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Question #45369
The Question
A hypothetical genetic modification aims to replace the thermolabile human acrosomal enzyme (acrosin) with a highly thermostable variant—structurally similar to Taq polymerase—to enhance sperm viability during in vitro storage. During in vivo trials at physiological temperature (37°C), these modified sperm completely fail to reach the ampullary region of the fallopian tube. Which of the following best explains this specific failure?
Options
- A.
The excessive metabolic cost of synthesizing heavily cross-linked, hyper-stable proteins during spermiogenesis compromises the proper assembly of the mitochondrial sheath, severely impairing flagellar motility.
- B.
The engineered thermostable acrosin exhibits severe conformational rigidity at 37°C, drastically reducing its catalytic efficiency to digest the zona pellucida.
- C.
The extreme thermostability of the modified enzymes prevents the calcium-mediated exocytosis of the acrosome during capacitation.
- D.
The modified enzymes undergo rapid denaturation upon exposure to the acidic pH of the vaginal tract, directly paralyzing the axonemal microtubules.
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
Acrosin|Thermal Stability|Taq Polymerase
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the functional consequence of an enzyme modification (catalytic failure at 37°C) and the developmental/metabolic consequence on the whole cell (motility failure).
Students will likely select Option B because they know Taq polymerase is rigid at 37°C.
However, they must carefully read the location constraint ('fail to reach the ampullary region') to realize the failure occurs during transit (motility), making Option A the only logically sound answer.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Reproduction - Class 12 |
| Concept | Acrosomal Enzyme Activation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |