Keystone species deserve protection because these

(1) are capable of surviving in harsh environmental conditions

(2) indicate presence of certain minerals in the soil

(3) have become rare due to overexploitation

(4) play an important role in supporting other species.

Most animals that live in deep oceanic waters are

(1) Tertiary consumers

(2) Detritivores

(3) Primary consumers

(4) Secondary consumers

Energy flow in an ecosystem is 

(1) unidirectional

(2) bidirectional

(3) multi-directional

(4) All the these 

Animals take phosphorous from 
(1) water 

(2) plants

(3) rock 

(4) soil.

In a stable ecosystem, which of the following limits the number of trophic levels?

(1) Biomass

(2) The number of nutrients

(3) Availability of nutrients

(4) Presence of contaminants that increase in concentration along the food chain

The bacteria which attack dead animals are 
(1) first link of the food chain and are known as primary producers.

(2) Second link of the food chain and are herbivorous

(3) third link of the food chain and are tertiary consumers

(4) the end of food chain and are decomposers.

What is PAR range?

(1) 200 nm - 800 nm          

(2) 400 nm - 700 nm

(3) 350 nm - 550 nm         

(4) 600 nm - 100 nm

Mr. X is eating curd/yoghurt. For this food intake in a food chain he should be considered

as occupying

1. first trophic level

2. second trophic level

3. third trophic level

4. fourth trophic level.