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Question #47587
The Question
If an intact C3 plant is continuously illuminated with monochromatic light of wavelength 710 nm, which of the following physiological consequences will be observed in the chloroplast?
Options
- A.
Photolysis of water continues in the thylakoid lumen, but the reduction of NADP+ is inhibited, halting the Calvin cycle.
- B.
Cyclic electron flow dominates, leading to an accumulation of 3-phosphoglycerate (3-PGA) as the reduction step of the biosynthetic phase fails.
- C.
The ATP/NADPH ratio increases, which accelerates the regeneration of RuBP and temporarily increases the rate of CO2 fixation.
- D.
The Emerson enhancement effect is triggered, shifting the plant entirely to non-cyclic electron flow to maintain triose phosphate synthesis.
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
Photosystem_I|Photosystem_II|Action_Spectrum|Absorption_Spectrum
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Linking the physical properties of light (Red Drop effect at >680 nm) to the biochemical consequences in the stroma.
Students often memorize that cyclic photophosphorylation produces ATP, but fail to deduce that the specific absence of NADPH creates a metabolic block at the reduction phase of the Calvin cycle, leading to 3-PGA accumulation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Red Drop and Emerson Enhancement Effect |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |