Final answer:
The chances of a heterozygous blood type A parent and a heterozygous blood type B parent having a child with blood group B is 25%.
Step-by-step explanation:
Probability of Child with Blood Group B
When considering the inheritance of ABO blood groups, both blood type A and blood type B are codominant. A man with blood group A (genotype Ao) and a woman with blood group B (genotype Bo) can have a child with any of the four ABO blood types, since both A and B alleles are dominant over the O allele (denoted as 'i').
If both parents are heterozygous, meaning they each carry one dominant allele for their respective blood type (A or B) and one recessive allele for blood type O (i), the possible genotype combinations for their offspring can be represented using a Punnett square with the following genotypes: Ai, Ai, Bi, and Bi.
This means that each child has the following probabilities for their blood type:
- Type A: 25% (Ai)
- Type AB: 25% (AB)
- Type B: 25% (Bi)
- Type O: 25% (ii)
Therefore, the chances of them having a child with blood group B is 25%.