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Question #46442
The Question
Two mammalian species possess forelimbs adapted for entirely different functions (swimming vs. flying). Analysis of a specific housekeeping gene reveals a 15% difference in their nucleotide sequences, yet the synthesized protein's amino acid sequence is 99% identical. Which of the following statements regarding this observation is INCORRECT?
Options
- A.
The forelimbs represent homologous structures that have undergone divergent evolution due to differing selection pressures.
- B.
The 15% nucleotide variance is largely accommodated by the degeneracy of the genetic code, representing silent mutations.
- C.
The 99% identity in the amino acid sequence is an example of molecular analogy, indicating convergent evolution for a shared biochemical function.
- D.
The nucleotide substitutions likely occurred at the third position of the codons, demonstrating the wobble effect without altering the phenotype.
Check Your Answer
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
Homologous Organ Ancestry|Genetic Code Degeneracy|Molecular Clock
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that if organisms have diverged morphologically, any striking similarity at the molecular level must be due to convergent evolution (analogy) to maintain a specific function.
The trap is failing to recognize that highly conserved biochemical sequences (like housekeeping proteins) are the ultimate proof of molecular homology (shared ancestry), while the underlying nucleotide differences reflect neutral evolution permitted by genetic code degeneracy.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Homologous Organ Ancestry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |