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Question #45584
The Question
A human male is heterozygous for an autosomal gene (). Upon cytogenetic analysis, a specific sperm cell is found to be aneuploid () and contains both the '' and '' alleles. Which of the following statements accurately identifies the meiotic error and the Mendelian principle it directly violates?
Options
- A.
Non-disjunction of sister chromatids occurred during Anaphase II, violating the Law of Segregation.
- B.
Non-disjunction of homologous chromosomes occurred during Anaphase I, violating the Law of Segregation.
- C.
Non-disjunction of homologous chromosomes occurred during Anaphase I, violating the Law of Independent Assortment.
- D.
Non-disjunction of sister chromatids occurred during Anaphase II, leading to polyploidy and violating the Law of Dominance.
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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
Mendelian Gamete Frequency|Aneuploidy vs Polyploidy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that non-disjunction causes aneuploidy but fail to map the specific allelic combinations to the exact meiotic stage.
A gamete with 'Aa' proves Meiosis I non-disjunction (homologs failed to separate), whereas a gamete with 'AA' or 'aa' proves Meiosis II non-disjunction (sister chromatids failed to separate).
Furthermore, it tests the fundamental definition of the Law of Segregation (single gene pair) versus Independent Assortment (multiple gene pairs).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Principles of Inheritance and Variation - Class 12 |
| Concept | Mendelian Gamete Frequency |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |