Here, you will get the CBSE Class 9 Science, Natural Resources: Chapter notes (Part-I). These chapter notes are prepared by the subject experts and cover every important topic from the chapter. You will get a crisp and brief explanation of all these topics so as to make your learning easy and organized. At the end of the notes you can try the questions asked from the discussed set of topics. These questions will help you to track your preparation level and get a hold on the subject.
Main topics covered in this part of CBSE Class 9 Science, Natural Resources: Chapter Notes, are:
- Carbondioxide, its production and fixation
- Role of Atmosphere
Key notes for Chapter - Natural Resources, are:
- The resources available on the earth and the energy from the sun are necessary to meet the basic requirements of all life forms on the earth.
- The land, the water and the air are the resources on the Earth. All of these three things are required for the existence of life forms.
Earth is divided into four spheres that interact to help life sustain on this planet:
- It us the outermost part of the Earth that includes crust and the uppermost mnantle.
- It is the most rigid part of the Earth's layers.
- It includes the entire water part of the earth.
- It is constituted of the oceans, rivers, lakes, and even the moisture in the air.
- It makes up about three fourths of the earth's surface.
- The air covering of earth is-called atmosphere.
- It is constuted of various gases, vapours, dust particles, etc.
- It is formed of the whole life-supporting zone of the Earth where the atmosphere, hydrosphere and the lithosphere interact and make life possible on this one planet.
Biosphere is further divided into two components:
(i) Biotic components : The living things constitute the biotic components of the Biosphere.
(ii) Abiotic components : The non-living things air, water and soil form the abiotic components of the Biosphere.
The Breath of Life: Air
- Air is a mixture of many gases like nitrogen, oxygen, carbon dioxide and water vapour.
- Oxygen gas present in air is essential to living organisms for respiration. That is why air is called breath of life.
- Air being a bad conductor of heat helps to maintain the moderate temperature on earth.
It constitutes 0.04% of the air. It helps maintain temperature on earth by acting as greenhouse gas.
Production of Carbon dioxide
It is produced in the atmosphere by following activities:
- During respiration process by organisms where breakdown of glucose takes place in presence of oxygen.
- During combustion of fuels.
Carbon Dioxide Fixation
- Green plants convert carbon dioxide into glucose by photosynthesis
- Many marine animals use carbonates dissolved in sea-water to make their shells.
The Movement of Air: Winds
- Moving air is called wind.
- Winds are caused due to uneven heating of atmosphere.
- Air moves from high pressure area 1o a low pressure area.
- During day time, the air above the land gets heated faster and starts rising. So air from above the sea comes to the low pressure region over land. So, wind blows from sea to land.
- During the night, the direction of wind is from land to sea as the earth cools faster than sea, creating a low pressure region above land.
Role of Atmosphere in Climate Control
- It acts as a protective blanket for organisms existing on earth.
- As air in the atmosphere is bad conductor of heat, it helps to maintain the erth’s temperature by preventing the sudden increase in temperature during day and also during the night, it slows down the escape of heat into the outer space.
Try the following questions:
Q1. Name two natural resources available on the earth.
Q2. Define biosphere. Name its components.
Q3. Name the three processes in which oxygen is used.
Q4. Why is the atmosphere referred as a protective blanket?
Q5. Write the three ways by which CO2 is returned back into atmosphere ?
Q6. What causes winds ?