Question

Molecular clocks are __________.

A. used to confirm or correct the divergence dates documented in the fossil record
B. superior to other methods of reconstructing the past because they are based on high-tech, molecular data
C. isotopes that decay to produce other isotopes at a constant rate in buried samples, allowing precise estimates of the ages of fossils
D. one of several ways to estimate divergence times between taxa, by comparing their gene sequences and assuming a constant rate of evolution over time

Answer 1

Molecular clocks are a method for D) estimating the time of divergence between species by assuming a constant rate of DNA evolution and comparing genetic differences.

Step-by-step explanation:

Molecular clocks are one of several ways to estimate divergence times between taxa, by comparing their gene sequences and assuming a constant rate of evolution over time. These clocks, also known as gene clocks or evolutionary clocks, are based on the premise that mutations in DNA accumulate at a steady average rate for a given region of DNA.

Therefore, by examining the amount of genetic differences between species, scientists infer how long it has been since those species diverged from a common ancestor. Importantly, the use of molecular clocks function as a complementary tool to other methods, such as the fossil record and geologic time scales, to understand the history of life on Earth.