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Question #46410
The Question
Mycorrhizal fungi (e.g., Glomus) act as an extended root system for plants, primarily aiding in phosphorus absorption in exchange for photoassimilates. However, when a plant is grown in heavily fertilized, phosphorus-rich soil, it restricts carbon allocation to the fungus, effectively silencing the symbiotic exchange. This resource-dependent suppression of an alternative nutrient acquisition strategy is conceptually most analogous to which of the following genetic regulatory mechanisms?
Options
- A.
The binding of the repressor protein to the operator of the lac operon in the absence of lactose.
- B.
The feedback repression of the trp operon by the binding of the tryptophan-repressor complex to the operator.
- C.
Catabolite repression of the lac operon, where the presence of glucose prevents the transcription of genes required for lactose utilization.
- D.
The transcriptional silencing of nematode-specific genes in tobacco plants via Agrobacterium-mediated RNA interference.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Glucose Repression|Mycorrhiza Nutrient Dynamics|Symbiotic Nitrogen Fixation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often fail to distinguish between the repression of an anabolic pathway (like the trp operon) and the suppression of a catabolic/acquisition pathway due to the presence of a preferred resource (Catabolite Repression in the lac operon).
Linking this molecular concept to ecological resource allocation (mycorrhiza) tests true NCERT-Plus synthesis and prevents rote memorization of operon mechanics.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Glucose Repression |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |