Which feature distinguishes eukaryotic cells from prokaryotic cells?

• A. Presence of a nucleus and membrane-bound organelles
• B. Absence of DNA
• C. They are always unicellular
• D. They lack mitochondria

Answer: (B)

The key idea here is that eukaryotic cells have a defined nucleus and membrane-bound organelles, while prokaryotic cells do not. In eukaryotes, DNA is enclosed within a nucleus, and the cell contains various organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus that are wrapped in membranes and compartmentalize different cellular processes. Prokaryotes lack a true nucleus and lack membrane-bound organelles; their DNA sits in a region called the nucleoid and the internal structure is simpler overall.

DNA is present in both types of cells, so saying there is an absence of DNA is incorrect. Eukaryotic organisms are not restricted to being unicellular—they can be multicellular as well. And while there are some anaerobic eukaryotes with reduced or specialized organelles, the general and most accurate distinguishing feature is the presence of a nucleus and membrane-bound organelles in eukaryotes.