The above represents

Secondary productivity is

Distinguish between 

$(a)$ Litter and detritus

$(b)$ Primary and secondary productivity

Choose correct answer.

$(1)$ Zooplanktons are primary producers in an aquatic ecosystem.

$(2)$ Decomposition is largely an oxygen requiring process.

$(3)$ In a natural ecosystem, fishes, wolf, etc. are carnivore.

$(4)$ The amount of energy decreases in each successive trophic level.

The transfer or energy from organisms to organisms in a natural community establishes

Assertion : In a food chain, members of successive higher levels are fewer in number.
Reason : Number of organisms at any trophic level depends upon the availability of organisms which serve as food at the lower level.