Which of the following best describes the term 'ecosystem'?

The term 'ecosystem' is best described as a community of organisms and their physical environment interacting as a system. This definition captures the essence of what an ecosystem is: it involves various living organisms—such as plants, animals, fungi, and microorganisms—interacting with each other and with their non-living environment, which includes elements like air, water, soil, and climate. The interactions can include things like food chains, nutrient cycling, and symbiotic relationships, all of which highlight the interconnectedness of different components within the ecosystem.

The other options do not fully encompass the definition of an ecosystem. For instance, simply stating a collection of individual species refers only to the biological component and does not account for the physical environment or the interactions that take place. A type of biome dominated by one species suggests a specific characteristic of a habitat rather than the broader concept of an ecosystem, which requires a mix of various organisms and environmental factors. Lastly, describing an environment without any living organisms misses the critical aspect of life that defines an ecosystem, as living organisms are essential for the interactions that create a functioning system.