E2 Summary

Stage 2 Biology – Ecosystems Notes

E2. A community has several trophic levels

·         Autotrophs

o   Convert inorganic materials into organic molecules through photosynthesis

o   Include plants

o   Called producers

·         Heterotrophs

o   Organisms that need to feed on other organisms to obtain their requirements

o   Involves eating organic material and digesting it so that essential requirements are absorbed

o   Herbivore, omnivore, carnivore

o   Called consumers

§  Primary, secondary, tertiary consumers

§  Higher order consumers

·         Trophic structure = a pattern of the feeding relationships in an ecosystem – a food chain

·         Everything relies on producers to trap the sun’s energy and store it in organic food

·         Decomposers   

o   Include bacteria, fungi, earthworms

o   Obtain their nutrition from dead material produced at all trophic levels

o   Includes animal waste, plant material, dead organisms

o   Recyclers of the community

o   Break down organic material and return essential nutrients to the environment

·         Most consumers in a community eat a range of foods – therefore a food chain does not adequately represent true feeding relationships

·         Many consumers sit at several trophic levels