Carbon constitutes . . . . . . of dry weight of organisms and . . . . . . percentage is dissolved in oceans out of total global carbon.

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

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

$A$ snake feeds on a rat,a hawk feeds on the snake,and the rat feeds on a grasshopper. In this food chain,what is the trophic level of the rat?

Choose the correct sentence regarding the carbon cycle.

Which of the following statements are correct regarding a food chain?
$(a)$ If $80\%$ of tigers are removed from an area,the growth of vegetation in that area increases.
$(b)$ If carnivores are removed from an area,the population growth of deer increases.
$(c)$ The length of a food chain is limited to $3$ to $4$ trophic levels because the amount of energy decreases in the ecosystem.
$(d)$ The length of a food chain is usually $2$ to $8$ trophic levels.