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Question #47607
The Question
A researcher isolates a mutant C3 plant in which the accessory pigments (carotenoids and chlorophyll b) are structurally defective. They can absorb light but completely fail to transfer resonance energy to the reaction center and lose their photo-protective properties. Under high light intensity, which of the following physiological cascades is most likely to occur?
Options
- A.
The action spectrum of photosynthesis will perfectly overlap with the absorption spectrum of the accessory pigments, and the Calvin cycle will stall at the carboxylation step.
- B.
Severe photo-oxidation of Chlorophyll-a occurs, and the Calvin cycle stalls at the reduction and regeneration stages due to insufficient ATP and NADPH throughput.
- C.
The plant relies exclusively on cyclic photophosphorylation, which prevents photo-oxidation but fails to provide the NADPH required for RuBP regeneration.
- D.
The action spectrum becomes broader than the absorption spectrum, leading to the accumulation of Glyceraldehyde-3-phosphate as the regeneration step accelerates.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Chlorophyll-a|Accessory_Pigments|Rubisco_Functionality
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often overlook the dual role of accessory pigments (energy transfer + photo-protection) and fail to map the exact energy requirements of the Calvin cycle stages.
The trap in Option C tests the specific quantitative nuance of the Calvin cycle (Regeneration needs ATP, not NADPH), while Option A tests the misconception that a metabolic cycle always stalls at its first step (Carboxylation) rather than its energy-dependent steps.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Rubisco Dual Functionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |