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Question #45897
The Question
In a co-evolutionary arms race, a eukaryotic host develops resistance to a specific retrovirus. Researchers observe that the host's spliceosomes have evolved altered splice-site recognition, causing the primary transcript of the integrated viral DNA (provirus) to be excised entirely as an 'intron'. Which of the following best explains how this mechanism confers cellular immunity?
Options
- A.
The spliceosome prevents the initial reverse transcription of the viral RNA genome into cDNA in the cytoplasm.
- B.
The excised viral RNA forms a double-stranded structure that is processed by Dicer, triggering RNA interference (RNAi).
- C.
The viral sequence is retained as an exon, causing a frameshift mutation that produces non-functional viral proteins.
- D.
The excised intronic viral RNA is capped and polyadenylated, competitively inhibiting host mRNA translation.
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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
Spliceosome Mechanics|RNAi Vector Source|Evolutionary Ecology of Parasitism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Connecting the spatial and temporal sequence of retroviral infection with host post-transcriptional modifications.
Students often fail to distinguish the timeline of retroviral replication (Reverse transcription -> Integration -> Transcription -> Splicing).
Furthermore, linking excised intronic RNA to the generation of dsRNA for the RNAi pathway tests deep synthesis of two separate NCERT topics (Splicing in 'Molecular Basis of Inheritance' and RNAi in 'Biotechnology and its Applications').
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Spliceosome Mechanics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |