The food chain in which microorganisms break down the food produced by primary producers is known as:

Secondary succession takes place on/in

Lichen is the pioneer vegetation on which succession?

Approximately $49 \%$ of the dry weight of organisms is composed of carbon. (in $\%$)

Out of the total cost of various ecosystem services, the soil formation accounts for $P$, while contributions of other services like recreation and nutrient cycling are less than $Q$ each. The value of climate regulation and habitat for wildlife is about $R$ each. Identify $P, Q,$ and $R$.

How many of the following basic components are found in a pond ecosystem?
Productivity,Decomposition,Energy flow,Nutrient cycling