The following provides the best argument for separating Archaea and Bacteria into their own domains instead of leaving them together in the single kingdom, Monera :
It was discovered that they make their membranes differently and copy their DNA differently.
Step-by-step explanation:
The reason that Archaea were determined to be a separate kingdom so late was because archaea often completely resemble eubacteria. But you can see that fungi and other eukaryotes are more similar to archaea than the bacteria.
Archaea have cell walls that lack peptidoglycan and have membranes that enclose lipids with hydrocarbons rather than fatty acids
Bacteria: cell membrane contains ester bonds; cell wall made of peptidoglycan; have only one RNA polymerase; react to antibiotics in a different way than archea do
Archaea and bacteria are both prokaryotes, meaning they do not have a nucleus and lack membrane-bound organelles.
Both archaea and bacteria have flagella, thread-like structures that allow organisms to move by propelling them through their environment.
In all organisms, cell membranes are made of molecules known as phospholipids.
The phospholipids of archaea are unusual as they have membranes composed of glycerol-ether lipids, whereas bacteria and eukaryotes have membranes composed mainly of glycerol-ester lipids