Assertion (A): Symbiosis, parasitism and predation are the categories of interdependence between organisms, which are the ways of transferring energy.

Reason (R): The transfer of energy from one trophic level to the other always occurs through the food chain.

1. Both A and R are true.
2. Both A and R are false.
3. A is true and R is false.
4. A is false and R is true.

Assertion (A): Flora and fauna of a forest are always the same throughout the world.

Reason (R): Usually, forest contains very big trees and animals. So, whatever climatic conditions are present, plants and animals remain the same.

1. Both A and R are true.
2. Both A and R are false.
3. A is true and R is false.
4. A is false and R is true.

Fill in the blanks :

(a) Lichens are the good example of …………… association.

(b) Two intermediate hosts of liver fluke are …………… and …………… .

(c) Evergreen trees are common flora of …………… forests.

(d) …………… will always be trophic level-1 in a food chain.

(e) …………… sanctuary is found in West Bengal which is famous for rhinoceros.

Mention if the following statements are true (T) or false (F):

(a) Snakes are primary consumers.

(b) Some humans are strictly primary consumers while others are secondary or tertiary consumers as well.

(c) No ecosystem can survive without light.