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Question #45387
The Question
A 32-week pregnant female experiences premature parturition. Karyotyping of the premature neonate reveals a 47, XX, +18 chromosomal complement. Which of the following best explains the physiological mechanism by which this specific genetic anomaly triggered the premature neuroendocrine reflex of parturition?
Options
- A.
Aneuploidy-induced fetal stress prematurely activates the fetal HPA axis, causing a cortisol surge that increases the estrogen-to-progesterone ratio and stimulates prostaglandin synthesis.
- B.
The polyploid condition of the fetus directly stimulates the maternal hypothalamus, causing an early surge of maternal oxytocin that bypasses placental signaling.
- C.
The chromosomal anomaly causes premature degeneration of the placenta, leading to a sudden spike in maternal progesterone that forcefully induces myometrial contractions.
- D.
Aneuploidy suppresses the fetal ejection reflex, forcing the maternal posterior pituitary to autonomously initiate mild uterine contractions via relaxin.
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
Non-disjunction|Uterine_Stress|Fetal_Distress
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating genetic anomalies (Aneuploidy) with human reproductive physiology.
Students often memorize the 'Fetal Ejection Reflex' but fail to realize that fetal stress (via cortisol) is the biochemical trigger that shifts the estrogen/progesterone ratio.
The trap also tests the fundamental difference between Aneuploidy and Polyploidy, and the opposing roles of estrogen (contractile) and progesterone (relaxant) on the myometrium.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Reproduction - Class 12 |
| Concept | Parturition Neuroendocrine Reflex |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |