Biology CLEP Prep 2025 – 400 Free Practice Questions to Pass the Exam

The key difference between procaryotes and eucaryotes is the presence of a membrane-bound nucleus. Procaryotes, such as bacteria, do not have a distinct nucleus and their genetic material floats freely in their cytoplasm. Eucaryotes, on the other hand, have a membrane-bound nucleus that contains their genetic material. This allows for more complex genetic processes to occur in eucaryotes. The other options are incorrect because while some eucaryotes may be multicellular (option A), have a cell wall (option C), or have a photosynthetic organelle (option D), these characteristics are not exclusive to eucaryotes and can also be found in certain types of procaryotes. Therefore, the presence of a membrane-bound nucleus is the most distinguishing difference between these two types of organisms.