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NCERT Exemplar Problems Class 7 Science Chapter 17 Forests: Our Lifeline
Multiple Choice Questions (MCQs)
Which of the following serve as green lungs?
(a) Green pigment of the plants
(c) Kitchen gardens
(d) Greenhouse gases
(b) Forests serve as green lungs as they produce oxygen for breathing and respiration and help in maintaining oxygen and carbon dioxide balance in the atmosphere.
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
(c) Both (a) and (b)
(c) As Boojho was entering the forest, his class teacher told him not to make noise in the forest because it could disturb both birds and animals.
Which among the following forests animals is the smallest?
(d) Porcupine is the smallest forest animal among the following given in the options.
Which of the following has the strongest stem?
(a) A tree
(b) A creeper
(c) A climber
(d) A bush
(a) A tree has the strongest stem.
Which of the following is not prepared from the wood obtained from forest?
(b) Thermocol is not prepared from the wood obtained from the forest. Paper, matchsticks and plywood are prepared from the wood.
Which of the following is not the name of a tree?
(c) Porcupine is not the name of a tree rather it is an animal. Teak, sal and kachnar are names of trees.
Pick the option which gives the names of a tree and an animal respectively from the following.
(a) Semal and hornbill
(b) Sal and khair
(c) Chinkara and blue bull
(d) Neem and palash
(a) From the above given options, semal and hornbill are the names of a tree and an animal, respectively.
Which of the products is not obtained from a forest?
(d) Honey, catechu (kattha) and gum are forest products but ginger is not a forest product.
The branchy part of a tree above the stem is know as
(a) The branchy part of a tree above the stem is known as the crown of the tree. The crown includes the top part of a tree which has all the branches and leaves of the tree.
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
(c) Forests are not responsible for creating flood conditions, as they protect form flood condition.
Very Short Answer Type Questions
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.
Paheli observed that there was no noise pollution in a forest even though there were lots of heavy vehicles passing from the nearby highway. It is because trees present in the forest absorb the noise.
State whether the following statements are true or false. If false give the correct statement.
(a) Forest influence climate, water cycle and air quality.
(b) In a forest, trees form the uppermost layer, followed by herbs. The shrubs foim the lowest layer of vegetation.
(c) The forest keeps on growing and changing and can regenerate.
(d) Forest protect the soil from erosion.
(b) False, in a forest, trees form the uppermost layer followed by shrubs. The herbs form the lowest layer of vegetation.
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.
The correct food chain is:
Grass —> Insects —> Frog —> Snake —>Eagle
An insect eats green plant or grass – a frog eats the insects – the frog Is eaten by snake – the snake is eaten by an eagle.
Short Answer Type Questions
Give names of any four birds which you expect to see in a forest.
The four birds which we expect to see in a forest are jungle crow, hornbill, myna and koel.
Two friends shared their experiences of their vacation trip to two different forests. Do you think they would have seen the same type of plants and animals during their respective trips? Give reason.
No, they would not have seen the same type of plants and animals. This is so, because climatic conditions in the two forests would vary leading to variations in the types of plants and animals.
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?
The seedling was being benefited from the animal dung as the decaying animal dung provided nutrients to the growing seedlings. This happens as follows-Animal dung or droppings keep on collecting on the forest floor. The decomposer organism (such as bacteria of fungi) act on animal wastes and convert them into humus.
The humus contains plant nutrients and it mixes with the forest soil and make it fertile, seeds obtain nutrients from forest soil and germinate to form seedlings and seedlings grow to form saplings.
Match the Column I with Column II.
The correct matching is as given:
(a)—(ii), (b)—(v), (c)—(iv). (d)—(i), (e)—(ii)
Deforestation may lead to floods. Why?
Deforestation leads to floods as lesser number of trees will be available due to the deforestation. In the absence of trees and plants of the forest, the excessive amount of rainwater falling during heavy rains cannot be absorbed into forest ground. The large amount of rainwater will then suddenly flow into rivers causing the flooding of rivers.
Name any four useful products other than wood, which we get from forests.
Four useful products other than wood which we get from forests are gum, spices, fodder for animals and medicinal plants.
Long Answer Type Questions
Figure shows a part of a forest.
Write any three activities going on in the forest on the basis of this figure.
The three activities going on in the forest on the basis of the given figure are:
(i)Oxygen is given out by plant leaves.
(ii) Carbon dioxide is consumed by the plants to prepare their food by the process of photosynthesis.
(iii) Nutrients are being added to the soil by the action of decomposers.
People say that nothing goes waste in a forest. Can you explain how?
Nothing goes waste in a forest because of the following reasons:
(i) Dry leaves and remains of dead animals are converted to a dark coloured substance called humus and increase the fertility of soil. The importance of humus to the soil is that it provide nutrients for the growth of plants.
(ii) Dead animals become food for vultures, crows, jackals and insects.
(iii) Broken branches of trees are used as fuel by the people living in the vicinity of
Give any four factors which are responsible for the destruction of forests.
The four factors which are responsible for the destruction of forests are:
(i) Construction of roads.
(ii) Construction of buildings.
(iii) Industrial development.
(iv) Increasing demand of wood.
Draw a figure showing two animals, two birds and a few trees as a part of a forest.
Here is a figure showing two animals, two birds and a few trees as a part of forest:
All the needs of animals living in a forest are fulfilled. Justify this statement in a few sentences.
Forest provides home (shelter), food and water to the animals living there. There are a large number of various types of animals in the forest. The forests provide a natural habitat to animals. The different layers of regulation present in a forest provide food and shelter. Forest provides leaves, flowers, fruits, seeds, nuts and bark of trees as food for herbivorous animals. The carnivorous animals hunt and eat herbivorous animals. The dense bushes, tall grasses and thick trees provides shelter and also protection for herbivorous animals.
Forests are valuable resources. Explain.
Forest products play vital role in socio-economic development. We get food (cereals, pulses and fruits), fire wood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins and perfumes) and products of medicinal importance. It is also the home of diverse wildlife which maintains the ecosystem.
Forests give oxygen to keep us alive and absorb carbon dioxide and it also help in maintaining water cycle in nature. Forests save the soil from erosion and help in maintaining the ground water level.
Thus, forests are valuable resources.