Necessary materials

1
Teacher Information!

• Necessary materials
• PowerPoint Guide
• Teacher may wish to hand out these note guides
• Carbon Cycle Guided Discussion
• Phosphorous Cycle Guided Discussion
• Nitrogen Cycle Guided Discussion

2
Food Chains and Webs
Principles of Ecology
3
Students will be able to

• Describe food chains and webs

4
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)

5
Ecosystems

• Definition reviewed
• Community abiotic factors ? interact to form
  stable system
• Depends on
• One-way flow of energy
• Energy input from sun
• Cycling of materials
• Nutrient inputs

6
Biogeochemical cycles

• Recycles chemicals
• Carbon cycle
• Phosphorous cycle
• Nitrogen cycle
• Life on earth depends on these cycles
  photosynthesis

7
Producers

• The base of ecosystems
• Convert sunlight energy to chemical energy
• Construct organic compounds from inorganic raw
  materials

8
Producers

• Photosynthesis ? a very fundamental process !!
• Chlorophyll
• Producer autotroph plants algae (green
  organisms)

9
Consumers

• 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

10
Detrivores

• 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
• Subgroup of detrivores

11
Food chains webs

• Food chain ? pathways of feeding relationships
• Producer-consumer relationships
• Parasite-host relationships
• Food web ? Complex pattern of interconnected food
  chains

12
A food chain
Nutrients
13
A food web
Nutrients
14
Review

• Describe food chains and webs
• What can happen with a disruption in a food web?