What will happen to an ecosystem if :

$(a)$ All producers are removed;

$(b)$ All organisms of herbivore level are eliminated; and

$(c)$ All top carnivore population is removed

Match the following columns.

Trees $\rightarrow$ Birds $\rightarrow$ Lice $\rightarrow$ Bacteria. Thus food chain is

Assertion : A network of food chains existing together in an ecosystem is known as food web.
Reason : An animal like kite cannot be a part of a food web.

In ecological pyramid the base always represent the $…A…$ and the apex represents $…B…$ Here $A$ and $B$ represents