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Question #45292
The Question
A 42-year-old female experiences an early miscarriage. Karyotyping of the abortus reveals an aneuploid karyotype (47, XX, +21). Her luteal phase progesterone levels and endometrial thickness were found to be optimal. Which of the following is the most likely cellular basis for this embryonic failure?
Options
- A.
Non-disjunction of homologous chromosomes due to the degradation of spindle apparatus during prolonged arrest in the dictyotene stage.
- B.
Failure of the syncytiotrophoblast to maintain the corpus luteum due to an age-related decline in endometrial LH receptors.
- C.
Premature splitting of centromeres during Anaphase I of oogenesis, leading to the unequal distribution of sister chromatids.
- D.
Inability of the sperm to trigger the Anaphase Promoting Complex (APC) for the completion of Meiosis II.
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
Progesterone/Estrogen Feedback|Implantation and Syncytiotrophoblast
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Linking the macroscopic clinical observation (age-related miscarriage/aneuploidy) to the microscopic NCERT fact (Dictyotene arrest in Prophase I).
The primary trap is Option C, which tests the fundamental difference between Anaphase I (separation of homologous chromosomes) and Anaphase II (splitting of centromeres).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell Cycle and Cell Division - Class 11 |
| Concept | Spindle Attachment Geometry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |