Final answer:
A collection of populations interacting with one another forms a community, which is the biotic part of an ecosystem, encompassing all species in a given area and their ecological relationships.
Step-by-step explanation:
A collection of populations interacting with one another forms a community. This term describes the biotic part of an ecosystem, including all the populations of different species in a given area and their interactions, such as symbiosis, predation, and competition. Biologists define a population as the individuals of a species living within a specific region. When multiple populations coexist and interact in a particular region, this forms a community. An ecosystem includes these interactions among living organisms, as well as the abiotic factors like nitrogen in the soil or rainwater. On the largest scale, the biosphere is the total collection of all ecosystems on Earth, encompassing all zones of life, including land, water, and parts of the atmosphere.