Which statement about biomes is true?

Which statement about biomes is true?

• A. Biomes are extremely small ecological zones defined by local microclimates.
• B. Biomes are large ecological zones defined by climate and vegetation.
• C. Biomes are determined solely by the types of microorganisms they host.
• D. Biomes are defined by human population density.

Answer: (B)

Biomes are broad, global-scale ecological zones defined by climate and vegetation. The climate—average temperature, precipitation, and seasonal patterns—shapes which plants can thrive, and the dominant vegetation in turn influences the animal life and overall ecosystem structure typical of that area. That’s why large regions with similar climate and plant types, like tropical rainforests or deserts, are grouped into the same biome despite variations within them. Microclimates exist inside biomes, but they don’t redefine the biome’s classification. Microorganisms are present everywhere and contribute to ecosystem processes, but they don’t determine biome boundaries on their own. Similarly, human population density doesn’t define the biome.

Biomes are broad, global-scale ecological zones defined by climate and vegetation. The climate—average temperature, precipitation, and seasonal patterns—shapes which plants can thrive, and the dominant vegetation in turn influences the animal life and overall ecosystem structure typical of that area. That’s why large regions with similar climate and plant types, like tropical rainforests or deserts, are grouped into the same biome despite variations within them. Microclimates exist inside biomes, but they don’t redefine the biome’s classification. Microorganisms are present everywhere and contribute to ecosystem processes, but they don’t determine biome boundaries on their own. Similarly, human population density doesn’t define the biome.