Question

You find unidirectional flow of energy from the sun to producers and then to consumers. Is this in keeping with the first law of thermodynamics?

Answer 1

Part 1: Unidirectional energy flow in an ecosystem
Energy flow in an ecosystem is always unidirectional as this energy never returns back to its source. The energy is transferred from one trophic level to another and some of it is lost as heat.

Part 2: First law of thermodynamics
This law states that energy is neither created nor destroyed but is transformed from one state to another.

Part 3: Food chain and the first law of thermodynamics
The solar energy trapped by the plants is transformed to chemical energy through the process of photosynthesis. When the plants are consumed by the animals, the organic matter (chemical energy) is transferred to the animal, some amount of this organic matter is lost as heat through the process of respiration. Death of the producers or consumers will result in the organic matter getting transferred to detritivores. As demonstrated, energy is not created nor destroyed but transformed from one form to another.