Oxygen: an element that we could say is responsible for life on Earth as we know it. We breathe oxygen, it is required for combustion, O3 in the atmosphere forms a protective shield around the planet. This model shows the reservoirs of oxygen and the processes that generate flux between reservoirs. An oxygen sink exists as oxygen is made unavailable in reactions with other elements to form oxides, carbonates, and nitrates within rocks and minerals. Oxygen is also in a state of flux: molecular oxygen (O2), cycles through the biosphere roughly every 3000 years.

Using the model, what conclusions can you draw about the mechanism causing the flux of oxygen that results in its recycling every 3000 years?
Responses
A The chemical weathering of rocks on Earth result in the release of oxygen into Earth's atmosphere.The chemical weathering of rocks on Earth result in the release of oxygen into Earth's atmosphere.
B The combustion of fossil fuels releases stored oxygen into the atmosphere that is then utilized in cellular respiration. Oxygen is once again incorporated into the bodies of organisms.The combustion of fossil fuels releases stored oxygen into the atmosphere that is then utilized in cellular respiration. Oxygen is once again incorporated into the bodies of organisms.
C The reciprocal relationship between photosynthesis and cellular respiration. Autotrophs use CO2 as a reactant in photosynthesis but release O2 as a by-product of the process.The reciprocal relationship between photosynthesis and cellular respiration. Autotrophs use CO 2 as a reactant in photosynthesis but release O 2 as a by-product of the process.
D Marine organisms in the biosphere create calcium carbonate shell material that is rich in oxygen. When the organism dies, its shell is deposited on the shallow sea floor and buried over time to create the limestone.