In ecology, what term describes the sum of living and nonliving parts and how they interact in an area?

• A. Niche
• B. Habitat
• C. Environment
• D. Ecosystem

Answer: (D)

Think about the whole system in a place where living things and their surroundings influence each other. When you include all the organisms (plants, animals, microbes) plus the nonliving parts (air, water, soil, sunlight) and the ways they affect one another, you’re describing an ecosystem. In an ecosystem energy flows from the sun to producers like plants, then to consumers and decomposers, and nutrients cycle through the system, linking all the parts together.

Niche refers to the role a species plays in its community—what it eats, where it lives, and how it interacts with other organisms. Habitat means the physical place where an organism lives. Environment is the general surroundings and conditions around living things. These terms are related, but they don’t capture the whole network of living and nonliving parts and their interactions the way ecosystem does.