A lake which is rich in organic waste may result in
(1) increased population of aquatic organisms due to minerals

(2) drying of the lake due to algal bloom

(3) increased population of fish due to lots of nutrients

(4) mortality of fish due to lack of oxygen

Depletion of which gas in the atmosphere can lead to an increased incidence of skin cancers
(1) ozone

(2) ammonia 

(3) methane

(4) nitrous oxide

Increase in concentration of the toxicant at successive tropic levels is known as

1. biomagnification

2. biodeterioration

3. biotransformation

4. biogeochemical cycling

Eutrophication of water bodies leading to killing of fishes is mainly due to non-availability of

1. food

2. light

3. essential minerals

4. Oxygen

Which of the following is not one of prime health risks associated with greater UV

radiation through the atmosphere due to depletion of stratospheric zone?

1. Increased skin cancer

2. Reduced immune system

3. Damage to eyes

4. Increased liver cancer

The zone of atmosphere in which the ozone layer is present is called

1. ionosphere

2. mesosphere

3. stratosphere

4. troposphere

A scrubber in the exhaust of a chemical industrial plant removes

1. Gases like sulphur dioxide

2. Particulate matter of the size 5 micrometer or above

3. Gases like ozone and methane

4. Particulate matter of the size 2.5 micrometer or less

Global warming can be controlled by 

1. Reducing deforestation, cutting down use of fossil fuel

2. Reducing reforestation, increasing the use of fossil fuel

3. Increasing deforestation, slowing down the growth of human population

4. Increasing deforestation, reducing efficiency of energy usage

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