Question

a couple has four children. the first child has type A blood.the second child has type o. The third child has type AB blood and the fourth child has type B. What are the genotypes of the parents?

Answer 1

One parent has blood genotype BO and the other has blood genotype AO.

Step-by-step explanation:

There are 4 different genotypes shown, so all 4 "letters" must be utilized. Additionally, the third child has type AB, and since each "letter" comes from a parent, one parent has "A", and the other has "B". Finally, since the second child has type O, and "O" only shows up when the genotype is "OO", that means that each parent must also have "O" in their genotype, which leaves us with one parent having genotype BO and the other with genotype AO.