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Question #45780
The Question
A maternally inherited mutation in the mitochondrial genome severely impairs the F1 headpiece of ATP synthase. In a population of specialized flightless birds, individuals survive this energetic bottleneck by adapting their skeletal muscles to rely exclusively on white (glycolytic) muscle fibers for locomotion. Which of the following is NOT a characteristic of the myofibril assembly and physiology in these adapted muscles?
Options
- A.
The detachment of the myosin cross-bridge during the sarcomere cycle depends on ATP synthesized primarily in the sarcoplasm.
- B.
The muscle fibers possess an extensive sarcoplasmic reticulum to ensure rapid Ca2+ release for unmasking active sites on actin.
- C.
To compensate for the mitochondrial defect, these fibers exhibit an increased density of myoglobin to maximize oxygen storage.
- D.
The energetic ceiling for sustained contraction is restricted, leading to rapid fatigue due to anaerobic metabolism.
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
Sarcomere Functional Boundaries|Darwinian Fitness|Trophic Efficiency Limits
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often fall for the 'teleological compensation trap'—assuming that a defect in energy production automatically triggers an increase in oxygen-carrying capacity (myoglobin).
To answer correctly, the student must synthesize two NCERT facts: 1) White muscle fibers inherently lack myoglobin, and 2) Oxygen is biologically useless for ATP generation if the F1 particle of ATP synthase is structurally impaired.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Sarcomere Functional Boundaries |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |