Students should be able to describe: different levels of organisation in an ecosystem from individual organisms to the whole ecosystem; the importance of interdependence and competition in a community. • Students should be able to, when provided with appropriate information: suggest the factors for which organisms are competing in a given habitat; suggest how organisms are adapted to the conditions in which they live. • An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment. • To survive and reproduce, organisms require a supply of materials from their surroundings and from the other living organisms there. • Plants in a community or habitat often compete with each other for light and space, and for water and mineral ions from the soil. Animals often compete with each other for food, mates and territory. • Within a community each species depends on other species for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community. This is called interdependence. A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.