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Question #46234
The Question
The transition from vegetative growth to the reproductive phase in angiosperms involves a profound shift in the developmental program of the Shoot Apical Meristem (SAM). Based on the principles of photoperiodism and phytochrome interconversion, which of the following statements is INCORRECT?
Options
- A.
The photoperiodic stimulus is perceived by mature leaves, where the ratio of Pfr to Pr regulates the synthesis of Florigen, which subsequently migrates to the SAM.
- B.
The SAM directly perceives the critical changes in the red/far-red light ratio via its own localized phytochrome network to initiate the transformation into a floral meristem.
- C.
During floral induction, the vegetative SAM ceases standard phyllome production and modifies its differentiation pattern to produce condensed internodes and floral appendages such as bracts.
- D.
In a Short Day Plant, a flash of red light (660 nm) during the critical dark period converts Pr to Pfr, thereby suppressing Florigen synthesis and maintaining vegetative phyllotaxy.
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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
Leaf Vernation and Phyllotaxy|Phytochrome Interconversion|Photoperiodism
Why This Question Is Tricky
Common Mistakes
Location Trap & Conceptual Pivot: Students frequently confuse the 'site of response' (Shoot Apical Meristem) with the 'site of perception' (Leaves).
While the SAM undergoes the physical transformation (altering phyllotaxy to produce bracts/flowers), it is entirely blind to the photoperiodic light stimulus itself, relying entirely on the mobile signal (Florigen) generated by the phytochrome system in the leaves.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Leaf Vernation and Phyllotaxy |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |