Which best defines a biome?

• A. A system of interacting organisms and their physical environment.
• B. A large urban area with human-made infrastructure.
• C. A small patch of land with similar weather.
• D. A large region with a particular climate and typical flora and fauna.

Answer: (D)

A biome is a large geographic region defined by its climate and the typical plants and animals that live there. That’s why the best option is the one describing a large region with a particular climate and a usual mix of flora and fauna. Biomes are bigger than individual ecosystems and can contain many different ecosystems—forests, rivers, and wetlands—within the same climate pattern. The other descriptions point to smaller features: an ecosystem is the interacting organisms and their immediate environment; a small patch of land with similar weather is not broad enough to be a biome; and a large urban area focuses on human-made structures rather than the climate and natural communities that define a biome.