What is a biome characterized by low temperatures and permafrost?

The biome characterized by low temperatures and permafrost is the tundra. This unique ecosystem typically exists in polar regions and is marked by long, harsh winters and short, cool summers. Permafrost, which is permanently frozen subsoil, plays a crucial role in the definition of tundra, as it significantly affects water drainage and plant growth.

In the tundra, the growing season is limited, which restricts the types of vegetation that can flourish, primarily consisting of low-growing plants such as mosses, lichens, and small shrubs. The cold climate also means that animal life has adapted to survive in these frigid conditions, leading to a diverse array of specially adapted flora and fauna.

In contrast, tropical rainforests thrive in warm temperatures and receive high amounts of rainfall, while grasslands and deserts present distinct climates and vegetation types unrelated to the characteristics of permafrost and low temperatures. This makes the tundra the correct and distinct classification for the environment described in the question.