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

Which of the following is the functional unit of nature?

1. A plant

2. An animal

3. Ecosystem

4. Environment

Identify the odd one out?

1. Forest

2. Grassland

3. Desert

4. Wetland

Which of the following is not a man-made ecosystem?

1. Pond

2. Crop-field

3. Swimming pool

4. Both ‘1’ and ‘3’

Which vertical strata is occupied by trees in a forest?

1. Top

2. Middle

3. Bottom

4. Any of the above.

Which of the following could affect the rate of function of a pond?

1. The solar input

2. The cycle of temperature

3. Day-length

4. All of the above