What is a defining feature of procaryotic cells?

Prokaryotic cells are characterized by the absence of a true membrane-delimited nucleus, which is a fundamental distinction between prokaryotes and eukaryotes. Instead of being enclosed within a nuclear membrane, the genetic material in prokaryotic cells is found in a region called the nucleoid, which is not membrane-bound. This structural simplicity is reflective of the overall organization of prokaryotic cells, which are typically unicellular and lack many of the complex organelles found in eukaryotic cells.

The incorrect options provide features that are not applicable to prokaryotes. For example, the presence of a true membrane-delimited nucleus defines eukaryotic cells, which is in direct contrast to prokaryotic cells. Similarly, prokaryotic organisms are predominantly unicellular, meaning that the option regarding multicellularity does not apply. The complexity of organelles is also a characteristic of eukaryotic cells, as prokaryotic cells generally contain fewer and simpler structures. Thus, the defining feature of prokaryotic cells is their lack of a true membrane-delimited nucleus.