CAIE A Level Biology 9700 · Cell structure
A microbiologist isolates a particle from a patient's respiratory sample. Analysis shows the particle is 0.08 µm in diameter, contains RNA but no DNA, has a protein coat surrounded by a phospholipid bilayer, and does not contain any ribosomes. The particle is unable to carry out respiration or protein synthesis on its own.
Explain whether this particle is a virus, a prokaryote, or a eukaryote.
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.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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