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Question #45123
The Question
A geneticist uses the biolistic (gene gun) method to introduce a resistance gene into a stenothermal monocot crop. Post-bombardment, the explants accidentally undergo a transient heat shock. Subsequent screening yields zero transformants. Which of the following physiological mechanisms best explains this failure?
Options
- A.
The heat shock activated endogenous nucleases via stress-response signaling, degrading the foreign DNA before genomic integration.
- B.
The thermal stress caused the Agrobacterium vector to lose its Ti-plasmid, preventing T-DNA transfer.
- C.
The heat shock created transient pores in the plasma membrane, causing the heavy gold microparticles to efflux from the cell.
- D.
The high temperature denatured the restriction endonucleases required to ligate the foreign DNA into the host genome.
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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
Biolistics/Gene Gun Physics|Thermal Tolerance Ranges
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often blindly associate 'heat shock' with facilitating transformation due to the bacterial competence protocol taught in NCERT.
This question subverts that expectation by applying heat shock as an environmental stressor in plant tissue culture, which activates defense pathways (nucleases) that destroy foreign DNA.
It also tests the fundamental distinction between vectorless (biolistics) and vector-mediated (Agrobacterium) gene transfer, alongside the functional difference between ligases and endonucleases.
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 |