Download Food Chains and Webs—PowerPoint Guide Student Objective

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Date
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Principles of Ecology
Food Chains and Webs—PowerPoint Guide
Student Objective:
 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
 Definition reviewed:

o
Depends on:
o
 interact to form stable system
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
Energy input from

Nutrient inputs
o
“Biogeochemical” cycles
 Recycles chemicals
o
o
o

Life on earth depends on these cycles & photosynthesis
Producers
 The

of ecosystems
o Convert
energy to
o Construct
compounds from
Photosynthesis  a very fundamental process!! :
o

Chlorophyll:
Producer = autotroph =
Consumers
 Organisms that eat other living plants, animals or microbes

Get energy from

Primary consumers 
organic molecules 
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energy
raw materials

Secondary 

Tertiary 
Detrivores
 Organisms that eat detritus
 Detritus 

Get energy from

 Live on detritus in such a way that it decays
o

organic molecules
Subgroup of detrivores
Examples:
Food chains & webs
 Food chain 
o
o

relationships
relationships
Food web 
A food chain—Draw an example of a food chain.
A food web—Draw an example of a food web.
What can happen with a disruption in a food web?
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