Ecosystem

In the syllabus and the exam

An ecosystem is defined as a community of interacting organisms (the biotic components) together with the non-living physical and chemical factors of their environment (the abiotic components), and the two must always be described together, since neither half alone is called an ecosystem. Candidates are expected to name specific abiotic factors relevant to a given ecosystem, such as temperature, light intensity, pH, water availability, mineral salts or oxygen concentration, rather than the vague phrase 'the environment', and to explain how a named abiotic factor limits the distribution or abundance of a named organism within that ecosystem. This chapter also introduces the levels of ecological organisation building up to an ecosystem: organism, population (all individuals of one species in an area), community (all populations of different species interacting in an area), and finally ecosystem (that community plus its abiotic environment); candidates should be able to place a given description at the correct level rather than only at the ecosystem level itself. A common error is treating 'habitat' and 'ecosystem' as identical terms: habitat is specifically where an organism lives, while an ecosystem is the whole functional system of interacting organisms and their physical surroundings across a defined area. Exam scenarios frequently draw on Malaysian ecosystems such as a mangrove swamp, a paddy field or a coral reef, and candidates should practise naming realistic biotic and abiotic components for each.

Example

A pond ecosystem includes the fish, algae, insects and bacteria living in it (the biotic community) together with the water, sunlight, dissolved oxygen and temperature of the pond (the abiotic environment), all interacting with one another.

Related terms

Food chainFood webBiodiversity

Source:SRC-DSKP-EN