SOME IMPORTANT POINTS FOR REVISION FOR CLASS 7 (03 CHAPTERS)
Light
1. Light travels along straight lines.
2. Any polished or a shiny surface changes the direction of light that falls on it. This change of direction by any
polished or a shiny surface is called reflection of light.
3. When a lighted candle is placed in front of a plane mirror, it appears as if a similar candle is placed behind the
mirror. The candle, which appears behind the mirror, is the image of the candle formed by the mirror. The
candle itself is the object.
4. An image formed by a plane mirror is erect and of the same size as the object.
5. An image which can be obtained on a screen is called a real image. „
6. An image which cannot be obtained on a screen is called a virtual image.
7. The image formed by a plane mirror is erect, virtual, and is of the same size as the object. The image is at the
same distance behind the mirror as the object is in front of it.
8. In an image formed by a mirror, the left side of the object is seen on the right side in the image, and right side
of the object appears to be on the left side in the image.
9. If the reflecting surface of a spherical mirror is concave, it is called a concave mirror. If the reflecting
surface is convex, then it is a convex mirror.
A Concave and a Convex mirror
9. The word ‘AMBULANCE’ is written as shown below on the vehicle: -
When the driver of a vehicle ahead of an ambulance looks in her/his rear view mirror, s/he can read
‘AMBULANCE’ written on it and give way to it. It is the duty of every one of us to allow an ambulance to pass
without blocking its way.
10. Image formed by a convex mirror is erect, virtual and smaller in size than the object.
11. In the side mirror of a scooter or a car the images of all the objects appear smaller than the objects
themselves.
12. The curved shining surface of a spoon acts as a mirror.
(i) Image from the outer side of a spoon: - The image will be erect and larger in size.
(ii) Image from the inner side of a spoon: - The image will be inverted and smaller in size.
The inner surface of a spoon acts like a concave mirror, while its outer surface acts like a convex mirror.
13. 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.
14. Doctors use concave mirrors for examining eyes, ears, nose and throat. Concave mirrors are also used by
dentists to see an enlarged image of the teeth. The reflectors of torches, headlights of cars and scooters are
concave in shape.
15. Convex mirrors can form images of objects spread over a large area. So, these help the drivers to see the
traffic behind them.
16. A magnifying glass is actually a type of a lens. Lenses are widely used in spectacles, telescopes and
microscopes.
17. Those lenses which feel thicker in the middle than at the edges are convex lenses. Those which feel thinner
in the middle than at the edges are concave lenses.
A convex lens and concave lens
18. A convex lens converges (bends inward) the light generally falling on it. Therefore, it is called a converging
lens. On the other hand, a concave lens diverges (bends outward) the light and is called a diverging lens.
19. A convex lens can forms real and inverted image. When the object is placed very close to the lens, the image
formed is virtual, erect and magnified. When used to see objects magnified, the convex lens is called a
magnifying glass.
20. A concave lens always forms erect, virtual and smaller image than the object.
21. White light is composed of seven colours. These are — red, orange, yellow, green, blue, indigo and violet.
22. Some uses of convex lens: (i) The lens in the human eyes is a biconvex lens. So the most common use of the lens is that it helps us to see.
(ii) Another common example of the use convex lens is a magnifying glass. When an object is placed in front of
it at a distance shorter than the focal length of the lens, it produces a magnified and erect image of the object on
the same side as the object itself.
(iii) It is used to correct hypermetropia or long-sightedness.
(iv) It is used in cameras because it focuses light and produces a clear and crisp image.
(v) It is also used in other magnifying devices such as microscopes and telescopes.
23. Despite being less useful than convex lenses, concave lenses have several uses, including in eyeglasses and
contacts, flashlights, peepholes, binoculars, telescopes, and in photography.
NOW TRY TO ANSWER THE FOLLOWING QUESTIONS
1. Boojho and Paheli were given one mirror each by their teacher. Boojho found his image to be erect and of the
same size whereas Paheli found her image erect and smaller in size. This means that the mirrors of Boojho and
Paheli are, respectively
(a) plane mirror and concave mirror.
(b) concave mirror and convex mirror.
(c) plane mirror and convex mirror.
(d) convex mirror and plane mirror.
2. Which of the following can be used to form a real image?
(a) Concave mirror only.
(b) Plane mirror only.
(c) Convex mirror only.
(d) Both concave and convex mirrors
3. If an object is placed at a distance of 0.5 m in front of a plane mirror, the distance between the object and the
image formed by the mirror will be
(a) 2 m
(b) 1 m
(c) 0.5 m
(d) 0.25 m
4. You are provided with a concave mirror, a convex mirror, a concave lens and a convex lens. To obtain an
enlarged image of an object you can use either
(a) concave mirror or convex mirror.
(b) concave mirror or convex lens.
(c) concave mirror or concave lens.
(d) concave lens or convex lens.
5. A rainbow can be seen in the sky
(a) when the sun is in front of you.
(b) when the sun is behind you.
(c) when the sun is overhead.
(d) only at the time of sun rise.
6. An erect and enlarged image can be formed by
(a) only a convex mirror.
(b) only a concave mirror.
(c) only a plane mirror.
(d) both convex and concave mirrors.
7. You are provided with a convex mirror, a concave mirror, a convex lens and a concave lens. You can get an
inverted image from
(a) both concave lens and convex lens.
(b) both concave mirror and convex mirror.
(c) both concave mirror and convex lens.
(d) both convex mirror and concave lens.
8. An image formed by a lens is erect. Such an image could be formed by a
(a) convex lens provided the image is smaller than object.
(b) concave lens provided the image is smaller than object.
(c) concave lens provided the image is larger than object.
(d) concave lens provided the image is of the same size.
9. A virtual image larger than the object can be produced by a
(a) concave lens
(b) concave mirror
(c) convex mirror
(d) plane mirror
10. David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he
moves 1 m towards the mirror, then the distance between David and his image will be
(a) 3 m
(b) 5 m
(c) 6 m
(d) 8 m
11. The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver
sees in his rear view mirror the image of a truck parked behind his car. The speed at which the image of the
truck appears to approach the driver will be
(a) 1 m/s
(b) 2 m/s
(c) 4 m/s
(d) 8 m/s
12. The image formed by a lens is always virtual, erect and smaller in size for an object kept at different
positions in front of it. Identify the nature of the lens.
13. State the characteristics of the image formed by a plane mirror.
14. What is a virtual image? Give one situation where a virtual image is formed.
15. Find out the letters of English alphabet or any other language known to you in which the image formed in a
plane mirror appears exactly like the letter itself. Discuss your findings.
16. State two differences between a convex and a concave lens.
17. Give one use each of a concave and a convex mirror.
18. Which type of mirror can form a real image?
19. Which type of lens forms always a virtual image?
20. Fill in the blanks:
(a) An image that cannot be obtained on a screen is called ____________.
(b) Image formed by a convex __________ is always virtual and smaller in size.
(c) An image formed by a __________ mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a _________ image.
(e) An image formed by a concave ___________ cannot be obtained on a screen.
(f) The inner surface of a steel spoon acts as a ___________ mirror.
(g) The outer surface of a flat steel plate acts as a ___________ mirror.
(h) The outer shining surface of a round bottom steel bowl acts as a __________ mirror.
(i) The inner surface of the reflector of a torch acts as a __________ mirror.
21. What type of mirror is used as a side mirror in a scooter? Why is this type of mirror chosen?
22. Boojho made light from a laser torch to fall on a prism. Will he be able to observe a band of seven colours?
Explain with a reason.
23. The side mirror of a scooter got broken. The mechanic replaced it with a plane mirror. Mention any
inconvenience that the driver of the scooter will face while using it?
24. The concave reflecting surface of a torch got rusted. What effect would this have on the beam of light from
the torch?
25. An erect and enlarged image of an object is formed on a screen. Explain how this could be possible.
26. Two different type of lenses are placed on a sheet of newspaper. How will you identify them without
touching?
27. A shopkeeper wanted to fix a mirror which will give a maximum view of his shop. What type of mirror
should he use? Give reason.
28. The distance between an object and a convex lens is changing. It is noticed that the size of the image formed
on a screen is decreasing. Is the object moving in a direction towards the lens or away from it?
29. Suppose we wish to obtain the real image of a distant tree. Explain two possible ways in which we can do it.
30. It was observed that when the distance between an object and a lens decreases, the size of the image
increases. What is the nature of this lens? If you keep on decreasing the distance between the object and the
lens, will you still able to obtain the image on the screen? Explain.
31. You are given three mirrors of different types. How will you identify each one of them?
32. Observe the figures given below carefully: -
The given figures show the path of light through lenses of two different types, represented by rectangular boxes
A and B. What is the nature of lenses A and B?
33. State the correct sequence (1-7) of colours in the spectrum formed by the prisms A and B, shown in the
figure given below: -
34. Match the items given in Column I with one or more items of Column II.
Column I
Column II
(a) A plane mirror
(i) Used as a magnifying glass.
(b) A convex mirror
(ii) Can form image of objects spread over a large area.
(c) A convex lens
(iii) Used by dentists to see enlarged image of teeth.
(d) A concave mirror
(iv) The image is always inverted and magnified.
(e) A concave lens
(v) The image is erect and of the same size as the object.
(vi) The image is erect and smaller in size than the object.
Water: A Precious Resource
1. 22 March is celebrated as the ‘world water day’.
2. We celebrate water day every year to attract the attention of everybody towards the importance of conserving
water.
3. The amount of water recommended by the United Nations for drinking, washing, cooking and maintaining
proper hygiene is a minimum of 50 litres per person per day. This amount is about two and a half buckets of
water per person per day.
4. Earth appears blue from space. About 71% of the earth’s surface is covered with water. Almost all the water
on the earth is contained in the seas and oceans, rivers, lakes, ice caps, as groundwater and in the atmosphere.
5. Freshwater makes up a very small fraction of all water on the planet. While nearly 71 percent of the world is
covered by water, only 2.5 percent of it is fresh. The rest is saline and ocean-based. And the water available for
use is roughly 0.006% of all water found on the earth.
6. Water on the earth has been maintained for millions of years by various processes which make the water
cycle.
The Sun's heat provides energy to evaporate water from the Earth's surface (oceans, lakes, etc.). Plants also lose
water to the air (this is called transpiration). The water vapor eventually condenses, forming tiny droplets in
clouds. When the clouds meet cool air over land, precipitation (rain, sleet, or snow) is triggered, and water
returns to the land (or sea). Some of the precipitation soaks into the ground. Some of the underground water is
trapped between rock or clay layers; this is called groundwater. But most of the water flows downhill as runoff
(above ground or underground), eventually returning to the seas as slightly salty water.
7. When water circulates through the water cycle it can be found in all the three forms, i.e., solid, liquid and
gas—at any given time somewhere on the earth. The solid form, snow and solid ice, is present as ice caps at the
poles of the earth, snow-covered mountains and glaciers. Liquid water Liquid is present in oceans, lakes, rivers,
and even underground. The gaseous form is the gaseous water vapour present in the air around us. The
continuous cycling of water among its three forms keeps the total amount of water on the earth constant even
when the whole world is using it.
8. Most towns and cities have water supply system maintained by the civic bodies. The water is drawn from
nearby lakes, rivers, ponds or wells. The water is supplied through a network of pipes.
9. Many villages do not have such a water supply system. There people fetch water directly from the sources.
Often women and children have to walk several kilometres to fetch water. The children suffer a lot. They cannot
attend school regularly since they spend hours in fetching water.
10. A large number of people draw water from wells, tube wells or hand pumps.
11. Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. It is stored in
and moves slowly through geologic formations of soil, sand and rocks called aquifers.
12. Water table may be at a depth of less than a metre or may be several metres below the ground. The water
found below the water table is called groundwater.
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.
13. At places underground, 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.
14. 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.
15. Water table may go down if the water is not sufficiently replenished. This may happen due to many reasons.
Increase in population, deforestation, decrease in the effective area for seepage of water, industrial and
agricultural activities are some common factors affecting water table. Scanty rainfall is another factor that may
deplete the water table.
16. Some
sources of water: -
17. 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. A pukka floor does not allow water to seep in easily, while in a grass lawn water seeps through in no
time.
A huge amount of water is required for construction work. Often groundwater is used for this purpose.
18. With the increasing population, number of industries is increasing continuously. Water used by most of the
industries is drawn from the ground.
19. Population pressure on agriculture forces increasing use of groundwater day by day. This also results in
depletion of water table.
20. When the civic authorities supply water through pipes not all of it may reach the destination. Water supply
pipes can be seen leaking at several places, and a lot of water gushing out of the pipes. It is the responsibility of
the civic authorities to prevent such wastage of precious water.
21. All of us, knowingly or unknowingly, waste water while brushing teeth, shaving, bathing, washing and
during many other activities. Leaking taps is another source of huge water wastage.
22. Most of the water that we get as rainfall just flows away. This is a waste of precious natural resource. The
rainwater can be used to recharge the groundwater. This is referred to as water harvesting or rainwater
harvesting.
23. Bawri/Baori (Stepwell) was the traditional way of collecting water.
24. A farmer using water in the field can also use water economically. Maybe you have heard of drip irrigation.
Drip irrigation is a technique of watering plants by making use of narrow tubings which deliver water directly at
the base of the plant.
25. Some ways to conserve water: Some ways to conserve water in kitchen
(i) When washing dishes by hand, fill the sink basin or a large container and rinse when all of the dishes have
been soaped and scrubbed.
(ii) Don’t let the faucet run while you clean vegetables. In-fact, clean them in the pan of clean water.
(iii) Always have the bottle of clean water in the refrigerator; This will help in reducing the running tap water.
(iv) Turn off water faucets tightly so they don’t drip.
(v) When you wash dishes by hand don’t leave the water running for rinsing.
(vi) Mop the floor instead of washing.
Some ways to conserve water in bathroom
(i) Don’t take lengthy showers. Though it may be comforting but it may lead to wastage of water.
(ii) Avoid flushing the toilet unnecessarily. Dispose of tissues, insects and other such waste in the trash rather
than the toilet.
(iii) Don’t let water run while shaving or washing your face. Brush your teeth first while waiting `for water to
get hot, then wash or shave after filling the basin.
(iv) Keep a bucket in the shower to catch water as it warms up or runs. Use this water to flush toilets or water
plants.
(v) Check faucets and pipes for leaks
(vi) If you’re taking a shower, don’t waste cold water while waiting for hot water to reach the shower
head. Catch that water in a container to use on your outside plants or to flush your toilet.
Some ways to conserve water outside
(i) Water your lawn and garden in the morning or evening when temperatures are cooler to minimize
evaporation.
(ii) Collect the water you use for rinsing fruits and vegetables, and then reuse it to water houseplants.
(iii) Collect water from your roof using a rainwater tank to water your garden.
(iv) Rather than following a set watering schedule, check for soil moisture two to three inches below the surface
before watering.
(v) Water only when necessary. More plants die from over-watering than from under-watering.
(vi) Wash your pets outdoors in an area of your lawn that needs water.
26. Effect of water scarcity on plants: (i) The first obvious effect of water stress is wilting because turgor pressure, which inflates plant cells and keeps
them erect, is lost. Without this force, the cells inside plant leaves begin collapsing, giving them a limp
appearance. As wilting increases, plant cells fully deflate, causing their deaths.
(ii) When water levels are low due to water stress, photosynthesis can slow or even stop, causing internal food
supplies vital to other processes to diminish or disappear -- yellowing may also occur if photosynthesis stops
completely.
(iii) Transpiration maintains turgor in plants, keeping cells evenly filled with water. When transpiration is
stopped or slowed, the plant begins to die from lack of nutrients, usually from the top down.
The green character of the planet shall be lost. This may mean the end of all life, for a world without plants shall
mean no food, no oxygen, not enough rain, and innumerable other problems.
NOW TRY TO ANSWER THE FOLLOWING QUESTIONS
1. The total water
(a) in the lakes and rivers of the world remains constant.
(b) under the ground remains constant.
(c) in the seas and oceans of the world remains constant.
(d) of the world remains constant.
2. Which of the following does not show water shortage?
(a) Taps running dry.
(b) Long queues for getting water.
(c) Marches and protests for demand of water.
(d) A family gets three buckets of water per person per day.
3. Seas and oceans are full of water on earth. However, a very small percentage of water present on earth is
available for us. This percentage is roughly
(a) 0.006%.
(b) 0.06%.
(c) 0.6%.
(d) 6%.
4. Which of the following are not the liquid forms of water?
(i) Snow (ii) Lake water (iii) River water (iv) Water vapour (v) Ice
Choose the correct combination from the options below.
(a) (i), (iv) and (v)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iv) only
5. A man digging the ground near a water body found that the soil was moist. As he kept digging deeper and
deeper he reached a level where all the spaces between particles of soil and gaps between rocks were filled with
water. The upper limit of this layer is called
(a) water level.
(b) water table.
(c) ground water.
(d) water limit.
6. On which of the following day is World Water Day observed?
(a) 22 March
(b) 14 November
(c) 2 October
(d) 21 December
7. The amount of water recommended by the United Nations for drinking, washing, cooking and maintaining
proper hygiene per person per day is a minimum of
(a) 5 litres
(b) 15 litres
(c) 30 litres
(d) 50 litres
8. “Every Drop Counts” is a slogan related to
(a) counting of drops of any liquid.
(b) counting of water drops.
(c) importance of water.
(d) importance of counting.
9. Water cycle does not involve which of the following?
(a) Evaporation
(b) Condensation
(c) Formation of clouds
(d) Rainwater harvesting
10. Which of the following inhibits the seepage of rainwater into ground?
(a) A pukka floor
(b) Playground
(c) Grass lawn
(d) Forest land
11. Some definitions are given below which can be corrected by changing one word. Correct them.
(a) Aquifer is ground water stored between layers of hard rock above the water table.
(b) The process of evaporation of water in the ground is called infiltration.
(c) The evaporation of water from oceans and its arrival back into oceans is called vapour cycle.
12. What is the source of water in each of the following ?
(a) Wells
(b) Ground
(c) Atmosphere
13. Fill in the blanks in the given passage.
The rainwater and ________________ from other sources such as rivers and ponds seeps through the
______________ and fills the empty spaces and cracks deep below the ground. The process of seeping of water
into the ground is called ______________.
14. Fill in the blanks and complete the story selecting words from the box given here.
cold, demand, leaders, dry, hot, scarcity, workers, wet, oceans, harvesting, rivers
Rajasthan is a _________ and dry place. The challenge of natural _______ of water was met by a successful
experiment. A band of social ________ had transformed a _________ area into a green place. They have
revived five dried-up ________ by constructing water ___________ structures.
15. Place the following statements in a proper order to form a meaningful paragraph.
(a) Which in turn decreases the seepage of rain water into the ground.
(b) This decreases the open areas like park, and playgrounds.
(c) Increasing population creates demand for construction of houses, shops, offices, roads and pavements.
(d) This results in depletion of water table and creates scarcity of more water.
16. How can you observe the three forms of water in (i) nature and (ii) at home?
17. A list of jumbled words are given here. Write the correct form of each word.
(a) WASHFERRET
(b) CHARREGE
(c) QUIFERA
(d) WOSN
18. From where do the following usually get water? In which form is water present in them?
(a) Clouds
(b) Plants
(c) Mountain tops
(d) Aquifer
19. What is ground water? What are the sources of water which are fed by ground water?
20. Water is very precious for all the living beings. What will happen in future if we do not save water now?
21. Match Column I with Column II: -
22. Make a sketch showing groundwater and water table. Label it.
23. Which one of the following is not responsbile for water shortage?
(i) Rapid growth of industries
(ii) Increasing population
(iii) Heavy rainfall
(iv) Mismanagement of water resources
24. Fill in the blanks with the appropriate answers:
(a) People obtain groundwater through________ and ________.
(b) Three forms of water are ________, ________ and ________.
(c) The water bearing layer of the earth is ________.
(d) The process of water seepage into the ground is called ________.
25. Explain the factors responsible for the depletion of water table.
26. You have been asked to maintain a garden. How will you minimize the use of water?
27. There are ten tube wells in a lane of fifty houses. What could be the long term impact on the water table?
28. Explain how groundwater is recharged?
29. Complete the following chart by writing appropriate words in the boxes marked (a) to (e).
Forests: Our Lifeline
1. The forests serve as green lungs and water purifying systems in nature.
2. Once inside a forest everyone should keep quiet because noise could disturb the animals living in the forest.
3. Sudden sound of birds and animals may be a type of warning call to alert other animals about the presence of
strangers or animals of prey.
4. Animals like boar, bison, jackals, porcupine, and elephants live in the deeper areas of the forest.
5. Forest provides a home for many animals and plants.
6. Plywood, fuel wood, boxes, paper, matchsticks, furniture, gum, oils, spices, fodder for animals and medicinal
plants are some of the products which we get from the forest.
7. Nobody need plant trees inside a forest. In nature trees produce enough seeds. The forest floor provides
favourable conditions for them to germinate and develop into seedlings and saplings. Some grow up into trees.
He added that branchy part of a tree above the stem is known as the crown of the tree.
8. In the forest most plant and animal life is not found on the forest floor, but in the leafy world known as
the canopy. The canopy, which may be over 100 feet (30 m) above the ground, is made up of the overlapping
branches and leaves.
9. Canopy - A tree’s upper branches are called the crown. The canopy is a horizontal layer of tree crowns
making up the top layer of a forest. The fast growing trees can grow taller than others around and are called
dominant. Dominant trees form an upper canopy. Trees with crowns making up most of the canopy may be
called co-dominant.
10. Understory - The understory includes the shorter trees in the forest, especially the trees and shrubs growing
between the forest canopy and the forest floor. . Some are young trees, but others are trees that are just growing
slowly because they don’t get much light filtering through the dense canopy. These may be called suppressed
trees. The understory also has bushes and other plants, as well as snags (dead trees that are still standing). Giant
and tall trees constituted the top layer followed by shrubs and tall grasses, and herbs formed the lowest layer.
11. 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
eaten by the frog. The frog is consumed by snakes. This is said to form a food chain:
Grass→ insects→ frog→ snake→ eagle.
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. Every part of the forest is dependent on the other parts. If we remove one component,
say trees, all other components would be affected.
12. Mushroom and other micro-organisms thriving in the forest feed upon the dead plant and animal tissues and
convert them into a dark coloured substance called humus. The micro-organisms which convert the dead plants
and animals to humus are known as decomposers.
13. Nothing goes waste in a forest. Dead animals become food for vultures, crows, jackals and insects. On
decomposition, the 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.
14. Plants release oxygen through the process of photosynthesis. The plants help to provide oxygen for animal
respiration. They also maintain the balance of oxygen and carbon dioxide in the atmosphere. That is why forests
are called lungs.
15. Trees take in water from their roots and release water vapour into the air through evaporation.
16. Some people belonging to different tribes live in forest. The forest provides them with food, shelter, water
and medicines. They have traditional knowledge about many medicinal plants in the forest.
17. The dense bushes and the tall grass provide animals with the food and shelter. They also protect them from
carnivores that live in the forest.
18. The forest officers could recognize the presence of some animals in the forest by their droppings and
footprints.
19. Several beetles and grubs feed on the animal droppings, and seedlings can also be found sprouting from the
droppings. These seedlings are of the herbs and shrubs. The animals also disperse the seeds of certain plants and
help the forest to grow and regenerate. The decaying animal dung provides nutrients to the seedlings to grow.
20. By harbouring greater variety of plants, the forest provides greater opportunities for food and habitat for the
herbivores. Larger number of herbivores means increased availability of food for a variety of carnivores. The
wide variety of animals helps the forest to regenerate and grow. Decomposers help in maintaining the supply of
nutrients to the growing plants in the forest. Therefore, the forest is a ‘dynamic living entity’ — full of life and
dynamic living entity vitality.
21. The forest also acts as a natural absorber of rainwater and allows it to seep. It helps maintain the water table
throughout the year. Forests not only help in controlling floods but also help maintain the flow of water in the
streams so that we get a steady supply of water. On the other hand, if trees are not present, rain hits 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.
22. The weather of the village surrounded by forest will be pleasant. Due to the surrounding forest, there will be
good rainfall. The air also would remain cool. Noise pollution too would be less because the forest absorbs the
noise of the nearby highway.
23. Construction of roads, buildings, industrial development, increasing demand of wood, overgrazing of
animals and indiscriminate felling of trees would create pressure on the forests and the forests would start
vanishing.
24. Forests provide us with oxygen. They protect soil and provide habitat to a large number of animals. Forests
help in bringing good rainfall in neighbouring areas. They are a source of medicinal plants, timber and many
other useful products. We must preserve our forests.
25. What would happen if forests disappear?
(i) If forests disappear, the amount of carbon dioxide in air will increase, resulting in the increase of earth’s
temperature.
(ii) In the absence of trees and plants, the animals will not get food and shelter.
(iii) In the absence of trees, the soil will not hold water, which will cause floods.
(iv) Deforestation will endanger our life and environment.
NOW TRY TO ANSWER THE FOLLOWING QUESTIONS
1. Which of the following serve as green lungs?
(a) Green pigment of the plants
(b) Forests
(c) Kitchen gardens
(d) Green house gases
2. Boojho visited a forest near his town with his classmates and his teacher. As they were entering the forest,
their class teacher told them not to make noise in the forest as noise could disturb the
(a) birds
(b) animals
(c) both birds and animals
(d) plants
3. Which among the following forest animals is the smallest?
(a) Fox
(b) Boar
(c) Bison
(d) Porcupine
4. Which of the following has the strongest stem?
(a) A tree
(b) A creeper
(c) A climber
(d) A bush
5. Which of the following is not prepared from the wood obtained from forest?
(a) Paper
(b) Thermocol
(c) Matchsticks
(d) Plywood
6. Which of the following is not the name of a tree?
(a) Teak
(b) Sal
(c) Porcupine
(d) Kachnar
7. Pick the option which gives the names of a tree and an animal, respectively from the following.
(a) semal, hornbill
(b) sal, khair
(c) chinkara, blue bull
(d) neem, palash
8. Which of the products is not obtained from a forest?
(a) Honey
(b) Catechu
(c) Gum
(d) Ginger
9. The branchy part of a tree above the stem is known as
(a) crown
(b) canopy
(c) sapling
(d) humus
10. Forests are not responsible for
(a) providing medicinal plants.
(b) maintaining the flow of water into the streams.
(c) creating flood conditions.
(d) absorbing rainwater and maintaining water table.
11. Which of the following is not a forest product?
(a) Gum
(b) Plywood
(ci) Sealing wax
(d) Kerosene
12. Which of the following statements is not correct?
(a) Forests protect the soil from erosion.
(b) Plants and animals in a forest are not depedent on one another.
(c) Forests influence the climate and water cycle.
(d) Soil helps forests to grow and regenerate.
13. Micro-organisms act upon the dead plants to produce
(a) sand
(b) mushrooms
(c) humus
(d) wood
14. Fill in the blank:
(a) The insects, butterflies, honeybees and birds help flowering plants in __________________.
(b) A forest is a purifier of and ______________________.
(c) Herbs form the _________________ layer in the forest.
(d) The decaying leaves and animal droppings in a forest enrich the __________________.
15. Why should we worry about the conditions and issues related to forests far from us?
16. Explain why there is a need of variety of animals and plants in a forest.
17. Explain how animals dwelling in the forest help it grow and regenerate.
18. Explain how forests prevent floods.
19. What are decomposers? Name any two of them. What do they do in the forest?
20. Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
21. Explain why there is no waste in a forest.
22. List five products we get from forests?
23. Paheli while moving in a forest observed that there was no noise pollution, though lots of heavy vehicles
were passing from the nearby highway. Explain why?
24. Paheli wrote a food chain in the following way: frog→ eagle → insects’ → grass→ snake
The chain is not in the correct order. Help her to write the food chain correctly.
25. Give names of any four birds which you expect to see in a forest.
26. “A bunch of seedlings were seen sprouting on a heap of animal dropping in a forest.” How do you think is
the seedling benefited from the animal dung?
27. Deforestation may lead to floods. Why?
28. Name any four useful products other than wood, which we get from forests.
29. People say that nothing goes waste in a forest. Can you explain, how?
30. Give any four factors which are responsible for the destruction of forests.
31. All the needs of animals living in a forest are fulfilled. Justify this statement in a few sentences.
32. “Forests are our lifeline.” Write five sentences on this topic.
33. Match Column I with Column II: -