6.1a Energy flows through ecosystems in one direction, usually from the Sun, through

producers to consumers and then to decomposers. This process may be visualized with

food chains or energy pyramids.

6.1b Food webs identify feeding relationships among producers, consumers, and

decomposers in an ecosystem.

6.1c Matter is transferred from one organism to another and between organisms and

their physical environment. Water, nitrogen, carbon dioxide, and oxygen are examples

of substances cycled between the living and nonliving environment.