Final answer:
The chance of a child having blood type O from parents with genotypes BO (type B) and AO (type A) is 6.25% because both parents must pass on the recessive 'i' allele.
Step-by-step explanation:
When two parents with blood types B (BO) and A (AO) have a child, the possible combinations of alleles that the child can inherit are AO, BO, AB, and OO. To calculate the probability of inheriting blood type O (genotype 'ii'), we need to consider that both parents must contribute the recessive allele 'i'. Parent 1 (type B, genotype BO) can pass on either the B allele or the O allele. Similarly, parent 2 (type A, genotype AO) can also pass on either the A allele or the O allele. In order for their child to have blood type O, the child must receive the O allele from both parents (genotype OO). This can only occur if both parents pass on the recessive 'i' allele.
Using a Punnett square, we can see that there is a 1 in 4 chance of the child having blood type O:
- Parent 1 (BO) contributes B: 25% chance
- Parent 1 (BO) contributes O: 25% chance
- Parent 2 (AO) contributes A: 25% chance
- Parent 2 (AO) contributes O: 25% chance
Therefore, the combination we're looking for (both parents contributing 'i') has a probability of 0.25 x 0.25 = 0.0625, or 6.25%. Thus, there is a 6.25% chance of the child having blood type O.