CHAPTER- 11 NATURE'S TREASURES
Notes
1. Air— The air present around the Earth is a mixture of different gases. Air contains nitrogen, oxygen, argon, carbon dioxide, and small amounts of other gases.
- “Moving air is called wind. Sometimes it blows at a very high speed, such as during a storm, and sometimes it blows slowly, like a breeze (gentle wind).
2. Wind Farm— A wind farm is an area where many windmills generate electricity using wind energy.
3. Water— We need water for many activities in our daily life, such as cooking food, bathing, and growing crops.
- About two-thirds of the Earth’s surface is covered with water. Most of this water is found in oceans and seas, and it is salty.
4. Because sources of fresh water are limited, many parts of India face water scarcity. In some places, people have to walk long distances to fetch drinking water.
5. Rainwater Harvesting— Rainwater harvesting is a method of water conservation. In many buildings, rainwater is collected and stored in large amounts for later use; this process is called rainwater harvesting.
- For example, due to water scarcity in Rajasthan and Gujarat, stepwells (baoris and vavs) were constructed for water harvesting.
6. We use the Sun’s heat (warmth) and light for various activities.
- Sunlight helps plants prepare their food. The Sun provides heat (warmth) and light to all living organisms on Earth. It is the main source of energy for the Earth.
- Solar panels collect solar energy and generate electricity.
7. Forest— A forest is also a natural habitat for many wild animals, including birds and insects.
- Due to human activities such as large-scale cutting of trees, forest areas are continuously decreasing.
- Van Mahotsav is celebrated across the country in the month of July. It is a week-long program. During this festival, new plants and trees are planted, and awareness is created to respect and conserve forests.
8. Soil— Soil contains many things such as sand, insects, and worms. It may also contain many tiny organisms that we cannot see with our naked eyes.
- Soil is formed over a long period of time (many thousands of years) by the weathering of rocks due to the action of the Sun, water, and living organisms.
- Soil is a valuable resource that provides shelter to biodiversity.
9. Rock— Rocks are used in the construction of houses, buildings, temples, roads, dams, and tabletops.
- Rocks are made up of minerals.
- Important metals such as aluminum, gold, copper, and iron are obtained from minerals. Minerals are used in the manufacture of airplanes, cars, jewellery, cosmetics, electrical and electronic equipment.
- Most of the vehicles we use for transportation run on fossil fuels.
10. Fossil Fuels— Natural gas, coal, and petroleum are commonly called fossil fuels. They are formed when microscopic organisms and plants get buried deep inside the Earth and are converted into petroleum, natural gas, and coal. These fuels take millions of years to form.
- Fossil fuels are available in limited quantities.
- When fossil fuels are burned, smoke and carbon dioxide gas are produced, which pollute the air.
11. Natural Resources— Resources that we obtain from nature are called natural resources. For example, light and water from rivers.
12. Human-made Resources— Electric bulbs, furniture, bicycles, etc., make our life convenient. All such resources that are made by humans are called human-made resources.
13. Renewable Resources— Resources that can be renewed, replenished, or restored within a reasonable period of time are called renewable resources. For example, air, water, and forests.
14. Non-renewable Resources— These resources are not formed within a reasonable period of time, nor can they be replenished. Such resources are called non-renewable resources. For example, minerals, soil, and coal.
15. Water, air, soil, and food from plants and animals are all resources that we obtain from nature, and we use these resources to make things for our consumption.
- We should conserve our natural resources and use them responsibly without wasting them. In this way, we can meet our needs without harming the environment and also preserve these resources for the future.
LET US ENHANCE OUR LEARNING
Question- 1. Fig. 11.9 shows items related to natural resources. Match them with their jumbled up names. Make another table and write the names of these resources. Classify these resources as renewable or non-renewable.
Answer-
Question- 2. State whether the following statements are True (T) or False (F). If false, correct them.
(1) Nature has all the resources to meet human needs. ( )
(2) Machines are a resource found in nature. ( )
(3) Natural gas is a non-renewable resource. ( )
(4) Air is a renewable resource. ( )
Answer- (a) Nature has all the resources to meet human needs. (✓)
(b) A machines are a resource found in nature. (×)
A machine is a human-made resource, not a resource found in nature.
(c) Natural gas is a non-renewable resource. (✓)
(d) Air is a renewable resource. (✓)
Question- 3. Fill in the blanks using the most appropriate option-
(1) A fuel is commonly used in two wheelers like scooters or bikes is .............
(a) Kerosene (b) Petrol (c) Diesel (d) L.P.G.
(2) An example of a renewable resource is ...........
(a) Coal (b) Water (c) Natural gas (d) Petrol
Answer- 3.1 (b) Petrol, 3.2 (b) Water
Question- 4. Classify the following as renewable or non-renewable resources- coal, natural gas, forests and minerals.
Answer- Renewable resource- Forests.
Non-renewable resource- Coal, Natural gas and Minerals.
Question- 5. Why do we say that petroleum is a non-renewable resource?
Answer- We call petroleum a non-renewable resource because it is formed over millions of years inside the Earth due to the effect of heat and pressure on buried organic matter. Once it is used, it cannot be regenerated, and its reserves are limited. That is why, after it is used once, it gets exhausted and cannot be produced again.
Question- 6. It is difficult to regrow forests. Justify this statement.
Answer- Regrowing forests is difficult because a mature forest contains many kinds of plants, animals, and other components that depend on one another. It takes many years for a forest to fully develop. In addition, deforestation and climate change make the regeneration of forests even more challenging.
Question- 7. Make a list of five daily activities in which you use natural resources. Suggest ways by which you can reduce their use.
Answer- 1. Drinking Water— Use water carefully and keep taps closed when they are not in use.
2. Use of Paper— Use less paper and prefer digital methods instead.
3. Use of Electricity— Switch off electricity when it is not in use and use energy-saving devices.
4. Use of Vehicles— Use public transport as much as possible and walk whenever feasible.
5. Use of Plastic— Use reusable items instead of plastic.
Question- 8. List four activities that are possible due to the presence of air.
Answer- Four activities that are possible in the presence of air—
1. Breathing or the process of respiration
2. Evaporation
3. Flying, such as by birds and insects
4. Combustion or fire
Question- 9. How can you contribute towards enhancing the green cover of your locality? Make a list of actions to be taken.
Answer- We can contribute through the following actions—
1. By planting trees and plants around our homes.
2. By participating in local tree-plantation drives and planting more trees.
3. By creating a vegetable or flower garden at home.
4. By encouraging people in our neighbourhood to plant trees and plants.
Question- 10. In the given illustration, we see that food is being cooked.
Answer the following questions-
(1) What type of energy is being used for cooking?
(2) Name one benefit and one drawback of using this type of energy for cooking.
Answer- (a) Solar energy is being used for cooking food.
(b) One benefit and one drawback of using energy:
Benefit: Solar energy is a renewable resource. Its use does not cause air pollution, which is beneficial for the environment.
Drawback: Solar energy can be used only when the Sun is present, that is, during the daytime. It cannot be used at night, which makes this energy source limited.
Question- 11. Cutting down trees on a large scale impacts the quality of the soil. Why do you think it is so?
Answer- Trees and plants play an important role in keeping the soil stable. The roots of trees hold the soil together, which reduces soil erosion. When trees are cut down, the soil surface becomes exposed, and due to rain, wind, etc., soil erosion occurs rapidly. As a result, the fertile top layer of soil is lost and the quality of the soil decreases, leading to a shortage of nutrients necessary for farming and plant growth.
Question- 12. Explain two ways in which human activities pollute the air. Propose one action which can help in reducing air pollution.
Answer- Two human activities that cause air pollution—
1. Smoke emitted from vehicles contains harmful gases that pollute the air.
2. Smoke released from industries and factories increases air pollution.
Helpful in reducing air pollution—
We can use public transport as much as possible, which can reduce the number of vehicles and help control air pollution.
Question- 13. A family uses solar panels to generate electricity, a gas stove to cook food and a windmill for pumping water from a well. What would happen if there were no sunlight for a week?
Answer- If there is no sunlight for a week, solar panels will not be able to generate electricity, which may cause a shortage of electricity for families. However, gas stoves and windmills will not be directly affected. Plants and agriculture will also be affected because without sunlight, plants will not be able to carry out photosynthesis, which will stop their growth. The absence of sunlight can have serious effects on both energy sources and the environment.
Question- 14. Fill up the blanks using the following terms-
(Fossil fuels, forest, air, petroleum, coal, water and non-renewable resource)
Answer-
Question- 15. There is an increasing demand of trees to meet the requirements of industries and for housing. Therefore, trees are being felled. Is it justified? Discuss and prepare a brief report.
Answer- Due to the increasing demand for trees, their uncontrolled cutting causes environmental imbalance. Trees are not only a source of oxygen but also play an important role in maintaining air quality, climate balance, and biodiversity. While it is necessary to meet industrial and housing needs, tree cutting should be balanced and sustainable. By giving priority to reforestation and forest conservation, we can ensure the safety of both humans and the environment.
Question- 16. Propose a plan to use less water in your school. What steps would you take to make this plan happen and how would it help the environment?
Answer- To reduce the use of water in schools, the following important steps can be taken—
1. Regular inspection of all taps and pipelines should be done to prevent leakage.
2. Water can be conserved by installing a rainwater harvesting system.
3. Students and teachers should be made aware of ways to save water.
4. Low-water irrigation systems should be used in school gardens.
5. Automatic taps that close on their own after use should be installed in the school, which will reduce water wastage.
