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Question #45856
The Question
A researcher analyzes the nitrogenous base composition of the genetic material isolated directly from a mature HIV virion (Sample A) and the integrated viral genome within an infected human macrophage (Sample B). Which of the following statements is correct regarding the base-pairing parity in these samples?
Options
- A.
Sample A will show a purine-to-pyrimidine ratio of exactly 1.0, while Sample B will deviate from this ratio due to host DNA methylation.
- B.
Sample A will not exhibit base-pairing parity, whereas Sample B will strictly follow Chargaff’s rule with A=T and G=C.
- C.
Both samples will violate Chargaff’s rule because retroviral genomes are inherently exempt from standard genomic structural constraints.
- D.
Sample A will show A=U and G=C equivalence, while Sample B will show A=T and G=C equivalence due to reverse transcription.
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
Reverse_Transcriptase|Chargaff’s_Rule_Limitation|Viral_Genome
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'RNA has U instead of T' but forget that Chargaff's rule (parity of bases) is a structural consequence of being double-stranded, not just a property of the nucleic acid type.
The trap lies in assuming that because the RNA and DNA carry the same genetic information, they share the same quantitative base ratios.
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 |