Catalyst
1. Based on the food chain shown,
what would most likely happen to
the rat population if another
predator began eating snakes?
2. Is the the change in number 1
biotic or abiotic?
3. What could cause a decrease in
the grasshopper population?
Agenda
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Catalyst
Energy Pyramids PowerPoint
Making an Energy Pyramid
Energy Pyramid Project
Objectives
• SWBAT distinguish between producers
and consumers and autotrophs and
heterotrophs
• SWBAT identify the category of organisms
and relative amount of energy represented
by each trophic level of an energy pyramid
• SWBAT explain how and why energy
changes from the base to the top of an
energy pyramid.
Energy Pyramids
Biology
Organisms and Energy
• All organisms need energy to survive, and
they receive energy from the food that
they produce or consume
Energy Flow
• For an ecosystem to exist, there must have
constant flow of energy between the organisms
of that ecosystem
Energy Pyramids
• Scientists model the flow
of energy in an
ecosystem with an
energy pyramid
• Contains different levels
of organisms known as
trophic levels
To take notes…
• Fill in the example energy pyramid
Producers
• The first trophic level is at
the bottom of the pyramid
• Organisms at the bottom
of the energy pyramid are
known as producers
• Producers are
autotrophs—organisms
that use energy from the
sun to produce food
Producers
• What are some
examples of
producers/autotrophs?
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Trees
Grass
Berries
Nuts
Algae
Phytoplankton
Consumers
• All other organisms in the energy pyramid
are consumers
• Consumers are heterotrophs—organisms
that obtain energy from the food they
consume
Primary Consumers
• Above producers in
the pyramid are
primary consumers.
– 2nd trophic level
– These are
herbivores—
organisms that
consume only plants.
Primary Consumers
• What are some examples
of primary
consumers/herbivores?
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Insects
Rabbits
Deer
Mice
Small fish
Secondary Consumers
• Above the primary
consumers in the
pyramid are
secondary
consumers.
– These are
carnivores—
organisms that
consume other
animals.
Secondary Consumers
• What some examples of
secondary
consumers/carnivores?
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Frogs
Snakes
Large fish
Foxes
Tertiary Consumers
• Above secondary
consumers are
tertiary consumers.
• These may be
carnivores or
omnivores—
organisms that
consume both plants
and animals
Tertiary Consumers
• What are some
examples of tertiary
consumers?
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Hawks
Eagles
Bears
Humans
Sharks
Energy in a Pyramid
• So why do scientists use a
pyramid to represent energy
in an ecosystem?
• How does a pyramid change
from bottom to top?
– It gets smaller!
• So does the amount of
energy in an ecosystem
from producers  high
level consumers
Energy Changes
• The bottom of the energy pyramid (producers)
contains the greatest amount of energy.
– 100% of energy originally present in the ecosystem
• The top (tertiary consumers) contains the least
amount of energy.
– ~0.1% of initial energy
• Energy is lost as heat between trophic levels
– ~90% lost as heat between each level
– Only 10% of available energy transferred to next level
Summary
Energy Pyramid
Question…
If there is less energy
available at higher trophic
levels, will there be more
organisms or fewer
organisms as you go up?
Number pyramids + Biomass
Pyramids
Number pyramids
show the population
decreasing at higher
levels
Biomass pyramids
show how much food
an organism needs to
consume to meet its
needs.
>> Check for understanding
A biologist finds that there is far
more algae (a producer) in an
ecosystem than anchovy. What is
the reason for this?
Anchovy is a secondorder producer, so
there is less energy
available than there is
for producers.
Energy Water Demo
Example: Copy the chain and
answer questions in your notes
Grass  Insects  Rodents  Owl
1. Create an energy pyramid.
2. Label each level with the appropriate term
and trophic level.
3. Put the names of each organism in the
appropriate level.
If there is 1500kcal of energy in the grass,
how much energy will be available for the
insects?
1500kcal x 0.10 = 150kcal
Exit Ticket
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4.
What level on the energy
pyramid shown has the
greatest amount of energy to
transfer to the next level?
What are the secondary
consumers in this example,
and are they autotrophs or
heterotrophs?
Which level receives the least
amount of energy from the
producers?
Why does the amount of
energy decrease as you move
from the bottom to top of an
energy pyramid?