The term ecosystem refers to which concept?

• A. A community of living organisms interacting with their physical environment
• B. A collection of unrelated species
• C. A system of geological features
• D. A network of roads and rivers

Answer: (A)

An ecosystem is a dynamic system in which living organisms interact with each other and with their physical surroundings. This means energy from the sun flows through producers, consumers, and decomposers, while nutrients are cycled through the environment, linking plants, animals, microbes, air, water, soil, and climate into a single functioning unit. The concept emphasizes how all these biotic and abiotic parts influence each other and the overall health and sustainability of the environment, from a forest to a pond to a coral reef.

If you described only a collection of species, you’d miss how their activities depend on and shape the environment; focusing on geological features leaves out the living interactions, and describing roads and rivers centers on human-made networks rather than ecological relationships.