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Question #47381
The Question
During acute metabolic stress, systemic glucose uptake by skeletal muscles is suppressed, forcing reliance on internal reserves. In this context, which of the following best explains the rapid onset of fatigue and impaired contractility specifically in white muscle fibers?
Options
- A.
White fibers rely on rapid glycogenolysis, and the resulting inefficient ATP yield impairs the Ca²⁺-ATPase pumps of their extensive sarcoplasmic reticulum, disrupting calcium cycling.
- B.
White fibers possess a poorly developed sarcoplasmic reticulum and must rely on extracellular calcium influx, which is competitively inhibited by stress hormones.
- C.
The high myoglobin content in white fibers strongly binds oxygen, preventing its utilization in the electron transport chain during rapid glycolytic flux.
- D.
Glucagon directly binds to white muscle sarcolemma to induce gluconeogenesis, depleting the ATP required for the detachment of myosin cross-bridges.
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
Glucose_Repression|Myocytes|Calcium_Homeostasis
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'lactic acid causes fatigue' but fail to connect the NCERT structural facts (extensive SR in white fibers) with the functional consequence of ATP depletion on ion pumps (SERCA) during excitation-contraction coupling.
Additionally, it tests the common misconception regarding hormone targets (Glucagon acts on the liver, not directly on muscle).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Red vs. White Muscle Fibers |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |