Sponsored by Food chains are important in biology, because they show how energy passes through all living things from one to another. This illustrates the way in which organisms depend on each other to survive. At the beginning of nearly all food chains we find plants, because plants need only air, water, sunlight and a few trace minerals to live and grow. The plants are the basic producers of the biological system and convert light energy from the sun into stored chemical energy in the biological molecules that make up their leaves, stems and roots.
Producers occupy the first level in the hierarchy of a food chain.
Animals cannot use the sun's energy in this way. They are consumers and must get the energy they need in order to survive by eating plants and extracting the chemical energy stored in plant material. They then use the energy to keep alive - to pump their blood, to move their muscles, and to operate their nerves. These plant-eating animals are called herbivores . Of the energy that is absorbed from an animal's food some goes to build up, maintain or repair its body and some may be stored as fat that can later be used as an energy source.