$Mr. X$ is eating curd. What is his trophic level in the food chain for this food?

Which of the following is the correct sequence for primary succession in water (hydrarch succession)?

The importance of an ecosystem lies in its function of:

Consider the following statements concerning food chains.
$I$. Removal of $80\; \%$ tigers from an area resulted in greatly increased growth of vegetation.
$II.$ Removal of most of the carnivores resulted in an increased population of deers.
$III.$ The length of food chains is generally limited to $3$ to $4$ trophic levels due to energy loss.
$IV.$ The length of food chains may vary from $2$ to $8$ trophic levels.
Which two of the above statements are correct?

Match the columns:

Column-$I$	Column-$II$
$(i)$ Primary succession	$(i)$ Development of ecosystem
$(ii)$ Ecological succession	$(ii)$ Lichens
$(iii)$ Pioneer species on rocks	$(iii)$ Near to the equilibrium with the environment
$(iv)$ Climax community	$(iv)$ New species on bare environment

Identify $Z$ in the given figure representing the carbon cycle.