OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is a key feature of prokaryotic cells compared to eukaryotic cells?

1. Presence of organelles

2. Absence of a nucleus

3. Presence of a complex structure

4. Ability to perform photosynthesis

The correct answer is: Absence of a nucleus

Prokaryotic cells are characterized by their simplicity and lack of compartmentalization. One of the defining features of prokaryotes is their absence of a nucleus; instead of having their genetic material contained within a membrane-bound nucleus as seen in eukaryotic cells, prokaryotes have their DNA freely floating in the cytoplasm in a region known as the nucleoid. This fundamental difference highlights the simpler structure of prokaryotic cells, which typically also lack other membrane-bound organelles such as mitochondria or the endoplasmic reticulum. This structural simplicity is a key distinction that defines prokaryotic life forms, including bacteria and archaea, in contrast to the more complex eukaryotic cells found in organisms like plants, animals, and fungi.