What primarily determines which biome covers a particular portion of earth?

The factor that primarily determines which biome covers a particular portion of the earth is the climate. Climates are described as the average conditions of an area which include amount of precipitation and temperatures. Biomes are characterized by their climates as well as the types of plants and animals that inhabit those areas.

Biome is group of ecosystems that share similar abiotic and biotic conditions. The climate is the factor that primarily determines which biome covers a particular portion of Earth. The climate describes the average conditions, including temperature and precipitation, over long periods in a given area