Section 13-3 & 13-4
“Energy
& Food Chains ”
Write everything
that is underlined
13.3 Energy in Ecosystems / 13.4 Food Chains
Section 13.3 KEY CONCEPT:
Life in an ecosystem requires a
source of energy.
13.3 Energy in Ecosystems / 13.4 Food Chains
I. Energy in an Ecosystem
1. Producers provide energy for
other organisms in an ecosystem.
2. Producers get their energy from nonliving resources (like the sun).
3. Producers are also called autotrophs
because they make their own food
(“auto” means “self”).
13.3 Energy in Ecosystems / 13.4 Food Chains
4. Almost all producers obtain energy from
sunlight.
a. Photosynthesis in
most producers uses
sunlight as an
energy source.
(plants do this)
b. Chemosynthesis in
prokaryote
producers uses
chemicals as an
energy source.
carbon dioxide + water +
hydrogen sulfide +
oxygen
sugar + sulfuric acid
13.3 Energy in Ecosystems / 13.4 Food Chains
5. Consumers are organisms that get their
energy by eating other living things.
(or dead things that used to be alive)
6. Consumers are also called heterotrophs
because they feed off of different things.
(“hetero” means “different)
13.3 Energy in Ecosystems / 13.4 Food Chains
Section 13.4 KEY CONCEPT:
Food chains and food webs model
the flow of energy in an ecosystem.
13.3 Energy in Ecosystems / 13.4 Food Chains
I.
Food Chains
1. A food chain is a model that shows a
sequence of feeding relationships.
2. A food chain follows the connection between
one producer and a single chain of consumers
within an ecosystem.
GRAMA GRASS
DESERT COTTONTAIL
HARRIS’S HAWK
13.3 Energy in Ecosystems / 13.4 Food Chains
II. Consumers are not all alike.
1. Herbivores eat only plants.
2. Carnivores eat only animals.
3. Omnivores eat both plants and animals.
4. Detritivores eat dead organic matter.
5. Decomposers are detritivores that break
down organic matter into simpler
compounds.
carnivore
decomposer
13.3 Energy in Ecosystems / 13.4 Food Chains
6. Specialists are consumers that
primarily eat one specific organism
or a very small number of
organisms.
7. Generalists are consumers that
have a varying diet.
13.3 Energy in Ecosystems / 13.4 Food Chains
III. Trophic levels are the nourishment levels in a
food chain.
– Primary consumers are herbivores that eat
producers.
– Secondary consumers are carnivores that
eat herbivores.
– Tertiary consumers are carnivores that eat
secondary consumers.
– Omnivores, such as humans that eat both
plants and animals, may be listed at different
trophic levels in different food chains.
13.3 Energy in Ecosystems / 13.4 Food Chains
5. Food Chains: Notice the arrow points
toward the animal that is doing the eating
(the eater)
The mouse is going into the snakes mouth
The snake is going into the fox’s mouth
13.3 Energy in Ecosystems / 13.4 Food Chains
6.A food web shows a complex
network of feeding relationships.
a. An organism may have multiple feeding
relationships in an ecosystem.
b. A food web emphasizes complicated
feeding relationships and energy flow in an
ecosystem.
13.3 Energy in Ecosystems / 13.4 Food Chains
Food WEB – notice all the different arrows
13.3 Energy in Ecosystems / 13.4 Food Chains
Review Questions 13.2 & 13.3
1.
2.
3.
4.
5.
What does all life in an ecosystem require?
What is another name for producer?
What are consumers also called?
What is a food chain and food web?
What do herbivores, carnivores, omnivores,
detritivores and decomposers eat?
6. Define Primary, secondary and teriary consumers.