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.

Animals take phosphorous from 
(1) water 

(2) plants

(3) rock 

(4) soil.

Most animals that live in deep oceanic waters are

(1) Tertiary consumers

(2) Detritivores

(3) Primary consumers

(4) Secondary consumers

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.

Energy flow in an ecosystem is 

(1) unidirectional

(2) bidirectional

(3) multi-directional

(4) All the these 

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

Most of the world's carbon is found:

(1) As carbon dioxide in the atmosphere.

(2) In living organisms.

(3) As bicarbonate and carbonate ions dissolved in the oceans.

(4) As carbonate minerals in sedimentary rock.

Photosynthesis and respiration are central to which cycle?

(1) The nitrogen cycle 

(2) The carbon cycle

(3) The phosphorus cycle

(4) The sulfur cycle

The phosphorus cycle differs from the carbon cycle in that:
a. Phosphorus does not enter living organisms, whereas carbon does.
b. The phosphorus cycle does not include a gaseous phase, whereas the carbon cycle does.
c. The phosphorus cycle includes a solid phase, whereas the carbon cycle does not
d. The primary reservoir of the phosphorus cycle is the atmosphere, whereas the primary reservoir for the carbon cycle is in rock.

Which of the following changes would not result in an increase in net primary production?

(1) Increased precipitation in an and area

(2) Increased soil fertility

(3) Increased latitude (moving from the equator toward the poles)

(4) Moving down a mountain to warmer temperatures