Assess learners' understanding of the carbon cycle by testing knowledge of major reservoirs and fluxes (photosynthesis, respiration, ocean uptake, sedimentation), human alterations (fossil fuel combustion, land-use change), timescales of carbon transfer, and climate implications (greenhouse warming, feedbacks, sink saturation, and basic mitigation approaches). Questions will require explanation, interpretation of changing fluxes or reservoirs, and application to simple real-world scenarios.