What term refers to all organisms and the parts of Earth where they exist?

• A. Biosphere
• B. Ecosystem
• C. Geosphere
• D. Hydrosphere

Answer: (A)

The concept being tested is the scale at which life on Earth is described. The term that refers to all organisms and the parts of Earth where they exist is the biosphere. It encompasses every habitat that supports life—land, water, and air—covering the global sum of living things and the environments they inhabit.

An ecosystem is a specific community of organisms and its immediate physical environment in a particular place, and many ecosystems exist within the biosphere. The geosphere comprises Earth's solid components such as rocks and minerals, while the hydrosphere includes all Earth's water. These latter terms describe non-living parts of Earth, not life itself, so they don’t capture the full span of habitats that support living organisms.