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Energy Flow in Ecosystems
• Life depends on the sun.
6 CO2
Energy is transferred
• Producer: an AUTOTROPH (means
self-feeder) –it makes it’s own food
through photosynthesis or from
chemical sources
• Consumer: an organism that gets
it’s energy from eating other
There are 4 types of consumers:
• Herbivore- energy from producers
• Carnivore- energy from other consumers
• Omnivore – energy from both producers
and consumers
• Decomposer- energy from breaking down
dead organisms in an ecosystem and
returns nutrients to soil, water, and air.
What am I?
Carnivore Herbivore Producer
Cellular Respiration
• The process by which food is broken down to
yield energy. (Occurs inside the cells.)
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Food chain
•It’s a sequence in which energy is transferred from one
organism to the next as each organism is eaten by another.
Food Web
• Shows many feeding relationships that are possible
in an ecosystem.
Trophic Levels
•Each step in the transfer of energy in the food chain or
web in an ecosystem is a trophic level.
•Each time energy is transferred from one organism to the
next, some energy is lost as heat and via cellular
•90% of the energy is used by the
organism for living.
•10% of the energy becomes part
of it’s body stored in it’s molecules.
That 10% is available to the next
trophic level.
Energy Pyramids
The Carbon Cycle
• The process by which carbon is cycled between the
atmosphere, land, water and organisms.
• There is a short term cycle and a long term cycle.
Summary: Carbon Cycle
• CO2 in the atmosphere is used by producers to produce carbohydrates.
• Consumers eat the producers and obtain the carbon from carbohydrates.
• As consumers break down the food via cellular respiration, some of the
carbon is released back to the atmosphere as CO2.
• Some of that atmospheric CO2 dissolves in water.
• The other carbon is stored in the bodies of the animals who eat it. When
they die it can be released into the soil or air.
• After a long period of time, the decomposition of dead matter forms
deposits of natural gas, oil or coal. (fossil fuels)
• Question: How do we affect the Carbon Cycle?
Nitrogen Cycle
• All organisms need nitrogen to build proteins.
• Nitrogen makes up 78% of our atmosphere.
• Problem: Most organisms cannot use atmospheric nitrogen.
• It must be altered or “fixed” before it can be used.
• The ONLY organisms that can do this are a few species of
bacteria known as Nitrogen-fixing bacteria.
• They take nitrogen from the air and transform it into
molecules that living things can use.
• The Nitrogen cycle is simply: the process in which nitrogen is
cycled between the atmosphere, bacteria and other
Ecological Succession
• Is the gradual process of change and replacement of the type
of species in a community.
• This can take hundreds or thousands of years .
• Primary Succession:
• Occurs on a surface where no ecosystem
existed before.
• Ex. Rocks, cliffs, sand dunes
• Secondary succession:
• Occurs on a surface
where an ecosystem
has existed.
• Occurs in ecosystems that have been
disturbed of disrupted.
• Ex. Humans, animals, storms, floods,
earthquakes, volcanoes
• Secondary succession:
• After the eruption at Mount St. Helens, in
Washington State the first plants that began to
colonize were called pioneer species.
Before eruption 1980
After eruption 1980
• Over time, pioneer species make the area
habitable again for other species.
One year later
Ten years later
Mount St Helens today, still recovering
If these organisms continue to grow, over time they
will form a climax community, a final and stable