4.3- producers, comsumers and decomposers, food web and chain, energy pyramid

producers

living things that produce their own food to get energy they need

consumers

living things that consume producers or other consumers to get the energy they need

decomposers

living things that break down dead organic material to get the energy they need

food chain

a model describing how food energy is passed from one living thing to another

food web

a model of feeding relationships shows a network of interacting and overlapping food chains

-animals depend on each other

-a change in number of animals can affect food chain in food web

why are there limits to food chain

-most energy transfered from one organism to another is lost to environment as unusable heat

-some energy has been used to support life functions (growth and cell resp)

-some energy is stored in wastes that are excreted

-less and less energy is available to each organism in chain

waterbucket example

-sponge with water

-run across field

-sponge loses water on the way

-bucket has less water each time

energy pyramid

a model showing amount of energy available in each level of food chain

each level

primary producers 100%

primary consumers 10%

secondary consumers 1%

third level consumers 0.1%

-available energy decreases as pyramid goes up, energy is lost as heat