Final answer:
Molecular clocks and reaction rates are linked by their dependency on time to measure change; molecular clocks track genetic changes over evolutionary time, while reaction rates measure the speed of chemical changes.
Step-by-step explanation:
Molecular clocks have to do with reaction rates in the sense that they too rely on change over time; however, molecular clocks measure evolutionary time and genetic change rather than chemical reactions. A molecular clock uses differences in DNA (or protein) sequences to measure the time since species diverged from a common ancestor. This is because mutations in DNA accumulate at a steady, predictable average rate in a given region of DNA. On the other hand, reaction rates are concerned with how fast a chemical reaction proceeds towards products, influenced by factors like temperature and reactant concentrations. The link between these two concepts is the use of time as a measure of change, whether it's genetic mutations in molecular clocks or the transformation of reactants into products in chemical reactions.