Final answer:
Different populations living together in an area form a community, while the combination of this community with abiotic factors makes an ecosystem. The biosphere is the highest level of ecological organization, encompassing all ecosystems on Earth.
Step-by-step explanation:
All the different populations that live together in an area make up what is known as a community. This term refers to the sum of all populations inhabiting a particular area. In the context of ecology, a population consists of all individuals of one species living within a specific area. When we consider multiple populations of different species living together, such as trees, flowers, insects, and various other organisms in a forest, we describe this as a community. An ecosystem encompasses a community along with all the abiotic factors of the environment, such as water, soil, sunlight, and nutrients. Lastly, the biosphere represents the broadest level of ecological organization, including all ecosystems on Earth, where life can be found, extending to land, water, and parts of the atmosphere.