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Question #45288
The Question
In an experiment mirroring Griffith’s Transforming Principle, a researcher uses a mutant live R-strain of Streptococcus pneumoniae that lacks the bacterial homolog of the enzyme primarily active within meiotic recombination nodules. If this mutant R-strain is mixed with heat-killed S-strain and injected into mice, which of the following represents the correct outcome and its molecular basis?
Options
- A.
Mice survive; exogenous DNA is taken up but fails to integrate into the host genome due to the absence of recombinase activity.
- B.
Mice die; the mutant R-strain utilizes DNA ligase to independently integrate the S-strain DNA, leading to capsule formation.
- C.
Mice survive; the absence of the enzyme prevents the physical uptake of naked DNA through the bacterial cell envelope.
- D.
Mice die; transformation is an episomal event and does not require homologous recombination for the expression of virulence.
Check Your Answer
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
Recombination Nodule Function|Griffith’s Transforming Principle|Gel Electrophoresis Migration
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Bridging Class 11 Cell Cycle (Recombination nodules/Recombinase) with Class 12 Molecular Basis of Inheritance (Griffith's Transformation).
Students often memorize transformation as a simple 'uptake' of DNA, failing to realize that stable transformation requires 'integration' via homologous recombination machinery.
The trap lies in confusing the mechanism of DNA entry (competence) with the mechanism of genomic integration (recombination).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell Cycle and Cell Division - Class 11 |
| Concept | Recombination Nodule Function |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |