Which term refers to the zone of life on Earth comprising the sum total of all ecosystems?

The term that refers to the zone of life on Earth, encompassing the sum total of all ecosystems, is the biosphere. The biosphere includes all living organisms and the environments they inhabit, spanning across various ecosystems such as forests, oceans, deserts, and wetlands. This concept emphasizes the interconnectedness of life throughout the planet, illustrating how different ecosystems interact and support diverse forms of life.

In contrast, a biome refers to a specific region characterized by certain climate conditions and ecosystems, such as tundra, tropical rainforests, or grasslands. The hydrosphere pertains to all of Earth's water, including oceans, rivers, lakes, and glaciers, while the atmosphere consists of the layers of gases surrounding the planet. Each of these other terms highlights different components of Earth's system, but they do not encompass the totality of life and ecosystems as the biosphere does.