Energy flow

Science

Definition

The movement of energy through an ecosystem, starting from the sun and passing through producers, consumers, and decomposers. At each trophic level, about 90% of energy is lost as heat, so only about 10% is transferred to the next level.

Examples

  • Sunlight → grass → rabbit → hawk, with energy lost as heat at each step
  • Only about 10% of energy from corn passes to a cow that eats it
  • Decomposers breaking down dead organisms and releasing heat energy
Key Fact

The 10% rule: only ~10% of energy transfers between trophic levels

Related Terms

Food webs Ecosystems Photosynthesis Cell respiration

Study This Concept

Practice energy flow with free review games in these units:

AP Environmental Science Unit 1: The Living World: Ecosystems Biology Unit 7: Ecology and Ecosystems