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Question #46418
The Question
A bacterial population comprising both wild-type (antibiotic-sensitive) and variant (antibiotic-resistant due to an R-plasmid) strains is cultured continuously in an antibiotic-free medium. Over several generations, the wild-type strain completely outcompetes the resistant variant. Which of the following principles of Darwinian evolution best explains this phenomenon?
Options
- A.
The absence of antibiotic pressure induces a targeted reverse mutation in the R-plasmid, converting variants back to wild-type.
- B.
Darwinian fitness is environment-specific; the metabolic cost of maintaining the R-plasmid reduces the reproductive fitness of the variant in the absence of antibiotics.
- C.
The wild-type strain develops co-evolutionary resistance against the variant strain by secreting bacteriocins to eliminate competition.
- D.
Antibiotic resistance is an acquired character that cannot be inherited across generations without a continuous environmental stimulus.
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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
Ecological Fitness (Darwinian Fitness)|Co-evolutionary Resistance|Stellar Distance vs. Geological Time
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The 'Superbug Misconception'.
Students often view antibiotic resistance as an absolute evolutionary 'upgrade'.
They fail to realize that evolutionary fitness is entirely contextual.
A trait that confers a massive advantage in one specific environment (antibiotic presence) can become a significant metabolic liability in another (antibiotic absence), perfectly illustrating that nature only selects for immediate reproductive advantage.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Stellar Distance vs. Geological Time |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |