How is an ecosystem defined?

An ecosystem is defined as a community of organisms and their environment, highlighting the interconnectedness of living organisms with their physical surroundings. This definition emphasizes the dynamic relationships between various species within an ecosystem and the non-living elements such as soil, water, and climate that support and interact with these organisms. The interactions that occur, including nutrient cycling, energy flow, and habitat formation, are essential to the functioning of the ecosystem as a whole.

The other options do not encompass the full concept of an ecosystem. A definition that includes only living organisms disregards the crucial role of their environment. Focusing solely on chemicals simplifies the complexity of interactions that define ecosystems. Lastly, describing an ecosystem as a structure formed by habitats misses the essential interactions between organisms and their roles within different environments. Thus, the definition that captures both the community of organisms and their environmental context is the most comprehensive and accurate representation of an ecosystem.