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Question #46286
The Question
A plant physiologist treats the shoot apical meristem of a developing dicot with N-1-naphthylphthalamic acid (NPA), a specific inhibitor of PIN efflux carriers. Which of the following cellular or developmental anomalies is most likely to be observed as a direct consequence of this treatment?
Options
- A.
Disruption in the differentiation of sieve tube elements due to the loss of polarity during cytokinesis.
- B.
Hyper-elongation of the internodal regions due to localized auxin accumulation at the shoot apex.
- C.
Complete suppression of lateral bud growth due to the absence of basipetal auxin flow.
- D.
Accelerated differentiation of primary xylem elements at the expense of phloem tissue.
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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
Meristematic Polarity|Companion Cell-Sieve Tube Symport|PIN Proteins
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize macroscopic effects of auxin (like apical dominance) but fail to connect Polar Auxin Transport (PAT) to cellular-level developmental polarity.
The trap tests the understanding that the apical-basal auxin gradient is an absolute prerequisite for the asymmetric cell divisions that differentiate the sieve element-companion cell complex.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Meristematic Polarity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |