The second trophic level in a lake is:

1. Phytoplankton

2. Zooplankton

3. Benthos

4. Fishes

The limitations of ecological pyramids include all the following except:

1. The do not take into account the same species belonging to two or more trophic levels

2. They do not represent relationships between organisms at different trophic levels

3. They assume a simple food chain and do not consider food webs

4. Saprotrophs are not given any place in the ecological pyramids

Most food chains are composed of 

1. 1 or 2 species

2. 3 or 4 species

3. 9 or 10 species

4. More than 16 species

Vertical distribution of different species occupying different levels in a biotic community is

known as 

1. divergence

2. stratification

3. zonation

4. pyramid

The mass of living material at a tropic level at a particular time is called

1. Gross primary productivity

2. Standing state

3. Net primary productivity

4. standing crop

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 functional unit of an ecosystem?

1. Energy flow                 

2. Decomposition

3. Productivity                 

4. Stratification

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

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%

The biomass available for consumption by the herbivores and the decomposers is called

1. net primary productivity

2. secondary productivity

3. standing crop

4. gross primary productivity