Question

give reason to justify the following
1) the existence of decomposers is essential in a biosphere
2) flow of energy in a food chain is unidirectional.

Answer 1

decomposers can get back the nutrients to the soil by absorption of those from dead ones .
flow of energy is unidirectional as energy flows from producers to consumers and so on because that energy is produced by the previous ones

Answer 2

the flow of energy is unidirectional. the energy that it captured by the autotrophs doesnot revert back to the solar inputs and the energy which passes to the herbivores doesn't come back to autotrophs.as it moves progressively through the various trophic levels it is no longer available to the previous level.