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Question #47583
The Question
A plant with an obligate mycorrhizal association (e.g., Pinus) is grown in sterilized, phosphorus-poor soil under optimal photosynthetically active radiation (PAR). Chloroplast analysis reveals a highly acidic thylakoid lumen but severely depressed ATP synthesis in the stroma. Which of the following is the most accurate explanation for this phenomenon?
Options
- A.
Absence of fungal symbionts restricts inorganic phosphate uptake, depriving the CF1 headpiece of the substrate required for ADP phosphorylation.
- B.
Phosphorus deficiency directly inhibits the oxygen-evolving complex, preventing the generation of a proton motive force.
- C.
The lack of mycorrhiza reduces water absorption, leading to stomatal closure and subsequent uncoupling of the electron transport chain.
- D.
The CF0 transmembrane channel requires phosphorus as a structural cofactor to facilitate the diffusion of protons.
Check Your Answer
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
Chemiosmotic ATP Synthesis Logic|Mycorrhiza Nutrient Dynamics|Proton Gradient
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often equate a steep proton gradient directly with ATP production, forgetting the absolute substrate requirement of inorganic phosphate (Pi).
The trap integrates mineral nutrition with photosynthesis, highlighting that without mycorrhiza-mediated phosphorus uptake, the chemiosmotic machinery stalls at the CF1 complex despite normal light absorption and active electron transport.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Action Spectrum vs Absorption Spectrum |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |