The slow rate of decomposition of fallen logs in nature is due to their

1. low moisture content

2. poor nitrogen content

3. anaerobic environment around them

4. low cellulose content

Consider the following statements concerning food chains

(i) Removal of 80% tigers from an area resulted in greatly increased growth of

vegetation

(ii) Removal of most of the carnivores resulted in an increased population of deers

(iii) The length of food chains is generally limited to 3-4 trophic levels due to energy loss

(iv) The length of food chains may vary from 2 to 8 trophic levels

Which two of the above statements are correct?

1. ii and iii

2. iii and iv

3. i and iv

4. i and ii

Which one of the following is not used for construction of ecological pyramids?

1. Dry weight

2. Number of individuals

3. Rate of energy flow

4. Fresh weight

About 70% of total global carbon is found in

1. grasslands

2. agro-ecosystems

3. oceans

4. forests

The correct sequence of plants in a hyrdosere is 

1. Oak→Lantana →Scirpus→Pistia→Hydrilla→Volvax
2. Volvax→Hydrilla→Pistia→Scirpus→Lantana→Oak
3. Pistia→Volvax→Scirpus→Hydrilla→Oak→Lantana
4. Oak →Lantana→Volvax→Hydrilla→Pistia→Scirpus

Which one of the following is one of the characteristics of a biological community ?

1. Stratification 

2. Natality 

3. Mortality 

4. Sex-ratio

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

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%

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

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