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Class 7 Lesson 16 (cardova), Water : A Precious Natural Resource, , EXERCISE, A. Tick the correct options., 1. (b) 2. (a) 3. (d) 4. (d), B- Fill in the blanks., nd, , 1. solid 2. infiltration 3. 22 March 4. Bawri, C. State whether the following statements are true (T) or false, (F). Rewrite the false statements correctly., 1. F, Correct statement – Our earth is called watery planet as, there is abundance of water., 2. F, Correct statement – Increase in agricultural activities has, decreased the water table abundantly., 3. T, 4. F, Correct statement – Revival of bawris will lead to, conservation of water., 5. T, D. Very Short Answer Questions., 1. (a) Ice (b) Steam, 2. The upper limit of groundwater is called water table., 3. Minimum amount of water per person per day as, recommended by the United Nations for various basic needs, is 50 litres., 1|Page
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Class 7 Lesson 16 (cardova), Water : A Precious Natural Resource, , 4. Drip irrigation and sprinkler irrigation are the modern, methods of irrigation which help in conservation of water., E. Short Answer Type-I Questions., 1. There is 97.5% of water available on the earth, but is still, unfit for human consumption because this water is salty or, saline. Therefore, it is unfit for human consumption., 2. The huge reservoirs of water inside the earth, formed by the, collection of groundwater between the layers of hard rock, below the water table are called aquifers., 3. The bawris are being revived due to the acute shortage of, water., 4. The three factors which deplete the water table at a place, are–, (i) Increase in population, (ii) Increase in industries, (iii) Increase in agricultural activities, 5. Any component of the earth or environment which can be, utilised by human beings to fulfill their needs is known as, natural resource., G. Short Answer Type-II Questions, 1. The process of collecting rainwater from roofs and street, corners and storing it for later use is called rainwater, harvesting., 2|Page
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Class 7 Lesson 16 (cardova), Water : A Precious Natural Resource, , Two advantages of rainwater harvesting are(i) The water table can be raised by rainwater harvesting., (ii) It reduces flood and topsoil erosion., 2. We can save water at home by minimizing its wastage by, following ways---i)- Do not keep the Tap open while brushing teeth, washing, hands or, cleaning utensils., ii) Collect rainwater in drums and use it to water the plants., iii) Use a bucket and mug instead of using a shower for a bath., iv) Get leaking pipelines and water taps repaired., v) Clean your vehicle with a wet cloth instead of washing with, running water., 3. (a) Saving water is important for us because the supply of, clean and fresh water is depleting at an alarming rate in, some regions and we may suffer from moderate to, severe water crisis in the coming years., (b) Concern for the society and needs of people, 4. The continuous circulation of water from the earth’s, surface and water bodies as water vapour to the, atmosphere and from the atmosphere back to the earth’s, surface as rain, hail and snow is called the water cycle in, nature., , The processes involved in water cycle are–, 3|Page
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Class 7 Lesson 16 (cardova), Water : A Precious Natural Resource, , (a) Evaporation, (b) transpiration, (c) Condensation, (d) precipitation, 5. Effects of water scarcity are–, (a) Non-availability of food – Plants cannot make food by the, process of photosynthesis without water. Animals, directly or indirectly depend on plants for food. Without, plants, animals will also have no food., (b) Non-availability of oxygen for breathing – Plants release, oxygen gas during photosynthesis (which needs water)., Without photosynthesis, no oxygen will be available to, animals for breathing., (c) Less rainfall, H. Long Answer Questions., 1. Following are the factors which deplete the water table at a, place:, (a) Increase in population: Human population is increasing day, by day. To meet the needs of an ever-increasing, population, more houses, offices, schools, shops and, roads are being build. These construction activities, require huge supply of water. Borings made at the, construction sites withdraw more and more, groundwater which leads to depletion of water table., (b) Increase in industries: The number of industries is also, increasing continuously so more water is used by, industries leading to depletion of water table., 4|Page
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Class 7 Lesson 16 (cardova), Water : A Precious Natural Resource, , (c) Increase in agricultural activities: The demand for, agricultural food crops has also increased due to, increasing population. A majority of farmers depend on, rainwater to grow crops. But due to unpredictable, rainfall, they depend on irrigation methods. In many, places, the canal system may suffer from the lack of, water due to erratic rainfall. Nowadays, farmers use, large quantities of groundwater by digging deep tube, wells to cultivate crops. This results in depletion of water, table., (d) Deforestation: Cutting down a large number of trees at a, place is called deforestation. This leads to failure of soil to hold, moisture. The water just runs off on the ground surface., 2- The following steps can be taken for proper management of, water:, (a) Rainwater harvesting: In this method, water is collected in, percolation pits and recharge wells so as to recharge, groundwater. This is an ideal solution to water problem, in areas with inadequate water resources., (b) Prevention of wastage of water: Wastage of water in, households, commercial buildings, schools and public, places can be prevented by closing taps when not in use,, repairing any leakage from pipes, etc., (c) Revival of bawris: Bawris are the ancient practice of water, storage and water recharge system in India. They, 5|Page
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Class 7 Lesson 16 (cardova), Water : A Precious Natural Resource, , provided water to the people during drought periods., Due to the acute water shortage faced by the people in, some places, the bawris are being renovated and, revived., (d) Drip Irrigation: It is a technique of watering plants by, making use of system of narrow pipes or tubes with small holes, which deliver water drop by drop directly around the roots., Thus, the wastage of water is avoided. This system allow the, farmers to produce a high yield with very little water., H. HOTS (Higher Order Thinking Skills) Questions., 1. Making of tube wells in the residential areas reduces the, water table due to which people will not get sufficient water. It, happens because a lot of water is pulled out by the tube wells., 2. India is a vast country and rainfall is not same everywhere., Some regions have excessive rain while some others have very, little rainfall. So, there is uneven distribution of water., , 6|Page
