Question

A mother with type A blood is about to have another baby. Her first child is type

O blood. Her husband is type B blood. What is the probability that their second
child will have a child with type AB blood?

Answer 1

The probability of the second child having type AB blood is 25%, given the parental genotypes are Ai (mother) and Bi (father) and the first child's type O blood indicating both parents carry the recessive O allele.

Step-by-step explanation:

The question is asking about the probability of a child having type AB blood given the parents' blood types. To determine this, we need to look at the genotypes of the parents. Since the first child has type O blood, which requires two recessive alleles (ii), and considering that type A and B can be either homozygous or heterozygous, we can infer that the mother is type A with a genotype of Ai (heterozygous), and the father is type B with a genotype of Bi (heterozygous).

When crossing these two genotypes, the possible genotypes of the offspring are:

• AB (expressing type AB blood)
• Ai (expressing type A blood)
• Bi (expressing type B blood)
• ii (expressing type O blood)

The probability of the second child having type AB blood is therefore 1 in 4, or 25%, as AB is one of the four possible genotypes resulting from this parental combination.