Ch. 18.3 Energy in Ecosystems
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Ch. 18.3: Energy in Ecosystems
Transcript of Ch. 18.3 Energy in Ecosystems
Lesson 3 Reading Guide
1. How does energy move in ecosystems?
2. How is the movement of energy in an ecosystem modeled?
Focus Questions
• Unlike other resources, energy does not cycle through ecosystems, but flows in one direction.
• In most cases, energy flow begins with the Sun and moves from one organism to another.
1. How does energy move in ecosystems?
How do the movements of matter and energy differ?
The law of conservation of energy states that energy cannot be created or destroyed, but it can change form.
1. How does energy move in ecosystems?
How organisms get energy
Producers
(make their own food)
Photosynthesis
Chemosynthesis (Chemical energy)
Consumers (get energy by
consuming other living
things)
Carnivores
Herbivores
Omnivores
Detritivores
(& Decomposers)
1. How does
energy move in
ecosystems?
Photosynthesis:
Light energy + CO2 + Water = Sugars (glucose) for plant’s energy & O2 into atmosphere
photosynthesis
from Greek photo, meaning “light”; and synthese, meaning “synthesis”
1. How does energy move in ecosystems?
• Consumers do not produce their own energy and can be classified as herbivores, carnivores, omnivores, and detritivores.
• Carnivores eat other animals & are usually predators. (wolf, hawk)
• Herbivores eat only producers (plants). (bison, grasshoppers)
1. How does energy move in ecosystems?
• Omnivores eat both producers and other consumers. (mouse, humans)
• Detritivores eat the remains of other organisms.
• Decomposers (bacteria & mushrooms) feed on dead organisms & help decompose them.
• They’re important because they release CO2 into the atmosphere & recycle nutrients into the soil.
1. How does energy move in ecosystems?
• Scientists use models to study the flow of energy through an ecosystem.
• Food chain – model that shows how energy flows in an ecosystem through feeding relationships.
• Energy decreases every time it transfers to another organism.
2. How is the movement of energy in an ecosystem modeled?
In a food chain, arrows show the transfer of energy.
Most energy Least energy
What happens to the amount of available energy when it is transferred from one organism to another?
A. B. C. D.
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A. it increases
B. it remains the
same
C. it decreases
D. it disappears
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• Food web – shows all the complex feeding relationships in an ecosystem.
• Some organisms in a food web might be part of more than one food chain in that web.
2. How is the movement of energy in an ecosystem modeled?
Like in a food chain, arrows show how energy flows in a food web.
Chapter 12 Standardized Test Preparation
The diagram below shows a typical food chain in a
grassland ecosystem. Notice that there is a missing
entry in the food chain.
Continued on the next slide
What description should go next to the
drawing of grass to complete the food
chain?
A. The zebra eats grass.
B. Scavengers, such as vultures, eat grass.
C. Grass is decomposed by sunlight and water.
D. Grass grows by absorbing nutrients from the soil.
The zebra
eats gr
ass.
Scavengers
, such
as vultu
...
Grass
is d
ecom
posed b
y s...
Grass
grow
s by a
bsorb
in...
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• Energy pyramid – shows the amount of energy available in each step of a food chain.
• Steps are called trophic levels.
• Producers, such as plants, make up the trophic level at the bottom of the pyramid.
2. How is the movement of energy in an ecosystem modeled?
Energy Pyramid
Where are the producers found in the energy pyramid?
A. Top level
B. Middle level
C. Bottom level
D. They are not in the
energy pyramid
Top leve
l
Mid
dle le
vel
Bottom
level
They are
not i
n the ener..
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Drought kills 70 percent of the plants in an ecosystem. How might this affect other organisms in the ecosystem?
A. herbivores will starve
B. producers will leave
the area
C. decomposers will
starve
D. scavengers will starve
herbivo
res w
ill st
arve
produce
rs w
ill le
ave th
e...
decom
posers
will
star
ve
scavengers
will
starv
e
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What model do scientists use to show the amount of energy available in each step of a food chain?
A. a food chain
B. a food web
C. an energy
pyramid
D. food pyramids
a food ch
ain
a food w
eb
an energ
y pyr
amid
food p
yram
ids
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Lesson 3
• Energy flows in ecosystems from producers to consumers.
Lesson 3
• Producers make their own food through the processes of photosynthesis or chemosynthesis.
Lesson 3
• Food chains and food webs model how energy moves in ecosystems.
