Standard Life Science 5-8 NSES Content Topic Populations and Ecosystems Populations consist of all individuals of a species that occur together at a given place. All of the populations living together and the physical factors which they interact compose an ecosystem. Populations of organisms can be categorized by the function they serve in an ecosystem. All animals including humans are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food.
Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem.
The Interdependence of Organisms Organisms both cooperate and compete in ecosystems. The interrelationship and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years. Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms. To define and understand the vocabulary associated with ecosystem and its functioning EnSc C.2.