Food Chains

Food chains are the sequence of feeding relationships through which plants and animals depend on each other for food. Food provides the nutrients plants and animals need to build and repair their body parts, and the energy they need to grow and function. There are countless food chains involving different plant and animal species in a variety of habitats all around the world. Every plant and animal belongs to at least one food chain, and these chains can be simple or very complex.

At the base of the food chain lie the producers. Producers are mainly green plants and certain bacteria, which convert sunlight into food energy. Above the producers are the consumers who ingest live plants or other animals. Decomposers, such as, bacteria, molds, and fungi make use of energy stored in already dead plant and animal tissues.

Energy from the Sun

The sun is the primary source of energy for all life. Even living organisms that seem to flourish in darkness feed on plants, insects, animals, or microorganisms that depend on sunlight for their survival. The sun provides energy that plants can use to make their own food. This is the first step in every food chain.

Natural Food Factories

All green plants can do something truly amazing and unique that no other living organism on earth can do. They can make their own food energy using sunlight, air, and water. This process by which plants produce food energy is called photosynthesis. The word photosynthesis comes from two Greek words. Photo means light and synthesis means putting things together to make something new.

Photosynthesis in Action

diagram of photosynthesis

Green plants have a special chemical in their leaves called chlorophyll which is the substance that makes leaves green. The chlorophyll is found in little compartments of green leaves, called the chloroplasts, and allows the leaves to act like miniature solar panels capturing and storing the sun’s energy far more efficiently than anything ever devised by humans. Green plants use the energy from sunlight shining on their leaves to produce their own food. Carbon dioxide gas from the air enters through pores in the leaves, and water is absorbed through its roots. Carbon dioxide and water are combined with the energy from the sun to create food energy.

Natural Food Energy

The foods that plants make using the process of photosynthesis are sugars. These include glucose and fructose, which are converted by the plant into sucrose for storage. Sucrose, glucose, and fructose are found naturally in all plants, and are the basis for all food energy.

The sugars that plants produce are stored in the root, leaf, seed, or fruit of the plant. Plants that produce sucrose in the largest quantities are sugar cane and sugar beets and thus are harvested to produce the sugar for commercial and industrial use.

The reaction of photosynthesis can be written as the following chemical equation when sucrose is being made:

12 CO2 + 11 H2O + energy = C12 H22 O11 + 12 O2
carbon dioxide + water + sunlight = sucrose + oxygen