Question

what happens in C3 plants when rubp instead of being converted to 2 molecule of PGA binds with O2?​

Answer 1

RUBISCO is a carboxylase oxygenase enzyme. It has affinity for both oxygen and co2.

If the concentration of co2 reduces, rubisco combines with o2 and carries out its oxygenase activity,ie, it converts rubp into 1 molecule of PGA and 1 molecule of phosphoglycolate in a pathway called photorespiration.

Photorespiration is a wasteful process as there is neither synthesis of sugars nor of ATP.

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