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CBSE Class 9 Biology Notes for Chapter 5 Natural Resources

Air is a mixture of many gases like nitrogen, oxygen, carbon dioxide and water vapour. These gases are required for cellular respiration.
Winds blow due to difference in pressure due to uneven heating of land and water. We’ve already studied this phenomenon as land breeze and sea breeze.
Rain is the part of the water cycle. When water from various water bodies evaporates and rises up in the atmosphere, it cools down. The cooling causes condensation of the water vapour and forms tiny water droplets. Once these droplets become heavy, they fall down on the earth’s surface as rain drops.
Degradation of air quality caused due to unwanted particles present in the atmosphere.
Burning of fossil fuels, toxic smoke from industries all contribute to air pollution and cause harmful respiratory diseases. Such activities must be avoided as much as possible.
Water pollution is caused by industrial and domestic waste that is dumped in the water bodies. It causes harmful diseases and endangers the aquatic life.
Waste should be handled carefully and should be treated before being dumped in the water bodies.
These natural resources are essential to us and should be conserved to make sure that the balance of nature remains intact.

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