 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 Nutrients

A food web Nutrients

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