What term describes organisms that contain a membrane-bound nucleus and specialized organelles?

The term that describes organisms containing a membrane-bound nucleus and specialized organelles is "Eukaryotes." Eukaryotic cells are characterized by their complex structure, which includes various organelles such as the endoplasmic reticulum, Golgi apparatus, mitochondria, and in plant cells, chloroplasts. The presence of a membrane-bound nucleus allows for the compartmentalization of genetic material, which is enclosed and kept separate from the cytoplasm. This cellular complexity enables eukaryotic organisms to perform more advanced functions and processes compared to simpler organisms.

In contrast, prokaryotes, which refer to organisms like bacteria and archaea, do not have a membrane-bound nucleus or specialized organelles. They are simpler in structure, with their genetic material floating freely in the cytoplasm. Archaea are a specific group of prokaryotes that are distinct in their genetic makeup and biochemistry. Viruses, on the other hand, are not considered living organisms; they lack cellular structure entirely and cannot perform metabolic processes on their own. Thus, eukaryotes uniquely fit the description provided in the question.