Photosynthesis Ques 1
The oxygenation activity of RuBisCo enzyme in photorespiration leads to the formation of phosphoglycerate
[2020]
(a) 1 molecule of 3-carbon compound
(b) 1 molecule of 6-carbon compound
(c) 1 molecule of 4-C compound and 1 molecule of 2-C compound
(d) 2 molecules of 3-carbon compound
Show Answer
Answer : a
Hints & Solution
(a) In photorespiration, $O_2$ binds to Rubisco. As a result, $RuBP$ instead of being converted to 2 molecules of PGA binds with $O_2$ to form one molecule each of phosphoglycerate (3 carbon compound) and phosphoglycolate (2 carbon compound). Photorespiration is the oxygenation of RuBP by RUBISCO followed by photorespiratory glycolate metabolism. Competition between $O_2$ and $CO_2$ reduces the rate of carbon assimilation, energetic efficiency of photosynthesis, and may reduce the photosynthetic quotient $(PQ=O_2.$ evolved $/ CO_2$ assimilated).
BETA
