CAIE A Level Biology 9700 · Classification, biodiversity and conservation

Classification, biodiversity and conservation: outline question

Outline5 marksStandard

A student is comparing the characteristics of two prokaryotic organisms, Organism X and Organism Y. Their features are shown in the table below.

Feature	Organism X	Organism Y
Membrane lipid linkage	Ether-linked	Ester-linked
Ribosomal RNA signature	Unique sequences	Typical bacterial sequences
Cell wall composition	Lacks peptidoglycan	Contains peptidoglycan

Outline how these features support the classification of Organism X into the domain Archaea and Organism Y into the domain Bacteria. In your answer, also outline the basis of the three-domain classification system.

How this question is marked

5 marks, so the mark scheme is looking for about 5 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.

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