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Question #45964
The Question
In biennial rosette plants like cabbage, bolting (internode elongation just prior to flowering) can be induced artificially by the application of Gibberellins (GA), bypassing the natural requirement for vernalization. However, if the plant is subjected to severe and prolonged heat stress, exogenous GA application fails to induce bolting. Which of the following best explains this physiological failure?
Options
- A.
Heat stress denatures the exogenous Gibberellic acid molecules, preventing their binding to membrane-bound receptors.
- B.
Heat Shock Proteins (HSPs) induced by thermal stress stabilize DELLA proteins, which act as negative regulators of the GA signaling pathway.
- C.
High temperatures shift the isoprenoid pathway to rapidly convert the applied Gibberellins directly into Abscisic Acid (ABA).
- D.
Thermal stress mimics vernalization by hypermethylating the FLC gene, which strictly inhibits vegetative internodal elongation.
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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
Gibberellins|Vernalization|Stress_Physiology
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the NCERT fact 'GA = Bolting' as an absolute rule.
The trap is failing to recognize that hormone signaling is not a standalone switch but is integrated with environmental stress responses.
The misconception is that exogenous application of a hormone will always override environmental extremes, ignoring the intracellular signal transduction machinery (like DELLA repressor proteins) that can be blocked by the Heat Shock Response (HSR).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Gibberellin Bolting Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |