Haemophilia is more common in males because

  1. it is on the Y chromosome
  2. males have two X chromosomes
  3. the allele is dominant
  4. males have only one X chromosome
Answer

D) males have only one X chromosome

X-linked recessive conditions show in hemizygous males. AS & A Level Biology · Topic 16 Inheritance · 16.2 The roles of genes in determining the phenotype

Biology MCQ · More A Level Biology: Inheritance MCQs · Practise