Answer:
Part 1:
The mother’s genotype is ii, rr, MN
The father’s genotype is IAIA/IAi, Rr, MM
Part 2:
Approximately 1/32 (3.125%) of children can be expected to have the stated blood types.
Explanation:
Part 1:
The mother has blood types 0, Rh- and MN. Therefore, her genotype has to be ii, rr, MN.
The father has ABO type A. His ABO genotype may therefore be either IAIA or IAi, as both are compatible with type A offspring with a type 0 mother. His Rh genotype must be rr, since his Rh- child necessarily has to have inherited one r allele from each parent. Finally, his MN genotype has to be MM since both alleles are codominant.
Part 2:
Using the given data, we build the following Punnett chart:
IA R N IA r N i R N i r N
IA R M
IA R N
IA r M
IA r N
IB R M
IB R N
IB r M X
IB r N
Note that, of all 32 possible combinations, only a single one of them (marked with “X” produces a genotype which matches the desired blood type, as follows:
genotype: IBi, rr, MN
blood type: B, Rh-, MN
