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Question #46798
The Question
A novel herbicide specifically inhibits the biosynthesis of suberin in the roots of a dicotyledonous plant. Despite the structural integrity of the pericycle and vascular bundles remaining intact, the plant rapidly exhibits symptoms of severe mineral toxicity and an inability to maintain root pressure. Which of the following best explains this physiological response?
Options
- A.
The herbicide induces an uncontrolled apoplastic bypass into the stele, neutralizing the root's ability to selectively filter solutes.
- B.
The loss of suberin forces all water and minerals to move exclusively through the symplastic pathway, overloading the transport proteins.
- C.
The pericycle loses its ability to actively pump mineral ions into the xylem, causing toxic accumulation in the cortex.
- D.
The hydraulic resistance of the root increases drastically, preventing the dilution of minerals within the xylem vessels.
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
Casparian_Strip_Chemistry|Stele_Definition|Root_Region_Differentiation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that the 'Casparian strip is water-impermeable' but fail to apply its ultimate physiological purpose: it acts as a biological checkpoint for solutes.
The trap lies in misunderstanding that removing a barrier decreases hydraulic resistance and shifts transport from the selective symplast to the non-selective apoplast, leading to mineral toxicity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Casparian Strip Chemistry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |