Chapter 3: How Ecosystems Work

Section 3.1: Energy Flow in Ecosystems

Life depends on the sun.

Plants, algae, and some types of bacteria

capture solar energy and store it as food.

Almost all organisms get their energy from

the sun.

Organisms that are able to make their own food are

called producers.

Producers are also called autotrophs.

Another type of organism found in the ecosystem is

the consumer.

Consumers are organisms that get their energy by eating other

organisms.

Consumers are also called heterotrophs.

Four types of consumers

•1. Herbivores•2. Carnivores•3. Omnivores•4. Decomposers

Herbivores are consumers that eat

only producers.

Carnivores are consumers that eat

only consumers.

Omnivores are consumers that eat both consumers

and producers.

Decomposers are consumers that get

their food by breaking down

dead organisms.

Consumers get their energy from food by the process called

cellular respiration.

Cellular respiration is the process of breaking down

food to yield energy.

Each time one organism eats another organism, a transfer of energy occurs.

We can trace the paths energy follows as it travels through an

ecosystem by studying food chains, food webs,

and trophic levels.

A food chain is a sequence in which energy is

transferred from one organism to the next as

each organism eats another.

A food web shows many of the feeding relationships

in an ecosystem.

Trophic levels are each step in the transfer of

energy through an ecosystem.

Each trophic level consumes 90 percent of the energy present – only 10 percent is passed onto

the next level.