State the law which governs the energy flow in an ecosystem.

Energy flow in an ecosystem is governed by the laws of thermodynamics that are stated below:

1. First law of thermodynamics (Law of conservation of energy) — Energy can be transformed from one form to another form, but it can neither be created nor destroyed.
2. Second law of thermodynamics — When energy is put to work, a part of it is always converted in unuseful form mainly as heat, due to friction and radiation.