Which among the following is not a functional unit of the ecosystem?

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?

Climax stage is achieved quickly in secondary succession as compared to primary succession. Why?

Phosphorus of the ocean becomes available to land plants due to:

In an ecosystem,the insectivorous plants are placed in

Choose the correct sentence.