Question

A child with blood type O is born to a woman named Ingrid, who has blood type B. Ingrid has narrowed down the possible father to two men she met on a wild ski vacation in the Swiss Alps. The first man, Lars, has blood type AB. The second man, Sven, has blood type A.​

Answer 1

1. Ingrid's blood type is BO.

2. No, Lars could not be the father.

3. Yes, Sven could be the father.

Step-by-step explanation:

Ingrids blood type is BO because she had to have an O recessive allele in order to have an O child. This means that her man has to have an O allele as well.

Lars has AB blood type so he has two dominant alleles that will always mask an O recessive. Lars children will never have an O blood type regardless of the female.

Sven has blood type A. Technically this could be he is AA or AO. However, the only way for Ingrid to have an O child is if the father also has an O allele so this means Sven has blood type AO.

Refer to the punnet squares that are attached.