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Question #47493
The Question
A researcher isolates the infectious agent responsible for Potato Spindle Tuber disease. To study its replication, they attempt to introduce the isolated agent into E. coli using the standard divalent cation (Ca²⁺) competent cell transformation protocol. The experiment fails to establish an infection or replication cycle. Which of the following best explains the fundamental biological error in this experimental design?
Options
- A.
The agent is a virus that requires specific surface receptor-ligand interactions for adsorption, which are bypassed by the Ca²⁺ treatment, leading to immediate degradation.
- B.
The agent is a viroid composed of linear dsRNA; while Ca²⁺ facilitates its entry, the bacterial host lacks the reverse transcriptase needed for its replication.
- C.
The agent is a viroid (naked, circular ssRNA) that naturally infects plants via mechanical wounding; Ca²⁺ transformation is chemically and topologically optimized for dsDNA plasmid uptake in bacteria.
- D.
The agent is a naked viral genome that naturally enters host cells via receptor-mediated endocytosis; Ca²⁺ ions neutralize the RNA, preventing its integration into the bacterial nucleoid.
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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
Satellite_RNA|Small_Interfering_RNA|Pathogenic_Interference
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often conflate all 'naked genetic material' uptake with bacterial transformation.
This question tests the ability to distinguish between the structural requirements for Ca²⁺ mediated plasmid (dsDNA) transformation in biotechnology and the biological reality of viroids (naked ssRNA), which lack the capacity to infect bacteria and rely on mechanical wounding rather than receptor-binding or chemical competence.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biological Classification - Class 11 |
| Concept | Viroid vs Virus Distinction |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |