In an area where DDT had been used extensively, the population of birds declined

significantly because

1. birds stopped laying eggs

2. earthworms in the area got eradicated

3. cobras were feeding exclusively on birds

4. many of the birds laid eggs and the eggs hatched early

Which one of the following is a wrong statement?

1. Most of the forests have been lost in tropical areas

2. Ozone in upper part of atmosphere is harmful to animals

3. Greenhouse effect is a natural phenomenon

4. Eutrophication is a natural phenomenon in freshwater bodies

Measuring Biochemical Oxygen Demand (BOD) is a method used for

1. estimating the amount of organic matter in sewage water

2. working out the efficiency of oil driven automobile engines

3. measuring the activity of Saccharomyces cerevisae in producing curd on a commercial

scale

4. working out the efficiency of RBCs about their capacity to carry oxygen

Which one of the following pairs of gases are the major cause of Green house effect?

1. CO₂ and CO

2. CFCs and SO₂

3. CO₂ and N₂0

4. CO₂ and O₃

Eutrophication is often seen in

1. fresh water lakes

2. ocean

3. mountains

4. deserts

dB is a standard abbreviation used for the quantitative expression of

1. the density of bacteria in a medium

2. a particular pollutant

3. the dominant Bacillus in a culture

4. a certain pesticide

Chipko movement was launched for the protection of

1. grasslands

2. forests

3. liverstock

4. wet lands

Montreal protocol aims at
1. reduction of ozone depleting substances
2. biodiversity conservation
3. control of water pollution
4. control of CO₂ emission

Checking of re-radiating heat by atmospheric CO₂ methane, ozone, dust is known as 

1. green house effect

2. radioactive effect

3. ozone layer

4. solar effect.

A large quantity of urban sewage is drained to nearby village river. Which among the given conditions would happen after mixing of sewage into the river?

(i) Biochemical oxygen demand (BOD) of receiving water body increases.
(ii) Dissolved oxygen of receiving water body decreases.
(iii) It will not cause mortality among fishes and other aquatic creatures
(iv) It will lead to nutrient enrichment of receiving water body.

(1) (i), (ii) and (iii)

(2) (i), (ii) and (iv)

(3) (ii) and (iii)

(4) (iii) and (iv)