Question

Why is it steps that flow of energy in an ecosystem is unidirectional?

Answer 1

The energy captured by autotrophs does not revert back to solar system. It passes to the herbivores and from there to the carnivores. The energy lost goes to the atmosphere .  Thus , energy flow from the sun through the producer to the consumer is in one dimensions only . This flow cannot be reversed .

Answer 2

the flow of energy in the ecosystem is said to be unidirectional because the energy lost as heat from the living organisms of a food chain cannot be reused by plants in photosynthesis. During the transfer of energy through successive trophic levels in an ecosystem, there is a loss of energy all along the path.