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Question #45209
The Question
In a mutant dicot root, an enzymatic defect prevents the polymerization of structural non-reducing polysaccharides in the endodermis, leading to an accumulation of reducing sugar monomers. This structural failure prevents the proper cross-linking and deposition of suberin on the radial and transverse walls. Which of the following physiological outcomes will directly result from this mutation?
Options
- A.
The plant will exhibit unusually high root pressure due to the osmotic effect of the accumulated reducing sugars.
- B.
Water and dissolved minerals will bypass the symplastic checkpoint, leading to unregulated apoplastic entry into the xylem.
- C.
Active transport of water by endodermal cells will increase to compensate for the defective barrier.
- D.
The movement of water from the root cortex to the pericycle will become strictly symplastic.
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
Reducing vs Non-reducing Sugars|Casparian Strip Chemistry|Cellulose Metabolism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'Casparian strip = suberin' but fail to apply its mechanical purpose.
The trap lies in Option A: students know sugars create osmotic potential and might assume this increases root pressure.
However, they must synthesize the fact that root pressure is a hydrostatic pressure that fundamentally relies on the Casparian strip acting as a physical 'gasket' to prevent ion leakage back into the cortex.
Without the strip, the stele cannot maintain the concentration gradient required for root pressure.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Reducing vs Non-reducing Sugars |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |