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

Which of the following biochemical cycles has a gaseous phase?

Which one of the following is a characteristic feature of a cropland ecosystem?

Which of the following statements are correct?
$(a)$ Net primary productivity is available biomass for consumption to heterotrophs.
$(b)$ Secondary productivity is defined as the rate of formation of new organic matter by heterotrophs.
$(c)$ The annual net primary productivity of the ocean is greater than that of land.
$(d)$ Warm and moist environment favours decomposition.

Which one of the following animals may occupy more than one trophic levels in the same ecosystem at the same time?

Which is the primary colonizer in primary succession on rock?