Which statement best defines an ecosystem?

An ecosystem is best defined as a community of organisms interacting with their environment, as this definition encompasses both biotic (living) and abiotic (non-living) components. In an ecosystem, various organisms, including plants, animals, fungi, and microorganisms, engage in complex relationships with one another and their physical surroundings, such as soil, water, and climate. This interaction is crucial for the sustainability of life as it encompasses various processes, including energy flow and nutrient cycling, which are vital for maintaining ecological balance.

Recognizing that an ecosystem includes not just living organisms but also their physical environment highlights the intricate interdependencies that exist. For instance, plants (as producers) rely on sunlight, water, and soil nutrients, while animals (as consumers) depend on plants and other animals for food.

Defining an ecosystem solely as a collection of non-living elements, as in one of the other options, would neglect the dynamic relationships between living organisms and their habitats. Similarly, characterizing it only as a classification of biological organisms or as a system of physical structures would fail to capture the interactive and functional nature that defines ecosystems.