Question

question 4(multiple choice worth 2 points)
(05.02a mc)
what should be true of a molecule being used as a molecular clock?
its mutations always affect the phenotype, making it easier to observe the changes.
it is a rare molecule that is not found in many living species that might be compared.
it serves an unnecessary function, making it less likely to be preserved over time.
it has a consistent rate of neutral mutations from generation to generation.

Explanation:

To determine the correct answer, we analyze each option:

• Option 1: Mutations affecting phenotype aren't necessary for a molecular clock; neutral mutations (not affecting phenotype) are key. So this is incorrect.
• Option 2: A molecular clock molecule should be found in many species for comparison, not rare. Incorrect.
• Option 3: Molecules with necessary functions are more likely preserved, but a molecular clock needs consistent mutation rate, not an unnecessary function. Incorrect.
• Option 4: A molecular clock relies on a consistent rate of neutral mutations (mutations that don't affect fitness) over generations to measure evolutionary time. This matches the definition.

Answer:

D. It has a consistent rate of neutral mutations from generation to generation.