Final answer:
The statement is true; Archaea and Bacteria, although both prokaryotes, have profound differences at a molecular level, just as they each differ from Eukaryotes, justifying their separation into distinct domains.
Step-by-step explanation:
The statement, "At a molecular level, the members of the two domains of prokaryotes—the archaea and bacteria—differ as much from each other as either does from the eukaryotes", is true. Although both Archaea and Bacteria are prokaryotic, meaning they lack a nucleus and membrane-bound organelles, they possess significant differences. For instance, Archaea and Bacteria have substantial differences in their cell membrane structures and cell wall compositions. Archaeal cell walls lack peptidoglycan, which is found in the cell walls of Bacteria. Moreover, the lipid composition of their cell membranes is distinctly different, with Archaea having phytanyl units linked to glycerol, as opposed to the fatty acids in bacterial membranes. Some archaeal membranes can even be lipid monolayers instead of bilayers, a feature not seen in bacteria. These molecular differences, among others, warrant their classification into separate domains.