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Question #46268
The Question
The 'triple response' in dicot seedlings is a classic ethylene-mediated mechanism. If a germinating dicot seed possesses a mutation that causes constitutive (continuous) ethylene signaling under the soil, which of the following accurately describes the most likely developmental and physiological outcome?
Options
- A.
The seedling will bypass physical obstacles through rapid vertical internodal elongation, establishing early autotrophy.
- B.
The radicle will exhibit enhanced downward elongation to secure water, while the hypocotyl maintains an apical hook.
- C.
The axis will swell and grow horizontally, but the inhibition of radicle elongation will ultimately abort the transition from heterotrophic to autotrophic nutrition.
- D.
The meristematic totipotency of the embryo will be suppressed immediately, preventing the breaking of seed dormancy.
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
Seed Embryology|Meristematic Totipotency|Ethylene Triple Response
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the 'triple response' as a purely beneficial survival mechanism for soil emergence.
The trap lies in failing to recognize that its constitutive expression is detrimental; it actively inhibits the vertical elongation required for root establishment.
Additionally, Option D exploits a 'Functional Confusion' trap—students might associate growth inhibition with the maintenance of dormancy, forgetting that NCERT explicitly states ethylene breaks seed and bud dormancy.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Seed Embryology |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |