Notes On Natural Resources - CBSE Class 9 Science
Natural resources Materials provided by nature on earth which can be used by living organisms are termed to be natural resources. Three different regions of earth are lithosphere, hydrosphere and atmosphere.      •  The solid outermost layer of the earth’s crust and the rigid upper part of its mantle is called the lithosphere.     •  The water that is found on the earth’s surface, above it as clouds and below it as groundwater, is called the hydrosphere.     •  The air which includes gases that cover the earth like a blanket, is called the atmosphere. Biosphere The region on earth comprising of both biotic and abiotic components is called as biosphere.     •  Biotic components include all the living organisms.     •  Abiotic components include air, water and the soil. Biotic components interact with all the abiotic components such as air, water and soil to sustain their life. Air Air is a mixture of gases like nitrogen, oxygen, carbon dioxide and water vapour.      •  Nitrogen is used to produce a number of organic molecules like proteins.  Nitrogen is fixed in plants and is transferred to animals through food chain.     •  Oxygen is used by plants and animals in the process of respiration. The combustion of fossil fuels also requires oxygen.     •  Carbon dioxide is used by plants in the process of photosynthesis. Marine animals absorb atmospheric carbon dioxide to form carbonic acid. These carbonate ions are used by marine animals to make shells. Functions of Air:     •  It helps to maintain a steady temperature on Earth during the day     •  It controls the climate.      •  It helps in the formation of rain.     •  The atmosphere on earth prevents the increase of temperature during day time.  Atmosphere slows down the heat from escaping to outer space during night time. Sea breeze and land breeze: During the day, air moving from the high pressure area over the sea to the low pressure area over land creates sea breeze. During night, since soil cools faster than water, the air above the land is cooler than the air above the sea. Now, the air moving from the high pressure area over land to the low pressure area over the sea creates land breeze. Formation of rain: Water bodies get heated during the day and evaporate into the air. As the vapour rises, it cools. This causes the vapour to condense into tiny water droplets, which fall down as rain by the process of precipitation. Wind: Air moving from an area of high pressure to an area of low pressure causes winds. Rains are brought by seasonal winds called as monsoons. Based on rainfall pattern, regions of India can be classified into three types, namely heavy rainfall regions, moderate rainfall regions and low rainfall regions. Regions receiving heavy rainfall exhibit high biodiversity. Air pollution: The contamination of air with chemicals, smoke, dust particles and disease-causing agents is called air pollution. Water Water is essential for the survival of plants and animals, as cellular processes take place in a water medium. Water is found on the Earth’s surface, under the ground and in the atmosphere as water vapour. Maximum amount of water available is marine water which is salty. Most of the fresh water available on the earth is in the form of frozen ice. Water pollution: The contamination of water by sewage, chemicals, detergents, fertilisers and other harmful substances is called water pollution. Increase in water temperature due to pollutants decreases the amount of dissolved oxygen. Dissolved oxygen is the source of oxygen for aquatic organisms. Reduction of dissolved oxygen results in the death of many aquatic organisms. Soil Soil is another important natural resource that supports life. Soil contains soil particles, humus and living organisms. It also contains some amount of water in the form of droplets or air in between the soil particles. Formation of soil: Soil is formed by many factors like sun, water, wind and living organisms.     •  Uneven contraction and expansion of rocks, cracks and breaks them into smaller particles of soil.     •  Frozen water logged in the cracks of rocks, cracks and breaks the rocks into soil.     •  Lichens growing on the surface of rocks release chemicals which powder the rocks into soil.     •  Flowing water in rivers breaks hard rocks into soil particles.     •  Strong winds erode rocks and carry sand particles. Soil pollution: The addition of substances that adversely affect soil fertility is called soil pollution. Use of fertilisers killed lot of useful microorganisms and reduced soil fertility. Deforestation has lead to erosion of topmost fertile layer of the soil.  Overgrazing by animals also led to the soil erosion. Fine particles of water are also carried away by wind and water.

#### Summary

Natural resources Materials provided by nature on earth which can be used by living organisms are termed to be natural resources. Three different regions of earth are lithosphere, hydrosphere and atmosphere.      •  The solid outermost layer of the earth’s crust and the rigid upper part of its mantle is called the lithosphere.     •  The water that is found on the earth’s surface, above it as clouds and below it as groundwater, is called the hydrosphere.     •  The air which includes gases that cover the earth like a blanket, is called the atmosphere. Biosphere The region on earth comprising of both biotic and abiotic components is called as biosphere.     •  Biotic components include all the living organisms.     •  Abiotic components include air, water and the soil. Biotic components interact with all the abiotic components such as air, water and soil to sustain their life. Air Air is a mixture of gases like nitrogen, oxygen, carbon dioxide and water vapour.      •  Nitrogen is used to produce a number of organic molecules like proteins.  Nitrogen is fixed in plants and is transferred to animals through food chain.     •  Oxygen is used by plants and animals in the process of respiration. The combustion of fossil fuels also requires oxygen.     •  Carbon dioxide is used by plants in the process of photosynthesis. Marine animals absorb atmospheric carbon dioxide to form carbonic acid. These carbonate ions are used by marine animals to make shells. Functions of Air:     •  It helps to maintain a steady temperature on Earth during the day     •  It controls the climate.      •  It helps in the formation of rain.     •  The atmosphere on earth prevents the increase of temperature during day time.  Atmosphere slows down the heat from escaping to outer space during night time. Sea breeze and land breeze: During the day, air moving from the high pressure area over the sea to the low pressure area over land creates sea breeze. During night, since soil cools faster than water, the air above the land is cooler than the air above the sea. Now, the air moving from the high pressure area over land to the low pressure area over the sea creates land breeze. Formation of rain: Water bodies get heated during the day and evaporate into the air. As the vapour rises, it cools. This causes the vapour to condense into tiny water droplets, which fall down as rain by the process of precipitation. Wind: Air moving from an area of high pressure to an area of low pressure causes winds. Rains are brought by seasonal winds called as monsoons. Based on rainfall pattern, regions of India can be classified into three types, namely heavy rainfall regions, moderate rainfall regions and low rainfall regions. Regions receiving heavy rainfall exhibit high biodiversity. Air pollution: The contamination of air with chemicals, smoke, dust particles and disease-causing agents is called air pollution. Water Water is essential for the survival of plants and animals, as cellular processes take place in a water medium. Water is found on the Earth’s surface, under the ground and in the atmosphere as water vapour. Maximum amount of water available is marine water which is salty. Most of the fresh water available on the earth is in the form of frozen ice. Water pollution: The contamination of water by sewage, chemicals, detergents, fertilisers and other harmful substances is called water pollution. Increase in water temperature due to pollutants decreases the amount of dissolved oxygen. Dissolved oxygen is the source of oxygen for aquatic organisms. Reduction of dissolved oxygen results in the death of many aquatic organisms. Soil Soil is another important natural resource that supports life. Soil contains soil particles, humus and living organisms. It also contains some amount of water in the form of droplets or air in between the soil particles. Formation of soil: Soil is formed by many factors like sun, water, wind and living organisms.     •  Uneven contraction and expansion of rocks, cracks and breaks them into smaller particles of soil.     •  Frozen water logged in the cracks of rocks, cracks and breaks the rocks into soil.     •  Lichens growing on the surface of rocks release chemicals which powder the rocks into soil.     •  Flowing water in rivers breaks hard rocks into soil particles.     •  Strong winds erode rocks and carry sand particles. Soil pollution: The addition of substances that adversely affect soil fertility is called soil pollution. Use of fertilisers killed lot of useful microorganisms and reduced soil fertility. Deforestation has lead to erosion of topmost fertile layer of the soil.  Overgrazing by animals also led to the soil erosion. Fine particles of water are also carried away by wind and water.

#### Activities

Activity 1 Ausarabexplore.info has constructed a small interactive module to emphasise on the importance of 'Water'. The selected module displays four photographs. Clicking on each photograph displays particular information about the region, climate, rainfall, other resources. It also makes user to understand the importance of water in the desert region, scarcity faced by the people living in that particular area and water resources they are provided with.  Go to Activity Activity 2 Clean-air-kids.org.uk has devised a new game to understand the concept ‘Pollution'. User needs to follow the instructions displayed on the screen. This is designed as a reflex action to check air pollution.   As the activity proceeds, students should be smart in hitting the squares. As the time proceeds, user gains interest of getting green clean air instead of brown polluted air. Go to Activity

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