Rock Your World with the 2026 Geosphere Practice Test – Unearth Your Genius!

The carbon cycle describes how carbon moves among the atmosphere, living organisms, the oceans, and rocks/soil. Carbon atoms shuttle between these reservoirs through processes like photosynthesis, which pulls CO2 from the air into plants and then into the food web; respiration and decomposition, which release CO2 back into the air; the oceans absorbing and releasing carbon; and long-term storage in rocks and fossil fuels formed through geological processes. This continuous flow directly links the atmosphere (air), biosphere (plants and animals), oceans (circulating carbon in water), and geosphere (rocks and soils), making it the best description of how carbon moves through these parts of Earth.

The other options don’t describe this flow of carbon. The nitrogen cycle centers on nitrogen, not carbon. Desert pavement and karst topography are landform terms, not cycles of carbon movement.