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Question #46458
The Question
In a small, isolated population of an endangered species, researchers observe the fixation of a synonymous mutation. Due to the degeneracy of the genetic code, this mutation does not alter the amino acid sequence, but it utilizes a non-optimal codon that slightly reduces translational efficiency. Which of the following best explains the fixation of this non-optimal codon?
Options
- A.
Genetic drift overrode weak purifying selection, allowing the chance fixation of the allele.
- B.
The wobble hypothesis ensures that all synonymous codons are equally selected for in small populations.
- C.
Degeneracy of the genetic code induces a high mutation rate to restore lost genetic diversity.
- D.
Directional selection actively favored the non-optimal codon to prevent the accumulation of lethal mutations.
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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
Allele Frequency Drift|Genetic Code Degeneracy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that 'silent mutations' are completely invisible to evolutionary forces or that any allele fixation must be driven by natural selection.
The trap lies in failing to recognize that genetic drift dominates in small populations, overriding weak selection (like codon usage bias) and fixing non-optimal alleles purely by chance.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Allele Frequency Drift |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |