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Question #46207
The Question
A researcher observes a dicot plant growing in a field with a severe hardpan layer that restricts taproot elongation, confining the root system entirely to the shallow topsoil. Despite soil tests showing adequate overall mineral reserves in the deeper soil profile, the plant exhibits death of shoot apices, and the young leaves become severely distorted. The older leaves, however, remain green and unaffected. Which of the following is the most accurate physiological explanation for this condition?
Options
- A.
The topsoil is deficient in Calcium, a structural component of the cell that is immobile and cannot be remobilized from older leaves to the growing apices.
- B.
The restricted root system fails to reach deep soil Nitrogen reserves, and since Nitrogen is highly immobile, the apical meristems starve first.
- C.
The topsoil lacks Magnesium, which cannot be translocated via the phloem to the shoot apex, leading to the necrosis of young tissues.
- D.
The plant is unable to absorb Phosphorus from the deep soil, causing an immediate structural collapse of the apical meristem due to its immobility.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Root System Architecture|Nutrient Immobility|Ecosystem
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The intersection of root architecture constraints and nutrient mobility.
Students must recognize that the spatial restriction of the taproot causes a localized topsoil deficiency, and the specific symptoms (apical death, young leaf distortion while older leaves are fine) are the classic hallmark of an immobile element (Calcium) deficiency.
A common misconception is failing to link the physical immobility of structural elements (like Ca in the middle lamella) to the sequence of symptom appearance (young vs. old leaves).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Root System Architecture |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |