1) The document defines key terms in ecology like ecology, ecosystem, population, community, species, habitat, autotrophs, heterotrophs, producers, consumers, detritivores and saprophytes. 2) It explains food chains and food webs, and how energy is lost as it transfers between trophic levels in a community. 3) Detritivores and saprotrophs help decompose dead organic matter and recycle nutrients back into the ecosystem.

1. 5.1: Communities Topic 5: Ecology & Evolution Miss Friedman

4. 5.1.2: Autotrophs & heterotrophs Obtains organic molecules from other organisms consumer Heterotroph An organism that synthesises its organic molecules from simple inorganic molecules Producer Autotroph