Explain4 marksStandard
Explain how the presence of lactose switches on the lac operon in E. coli. In your answer, refer to the roles of regulatory and structural genes, and state whether the enzyme produced is inducible or repressible.
CAIE A Level Biology 9700 · Inheritance
Inheritance: explain question
How this question is marked
4 marks, so the mark scheme is looking for about 4 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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