SAT Subject Biology Practice Question 269: Answer and Explanation
19. Scientists sequenced a portion of the aspartate transaminase enzyme from different species. The amino acid sequences are shown in the table. Each letter stands for an amino acid. Differences from the human sequence are indicated by bold letters. Missing amino acids are indicated by a dash (–).
All of the following types of mutations could have resulted in the amino acid differences shown EXCEPT
A. a deletion
B. an insertion
C. a missense mutation
D. a silent mutation
E. a substitution
Correct Answer: D
A silent mutation is a point substitution resulting in a codon that specifies the same amino acid as the original codon. It does not result in an amino acid difference.