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Question #46782
The Question
During active photosynthesis, the thylakoid lumen experiences a significant drop in pH due to proton accumulation. Proteins functioning in this region, such as those of the water-splitting complex, possess specific R-group pKa values to maintain their secondary structure in highly acidic conditions. If an exogenous chemical shifts the isoelectric point (pI) of these lumen-facing proteins, causing their structural collapse, which of the following will be the most immediate physiological consequence despite continuous illumination?
Options
- A.
Immediate cessation of oxygen evolution and a subsequent halt in the reduction of NADP+.
- B.
Continuous non-cyclic electron transport with a complete failure of ATP synthesis.
- C.
Rapid acidification of the stroma due to the structural collapse of the CF0-CF1 complex.
- D.
Enhanced cyclic photophosphorylation to maintain the proton gradient in the absence of Photosystem I activity.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Amino Acid Zwitterion Equilibrium | Peptide Bond Geometry | Thylakoid Lumen Sequestration
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: This question tests the spatial location of photosynthetic complexes and the biochemical dependency of the Z-scheme.
Students often memorize that 'extreme pH denatures proteins' but fail to apply this to the fact that lumenal proteins are evolutionarily adapted to low pH.
The trap relies on the student connecting the denaturation of lumenal proteins specifically to the Oxygen Evolving Complex, and subsequently realizing that without water splitting, the entire non-cyclic electron transport chain collapses.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Amino Acid Zwitterion Equilibrium |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |