Keep a notebook that describes observations made, carefully distinguishes actual observations from ideas and speculations about what was observed, and is understandable weeks or months later. All populations living together and the physical factors with which they interact compose an ecosystem. Populations and Ecosystems - 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.
When an area becomes overpopulated, the environment will become degraded due to the increased use of resources. Populations, Resources, and Environments - Causes of environmental degradation and resource depletion vary from region to region from country to country.