In which of the following both pairs have the correct combination?

1.	Gaseous nutrient cycle Sedimentary nutrient cycle	Carbon and nitrogen Sulphur and phosphorus
2.	Gaseous nutrient cycle Sedimentary nutrient cycle	Carbon and sulphur Nitrogen and phosphorus
3.	Gaseous nutrient cycle Sedimentary nutrient cycle	Nitrogen and sulphur Carbon and phosphorus
4.	Gaseous nutrient cycle Sedimentary nutrient cycle	Sulphur and phosphorus Carbon and nitrogen

Secondary succession takes place on/in

(1) bara rock

(2) degraded forest

(3) newly created pond

(4) newly cooled lava

Match the following and select the correct option.

     Column I                      Column II

A.  Earthworm                 1. Pioneer species

B. Succession                  2. Detritivore

C. Ecosystem service       3. Natality

D. Population growth        4. Pollination

      A          B         C         D

(1) 1           2         3         4

(2) 4           1         3         2

(3) 3           2         4         1

(4) 2           1         4         3 

Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with

four blanks (A-D). Identify the blanks.

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