a large region unit characterised by a specific flora n fauna

1. biome
2. biosphere
3. ecosystem
4. landscape

The correct option is 1.
Biomes are climatically and geographically defined as contiguous areas with similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems. Some parts of the earth have more or less the same kind of abiotic and biotic factors spread over a large area, creating a typical ecosystem over that area. Such major ecosystems are termed as biomes.