Identify the possible link '$M$' in the following food chain.
Plant $\rightarrow$ Insect $\rightarrow$ $M$ $\rightarrow$ Snake $\rightarrow$ Eagle

Which one of the following is not a function of an ecosystem?

Which one of the following is not a functional unit of an ecosystem?

When a peacock eats a snake,which eats insects,and insects feed on green plants,the peacock is a/an:

Some of the stages in the hydrarch succession are labelled as:
$I.$ Marsh meadow stage
$II.$ Reed swamp stage
$III.$ Submerged plant stage
$IV.$ Phytoplankton stage
$V.$ Submerged free floating plant stage
Identify the choice that represents the correct sequence of these stages.

The changes that occur in successive seral stages to reach a climax community are:
$I.$ Changes in the diversity of species of organisms.
$II.$ Increase in the number of species and organisms.
$III.$ Increase in the total biomass.
Choose the correct option.