(a) Plants are called as Autotrophs because they fix carbon dioxide and produces their own food.(b) In an ecosystem dominated by trees, the pyramid (of numbers) is of Inverted type because it makes more biomass that leads to the large population of birds and insects as compared to the trees.(c) In aquatic ecosystems, the limiting factor for productivity is light as plants and algae cannot grow in the absence of light.(d) Common detritivores in our ecosystem are earthworms as they get nutrients from decaying organic matter.(e) A major reservoir of carbon on earth is oceans.