What happens to energy as it is passed up a food chain?

As energy moves up a food chain, it follows the laws of thermodynamics, particularly the principle that energy is transformed and often lost in the process. When organisms consume energy, not all of it is converted into biomass or passed on to the next trophic level. A significant amount of energy is released as heat due to metabolic processes, such as respiration, growth, and maintenance of bodily functions. This loss of energy in the form of heat means that only a fraction of the energy captured by primary producers—like plants—is available to primary consumers, and even less to secondary and tertiary consumers. This inefficient transfer of energy is a key reason why food chains tend to have fewer trophic levels, as the energy available decreases sharply with each step up the chain. Thus, the correct understanding is that as energy is transferred from one level to the next, it is lost primarily in the form of heat.