Understanding the Energy Pyramid
8th Grade Science Spring 2015
Consider This:
• How do you think ENERGY flows through
a food chain?
– Do you think that every organism passes on
the same amount of energy to the next
organism in the food chain?
• Think about this question during the
BrainPop video
• Be prepared to share your understanding
of the question after the video
Guided Notes
Learn more about the transfer of
energy through the energy pyramid
here
– Teachers: You will have to click
“view” to begin the guided notes
presentation
– Students: Follow along with the
presentation and fill in the blanks
on your handout
A burger and corn for lunch!
They’ll provide me with much of the energy
my body needs this afternoon:
250 calories of energy in the burger and
75 calories in the corn!
The story begins at the Sun, which sends
energy out into our solar system. We can
see some of that energy as Sunlight. Only a
small amount of the energy that leaves the
Sun actually reaches the Earth.
Can you guess how much
energy reaches Earth?
Choose one:
5% (1/20)
OR
0.0000005%
0.0000005%
About half a billionth of the Sun’s
energy strikes the Earth.
Lucky for you, it’s not 5 percent- you’d
be vaporized!
That cornfield over there is one tiny
part of the Earth that receives the Sun’s
light. That’s the scene for the next part
of our story: photosynthesis.
In
photosynthesis,
green plants
capture the
energy from
sunlight to
manufacture
sugar from water
and carbon
dioxide.
Can you guess how much of the Sun’s energy
that reaches the plant gets stored in them?
Choose one: 20%
OR
5%
5%
Most of the energy gets reflected back into
space by the leaves or is absorbed by the
plants and warms them.
The chemical reactions of photosynthesis
store only 5 percent of the energy, in the
chemical bonds of glucose molecules.
So 5 percent of the energy that lands on the
corn plant’s leaves gets absorbed into the
chemical bonds made by photosynthesis.
Much of this energy is bounced from
molecule to molecule as the sugars provide
energy for the production of proteins and
other plant materials in complex sets of
reactions.
Some of the energy is stored in the form of
Starch in corn kernels.
Can you guess what percentage of the
energy the corn plant captures in
photosynthesis ends up in its kernels?
Choose one: 10%
OR 75%
10%
People raise corn for its Ears, but most of
the solar energy it captures in
photosynthesis goes into building and
operating the plant itself, not preparing for
the next generation of plants.
That’s what the kernels on an ear of corn
are really all about.
Each of those kernels is a seed that can
grow into a new corn plant.
Now the story takes us into the body of a cow!
The cow is feed some of the corn. Then in
digestion and in the cow’s cells, many more
chemical reactions take place, releasing
energy.
The Energy is used to keep the cow warm,
to produce and power its muscle cells, and
to take care of other needs.
Some of the energy gets stored for later use
in cells containing fat. And then one day, the
cow’s muscle and fat gets turned into
hamburger Meat.
Can you guess what percentage of the
energy stored in the ears of corn winds
up in burgers?
Choose one:
50%
OR 10%
10%
Most of the cow’s energy, like yours,
goes into heating and operating the
body, not making meat.
Only about 10 percent of the energy in
an animal’s food winds up in the meat
you might eat.
That’s why some vegetarians say
eating more plants would help the
world feed itself: You lose 90 percent
of the captured solar energy by
passing it through animals.
Energy Flow Summary
1: Sun
_10_% of
energy
_10_ % of
energy
4:
Secondary
Consumers
(Humans)
Only half a billionth of the
Sun’s energy strikes the
Earth.
3: Primary Consumers
(Cows)
2: Producers (Corn Plant)
One-tenth of the solar energy captured
is stored in corn on the cob
Thinking Questions
• Discuss the following
questions as a class after
completing the guided
notes
• Students: Record your
answers on your handout
Question 1
Why is a pyramid a
good representation
of energy moving
through a food
chain?
Question 2
What happens to
the energy that is
not available to be
passed from one
level to the next?
Question 3
Where in a food
chain are the
largest populations?
How is this shown
by a food pyramid?
Question 4
Where in the food
chain are populations
the smallest? How is
this represented by a
food pyramid?
Question 5
What happens to the
total amount of energy
in a food chain as the
energy moves through
the chain from
producer to different
levels of consumers?