Which of the following best describes an ecosystem?

An ecosystem is best described as a community of living organisms interacting with their physical environment. This definition encompasses the various relationships that exist between organisms (such as plants, animals, bacteria, and fungi) as well as their interactions with abiotic components like air, water, soil, and climate. In an ecosystem, these living organisms rely on one another for food, shelter, and reproduction, while also adapting to and modifying their physical environment.

Understanding an ecosystem involves recognizing the balance and flow of energy and nutrients among its members. For example, plants (producers) convert sunlight into energy through photosynthesis, herbivores (primary consumers) feed on these plants, and carnivores (secondary consumers) may prey on the herbivores. Decomposers play a crucial role by breaking down dead organic matter, returning nutrients to the soil and allowing the cycle to continue.

In contrast, the other options do not accurately capture the essence of an ecosystem. A network of human-made structures refers more to urban environments or infrastructure, while a collection of non-living elements describes abiotic factors without including living organisms. Scientific experiments in laboratories do not represent ecosystems either, as they usually occur in controlled environments that lack the complex interactions found in natural ecosystems.