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Question #46919
The Question
In a population of Drosophila, DNA sequencing of a specific gene locus reveals the presence of 8 distinct alleles. However, biochemical analysis demonstrates that all individuals in the population synthesize an identical polypeptide for this gene, effectively hiding this genetic variation from natural selection. Which of the following molecular principles best explains why this multiple allelism is masked at the phenotypic level?
Options
- A.
The unambiguous and specific nature of the genetic code ensures that each codon codes for only one amino acid.
- B.
Degeneracy of the genetic code allows synonymous nucleotide substitutions to accumulate without altering the amino acid sequence.
- C.
Epistatic interactions from a dominant regulatory gene completely suppress the translation of the variant alleles.
- D.
Post-transcriptional splicing removes the mutated exonic sequences, resulting in identical mature mRNAs.
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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
Genetic Code Degeneracy|Multiple Allelism Limitation|Missense Mutation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often compartmentalize Mendelian genetics (Multiple Allelism) and Molecular genetics (Degeneracy).
The trap is assuming that multiple alleles must always produce multiple distinct phenotypes (like the ABO blood group).
The logical leap requires understanding that alleles are fundamentally just different DNA sequences; if mutations are 'silent' due to the degenerate nature of the genetic code, massive genotypic variation can exist without any phenotypic manifestation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | The Living World - Class 11 |
| Concept | Botanical and Zoological Codes |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |