The amount of energy reaching an upper trophic level is determined by:

1. Net primary production

2. Net primary production and the efficiencies with which food energy is converted to biomass

3. Gross primary production

4. Gross primary production and the efficiencies with which food energy is converted to biomass

Fill in the blanks, in the following simplified model of a nutrient cycle:

           1             2                    3                       4                  5

(1) Producers   Detritus         Soil solution      Decomposition    Weathering

(2) Producers   Detritus         Soil solution      Weathering         Decomposition

(3) Producers   Soil solution   Detritus            Decomposition    Weathering

(4) Producers   Soil solution   Detritus            Weathering         Decomposition

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)

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

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