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Ecological relationships and energy flow (CCEA)Food chains and food webs

The Sun is the original source of energy for almost all organisms on the Earth. The way energy passes through an ecosystem is described as energy flow.

Part of Combined ScienceBiodiversity

Food chains and food webs

Specific feeding sequences (and therefore flow of energy) can be represented as a food chain.

A 'grass seeds-vole-barn owl' food chain

Arrows between each organism show the direction of:

  • Feeding (consumption).
  • Energy flow.
  • The transfer of substances such as carbon and nitrogen.

Food webs show a number of food chains that are interlinked due to the organisms involved living in close proximity.

Food web

Most organisms will have more than one food source that can be seen in a food web but not a food chain.

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