Answer: The correct answer is An ecosystem consists of a community of organisms and its physical environment, and a community is made up of many different populations of organisms.
When living organisms ( like plants and animals) interact with each other and their environment ( non living factors), they constitute an ecosystem.
Community in an ecosystem is defined as the group of populations of different species, which are present in a particular area. Population is a group of living organisms belonging to the same species.
Thus, population makes community and community makes ecosystem.
Therefore, an ecosystem consists of a community of organisms and its physical environment, and a community is made up of many different populations of organisms.