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

Teacher Information!

Food Chains and Webs

Principles of Ecology

Students will be able to… 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:

Community + abiotic factors interact to form stable system

Depends on: One-way flow of energy

Energy input from sun

Cycling of materials Nutrient inputs

“Biogeochemical” cycles Recycles chemicals

Carbon cycle Phosphorous cycle Nitrogen cycle

Life on earth depends on these cycles & photosynthesis

Producers The base of ecosystems

Convert sunlight energy to chemical energy Construct organic compounds from inorganic raw

materials

Producers Photosynthesis a very fundamental

process !! Chlorophyll

Producer = autotroph = plants & algae (green organisms)

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

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

Food chains & webs Food chain pathways of feeding

relationships Producer-consumer relationships Parasite-host relationships

Food web Complex pattern of interconnected food chains

A food chain

Nutrie

nts

A food webN

utri

ents

Review Describe food chains and webs What can happen with a disruption in a food

web?