Question

Blood types A and B are codominant to blood type O. If Lola is heterozygous for blood type A and Keenan is heterozygous for Type B blood, what is the probability their offspring will have type O blood?

A.
0% (0/4)
B.
25% (1/4)
C.
50% (2/4)
D.
75% (3/4)
E.
100% (4/4)

Answer 1

Since blood type A and B are codominant, Lola’s genotype is IAi (where IA is a dominant allele for blood type A and i is a recessive allele for blood type O). Similarly, Keenan’s genotype is IBi (where IB is a dominant allele for blood type B and i is a recessive allele for blood type O).

When these two individuals have offspring, there are different possible combinations of their alleles in the offspring. Specifically, the possible genotypes for their offspring are IAIB (blood type AB), IAi (blood type A), IBi (blood type B), and ii (blood type O).

To determine the probability of having offspring with blood type O, we need to calculate the probability that each offspring receives an i allele from both parents.

- If an IAi parent and an IBi parent each donate an i allele, the offspring would have blood type O. The probability of this occurring is:

1/2 (chance of getting i allele from Lola) x 1/2 (chance of getting i allele from Keenan) = 1/4

Therefore, the probability of their offspring having blood type O is 1/4 or 25%, so the answer is (B) 25% (1/4).