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)

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

What do you mean by ecological succession?

1. One community is succeeded by another

2. One community is dominant over another

3. The gradual and fairly predictable change in the species composition of a given area

4. Success of the ecological community.

During succession some species colonise an area, what does happen to the native species then?

1. Decline and even disappear

2. Flourish equally

3. Migrate

4. Decline in number

Nature of change in community during succession is –

1. Orderly, sequential and parallel with the changes in the physical environment.

2. Independent of the changes in the physical environment.

3. Constant change

4. Depends upon the community

What do you mean by sere?

1. Series of communities in an area

2. The entire sequence of communities that successively change in a given area

3. The entire sequence of communities.

4. The entire sequence of communities that do not change in a given area.

The individual transitional communities in a sere are termed as-

1. Seral stages

2. Seral communities

3. Seral species

4. Both 1 and 2.

When did ecological succession start on earth?

1. after the rise of mammals

2. since life started

3. after the rise of plants

4. can’t say