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WAEC Biology 2013 Objective — Question 54

Question 54 of 60 from the West African Examinations Council (WAEC) Biology 2013 Objective paper, with the correct answer and a full explanation.

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A man who suffers from haemophilia marries a woman who is a carrier, what percentage of their children are likely to be haemophilic?

  • A. 25%
  • B. 50%Correct
  • C. 75%
  • D. 100%

Explanation

As explained in the related genetics question on incompatibility of Rhesus factor between an intending couple leading to still-births, using the cross for haemophilia carriers, 50% of the children are expected to be affected (note that females will only suffer from the disease when both X-chromosomes are affected).

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