CAIE A Level Biology 9700 · Classification, biodiversity and conservation
The table below shows some differences between Archaea and Bacteria.
| Feature | Archaea | Bacteria |
|---|---|---|
| Membrane lipid structure | Branched hydrocarbon chains | Straight-chain fatty acids |
| Ribosomal RNA sequence | Distinct from Bacteria and Eukarya | Distinct from Archaea and Eukarya |
| Cell wall composition | No peptidoglycan; may be composed of other polysaccharides | Contains peptidoglycan |
Outline the evidence that led to the classification of Archaea and Bacteria into separate domains.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Outline means: Give the main points briefly. Less detail than describe, but every key step has to be there. One short line per step, in order. The marks are for coverage, not depth.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.