Which of the following is an example of a man-made ecosystem?

Which of the following has the largest population in a food chain?

Fill in the blanks.
$(a)$ Plants are called as . . . . . . because they fix carbon dioxide.
$(b)$ In an ecosystem dominated by trees,the pyramid (of numbers) is . . . . . . type.
$(c)$ In aquatic ecosystems,the limiting factor for the productivity is . . . . . . .
$(d)$ Common detritivores in our ecosystem are . . . . . . .
$(e)$ The major reservoir of carbon on earth is . . . . . . .

Choose the correct sequence of True $(T)$ and False $(F)$ statements:
$(1)$ 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 carnivores.
$(4)$ The amount of energy decreases at each successive trophic level.

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 of the following are not primary producers in an aquatic ecosystem?