Food chains use a unidirectional transfer of energy. Plants absorb energy from the sun, then the energy goes on to next tropic level and so on. But in this system, energy source is the Sun.

When any organism dies, it’s decomposition doesn’t contribute energy back to the sun (as the nuclear process in the sun keeps on generating energy).

So my question is - doesn’t it violate the law of conservation of energy? As energy is not flowing back to the sun? Here Sun is the ultimate source of energy as it just keeps on creating energy, so energy isn’t conserved?


The Sun doesn't create energy; it converts energy from one form to another - in particular, it makes light. The physical details need not concern us here: what matters is that the Sun's fuel supply is gradually depleted (over billions of years), producing light. What interests biologists is that photosynthesis harnesses some of this light energy, and each trophic level receives, on average, about 10% of the one below it.

  • $\begingroup$ I agree with you, But if we look at a food chain, Sun is a source of energy. At the end of the chain the energy doesn't go back to the sun. That is the reason for my question... $\endgroup$ – neel g Mar 2 '20 at 11:06
  • $\begingroup$ @neefg Conservation doesn't require energy to go back to where it started. If you use a hob to boil water, the oven never gets back the thermal energy. $\endgroup$ – J.G. Mar 2 '20 at 11:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.