CAIE A Level Biology 9700 · Nucleic acids and protein synthesis
A student compares DNA from two bacterial species. Species A has a GC content of 70%, while Species B has a GC content of 40%. The student finds that the DNA from Species A denatures at a significantly higher temperature than the DNA from Species B.
Explain why DNA with a higher GC content is more stable and requires a higher temperature to denature.
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.
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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