Both energy and nutrients are passed along a food chain. While energy is eventually lost to heat, nutrients are constantly being recycled.

Sunlight is converted into energy as glucose by a process called photosynthesis and stored in plants. As first level consumers eat plants this stored energy is transferred through carbon-carbon bonds which release energy when they are broken. During respiration the bonds are broken and carbon combines with oxygen to form carbon dioxide. The energy that is released is used by the organism or is lost as heat. Ultimately all energy in a food chain returns to the system as heat.

plant --> eaten by animal --> carbohydrates digested into glucose --> respiration --> energy for cell processes

Some of the carbohydrates digested into glucose will be converted into other substances, such as fats.

The other component that travels through a food chain is inorganic nutrients, which do not contain carbon-carbon bonding. These include phosphorous, cellular membranes, nitrogen and iron. The movement of these substances comes from an inorganic nutrient pool, usually the soil or water surrounding plants or algae. They are absorbed by the plants and passed from organism to organism as they are consumed. When the organism dies the nutrients are recycled as they are decomposed. and become available for plants as the cycle continues.

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