Final answer:
Viruses are the only option listed that are not considered prokaryotic cells because they lack a cell structure and are acellular entities that require a host to replicate.
Step-by-step explanation:
All of the following are examples of prokaryotic cells EXCEPT:
1) viruses
Prokaryotic cells are defined as unicellular organisms that lack a nucleus and other internal membrane-bound organelles. Bacteria, which include cyanobacteria and mycoplasma, are considered prokaryotes. Viruses, on the other hand, are not considered cells at all because they do not have a cell structure and cannot reproduce independently without a host. They are essentially nucleic acid enclosed in a protein coat and lack the characteristics of living cells. Additionally, they do not fit the definition of prokaryotic or eukaryotic because they are acellular. In contrast, bacteria and cyanobacteria have rigid cell walls, reproduce asexually, and have been on Earth for approximately 4 billion years. Mycoplasma, despite lacking a rigid cell wall, is still classified as bacteria, thus it falls under the prokaryotic category.
While viruses are typically considered non-living, they are not classified as prokaryotic cells. Prokaryotic cells, such as bacteria, cyanobacteria, and mycoplasma, lack a nucleus and other organelles. They have a simple structure and reproduce asexually.