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

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

	A	B	C	D
1.	Rock minerals	Detritus	Litterfall	Producers
2.	Litterfall	Producer	Rock minerals	Detritus
3.	Detritus	Rock minerals	Producer	Litterfall
4.	Producer	Litterfall	Rock minerals	Detritus

Secondary productivity is rate of formation of new organic matter by

1. producer

2. parasite

3. consumer

4. decomposer

Which one of the following processes during decomposition is correctly described?

1.  Fragmentation-Carried out by organisms such as earthworms

2.  Humification-Leads to the accumulation of a dark-coloured substance humus, which

undergoes microbial action at a very fast rate

3.  Catabolism-Last  step in the decomposition under fully anaerobic condition

4.  Leaching-Water soluble inorganic nutrients rise to the top layers of soil.

Which one of the following is not a gaseous biogeochemical cycle in ecosystem?

1. Oxygen cycle

2. Phosphorus cycle

3. Nitrogen cycle

4. Carbon cycle

Identify the possible link A in the following food chain

Green plant -> Insect -> Frog -> A -> Eagle

1. rabbit                         

2. wolf

3. cobra                         

4. parrot

Given below is an imaginary pyramid of numbers. What could be one of the possibilities

about certain organisms at some of the different levels?

1. Level PC is insects and level SC is small insectivorous birds.

2. Level PP is phytoplanktons in sea and whale on top level TC

3. level one PP is pipal trees and the level SC is sheep

4. Level PC is rats and level SC is cats 

Which one of the following statements is correct for secondary succession?

1. It occurs on a deforested site 

2. It follows primary succession

3. It is similar to primary succession except that it has a relatively fast pace

4. It begins on a bare rock

Which one of the following statements for pyramid of energy is incorrect, whereas the

remaining three are correct ?

1. It shows energy content of different trophic level organisms

2. It is inverted in shape

3. It is upright in shape

4. Its base is broad

Mass of living matter at a trophic level in an area at any time is called 

1. Detritus

2. Humus

3. Standing state 

4. Standing crop

Of the total incident solar radiation the proportion of PAR is 

1. about 60%

2. less than 50%

3. more than 80%

4. about 70%