Chapter 23.1

Energy Roles An organism’s energy role in an ecosystem may be that of a producer, consumer, or decomposer. An organism’s energy role is determined by how it obtains energy and how it interacts with the other living things in its ecosystem.

Organisms that carry out photosynthesis are called autotrophs. Another word for an organism that can make its own food is a producer. Producers are the source of all the food in an ecosystem. Energy Roles

Heterotrophs cannot make their own food. These organisms depend on the producers for food and energy. Another word for an organism that obtains energy by feeding on other organisms is a consumer. Energy Roles

Organisms that break down wastes and dead organisms and return the raw materials to the environment are called decomposers. Two major groups of decomposers are bacteria and fungi, such as molds and mushrooms. Energy Roles

Food Chains and Food Webs

A food chain is a series of events in which one organism eats another and obtains energy. Food Chains and Food Webs ?

A food chain is a series of events in which one organism eats another and obtains energy. Food Chains and Food Webs

Trophic Levels Nourishment or eating

Producers Second Level (or Secondary) Consumers decomposers First Level (or Primary) Consumers Trophic Levels

Producers Consumers decomposers Consumers Trophic Levels

A food web consists of the many overlapping food chains in an ecosystem. Food Webs

An energy pyramid shows the amount of energy that moves from one feeding level to another in a food web. Food Chains and Food Webs

Energy is used at each level to carry out life processes. The most energy is available at the producer level. Less energy is available to the upper levels because it’s been used up. Food Webs