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Question #45793
The Question
Skeletal muscles contain distinct motor units adapted for different types of physical activity. Motor Unit 'P' is recruited via high-frequency, transient signaling at the neuromuscular junction, while Motor Unit 'Q' is recruited via low-frequency, tonic signaling. Which of the following statements is INCORRECT regarding their physiological and structural adaptations?
Options
- A.
Unit P fibers possess an extensive sarcoplasmic reticulum to ensure rapid and massive Ca2+ release for fast-twitch responses.
- B.
Unit Q fibers exhibit lower myosin ATPase activity, resulting in a slower rate of cross-bridge cycling compared to Unit P.
- C.
Unit P fibers primarily depend on anaerobic glycolysis, leading to rapid metabolic exhaustion and lactic acid accumulation.
- D.
Unit Q fibers contain high amounts of myoglobin and mitochondria to sustain the high-frequency phasic contractions required for posture maintenance.
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
Neuromuscular Junction Signal|Red vs. White Muscle Fibers|Neural Control
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the structural differences between red and white fibers (myoglobin/mitochondria vs SR) but fail to link them to their specific neural signaling patterns.
The trap in Option D is a 'Common Half-Truth'—it correctly assigns the structural adaptation (high myoglobin) and functional outcome (posture) to Red fibers, but deliberately swaps the intermediate physiological mechanism (inserting 'high-frequency phasic' instead of 'low-frequency tonic').
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Neuromuscular Junction Signal |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |