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Question #45992
The Question
Consider the activation mechanisms of vernalization in winter-variety plants and the insecticidal action of Bacillus thuringiensis (Bt) protoxin in target insects. Which of the following statements accurately differentiates the molecular basis and environmental dependency of these two phenomena?
Options
- A.
Vernalization is mediated by a physical cue (cold) leading to epigenetic transcriptional silencing, whereas Bt protoxin activation is mediated by a chemical cue (alkaline pH) resulting in post-translational proteolytic cleavage.
- B.
Both phenomena represent post-translational modifications where low temperature and alkaline pH respectively alter the tertiary structure of pre-synthesized inactive proteins.
- C.
Vernalization involves the cold-induced transcriptional activation of the cry gene, whereas Bt toxin requires an acidic midgut pH to solubilize the parasporal crystals.
- D.
Vernalization relies on a chemical cue to induce irreversible genetic mutations in the shoot apical meristem, while Bt toxin activation relies on a physical cue to create pores in the insect midgut.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Vernalization Mechanism|Bt Toxin Activation Trigger
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between different levels of biological regulation (Transcriptional/Epigenetic vs.
Post-translational) and the specific nature of their environmental triggers (Physical/Temperature vs.
Chemical/pH).
Common Misconception: Students often memorize the triggers (cold and alkaline pH) but fail to categorize how these triggers act at the molecular level, confusing gene expression regulation with protein activation.
Furthermore, the 'acidic vs alkaline' trap for Bt toxin is a high-frequency NEET distractor.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Vernalization Mechanism |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |