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Environmental Issues

Q1. What is Montreal protocol?

Ans: Montreal Protocol is an international treaty, was signed at Montreal, Canada, in 1987 to curb the emission of ozone depleting substances.

Q2. Discuss the consequences of
a) Global warming
b) Ozone depletion


Global warming:

  • The temperature of the earth has increased by 0.60C in last three decades, which will lead to changes in precipitation patterns.

  • Rise in temperature leads to deleterious changes in environment resulting in odd climatic changes called El Nino effect.

  • The rise in temperature will lead to the increased melting of polar ice caps which will cause the rise in sea level and many coastal areas will be submerged.

  • Increased temperature will lead to increased weed growth, eruption of diseases and pests. Thus, crop productivity will decrease.

Ozone depletion:

  • UV-B damages DNA and proteins of living organisms causing mutation.

  • It causes skin aging, skin cell damage and skin cancers.

  • UV-B is absorbed by human eye and in high dose, it causes inflammation of cornea. This is called snow-blindness cataract.

Q3. Write a note on biomagnification, Eutrophication, and Biochemical oxygen demand.



  • Biomagnification or biological magnification is defined as increase in concentration of toxicants at successive trophic levels.

  • Toxic substances cannot be metabolised or excreted, therefore they get accumulated in an organism and passed on to higher trophic levels.

  • Mercury and DDT are well known for biological magnification.


  • It is defined as the natural aging of a lake by biological enrichment of its water.

  • Water in a young lake is cold and clear to support life.

  • With time, it is enriched with nutrients by streams draining into it.

Biochemical Oxygen Demand (BOD):

  • The amount of oxygen required for microbial breakdown of biodegradable organic matter called BOD.

  • It is higher in polluted water and lesser in drinking water.

Q4. What is meant by Terror of Bengal?


Excessive growth of water hyacinth (Eichhornia crassipes), the world's most problematic aquatic weed, also called "Terror of Bengal”, grows abundantly in eutrophic water bodies and imbalances water ecosystem.

Q5. List the advantages of CNG over diesel/petrol.


Advantages of CNG over diesel/petrol:

  • CNG burns most efficiently without leaving any unburnt remnant behind.

  • CNG is cheaper than petrol or diesel.

  • CNG cannot be siphoned off by thieves and adulterated like petrol or diesel.

Q6. Write a note on the following;

a. Radioactive wastes

b. Remedy for plastic wastes


a. Radio active wastes:

  • Nuclear waste should be pre-treated and stored in shielded containers and then buried about 500 m deep below earth's surface.

  • Keep people away from it to reduce their exposure to radiation.

b. Remedy for plastic wastes:

A fine powder of recycle modified plastic is called polyblend. Polyblend has been mixed with bitumen to lay roads in Bangalore. Polyblend enhanced bitumen's water repellent properties and helped increase the life of road.


✓ Chipko Movement was started in Garhwal, Himalayas in 1974 by Shri Sundar Lal Bahuguna to prevent cutting down of trees. Local women hugged trees to prevent their cutting by the contractors.

✓ In 1980, the Government of India has introduced the concept of 'Joint Forest Management' (JFM) to work closely with the local communities for protecting and managing forests on mutual benefits

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