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This PowerPoint guide provides an in-depth discussion on food chains and webs in ecological systems, including the flow of energy and the importance of biogeochemical cycles. It also covers the roles of producers, consumers, and decomposers in maintaining a stable ecosystem. Students will gain a clear understanding of these concepts and be able to describe and analyze food chains and webs.
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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
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 • Foodchain pathways of feeding relationships • Producer-consumer relationships • Parasite-host relationships • Foodweb 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?