Which term best describes organisms that can be unicellular or multicellular and contain a nucleus and membrane-bound organelles?

• A. Eukaryote
• B. Prokaryote
• C. Cell
• D. Organism

Answer: (A)

Organisms that can be unicellular or multicellular and contain a nucleus and membrane-bound organelles are eukaryotes. This means their cells have a true nucleus enclosed by a membrane and internal compartments—like mitochondria and, in plants and algae, chloroplasts—that perform specialized functions. This combination sets them apart from prokaryotes, which are typically unicellular and lack a true nucleus and the membrane-bound organelles. While a cell is simply the basic unit of life and an organism is any living being, those terms don’t specify the cellular organization that defines eukaryotes. Examples include plants, animals, fungi, and many protists, whether they live as single cells or as many-celled bodies. So the term that best fits is eukaryote.