What is the definition of a food chain, a food web, and a food pyramid?
A food web is made up of several food chains and a food pyramid includes energy flow up the food chain. See below.
Food chain : A food chain describes the feeding relationships of different organisms in a linear fashion. This is the simplest way of showing feeding relationships.
Food web : A food web shows multiple food chains, multiple relationships and connections. This a more complicated but more realistic way of showing feeding relationships, as most organisms consume more than one species and are consumed by more than one species.
Food pyramid : More commonly known as an energy pyramid, a food pyramid takes the food chain but uses it to show how energy moves through a community.
Because each organism uses some of the energy it received from the previous level for growth and other processes, the energy available to the next level is less (because some of that energy has been used). This is why we have more primary producers than carnivores.