[Campbell Biology P.537] Based on the information provided regarding the Drosophila melanoga... | Practice Question

Based on the information provided regarding the Drosophila melanogaster Adh gene, which statement accurately describes genetic variation at the molecular level?

• A: Most nucleotide variations within the Adh gene, including those in exons, result in a change in the amino acid sequence, leading to phenotypic variation.
• B: While 43 nucleotide sites show variation in the Adh gene, only 18 of these are located within the exons, and only one specific site (1,490) leads to an amino acid change.
• C: Genetic variation at the whole-gene level (gene variability) is primarily due to nucleotide changes within introns, as these regions are translated into proteins.
• D: The presence of two different forms of the Adh enzyme is due to multiple base-pair substitutions, insertions, and deletions occurring exclusively in the Adh gene's introns.