Matter & Energy in Food Webs

Key points:

• Matter describes the atoms that make up an ecosystem’s parts. Matter cycles between the living and nonliving parts of an ecosystem.

• Energy changes form as it moves through an ecosystem. Energy that enters an ecosystem eventually leaves as heat.

• Producers are organisms that make their own food inside their cells. Photosynthetic organisms are producers. Producers allow energy to enter an ecosystem.

• Consumers are organisms that eat other organisms. When this occurs, the matter and energy stored in the other organism’s biomass moves to the consumer.

  • Primary consumers eat producers.

  • Secondary consumers eat primary consumers.

• Decomposers are organisms that consume dead plant and animal matter. When they do this, they return matter back to the environment.

• Food webs are models that show how energy and matter move in an ecosystem. The arrows in a food web show what organisms eat. The arrows point away from the organism being eaten, and toward the organism doing the eating.