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Question #45167
The Question
A biotechnologist develops a transgenic tomato using an antisense RNA construct against the polygalacturonase gene to mimic the delayed ripening of the Flavr Savr variety. However, the plant subsequently suffers a viral infection that generates massive amounts of non-target double-stranded RNA (dsRNA) in the cytoplasm. Consequently, the transgenic tomatoes exhibit rapid softening post-harvest. Which of the following best explains this systemic failure at the molecular level?
Options
- A.
Saturation of the host's Dicer and RISC machinery by viral dsRNA prevents the processing of the specific antisense-mRNA complex, allowing translation of polygalacturonase and subsequent degradation of the middle lamella.
- B.
The viral dsRNA competitively binds to the antisense RNA, preventing it from blocking the transcription of the polygalacturonase gene in the nucleus.
- C.
The excessive viral dsRNA triggers systemic acquired resistance, which inadvertently activates endogenous cellulases to degrade the primary cell wall for viral defense.
- D.
The antisense construct undergoes post-transcriptional modification by viral enzymes, converting it into sense RNA that amplifies polygalacturonase synthesis.
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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
Monoculture Patenting|Habitat Fragmentation|Genetic Homogenization
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'Antisense RNA' without understanding that it relies on finite host cellular machinery (RNAi pathway proteins like Dicer/RISC) to execute Post-Transcriptional Gene Silencing (PTGS).
The trap also tests the precise location of the biological consequence (pectin in the middle lamella vs. cellulose in the primary cell wall) and the exact phase of the central dogma being inhibited (translation, not transcription).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology and Its Applications - Class 12 |
| Concept | Biopiracy and Patents |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |