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Question #45858
The Question
During the evolutionary transition from a diploid ancestor to a hexaploid plant like Triticum aestivum, researchers observe 'base composition drift', where the overall genomic GC content significantly increases. Which of the following statements regarding this phenomenon and related genetic principles is strictly INCORRECT?
Options
- A.
It is often driven by GC-biased gene conversion during recombination in the expanded polyploid genome.
- B.
The significant shift in GC content invalidates Erwin Chargaff’s rule of base equivalence (A=T and G=C) for the polyploid's DNA.
- C.
The (A+T)/(G+C) ratio of the hexaploid species will become distinct from that of its diploid ancestor.
- D.
This genomic expansion is a consequence of whole sets of chromosomes increasing (polyploidy) rather than individual chromosome non-disjunction (aneuploidy).
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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
Aneuploidy_vs_Polyploidy|Chargaff’s_Rule_Limitation|DNA_Stability
Why This Question Is Tricky
Common Mistakes
The 'Conceptual Pivot' is distinguishing between Chargaff's First Parity Rule (A=T, G=C, which is universal for dsDNA) and the (A+T)/(G+C) ratio (which is species-specific and subject to evolutionary drift).
Students often mistakenly believe that a massive shift in overall base composition implies a violation of Chargaff's base equivalence.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Chargaff’s Rule Limitation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |