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

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 individual transitional communities in a sere are termed as-

1. Seral stages

2. Seral communities

3. Seral species

4. Both 1 and 2.

Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks. 

The reservoir for the gaseous type of bio-geochemical cycle exists in

1. stratosphere

2. atmosphere

3. ionosphere

4. lithosphere

Where do we find reservoir for sedimentary type nutrient cycling?

1. Land

2. Sea

3. Earth’s crust

4. Atmosphere

The amount of nutrients, such as carbon, nitrogen, phosphorus, calcium, etc. present in the soil at any given time, is referred to as the-

1. Nutrient status of a soil

2. Standing state

3. Standing crop

4. Mineral state.

What is the global gross national product GNP value?

1. US $ 16 trillion
b

2. US $ 18 trillion

3. US $ 24 trillion

4. US $ 26 trillion.

In response to the changing environmental conditions, composition and structure of a community-

1. Remains constant

2. Constantly changes

3. Changes sometime

4. Never changes