Question

multiple choice question
in comparing nucleotide or amino acid sequences, researchers base evolutionary relationships on the assumption that

the more closely related two species are, the greater the similarity in their dna and proteins.

the more nucleotide and amino acid differences, the more closely related two species are.

similarities in molecules cannot be correlated with evolutionary relationship among organisms.

similarities in dna and proteins most like arose from independent mutation events.

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Explanation:

To determine the correct answer, we analyze each option:

• Option 1: The more closely related two species are, the more similar their DNA (nucleotide sequences) and proteins (amino acid sequences) should be because they share a more recent common ancestor, leading to fewer evolutionary changes. This aligns with the principles of molecular evolution.
• Option 2: More differences in nucleotides and amino acids would imply a more distant evolutionary relationship, not a closer one, so this is incorrect.
• Option 3: Molecular similarities (like DNA/protein sequences) are widely used to determine evolutionary relationships (e.g., in phylogenetics), so this is incorrect.
• Option 4: Similarities in DNA and proteins are more likely due to common ancestry (homology) rather than independent mutations (which would be rare and not a primary source of similarity for related species), so this is incorrect.

Answer:

A. the more closely related two species are, the greater the similarity in their DNA and proteins.