CAIE A Level Biology 9700 · Inheritance
Haemophilia in humans is caused by an X-linked recessive allele. A woman whose father had haemophilia (but whose mother had no family history of the condition) is expecting a child with a man who has no family history of haemophilia. Determine the probability that the child will have haemophilia. Support your answer with a genetic diagram showing the genotypes of the parents and the possible offspring.
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.
Determine means: Find a value or an answer from the information or data provided. Show the working that gets you there, so a slip still leaves the method marks.
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