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Question #46298
The Question
In dicotyledonous stems, vascular bundles are described as 'open' due to the presence of the intrafascicular cambium. However, the initiation of secondary growth requires a strict hormonal gradient. If a mutation severely disrupts polar auxin transport (PAT) in a developing dicot stem, which of the following anatomical outcomes will be observed?
Options
- A.
The intrafascicular cambium fails to activate and medullary ray cells fail to dedifferentiate, preventing the formation of a continuous cambial ring and secondary tracheary elements.
- B.
The intrafascicular cambium differentiates completely into primary vascular tissues, permanently converting the open vascular bundles into closed vascular bundles.
- C.
The interfascicular cambium forms normally from the pericycle, but fails to fuse with the intrafascicular cambium, restricting stem girth.
- D.
The vascular cambium ring forms but exclusively produces secondary phloem centrifugally, leading to a failure in water transport efficiency.
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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
Vascular Cambium|Auxin Polarity|Lateral Meristem
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the anatomical presence of a meristem (open vascular bundle) and its physiological activation (auxin-dependent).
Common Misconception: Students often confuse the origin of the cambial ring in stems (medullary rays) versus roots (pericycle), and mistakenly assume that an inactive cambium anatomically converts an open bundle into a closed bundle (which genetically lacks procambial remnants).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Vascular Bundle Openness |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |