Describe the differences between prokaryotic cells and eukaryotic cells.

WJEC A-Level Biology (Wales) — 1.2 Cell structure and organisation · Describe · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Bacteria are prokaryotic cells. Human body cells are eukaryotic cells.

Model answer (5 marks)

1. Eukaryotic cells contain a nucleus, whereas prokaryotic cells lack a nucleus.
2. Eukaryotic cells have membrane‑bound organelles (e.g. mitochondria, endoplasmic reticulum), while prokaryotic cells do not.
3. Prokaryotic cells often contain plasmids – small, circular DNA molecules – which are generally absent in eukaryotic cells.
4. In prokaryotes, DNA is free in the cytoplasm; in eukaryotes, DNA is confined within the nuclear envelope.
5. Both cell types possess a plasma membrane and cytoplasm.

Examiner tips

Use the exact terms ‘nucleus’, ‘membrane‑bound organelles’, ‘plasmids’, and ‘cytoplasm’. Show the contrast for each point to gain full marks. Keep each point concise and separate with numbers or bullet points.

Common mistakes

Confusing ‘cytoplasm’ with ‘cell wall’ or omitting the plasma membrane. Using vague language such as ‘organelles’ without specifying ‘membrane‑bound’. Failing to mention plasmids or the free DNA in prokaryotes.

Mark scheme (5 marks)

Eukaryotic cells contain a nucleus / prokaryotic cells do not contain a nucleus
Eukaryotic cells contain membrane-bound organelles / prokaryotic cells do not contain membrane-bound organelles
Prokaryotic cells contain plasmids (circular loops of DNA) / eukaryotic cells generally do not
In prokaryotic cells, genetic material / DNA moves freely in the cytoplasm rather than being contained in a nucleus
Both prokaryotic and eukaryotic cells have a cell membrane and cytoplasm

Key terms in this question

prokaryotic cell · eukaryotic cell