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Question #45935
The Question
A researcher treats a healthy C3 plant with an uncoupling agent that renders the thylakoid membrane highly permeable to protons. Assuming the photosynthetic electron transport chain remains functional, which of the following best describes the immediate metabolic consequence and its effect on the plant's CO2 compensation point?
Options
- A.
Photophosphorylation ceases due to the loss of the proton motive force; a compensatory surge in mitochondrial respiration increases CO2 evolution, thereby elevating the CO2 compensation point.
- B.
The destruction of the proton gradient halts NADPH synthesis, forcing the plant to rely on photorespiration, which lowers the CO2 compensation point.
- C.
Cyclic electron transport upregulates to bypass the membrane leak, restoring ATP synthesis and maintaining a stable CO2 compensation point.
- D.
ATP synthesis halts, but the Calvin cycle utilizes the accumulating NADPH to sustain CO2 fixation, keeping the CO2 compensation point unchanged.
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
Thylakoid_Lumen|ATP_Synthase|Proton_Motive_Force
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often conflate the Electron Transport Chain (ETC) with Chemiosmosis.
A common misconception is that if the ETC is functional (producing NADPH and splitting water), photosynthesis continues.
This question tests the understanding that ATP synthesis strictly requires an intact thylakoid membrane for the Proton Motive Force.
Furthermore, it bridges chloroplast bioenergetics with whole-plant metabolic integration, showing how a localized ATP deficit triggers compensatory mitochondrial respiration, thereby shifting the macroscopic CO2 compensation point.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | Compensation Point Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |