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.