Biological equilibrium is an equilibrium among the

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.

Consider the following four statements $(A-D)$ and select the correct option stating which ones are true $(T)$ and
which ones are false $(F)$.
Statements :
$(A)$ Vertical distribution of different species occupying different levels in a community is called stratification.
$(B)$ Net primary productivity minus respiration losses is the gross primary productivity.
$(C)$ Rate of biomass production is called decomposition
$(D)$ Annual net primary productivity of oceans is $55$ billion tons

In a food chain, which of the following produces in the largest amount

Distinguish between 

$(a)$ Litter and detritus

$(b)$ Primary and secondary productivity