1. Define natural resources. How are they classified?
The living (biotic) and non-living (abiotic) components of nature which are being used by humans for meeting their requirements are called natural resources. Depending upon their abundance, natural resources are classified into two main categories: 1. Inexhaustible natural resources: these are natural resources that occur in such abundance that they are not likely to get exhausted even by continuous use. Eg. Air, water, solar energy. 2. Exhaustible natural resources: these are natural resources which are in limited quantity. They are likely to get exhausted by indiscriminate human use. Exhaustible natural resources are further classifies into --- a) Renewable sources: these are exhaustible resources both living and non-living that get replenished naturally, when not misused or used indiscriminately. Eg. Forests, wild life, oil, underground water etc. b) Non renewable resources: these are exhaustible resources that do not get replenished very easily because the time taken for generation of these resources in nature are millions of years. These are non living things in the environment such as coal and petroleum ( fossil fuels), minerals.
2. What is Biosphere?
Biosphere is the living mantle of Earth where living beings occur. There are three physical divisions of the biosphere : atmosphere (air), lithosphere ( land / soil), hydrosphere (water, including ground water deeper in the earth). Biosphere is where these three physical divisions of Earth interact. The living beings in the biosphere form the biotic component of our environment and The non living things in the biosphere form the abiotic component of our environment.
3. What is atmosphere? What is the role of atmosphere in climate control?
The multilayered gaseous envelope surrounding the planet Earth, that is retained by the Earth’s gravity is called atmosphere. The atmosphere acts as a blanket surrounding the earth. It prevents harmful solar radiation from reaching the earth’s surface. It keeps the average temperature of the earth fairly steady by preventing excessive radiation heat reaching the earth. It acts as an insulator preventing sudden fall in the temperature during night, thus maintaining ideal temperatures for life to exist.
4. Why is there a very small percentage of CO2 in earth’s atmosphere?
The percentage of CO2 in our atmosphere is a mere fraction of a percent because CO2 is fixed in two ways: i. green plants convert CO2 into glucose in the presence of sunlight (photosynthesis) and ii. many marine animals use carbonates dissolved in sea water to make their shells.
5. What causes wind?
The air above the land gets heated faster and being light, starts rising. As the air rises, a region of low pressure is created. Due to this, air above the sea moves into this area of low pressure. The movement of air from one region to the other creates wind.
6. Name the factors which influence the patterns of winds. a) The uneven heating of the atmosphere in different regions of the earth b)The rotation of the earth c)The presence of mountain ranges in the paths of the wind.
7. How are clouds formed?
when water bodies are heated during the day, then a large amount of water evaporates and goes into the air. Some amount of water vapour also gets into the atmosphere because of various biological activities like transpiration, respiration etc. The air gets heated and rises up carrying the water vapour with it. The air expands on rising and cools, which causes the water vapour in the air to condense in the form of tiny droplets. These water droplets get bigger to form clouds. When the droplets have grown big and...