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WAEC Biology 1997 Question 55

Question 55

Chromosomes, DNA and Sex Linkage

In man haemophilia is recessive and sex linked. The probability of a carrier mother and a normal father having a haemophilic male is

  1. A.1/4
  2. B.1/8
  3. C.2/3
  4. D.1/2
  5. E.1
Show the answer and explanation

Answer: A (1/4)

Explanation

XHXh × XHY gives XHXH, XHXh, XHY, XhY, so 1 child in 4 is a haemophilic boy.