Rubisco is an enzyme that can be shut down by the prescense of too much oxygen because oxygen is a competitive inhibitor that blocks the binding site of carbon

Question

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dioxide. How do you think this impacts the production of sugar? Can you think of ways in which a photo autotroph can avoid having this occur?

Answer 1

Rubisco can bind both to oxygen and carbon dioxide. It binds to oxygen when  carbon dioxide is limiting in the leaf spaces and such oxygen binding leads to a process known as photorespiration. This process consumes oxygen and  produces carbon dioxide just like regular respiration, however, it is called photorespiration since it occurs in presence of light. Unlike respiration, photorespiration does not generate any ATP, instead it consumes ATP. Moreover, unlike photosynthesis, photorespiration does not any sugar molecules. Actually, photorespiration decreases photosynthetic output by siphoning organic material from the Calvin cycle and releasing carbon dioxide that would otherwise be fixed to produce sugar. 

 

Hope this helps.