NEETBotanyPhotosynthesis in Higher Plants
When a C₃ plant is subjected to high light intensity and high temperature, it often responds by partially closing its stomata. Which of the following biochemical events will predominantly occur at the active site of RuBisCO under these internal leaf conditions?
Options
- AIncreased carboxylation of RuBP leading to enhanced synthesis of sugars
- BRuBisCO binding to CO₂ to form two molecules of 3-phosphoglyceric acid
- CRapid synthesis of ATP and NADPH to combat the heat stress
- DRuBP binding with O₂ to form one molecule of phosphoglycerate and one molecule of phosphoglycolate
Correct answer
D. RuBP binding with O₂ to form one molecule of phosphoglycerate and one molecule of phosphoglycolate
Step-by-step solution
Under high temperature and high light intensity, C₃ plants partially close their stomata to prevent excessive water loss. This stomatal closure leads to a rapid decrease in the internal CO₂ concentration and a relative increase in the O₂ concentration within the leaf as light reactions continue to evolve oxygen. Because RuBisCO can bind both CO₂ and O₂ , the high O₂ to CO₂ ratio shifts its activity from a carboxylase to an oxygenase. Consequently, RuBP binds with O₂ instead of CO₂ to form one molecule of phosphogly