1. Biology I: Energy Flow
Through an Ecosystem
(part 2)
Food Chains, Food Webs, Energy Pyramids

2. Agenda – Tues. Oct. 4,
2011
Warm-Up
Lesson
Wrap-Up (Identifying food chains)
Wrap-Up (Identifying producers, consumers, decomposers)
Homework Worksheet

3. Today’s Objectives
I will explore energy flow within an ecosystem.
I will define: ecosystem, herbivores, omnivores,
carnivores, food chain, food web, energy pyramid.
I will trace food chains within a food web.
I will classify organisms as: producers, consumers,
or decomposers.

4. Warm-Up
1. What do decomposers do?
2. If you ate chicken that previously ate
grass, what type of consumer would you
be?
3. Where does energy flow ultimately begin?

5. What is an Ecosystem?
An Ecosystem is all of the living organisms and
non-living environment found in a particular
place

6. What is an Ecosystem?
Example: a pond or aquatic ecosystem
Living Things: fish, turtles, algae, insects,
bacteria
Non-Living Things: physical and chemical properties
of the pond like the amount of oxygen in the pond
and its pH

7. Trophic Level
Each feeding level in an ecosystem
Each level of a food chain or food web
First Trophic Level: made up of only
producers

8. Trophic Level
Second Trophic Level:
made up of primary
consumers
Herbivores: primary
consumers that mainly eat
plants
Examples: rabbits and
grasshoppers

9. Trophic Level
Third Trophic Level:
made up of secondary and
tertiary consumers
Omnivores: consumers that
eat both plants and animals
Examples: humans and
squirrels

10. Trophic Level
Carnivores: consumers that
mainly eat other animals
Examples: lions and sharks

11. Food Chain
The flow of energy from the sun to producers to
primary consumers then to higher order
consumers can be shown in a food chain.

12. Food Chain
Shows only one path for the flow of energy in
an ecosystem.

13. Food Web
Ecosystems have many different types of food
chains.
A food web shows how many different types of
food chains are connected.
Food webs show the feeding relationships in an
ecosystem.

14. Example Food Web

15. Energy Pyramid
Energy Pyramids show the energy loss between
trophic levels in an ecosystem.
The flow of energy:
radiant energy (sunlight)
chemical energy (stored in plants)
kinetic energy and heat loss (created as consumers
feed on each other)

16. Energy Pyramid
The amount of available energy decreases up
the energy pyramid.

17. Energy Pyramid
Most of the “lost”
energy is released as
heat into the
environment.
Each trophic level
contains fewer
organisms.
Why does this make
sense?

18. 18
How Many Chains are in
this web?
copyright cmassengale

19. Identify the Producers, Consumers,
and Decomposers