Quote Originally Posted by stinkyattic
The two cycles of photosynthesis each use air-borne gases. One uses O2 and the other uses CO2.
The net is that the plant uses more CO2 than O2 and has a net INTAKE of CO2 and net OUPUT of O2. But you can still suffocate the plant or at least retard its growth by depriving it of either of those.
Oh yeah, I forgot. The o2 used during those cycles isn't from the air. It comes from the splitting of water into H+ and o2 during the first cycle