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Question #46218
The Question
A Pinus tree growing near a lake subjected to severe agricultural runoff (eutrophication) loses its mycorrhizal association due to altered soil chemistry. Despite the nutrient-abundant soil, the plant exhibits severe stunting and metabolic starvation. Based on the principles of mineral nutrition and transport, which of the following best explains this 'starvation in the midst of plenty'?
Options
- A.
The absence of the fungal mantle forces the root epidermal cells to rely exclusively on passive apoplastic flow, bypassing the Casparian strip and causing systemic ion toxicity.
- B.
The plant is forced to upregulate ATP-dependent specific carrier proteins to selectively absorb trace minerals against competitive inhibition, creating an energy demand that outstrips photosynthetic output.
- C.
High external nutrient concentrations cause a steep influx of ions via facilitated diffusion, which competitively inhibits the synthesis of ATP in the root mitochondria.
- D.
The loss of mycorrhizae drastically reduces the root surface area, forcing the plant to switch from active symplastic transport to passive apoplastic transport for all essential minerals.
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_Modifications|Active_vs_Passive_Gradient_Logic|Competent_Cell_Preparation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that 'nutrient-rich soil' automatically equals 'easy passive absorption'.
The trap is failing to recognize that the loss of the mycorrhizal surface area forces the plant to rely entirely on its own root hairs, necessitating highly selective, ATP-intensive active transport to filter out excess toxic ions and pump in competitively inhibited trace minerals.
This bridges NCERT concepts from 'Transport in Plants' (active ion uptake) and 'Biological Classification' (Pinus-mycorrhiza obligate mutualism).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Root Modifications |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |