Which of the following is/are incorrect:

A. All ecosystems are constant in size
B. In nature food chains exist, not food web
C. Flow of energy in ecosystem is unidirectional
D. Gene flow occurs between 2 different population (of 2 species)

(1) A, C

(2) A, D

(3) A, B, D

(4) A, B, C, D

The important step in the process of decomposition in order is:

Which of the following is false?

I. Quantity of biomass in a trophical level at a particular period is called standing crop.
II. The energy content in a trophic level is determined by considering a few individuals of a species         in that trophic level.
III. The succession that occurs in nearly cooled lava is called primary succession.
IV. Rate of succession is faster in the secondary succession
V. Phytoplankton are the pioneers in aquatic succession

(1) Only II

(2) Only III

(3) Only V

(4) Only I and IV

The amount of biomass or organic matter produced per unit area over -a time period by plants during photosynthesis is called primary production, which is expressed as:

(1) g m⁻²

(2) kcal m⁻²

(3) (kcal m⁻²) yr⁻¹

(4) Both (1) and (2)

An ecosystem, which can be easily damaged, but can recover after some time if damaging effect stops will be having:

(1) High stability and high resilience

(2) Low stability and high resilience

(3) High stability and low resilience

(4) Low stability and low resilience

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)

The removal of 'Keystone' species will affect:

(1) The producers                     

(2) The consumers

(3) The ecosystem                   

(4) The decomposers