Answer :
Answer:
Photorespiration
Explanation:
RuBisCo is the enzyme that catalyzes the first reaction of the Calvin cycle which in turn is a rate-limiting step. Photorespiration is the process during which the enzyme RuBP carboxylase/oxygenase (RuBisCo) catalyzes the reaction between oxygen and ribulose 1,5-bisphosphate to form 3-phosphoglycerate and 2-phosphoglycolate.
These two products are useless for the metabolism of cells. Photorespiration occurs since the RuBisCo enzyme has an affinity for both CO2 and oxygen. When CO2 is not available, as it occurs when plants close stomata during hot dry days to prevent water loss, photorespiration takes place. Therefore, stomatal closing in C3 plants to prevent water loss promotes photorespiration.