To determine the phenotypic ratio for the offspring of parents 3, we need to consider the genotypes of the parents. For parents 3, the mother has blood type AB, and the father has blood type O.
Mother's genotype: AB (can donate either A or B allele)
Father's genotype: OO (can donate only O allele)
Given these genotypes, the possible alleles that each parent can pass on to their offspring are as follows:
- Mother can pass on A or B.
- Father can pass on O.
The potential combinations of alleles in the offspring are:
- A from mother and O from father (resulting in genotype AO)
- B from mother and O from father (resulting in genotype BO)
Next, we list the possible genotypes of the offspring:
- AO
- BO
Now, we examine the phenotypes corresponding to these genotypes:
- Genotype AO results in blood type A.
- Genotype BO results in blood type B.
Since each combination (AO and BO) is equally likely, the phenotypic ratio of the offspring is:
- 50% (1/2) blood type A (from AO)
- 50% (1/2) blood type B (from BO)
Thus, the correct answer is:
A. [tex]$1 / 2$[/tex] type A and [tex]$1 / 2$[/tex] type B
