Lesson 3
Energy in Ecosystems
Key Concepts/essential questions:
 How does energy move in ecosystems?
 How is the movement of energy in an ecosystem
modeled?
Vocab
 Photosynthesis
 Chemosynthesis
 Food chain
 Food web
 Energy pyramid
Agree OR Disagree
 The sun is the source for all energy used by living
things on Earth?
 All living things get their energy from eating other
living things?
How does the grass get the energy
it needs?
 The grass gets energy from sunlight and performs
photosynthesis.
Producers
 What powers the process of photosynthesis?
 Light energy, usually from the Sun, powers
photosynthesis.
WORD ORIGIN: photosynthesis…
 What words do you know that begin with photo?
 root -graph means "write”
 What is the meaning of photograph?
 A photograph is an image created using light energy
 How does light relate to photosynthesis?
 The energy from light powers the processes that create
food through photosynthesis.
chemosynthesis
 What other words begin with chemo-?
 Chemotherapy???
 What is the meaning of the word chemotherapy?
 medical treatment with chemicals
 look up the word chemotherapy in a dictionary to find
the meaning of the root chemo-.
 look up the word synthesis.
 synthesis means "to put together" or "to build.“
 Chemosynthesis: to build, using chemicals
 What is the role of chemicals in chemosynthesis? They
provide chemical energy. What is being built?
 food molecules
What materials do producers use
to make food during
chemosynthesis?
 Producers use chemical energy in inorganic
compounds to make food during chemosynthesis.
Look at Figure 10 in text on pg.
724.
 What does the arrow tell you about where the plant
gets carbon dioxide for photosynthesis?
 Carbon dioxide enters the leaf directly from the
atmosphere
 What does the arrow tell you about where the plant
gets water for photosynthesis?
 The water travels into the leaf from other parts of the
plant (roots).
LESSON
3
Energy in Ecosystems
Lesson 3: Energy in Ecosystems-notes
A. How does energy move in ecosystems?
1. Matter cycles through an ecosystem.
2. Energy flows through an ecosystem.
3. Energy can change form as it moves through an
ecosystem, but the total amount of energy stays
the same. This rule is called the law of
conservation of energy.
LESSON
4. Organisms that make their own food are
producers.
a. The process of photosynthesis uses light energy
to make food and oxygen from carbon dioxide and
water.
b. Chemosynthesis is the process of making food
using chemical energy instead of light energy.
LESSON
5. Consumers obtain energy by eating other organisms.
a. A(n) herbivore eats only plants.
b. Carnivores are animals that eat other animals.
c. Omnivores eat producers and other consumers.
d. Consumers called detrivores (scavengers) eat dead
organisms.
e. Another name for bacteria and mushrooms is
decomposers.
f. Decomposers help cycle nutrients through
ecosystems.
LESSON
B. Modeling Energy in Ecosystems
1. As energy changes from one organism to
another in an ecosystem, some stored
chemical energy changes to thermal energy.
2. A(n) food chain is a model that shows how
energy flows in an ecosystem through feeding
relationships.
LESSON
C. Food Webs
1. When you overlap the food chains in an
ecosystem, the result is a(n) food web.
2. In a food chain and a food web, arrows show the
movement of energy.
LESSON
D. Energy Pyramids
1. A(n) energy pyramid shows the amount of energy
available in each step of a food
chain.
2. The steps of this energy model are called trophic levels.
a. The bottom layer of an energy pyramid contains
producers.
b. The middle layer of an energy pyramid contains
consumers that eat producers.
LESSON
c. The top layer of an energy pyramid contains
consumers that eat other consumers.
3. Only about 10 percent of the energy in one step
of an energy pyramid transfers to the next higher
step.
Brainpop
 http://connected.mcgraw-
hill.com/media/repository/protected_content/COMP
OUND/50000025/8/27/Photosynthesis_and_Respirati
on/00053412.htm?mghCourseID=J3B3WWJLT82D2DY
G587957LKB4
Consumers
 Look at figure 12….
 How does the worm get energy?
 It gets energy by consuming the remains of other
animals and plants.
 How does the worm help the environment?
 By decomposing dead organisms, the worm helps keep
the environment clean
Food Chains
 Look at figure 13….
 What is a feeding relationship?
 It is an interaction between two organisms where one
organism eats the other.
 Draw a food chain
 Share answers (discuss feeding relationship)
How does a food chain model
energy flow?
 Arrows in a food chain show how energy is transferred
from one organism to another through a feeding
relationship.
 In terms of school and science…What is a model?
 A model is a way of describing or showing an
observation or process.
Food chain
 arrows that indicate the transfer of energy.
• What does the arrow below the hawk tell you about the energy transfer?
• Energy is transferred to the hawk when it eats another organism (snake)
• Why is there no arrow pointing away from the hawk?
• Because there is no organism shown that eats the hawk
Video clip
 http://connected.mcgraw-
hill.com/c2j/syllabus.syllabusLesson.do?bookId=J3B3
WWJLT82D2DYG587957LKB4&lessonId=7EOP91DMC
XOL51SX6CP8JQP4QY
 (video 1)
Food Webs
 Look at Figure 14….
 Try to make as many
food chains using this
web as you can
Video clip
 http://connected.mcgraw-
hill.com/c2j/syllabus.syllabusLesson.do?bookId=J3B3
WWJLT82D2DYG587957LKB4&lessonId=7EOP91DMC
XOL51SX6CP8JQP4QY
 (video 2)
What models show the transfer of
energy in an ecosystem?
 The transfer of energy in an ecosystem is shown with
food chains and food webs.
 What kind of organism must be at the bottom of a
food web? Why?
 A producer must be at the bottom of a food web because
energy must flow into the food web from an outside
source, such as the Sun.
Food Web
 Is the portion of the food web
shown below a complete food
chain? Explain.
 Yes, it includes
producers(diatoms) and
consumers.
 Do any organisms pictured in
the portion of Figure 14 below
get energy from the leopard
seal?
 No
 If the leopard seal has no
predators in a given area, do
any organisms get energy
from it?
 Yes, decomposers get energy
from the leopard seal.
does the amount of
Energy Pyramids How
available energy change at
each trophic level?
 The amount of available
energy decreases at each
trophic level.
 Which trophic level contains
the fewest organisms? Why?
 Trophic level 3 contains the
fewest organisms because it
has the least energy
available.
 What kind of organism is in
trophic level 1?
 Trophic level 1 contains
producers that get energy
from an outside source,
usually the Sun.
*note fading blue arrow*
Video clip
 http://connected.mcgraw-
hill.com/c2j/syllabus.syllabusLesson.do?bookId=J3B3
WWJLT82D2DYG587957LKB4&lessonId=7EOP91DMC
XOL51SX6CP8JQP4QY
 (video 3)
Questions
 What is an example of a producer in the trophic level
at the bottom of the pyramid?
 Plants
 Can carnivores occupy trophic level 1? Explain.
 No, carnivores get energy by eating meat. The only
available energy in trophic level 1 comes from the Sun.
Discussion
 What did you have for dinner last night?
 Use an energy pyramid to trace the flow of energy from
the Sun to each kind of food.
Agree OR Disagree
 The sun is the source for all energy used by living
things on Earth?
 Disagree. The sun in the main source of energy for most
life on Earth; some producers, deep in the ocean, use
chemical energy rather than light energy.
Agree OR Disagree
 All living things get their energy from eating other
living things?
 Disagree. Many organisms get their energy by eating
other organisms; some organisms are producers and get
their energy through the process of chemosynthesis or
photosynthesis to make their food.
 Key Concepts/essential questions:
 How does energy move in ecosystems?

Energy moves in a flow,
 How is the movement of energy in an ecosystem
modeled?

Arrows in a food chain show how energy is transferred from
one organism to another through a feeding relationship. (food
chain, food web, energy pyramid)
LESSON
Discussion Question
How does energy flow through an ecosystem?
LESSON
Energy flow begins with energy in sunlight. It is
stored as chemical energy in plants. As
animals eat plants, energy moves from the plant to
the animal. As animals eat other
animals, energy flows from the animal being eaten
to the animal eating it. During each of
these steps, energy can change form, such as
changing from chemical to thermal energy.