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Question #46738
The Question
An experimental toxin selectively and irreversibly inhibits the Ca2+-ATPase pumps on the sarcoplasmic reticulum (SR) membrane of a skeletal muscle fiber immediately after a neural stimulus has triggered calcium release. Based on the sliding filament theory, what will be the direct physiological consequence?
Options
- A.
The muscle will exhibit flaccid paralysis because the absence of pump activity prevents further release of Ca2+ into the sarcoplasm.
- B.
The muscle will enter a state of sustained contraction, leading to sarcomere degradation due to prolonged sarcoplasmic calcium overload.
- C.
The cross-bridge cycle will halt in the relaxed state because ATP cannot be hydrolyzed by the myosin head without SR pump activity.
- D.
The Z-lines will rapidly return to their resting position as calcium is passively sequestered back into the SR cisternae down its concentration gradient.
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
ER_Membrane|Sarcoplasmic_Reticulum|Ca2+_ATPase
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the passive release of calcium (via channels for contraction) and the active reuptake of calcium (via ATP-dependent pumps for relaxation).
Students frequently confuse the roles of the two distinct ATPases in muscle fibers (Myosin ATPase vs.
SR Ca2+-ATPase) and often mistakenly assume that calcium returns to the SR passively.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Endomembrane System Connectivity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |