Answer:
The flow of energy through an ecosystem is generally unidirectional in nature, starting from sunlight and ending as heat.
Step-by-step explanation:
Energy enters from the atmosphere in the ecosystem in the form of sunlight being utilized by plants through the process of photosynthesis. These plants when consumed by herbivores or omnivores, some part of the energy is used and rest is lost as heat. Similarly when these herbivores forming the primary consumers are attacked and consumed by secondary consumers, then also some part of energy used up and the rest is lost as heat. The energy is unidirectional, because the plants could not reuse this energy once it starting progressing through the various levels of ecosystems and finally lost as heat to the atmosphere.