Final answer:
Approximately 10% of energy is transferred to the next trophic level in a food chain, and the remaining energy is primarily lost as heat due to metabolic processes and the second law of thermodynamics.
Step-by-step explanation:
In biological systems, energy transfers along a food chain from one trophic level to the next. However, not all of the energy is passed on; about 90% of energy is lost at each level, primarily as heat. The remaining 10% of the energy is what is stored in the biomass of the organisms at the next trophic level. This loss of energy is largely due to metabolic processes and the second law of thermodynamics, which states that whenever energy is converted from one form to another, some of it is lost as heat, which is not useful for doing work at the cellular or organism level.
The energy that is not transferred to the next level is either used by the organisms at their current level to sustain their life processes or lost to the environment, much of it as heat. This heat is not readily reusable by the ecosystem, hence we say it is 'lost', although in terms of the law of conservation of energy, it is simply converted into a form that is not useful for the organisms within the ecosystem.