Explain5 marksChallenge
A woman who is a carrier for haemophilia (genotype X^H X^h) and a man with haemophilia (X^h Y) have ten children. The observed numbers, determined by DNA analysis, are:
- Normal male (blood clotting normal): 1
- Haemophiliac male: 4
- Carrier female (normal clotting): 4
- Haemophiliac female: 1
Explain the genetic basis of haemophilia inheritance and carry out a chi-squared test to determine whether these observed numbers are consistent with the expected Mendelian ratio for this cross.
Use the chi-squared formula: χ² = Σ (O - E)² / E. The critical value for 3 degrees of freedom at p = 0.05 is 7.815.