What characteristic differentiates eukaryal microbes from bacteria? membrane bound nucleus. phospholipid-based cytoplasmic membrane. presence of small subunit rrna. presence of cell walls?

The correct answer is that eukaryal microbes such as certain protists and fungi are different from bacteria (prokaryotes) because eukaryotes have a true membrane bound nucleus and prokaryotes do not; but they rather have a non-membrane bound nucleoid complex where genetic information is stored.

Both prokaryotes and eukaryotes have phospholipid-based cytoplasmic membranes. The presence of small subunit rRNA and cell walls do not differentiate prokaryotes from eukaryotes. 

The characteristic that differentiates eukaryal microbes from bacteria is the membrane bound nucleus. Bacteria are all examples of prokaryotic cells, while eukaryal microbes are eukaryotes. One of the major difference between eukaryotic cells and prokaryotic cells is that prokaryotic cells lack membrane bound nucleus and also other membrane bound organelles, while eukaryotic cells contain membrane bound organelles including nucleus. So like other prokaryotes bacteria lack membrane bound nucleus and the membrane bound organelles.