Question

1. when scientists compare molecular clocks between species, they have to use the same segment of dna. which of these statements would explain why that is necessary? a. not every segment of dna mutates. b. different genes mutate at different rates. c. species accumulate neutral mutations at random rates. d. all mutations cause harmful effects.

Explanation:

When comparing molecular clocks between species, using the same DNA segment is crucial because different genes mutate at different rates. If different segments were used, the mutation - rate comparison would be inaccurate. Option A is incorrect as all DNA segments can mutate over time. Option C is not the main reason for using the same segment; the focus is on consistent mutation - rate genes. Option D is false as not all mutations are harmful.

Answer:

B. Different genes mutate at different rates.