In an energy pyramid, what occurs as energy moves up through the trophic levels?

As energy moves up through the trophic levels in an energy pyramid, there is a net loss of energy at each successive level. This phenomenon is explained by the inefficiency of energy transfer within ecosystems. Typically, when energy is transferred from one trophic level to the next—such as from producers to primary consumers and then to secondary consumers—only about 10% of the energy is passed along. The remainder of the energy is lost primarily as heat through metabolic processes, growth, and cellular respiration.

This loss of energy is significant because it explains why there are fewer organisms at higher trophic levels and why these organisms tend to be larger and require more energy to sustain themselves. This is also why ecosystems often have a broad base of producers, as they provide the energy foundation necessary to support fewer consumers. Thus, the correct answer highlights the critical understanding of energy flow in an ecological context.