Teacher Information!
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Necessary materials:
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PowerPoint Guide
Teacher may wish to hand out these note guides:
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Carbon Cycle Guided Discussion
Phosphorous Cycle Guided Discussion
Nitrogen Cycle Guided Discussion
Food Chains and Webs
Principles of Ecology
Students will be able to…
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Describe food chains and webs
The flow of energy
“Three hundred trout are needed to support one
man for a year. The trout, in turn, must
consume 90,000 frogs, that must consume 27
million grasshoppers that live off of 1,000
tons of grass.”
—G. Tyler Miller, Jr., American Chemist (1971)
Ecosystems
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Definition reviewed:
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Community + abiotic factors  interact to form
stable system
Depends on:
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One-way flow of energy
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Energy input from sun
Cycling of materials
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Nutrient inputs
“Biogeochemical” cycles
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Recycles chemicals
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Carbon cycle
Phosphorous cycle
Nitrogen cycle
Life on earth depends on these cycles &
photosynthesis
Producers
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The base of ecosystems
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Convert sunlight energy to chemical energy
Construct organic compounds from inorganic raw
materials
Producers
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Photosynthesis  a very fundamental
process !!
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Chlorophyll
Producer = autotroph = plants & algae (green
organisms)
Consumers
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Organisms that eat other living plants,
animals or microbes
Get energy from preformed organic molecules
 heterotrophs
Primary consumers  eat producers
Secondary  eat primary consumers
Tertiary  eat secondary consumers
Detrivores
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Organisms that eat detritus
Detritus  Dead plants, animals, & microbes
& fecal wastes of animals
Get energy from preformed organic molecules
Decomposers  Live on detritus in such a
way that it decays
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Subgroup of detrivores
Food chains & webs
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Food chain  pathways of feeding
relationships
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Producer-consumer relationships
Parasite-host relationships
Food web  Complex pattern of
interconnected food chains
A food chain
A food web
Review
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Describe food chains and webs
What can happen with a disruption in a food
web?