Biome is the sum of ecosystems in a geographical area.

Explanation:
A biome is a large-scale community of plants and animals that are adapted to a specific type of environment. It is characterized by distinct climate, soil, and vegetation patterns. Biomes are defined based on the dominant plant life and the climate conditions of a particular region. There are several different types of biomes, including forests, grasslands, deserts, tundra, and aquatic biomes such as oceans and freshwater bodies.

Sum of ecosystems in a geographical area:
A biome encompasses all the ecosystems within a specific geographical area. An ecosystem is a smaller-scale community of organisms that interact with each other and their physical environment. It includes living organisms, such as plants, animals, and microorganisms, as well as their non-living surroundings, such as soil, water, and air. Each ecosystem is unique and has its own set of biotic (living) and abiotic (non-living) components.

For example, the Amazon rainforest is a biome that includes various ecosystems, such as tropical rainforests, rivers, and wetlands. Each of these ecosystems has its own set of organisms and environmental conditions. The tropical rainforest ecosystem within the Amazon biome is home to a diverse range of plants, animals, and microorganisms that are adapted to the high humidity, warm temperatures, and abundant rainfall of the region.

Therefore, a biome is the sum of ecosystems in a geographical area. It represents the larger-scale patterns and characteristics of a specific region, while ecosystems represent the smaller-scale interactions and dynamics within that region. Understanding biomes is crucial for studying and conserving the Earth's biodiversity and for understanding the distribution and functioning of different ecosystems around the world.