Food chain is a link of organisms through which energy is transferred in the form of food by the process of one organism consuming the other. it describe the relationship of organisms about ‘who eats whom’.

Each step a level of the food chain forms are trophic level. The producers (autotrophs) are at the first trophic level. They fix up the solar energy and make it available for consumers (hetrotrophs). The herbivorous or the primary consumers have at second, small carnivorous or secondary consumers are the third and large of the tertiary consumers form the fourth trophic level.

Food chain shows how food and energy passes from one organism to another in a habitat. Arrows in the food chain indicates the direction in which the energy flows in an ecosystem. It is the one way process that is undirectional flow of energy. The energy captured by organism of a particular trophic level does not revert back to the previous trophic level. Each food chain is the possible pathway that energy and nutrition can flow throughout the ecosystem. A simple food chain in a grassland ecosystem could be

Grass -> Shree -> owl.

In this food chain grass is the primary producer. The grasshopper is a primary consumer which utilise the ATP produced during photosynthesis in produces. ATP stored in food matter, which is utilised by this plant eater that is herbivores. The Shrew is a secondary consumer and the Owl is a tertiary consumers. Food chains are of two types. The chain is based on living plant and it is termed as a grazing chain and the one based on a dead plant material it is that detrial chain or a decomposer chain.