What best describes an ecosystem?

• A. A single species in a habitat.
• B. Living and nonliving things interacting.
• C. The genetic makeup of a population.
• D. The climate and weather of a region.

Answer: (B)

An ecosystem is a system in which living things interact with each other and with their physical environment. In an ecosystem, energy moves through feeding relationships and nutrients cycle through air, water, soil, and organisms, all shaped by nonliving factors like sunlight, temperature, and moisture. This interconnected web—where organisms affect and are affected by their surroundings—best captures what an ecosystem is.

Focusing on a single species misses the interactions that connect organisms to their environment. Genetics looks at inherited traits within a population, not how organisms relate to their surroundings. Climate and weather describe abiotic conditions but don’t include the living components and their interactions.