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Haemophilia is a recessive sex-linked disorder - Edexcel - GCSE Biology - Question 1 - 2014 - Paper 1
Question 1
Haemophilia is a recessive sex-linked disorder. This family pedigree shows the inheritance of haemophilia. (a) (i) State the sex chromosomes of person B. (ii) Exp... show full transcript
Worked Solution & Example Answer:Haemophilia is a recessive sex-linked disorder - Edexcel - GCSE Biology - Question 1 - 2014 - Paper 1
Step 1
Step 2
Explain why the male offspring from A and B do not have haemophilia.
Answer
The male offspring from A and B do not have haemophilia because they inherit the Y chromosome from their father (A), which does not carry the haemophilia allele. Furthermore, person B is a carrier and does not have the disorder, meaning she possesses one normal allele on one of her X chromosomes. Therefore, there is a chance that the male offspring would inherit the normal X chromosome from B, thus they would not express the haemophilia condition.