Which term describes the movement of carbon between living organisms and the nonliving environment?

• A. Tides
• B. Organ system
• C. Decomposer
• D. Carbon cycle

Answer: (D)

The movement of carbon between living organisms and the nonliving environment is described by the carbon cycle. This term captures how carbon continually cycles through different reservoirs—the atmosphere, bodies of living things, oceans, soil, and rocks. Plants pull carbon dioxide from the air during photosynthesis to build organic matter; when they respire or when organisms decompose, carbon is released back into the air or soil. The oceans exchange carbon with the atmosphere, absorbing and releasing CO2. Human activities like burning fossil fuels accelerate this cycling by adding more carbon to the atmosphere. Tides describe water movement, organ systems refer to parts of an animal's body, and a decomposer is an organism that breaks down dead matter but doesn’t describe the overall carbon movement.