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Question #47642
The Question
Cyanide is a potent respiratory poison that binds to the heme center of Complex IV (cytochrome c oxidase). If a human skeletal muscle cell is exposed to cyanide, which of the following biochemical consequences is NOT expected to occur?
Options
- A.
The proton motive force collapses as protons are no longer pumped from the matrix to the intermembrane space, a direction opposite to that of chloroplasts.
- B.
Cytochrome c remains in a permanently oxidized state because it is unable to transfer its electrons to the inhibited Complex IV.
- C.
The cell shifts to anaerobic fermentation, reducing pyruvate to lactic acid in the cytoplasm to regenerate .
- D.
The Tricarboxylic Acid (TCA) cycle halts due to the severe depletion of oxidized electron carriers ( and ) in the matrix.
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
Mitochondrial Matrix|ETS|Cytochrome c Oxidase
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Redox states of ETC intermediates during inhibition.
A common misconception is that respiratory inhibitors cause carriers to become 'oxidized' because 'oxidation stops'.
In reality, a block in the ETC causes all carriers upstream of the block (like Cytochrome c) to become fully reduced (holding onto electrons), while only the final acceptor (oxygen) remains oxidized.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Proton Gradient Directionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |