How does a molecular clock measure time?
A)by observing that some genes and other regions of genomes appear to evolve at different rates
B)by detecting gene irregularities that result from natural selection
C)by counting the number of nucleotide substitutions over a fixed period of time
D)by using few gene mutations to calibrate the clock

Question

Quizplus · Accepted Answer

A molecular clock measures time by counting the number of nucleotide substitutions over a fixed period of time. The rate of nucleotide substitutions is generally constant for a given gene or region of the genome, and this rate can be used to estimate the time since two organisms diverged from a common ancestor. This approach assumes that the rate of nucleotide substitutions is approximately constant and that mutations are selectively neutral, meaning they do not confer any advantage or disadvantage to the organism.

How Does a Molecular Clock Measure Time