. Cut coloured papers and make 8 balls of different sizes to show planets
and one biggest ball of yellow colour to shown the sun.
Ans. Do yourself.
15.
WASTE MANAGEMENT
Exercise
A. Answer the following questions :
1. What is waste?
Ans. Waste means anything which is of no use for us.
2. What are the different types of wastes produced at our home?
Ans. Most of the household wastes come from kitchen. It includes poly
pouch, vegetable peels, fruits, meat, etc. Waste from packing, waste
water and sewage also come under household waste.
3. Differentiate between biodegradable and non-biodegradable
wastes giving examples.
Ans. Biodegradable Waste : This include organic waste which easily gets
decomposed by bacteria and other micro-organisms with time. Some of
the biodegradable wastes are fruits, vegetable peels, meat, leaves,
flowers, rags and papers.
Non-biodegradable Waste : Wastes such as plastics, metals and glasses
are obtained from non-living things. These do not rot and mix with the
soil with time. They remain as such even after years.
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4.
Ans.
5.
Ans.
What is meant by recycling of wastes?
Recycling means processing the waste again to make new items from it.
What are the benefits of waste management?
Waste management is beneficial for us in many ways. Some of them are :
· It reduces the pollution of air, water and land.
· It conserves the natural resources for future use.
· It saves energy required for production.
· It provides a clean environment.
B. Classify these as biodegradable and non-biodegradable :
1. vegetable peels
2. paper bags
3. broken glass
4. cotton dressing
5. wooden dust
6. plastic toys
7. fruits and meat
8. polythenes
9. flowers
Ans. Biodegradable
Non-biodegradable
vegetable, peels, paper bags,
broken glasses, plastic toys,
cotton dressing, wooden dust,
polythenes
fruits and meat, flowers
C. Choose the correct word from side box and fill in the blanks :
1. All human activities produce waste.
air pollution
2. Plastic is an example of non-biodegradable waste. non-biodegradable
3. Waste cannot be piled and burnt as it leads to air
pollution.
clean
4. Organic waste is biodegradable in nature.
biodegradable
5. Waste management is essential to have a clean
environment.
waste
Let us Enjoy
Fill the following crossword puzzle with the help of given clues :
Across :
1
D
3. using objects again for some 2
U
G
other purpose
3 R E U S E
A
5. waste that rots easily
4
R
T
6. a non-biodegradable waste R
5 B I O D E G R A D A B L E
Down :
C
I
A
1. object to collect waste
Y
N
G
2. another word for waste
C
E
4. to process old things to
6 P O L Y T H E N E
make new things from them
E
Fun Time Activity
1. Make a list of waste materials produced in your household in a week.
Categorize these wastes as :
(i) biodegradable and non-biodegradable (ii) recyclable reusable
Ans. Do yourself.
2. Make two dustbins of your home one for biodegradable waste (green
colour) and other for non-biodegradable waste (blue colour). Observe
the garbage items produced your home. Put biodegradable wastes in
the green coloured bin and non-biodegradable wastes in the blue
coloured bin. How is this segregation beneficial to you?
Ans. Do yourself.
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