Which feature defines eukaryotes?

Which feature defines eukaryotes?

• A. Cells with a nucleus and membrane-bound organelles.
• B. Lack of a nucleus.
• C. Unicellularity only.
• D. Cell walls without cellulose.

Answer: (A)

The defining feature of eukaryotes is that their cells have a true nucleus enclosed by a membrane and contain membrane-bound organelles that compartmentalize cellular processes. This organization sets them apart from prokaryotes, which lack a nuclear envelope and most internal membranes, with their DNA located in a nucleoid region and metabolism carried out in a more open cytoplasm. Unicellularity occurs in both groups, so it doesn’t define eukaryotes, and cell walls are not universal or restricted in a way that would distinguish the group—plants and some algae have cellulose, fungi have chitin, while many organisms lack cell walls altogether.

The defining feature of eukaryotes is that their cells have a true nucleus enclosed by a membrane and contain membrane-bound organelles that compartmentalize cellular processes. This organization sets them apart from prokaryotes, which lack a nuclear envelope and most internal membranes, with their DNA located in a nucleoid region and metabolism carried out in a more open cytoplasm. Unicellularity occurs in both groups, so it doesn’t define eukaryotes, and cell walls are not universal or restricted in a way that would distinguish the group—plants and some algae have cellulose, fungi have chitin, while many organisms lack cell walls altogether.