About 70% of total global carbon is found in

1. grasslands

2. agro-ecosystems

3. oceans

4. forests

Animals take phosphorous from 
(1) water 

(2) plants

(3) rock 

(4) soil.

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.

During the stages of succession in a given ecosystem the following changes in characteristics may be observed:

Which one of the characteristics, A, B, C, D or E is responsible for the apparent high degree of stability associated with a climax ecosystem?

(1) B

(2) D

(3) A

(4) E

Perturbation of which of the following cycles contributes most to global warming?

(1) The global carbon cycle   

(2) The global water cycle

(3) The global nitrogen cycle 

(4) All of these cycles contribute equally

Some of the stages in the hydrarch are labelled as:

A. Marsh meadow stage
B. Reed swamp stage
C. Submerged plant stage
D. Phytoplankton stage
E. Submerged free floating plant stage

Identify the choice that represents the correct sequence of these stages:

(1) D, C, E, B and A

(2) C, E, A, B and D

(3) B, D, C, A and E

(4) D, E, C, B and A

Read the following statements carefully.

(i) Primary succession is a very slow process taking thousands of years for the climax to reach.
(ii) Energy at a higher trophic level is always more than that at a lower level.
(iii) Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called fragmentation.
(iv) All succession, whether taking place in water or on land, proceeds to a similar climax community - the mesic.

Which of the two above statements are correct?

1. (i) and (ii)             

2. (ii) and (iii)               

3. (i) and (iv)             

4. (iii) and (iv)

In response to the changing environmental conditions, composition and structure of a community-

1. Remains constant

2. Constantly changes

3. Changes sometime

4. Never changes