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Question #46751
The Question
Under conditions of high temperature and high oxygen concentration, C3 plants experience photosynthetic stress due to the oxygenase activity of RuBisCO. This initiates the photorespiratory pathway (C2 cycle), requiring coordination between three organelles. Which of the following statements is INCORRECT regarding the metabolic events of this pathway?
Options
- A.
The initial oxygenation of RuBP in the chloroplast stroma yields one molecule of 3-phosphoglycerate and one molecule of 2-phosphoglycolate.
- B.
The actual 'photorespiratory' loss of fixed carbon occurs in the mitochondrial matrix during the conversion of two molecules of glycine into one molecule of serine.
- C.
The mitochondrial conversion of glycine to serine directly consumes ATP, creating the primary metabolic energy debt associated with the wasteful cycle.
- D.
The peroxisome acts as an intermediate organelle where glycolate is oxidized to glyoxylate, accompanied by the generation of hydrogen peroxide.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Mitochondria|Red Drop and Emerson Enhancement Effect|Photorespiration Metabolic Cost
Why This Question Is Tricky
Common Mistakes
Location Trap / Functional Overlap: Students correctly associate photorespiration with a wasteful 'ATP burden' and 'energy debt' (NCERT states it utilizes ATP without synthesizing sugars).
However, they often incorrectly assume the mitochondrial step (which is the defining decarboxylation event of the cycle) is the direct site of ATP consumption.
This tests the ability to distinguish between the site of carbon loss (mitochondria) and the site of ATP utilization (chloroplast).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Mitochondrial Endosymbiotic Evidence |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |