Energy is transferred in chemical form through the food chain. Some of the energy is preserved in the form of tissue in the organism that receives the energy. The rest is lost as heat, and possibly kinetic energy. Very roughly, one calculates that 90% of the energy is lost in each link, while 10% is available for the next link.

The chemical energy of food is the main source of energy required by all living organisms. This energy is transmitted to different trophic levels along the food chain. In the food chain, energy is transferred from one living organism through another in the form of food. There are primary producers, primary consumers, secondary consumers and decomposers- all part of the food chain. The sun is the source of energy in the food chain. Solar energy is used by producers or plants to synthesize their own food through photosynthesis. The plants are then consumed by organisms of the higher trophic level leading to the transmission of energy. The energy transfer is only ten percent efficient because much of the energy is used up on life processes, such as respiration, growth, movement, and reproduction. A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. In a food chain, each organism occupies a different trophic level, defined by how many energy transfers separate it from the basic input of the chain.This transfer happens in three different ways by conduction within solids, by the flow of liquid or gas, and by radiation, which can travel across space. Even when a system is isolated energy is continually being transferred into and out of it by radiation. At each step up the food chain, only 10 percent of the energy is passed on to the next level, while approximately 90 percent of the energy is lost as heat. Each time something eats something else, food energy is transferred from one organism to another. The transfer of energy between organisms is called a food chain. Biomass is the energy in living organisms. Autotrophs, the producers in a food web, convert the sun's energy into biomass. A food chain describes how energy and nutrients move through an ecosystem. At the basic level there are plants that produce the energy, then it moves up to higher-level organisms like herbivores. After that when carnivores eat the herbivores, energy is transferred from one to the other. Energy is transferred between trophic levels when one organism eats another and gets the energy-rich molecules from its prey's body. However, these transfers are inefficient, and this inefficiency limits the length of food chains. In fact, the Sun is the ultimate source of energy for almost all cells, because photosynthetic prokaryotes, algae, and plant cells harness solar energy and use it to make the complex organic food molecules that other cells rely on for the energy required to sustain growth, metabolism, and reproduction.