Class 12th Biology 2017 Set1 Delhi Board Paper Solution

Question 10

Plenty of algal bloom is observed in a pond in your locality.

(a) Write what has caused this bloom and how does it affect the quality of water.

(b) Suggest a preventive measure.

Answer

Presense of large amounts of nutrient in water leads to growth of planktonic algae cause algal bloom.

It affect quality of water in many ways:

1. Deterioration of water quality

2. Increased fish mortality rate

3. Some bloom forming algae are toxic to human and animals

4.Eutrophication (natural ageing of water bodies) is accelerated, resulting in hypoxic conditions (i.e. low oxygen).

(b)

1. Avoid excess use of fertilisers and manures on agriculture land.

2. Protect soil from erosion

3. Treating sewage to remove the nutrients, nitrogen and phosphosous.

4. Artificial destratification

5. Biomanipulation.