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Question #45986
The Question
A batch of light-sensitive seeds is exposed to the following sequence of light treatments: Red -> Far-Red -> Red -> Far-Red. Following this treatment, the seeds fail to germinate. Which of the following best explains the biochemical state within these seeds that prevents germination?
Options
- A.
The phytochrome remains in the inactive Pr form, failing to trigger Gibberellin synthesis, thus leaving Abscisic acid unantagonized.
- B.
The phytochrome accumulates in the active Pfr form, which directly suppresses the transcription of alpha-amylase in the aleurone layer.
- C.
The Pr form accumulates and acts as a transcription factor to actively synthesize Abscisic acid, maintaining dormancy.
- D.
The far-red light irreversibly denatures the phytochrome pigment, permanently blocking the G-protein mediated signaling pathway.
Check Your Answer
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
Phytochrome|Pfr_Form|Gibberellin|Abscisic_Acid
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Linking the photoreversibility of phytochrome to the antagonistic relationship between GA and ABA.
Students often know that Far-Red light inhibits germination, but the trap lies in understanding the exact downstream biochemical failure: the lack of Pfr prevents GA synthesis, leaving ABA dominant.
It tests the integration of photomorphogenesis with plant hormone action.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Phytochrome Interconversion |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |