Final answer:
Energy decreases as it moves up the food chain due to metabolic losses and the second law of thermodynamics, leading to a significant loss of energy at each trophic level.
Step-by-step explanation:
Energy is passed up a food chain or web from lower to higher trophic levels. However, generally only about 10 percent of the energy at one level is available to the next level. This is represented by the ecological pyramid, where each trophic level has less energy than the one below it. The rest of the energy is used for metabolic processes or given off as heat, limiting the number of trophic levels in a food chain.
Energy decreases as it moves up the food chain due to metabolic losses. In an ecosystem, energy flows from primary producers through various trophic levels. However, this transfer is not 100% efficient. Approximately only 10 percent of the energy at one trophic level is available to organisms at the next higher level. Most of the energy is used for metabolism, growth, and repair, with a significant amount lost as thermal energy or undigested food. This substantial loss of energy at each level, explained by the second law of thermodynamics, leads to entropy in the system. Consequently, there are rarely more than four trophic levels in a food chain or web because there simply isn't enough energy left to support additional levels of consumers.