Here are the key factors that define a biome:

1. Climate:

* Temperature: Average annual temperature and seasonal temperature variation are key.

* Precipitation: Total annual rainfall and its seasonal distribution are crucial.

* Sunlight: The amount of sunlight received, which is influenced by latitude and cloud cover.

2. Plant Life:

* Dominant plant species: The types of plants that are best adapted to the climate will determine the biome.

* Plant structure: The height, spacing, and overall structure of plants (e.g., forest canopy, grasslands) will influence the biome.

3. Animal Life:

* Adaptation: Animals will have evolved specific adaptations to survive in the climate and the available food and shelter provided by the plant life.

* Food web: The complex interactions between different animal species within the biome.

In summary, biomes are defined by a combination of factors that influence the types of organisms that can thrive in a particular region.

Here are some examples of how these factors play out in different biomes:

* Tropical Rainforest: High temperatures, abundant rainfall, dense forest canopy, diverse plant and animal life.

* Desert: High temperatures, low precipitation, sparse vegetation, adapted animals (e.g., camels).

* Tundra: Low temperatures, permafrost, low-growing vegetation, adapted animals (e.g., caribou).

* Temperate Deciduous Forest: Moderate temperatures, distinct seasons, trees that lose their leaves in the fall.

* Grassland: Moderate temperatures, seasonal rainfall, grasses as dominant vegetation, large herbivores.

It's important to note that biomes can have some variations within them, and there are also transitional zones between biomes called ecotones.