What term is used to describe the regions of the surface and atmosphere of the Earth where living organisms exist?

The term that accurately describes the regions of the surface and atmosphere of the Earth where living organisms exist is "biosphere." The biosphere encompasses all ecosystems on Earth, including land, air, and water environments, where life can thrive. It includes various habitats and ecosystems that provide the necessary conditions for living organisms.

In contrast, "habitat" refers specifically to the natural home or environment of a particular species or organism, while "ecosystem" encompasses a community of living organisms and their interactions with each other and their physical environment in a specific area. "Population" pertains to a group of individuals of the same species living in a specific area at a given time. The biosphere integrates all these concepts, making it the broadest term that highlights the global ecological system where life exists.