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Question #45121
The Question
In plant biotechnology, both Agrobacterium-mediated transfer and biolistics (gene gun) are utilized to introduce recombinant DNA into host cells. However, transgenic plants developed via biolistics frequently exhibit 'transgene silencing' or highly variable expression levels compared to those developed using Agrobacterium. Which of the following statements best explains the molecular basis for this discrepancy?
Options
- A.
Biolistics leads to random integration of the transgene into the host genome, increasing susceptibility to position effects, whereas Agrobacterium facilitates controlled integration mediated by T-DNA borders.
- B.
Agrobacterium transfers the entire recombinant Ti-plasmid into the host euchromatin ensuring stable expression, while biolistics transfers only naked DNA that gets degraded.
- C.
Biolistics delivers DNA exclusively into the cytoplasm leading to episomal degradation, whereas Agrobacterium directly injects the gene of interest into the host nucleolus.
- D.
The gold or tungsten microparticles used in biolistics chemically induce epigenetic methylation of the host genome, whereas the vir genes of Agrobacterium prevent DNA methylation.
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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
Biolistics/Gene Gun Physics|Plasmid vs Chromosomal DNA
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the tools of biotechnology (Agrobacterium for dicots, Gene gun for monocots) but fail to synthesize the molecular consequences of the delivery method.
The trap in Option B exploits a very common NCERT misconception: students often forget that only the T-DNA region of the Ti-plasmid is transferred and integrated, not the entire plasmid.
The question bridges NCERT core facts with advanced application (position effect variegation).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology : Principles and Processes - Class 12 |
| Concept | Biolistics/Gene Gun Physics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |