In energy transfer within an ecosystem, what happens to most of the energy as it moves to higher trophic levels?

• A. It is lost as heat; typically only about 10% is transferred to the next level
• B. Energy is stored in chemical bonds at higher levels
• C. It is converted into light energy
• D. Energy is destroyed during transfer

Answer: (D)

The main idea here is how energy moves through ecosystems and how efficiently it can be transferred between trophic levels. When organisms at one level use energy for metabolism, growth, movement, and maintaining body temperature, most of that energy is released as heat and escapes to the surroundings. Only a small portion remains to be stored in new biomass that can be passed on to the next level. In practice, about 10% of the energy at one level makes it into the next level as usable biomass. Because energy is continually dissipated as heat and used in life processes, the amount available to higher levels drops quickly, which is why ecosystems have relatively few trophic levels. Energy isn’t destroyed; it’s transformed into heat and other forms, with only a fraction kept as energy stored in biomass at each step.