Final answer:
When energy is transferred between trophic levels in an ecosystem, heat is always given off to the environment due to the second law of thermodynamics, and only about 10% of the energy is passed on to the next level.
Step-by-step explanation:
When energy is transferred between trophic levels, the form of energy that is always given off to the environment is heat. The transfer of energy through the food chain is not 100% efficient.
This concept is associated with the laws of thermodynamics, particularly the second law, which states that every energy transfer increases the entropy of the universe and results in a loss of usable energy as heat. In biological systems, such as an ecosystem, this is evident by the fact that only about 10% of the energy at one trophic level is actually passed on to the next level. The remaining 90% is utilized for metabolic processes or lost as heat, demonstrating the ecological efficiency of an ecosystem.
The concept of ecological efficiency is fundamental to understanding why ecosystems rarely have more than four trophic levels. As energy moves from producers up to consumers, the energy transfer efficiency, known as the trophic level transfer efficiency (TLTE), is low; less energy is available at higher levels, which limits the number of trophic levels.