Effects of CO2; carbon dioxide on photosynthesis

– Carbon dioxide is needed as raw material in the dark reaction
– provides the carbon for organic molecular skeleton
– first fixed into a 3-carbon sugar PGA
– ultimately released as 6-carbon (hexose) molecule
– hexose may subsequently be incorporated into polymers (e.g starch) for storage
– carbon dioxide concentration above optimum do not result in increased photosynthesis.