Final answer:
The incorrect statement about prokaryotic cells is that they lack a plasma membrane; they do have a plasma membrane which serves as an essential barrier for the cell.
Step-by-step explanation:
The incorrect statement regarding prokaryotic cells is: They lack a plasma membrane. This statement is not true because all prokaryotic cells do have a plasma membrane which contains the cell contents and acts as a protective barrier. Other characteristics of prokaryotic cells include the absence of membrane-enclosed organelles, having typically a single circular chromosome, lacking a nucleus with the DNA not enclosed within a membrane, and reproducing by binary fission.