NCERT Class X Science Solutions: Chapter 15 – Our Environment Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 7:

What are the problems caused by the non-biodegradable wastes that we generate?


Non-biodegradable wastes cannot be broken-down into simpler substances. Their volume keeps on increasing creating the problem of their safe disposal. Some of the non-biodegradable wastes like heavy metals and pesticides enter into the food chain and increases in the upper trophic levels. Non-biodegradable wastes reduce the soil fertility by changing the natural pH balance.

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Question 8:

If all the waste we generate is biodegradable, will this have no impact on the environment?


Biodegradable wastes are decomposed by microorganisms into simpler substances themselves and provide raw materials for producers, but they also have adverse effects on the environment:

  • Slow decomposition of biodegradable waste will result in the release of foul smell and harmful gases. When inhaled by human beings, they may cause irritation, nausea, giddiness, etc.
  • Decomposing waste provides breeding ground for some harmful organisms. Abundance of harmful microorganisms may cause diseases in animals, plants and human beings.
  • Increase in the number of microorganisms in aquatic medium will- cause oxygen deficiency in water bodies.

Question 9:

Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?


Ozone layer is a protective shield around the earth. It prevents harmful ultraviolet radiation of the sun from reaching the earth. Air pollutants, like chlorofluorocarbons (CFCs) , are causing depletion of ozone layer. This is allowing greater amount of UV radiation to reach the earth. UV radiation can upset the ecosystem by affecting photosynthesis in plants, destroying planktons and decomposers. In human beings, UV radiation may cause skin cancer, cataract of eyes and damage to immune system. Several developed as well as developing nations of the world have agreed to sign and obey the directions of TINEP (United Nations Environment Programme) to freeze the production of CFCs or to limit their production to some extent.

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