Assess students' conceptual understanding of the global carbon cycle by requiring them to identify and describe major reservoirs (atmosphere, terrestrial biosphere, oceans, sediments/fossil fuels), key natural fluxes and their directions (photosynthesis, respiration, ocean–atmosphere exchange, sedimentation), typical residence times at a basic level, and the principal anthropogenic influences (fossil fuel combustion, land-use change) and their effects on atmospheric CO2; focus on recall, identification, and concise explanation within a mass-balance framework.