What would be a child's blood type if the mother is a plus and the father is o plus?

Answer 1

Since the mother has an "O" blood type (which is recessive), she can only pass down "O" blood type alleles. This means both children must have at least one "O" allele (whether they express it depends on the allele they inherit from their father). Since the mother is RH positive, she has to have at least one positive allele. It is possible she carries a recessive RH negative allele. (An allele makes up half of your genes: one from dad, one from mom.)

This being said, we can now determine what alleles the children got from the mother and, by process of elimination, what was inherited by the father. The O negative child would have two O alleles, which means the parents must each have had an O allele. The negative allele again is recessive, so for the child to express this, he/she must have gotten a negative allele from both parents. This confirms that the mother has a recessive negative allele, although her blood type is O positive.

Now the B positive child gives us more limitations on what the father could be. The mother would have passed down an O allele to this second child, meaning that the B allele must have come from the father. The positive allele could have come from either the father or the mother (since the mother has a positive and negative allele), so it is undetermined what RH alleles the father completely has.

Since the father must have an O allele to pass down to the first child, a negative allele to pass down to the first child, and a B allele to pass down to the second child, it leaves us with only two possibilities of the father's blood-type:

B positive or B negative.

Hopefully this helps, but do remember that blood type is not completely a reliable way to eliminate a father. Any mutations in the child's genes may have caused him to express an allele that was not from the father, thus a paternity test would still be needed to know for sure. But from what we learn in High School Biology, "B+" and "B-" would be the correct answers in this case and probably follow 90% of the time (I am estimating here.)

Answer 2

Mother's blood group is B--it has to be if daughter is B and father is O. She could be either Rh positive or negative.

Brother could be either B or O and either Rh positive or negative.

Answer 3

Depending on the gene type of the A group the possible blood type could be 100% A

or

50% A and 50% O

Answer 4

O pos or B pos

Answer 5

B+