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Question #46330
The Question
During intense physical exercise, an athlete experiences a transient failure in pulmonary capillary recruitment, leading to an increase in physiological dead space. This ventilation-perfusion mismatch induces localized hypoxemia in active skeletal muscles. Which of the following represents the most direct molecular mechanism responsible for the subsequent premature muscle fatigue?
Options
- A.
Accumulation of H+ ions from anaerobic glycolysis interfering with Ca2+ binding to the troponin complex.
- B.
Complete depletion of intracellular ATP preventing the detachment of myosin cross-bridges from actin.
- C.
A leftward shift of the oxygen dissociation curve in the muscle capillaries due to increased lactic acid.
- D.
Direct inhibition of the motor end-plate by accumulated carbon dioxide, preventing acetylcholine release.
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
Dead Space Ventilation|Muscle Fatigue Factors|Cross-bridge Cycling Energy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Bridging respiratory pathophysiology (dead space) with musculoskeletal molecular biology.
Students often memorize 'lactic acid causes fatigue' but fail to link it to H+ interference with Ca2+-troponin binding.
Additionally, it tests the classic 'Left vs Right shift' trap in the Bohr effect and the misconception that fatigue equals zero ATP (which actually causes rigor).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Breathing and Exchange of Gases - Class 11 |
| Concept | Dead Space Ventilation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |