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Class 7 Lesson 17 (Cordova), Forests : Our Lifeline, , EXERCISE, A. Tick the correct options., 1. (c) 2. (b) 3. (c) 4. (d) 5. (a) 6. (d) 7. (d), B- Fill in the blanks., 1. sun 2. food web 3. vegetation 4. afforestation 5. tribal, C. Very Short Answer Questions., 1. Forests cover approximately one-third of the earth’s total land, surface., 2. On forest floor, 3. Understorey layer, 4. Canopy layer, 5. Carbon dioxide and Methane, 6. Snake, , D. Short Answer Type-I Questions., 1. Forest is a large area of land covered thickly with different, kinds of trees, shrubs, herbs, grasses, creepers and, climbers., 2. A series of organisms linked together by the process of, eating and being eaten for food is called a food chain., 3. Decomposers are those organisms which feed upon the, dead plant and animal tissues and convert them into a, dark-coloured substance called humus., 1|Page
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Class 7 Lesson 17 (Cordova), Forests : Our Lifeline, , 4. The forest’s top layer consists of branches and leaves of tall, trees. These branches overlap with each other and this, layer is so dense that it allows very little sunlight to, penetrate through it. So, there is dark inside the forests., 5. The uppermost branches and leaves of all tall trees which, act like a roof or umbrella over the smaller trees in the, forest is called canopy., E. Short Answer Type-II Questions, 1. Plants are beneficial to animals in the following ways:, (a) Animals directly or indirectly depend on plants for food., (b) Tall trees give shelter to various animals., (c) Plants produce oxygen during photosynthesis which is taken up, by animals for respiration., 2. Some of the ways to conserve forests are given below:, (a) Excessive cutting down of forest trees should not be allowed, by the government., (b) ‘Tree for a tree’ principle should be adopted. For every tree, that has been fallen, a new tree should be planted., (c) Paper products such as old newspapers, magazines, books and, notebooks, etc., should be recycled to conserve forests., 3. Clearing a forest by cutting trees to fulfil our need of wood and, land is called deforestation., , 2|Page
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Class 7 Lesson 17 (Cordova), Forests : Our Lifeline, , 4. Causes of deforestation :, (i) Forest fires: Once the forest fire starts, it does not stop easily, and many trees are burnt causing deforestation., (ii) Increase in population: With increasing population, more land is, required. Forest area is cleared to obtain this land., (iii) Construction of dams: A large forest area has to be cleared to, construct a dam. This causes deforestation., , F. Long Answer Questions., 1. Harmful effects of deforestation are as follows:, (a) Deforestation causes soil erosion, leading to loss of soil fertility., (b) It causes change in the rainfall pattern and results in drought., (c) Burning of wood, obtained from deforestation, causes increase in, the concentration of carbon dioxide in the atmosphere. Excess of, carbon dioxide causes air pollution. Carbon dioxide is a, greenhouse gas and causes global warming (increase in the earth’s, temperature)., (d) In the absence of trees of the forest, the rainwater flows faster, causing flood conditions., (e) By deforestation, climate becomes warmer and drier in the, absence of humidity in the deforested area., (f) In the absence of trees and plants, the animals will not get food and, shelter., , 3|Page
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Class 7 Lesson 17 (Cordova), Forests : Our Lifeline, , 2- Forests are useful to us in many ways, such as –, (a) Forests are a good source of wood like teak, sheesham, rosewood, and sal which are used in making furniture., (b) Several plants that grow in forests are used in the preparation of, medicines. The bark of Cinchona tree is source of a medicine called, quinine which is used in treatment of malaria., (c) Forests maintain balance of gases in nature, maintain water cycle,, prevent soil erosion., (d) Forests prevent floods, replenish groundwater, provide food and, shelter to wildlife and help in reducing pollution., , H. HOTS (Higher Order Thinking Skills) Questions., 1. Recycling of paper helps in the conservation of forests, because paper is made from wood which is obtained from, forests. We need to cut trees for it. If paper is recycled, more, trees will not be required to be cut., 2. Forests are called ‘green lungs’ because the forests help the, atmosphere in the same way like the lungs. Forests help in, exchange of gases taking in CO2 and giving out O2 whereas, lungs also take the oxygen from the atmosphere, provide it to, body parts, collect carbon dioxide and pass it out., ******************, , 4|Page
