Question

Complete the Punnett square and select the best response for this cross. (May take more than one Punnett Square)

Mrs. Lee has type A blood

Mr. Lee has a type B blood

Baby Lee has type O blood

Is it possible that Mr. Lee is NOT the baby daddy, and why?

a
no, he is most likely the father
b
yes, he is not the father because B is dominant
c
yes, if he is homozygous for B
d
no, a cross between type A and B can always produce type O

Answer 1

fathers blood type is B, he can be BB or Bi
mothers blood type is A, she can be AA or Ai

if the baby has type O blood, he/she must be ii

therefore the mother should be Ai, father should be Bi

If the father is homozygous for B, he would be BB, so the baby can only be AB or Ai, which will not give type O blood

So Mr Lee cannot be the father if he is homozygous for B

Answer: C