Question

explain why the flow of energy in ecosystem is said to be unidirectional?

Answer 1

According to Energy Transfer Law only 10% of energy is transferred from one trophic level to other. So the energy that is captured by autotrophs is not revert back to sun and the energy transferred to herbivores does not came back to autotrophs. It just keep on moving to next trophic level in unidirectional way. When the organisms die their body decomposes and the nutrients are returned back to the soil which can be absorbed by the plants.