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Question #45368
The Question
If a mammalian oocyte is experimentally extracted from a mature tertiary follicle just before the LH surge and exposed to fully capacitated spermatozoa in vitro, fertilization fails despite the sperm possessing normal acrosomal enzymes. What is the primary physiological reason for this failure?
Options
- A.
The oocyte is arrested in Prophase-I of Meiosis I, and its zona pellucida lacks the mature ZP3 receptor conformation necessary for sperm binding.
- B.
The oocyte is arrested in Metaphase-II, and the absence of the LH surge prevents the activation of the anaphase-promoting complex (APC).
- C.
The lack of an LH surge prevents the secretion of hyaluronidase by the corona radiata, which is essential for sperm penetration.
- D.
The oocyte prematurely releases its cortical granules due to the lack of LH, causing hardening of the zona pellucida prior to sperm contact.
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
LH|Zona Pellucida|Acrosin
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that the 'LH surge causes ovulation' but overlook its critical intracellular role: triggering the completion of Meiosis I (transitioning the primary oocyte to a secondary oocyte).
The trap tests the ability to link meiotic arrest stages (Prophase-I vs Metaphase-II) with the structural maturation of the zona pellucida required for sperm docking.
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 |