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Question #47648
The Question
A C3 plant is subjected to severe water stress, leading to stomatal closure, a sharp drop in internal CO2 concentration, and a relative rise in O2 levels. This triggers a shift in RuBisCO's enzymatic activity. Which of the following statements regarding the subsequent metabolic domino effect is INCORRECT?
Options
- A.
RuBisCO acts as an oxygenase, binding O2 to RuBP to form one molecule of 3-phosphoglycerate (3-PGA) and one molecule of phosphoglycolate.
- B.
The photorespiratory pathway acts as a metabolic drain by consuming ATP and releasing CO2 without the synthesis of sugars or ATP.
- C.
The diminished pool of 3-PGA restricts glycolysis, reducing the availability of intermediates like PEP and pyruvate for the amphibolic synthesis of secondary metabolites.
- D.
To compensate for the carbon deficit, the plant reverses the link reaction, converting Acetyl CoA back into pyruvic acid to replenish the 3-PGA pool.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Phosphoglycerate|Rubisco|Amphibolic_Pathway
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often misunderstand the 'Amphibolic' nature of respiration, assuming all metabolic pathways are fully reversible to compensate for stress.
While respiratory intermediates can be withdrawn for anabolism, the conversion of Pyruvate to Acetyl CoA is a one-way metabolic valve.
Failing to recognize the irreversibility of the link reaction is a classic high-level misconception.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | Amphibolic Pathway |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |