Question

the 10% rule of ecosystems says that only 10% of the energy is passed on to the next trophic level. what happens to the rest of the energy? we dont know what happens to it. it gets released into the environment as heat. it goes back into plants.

Explanation:

The 10% rule states that only 10% of energy is passed to the next trophic level. The rest is used for metabolic processes like respiration. During respiration, energy is converted and some is lost as heat. This heat is released into the environment. Energy flow in ecosystems is unidirectional, so it doesn't go back to plants. And we do know what happens to the energy (it's not an unknown).

Answer:

It gets released into the environment as heat.