If offspring is O+ what blood type would parents have to have to make this possible?
closed as off-topic by rg255, MattDMo, anongoodnurse, fileunderwater, AliceD♦ Mar 30 '16 at 8:57
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Homework questions are off-topic on Biology unless you have shown your attempt at an answer. For more information see our homework policy." – rg255, MattDMo, anongoodnurse, fileunderwater, AliceD
The parents of a child with 0+ have the blood group A, B or 0, but not AB. And one or both parents are positive regarding the Rhesus-Factor (+).
There are several factors and derived systems that allow a classification into blood groups. Your example covers two: the AB0-system and the rhesus-system.
The AB0-system covers four groups: A, B, AB, and 0. In other words: people either have factor A, factor B, both factors or none. People with factor A either hand this factor down to their child, or they don't. Accordingly, people with factor B either hand it down or not. People with AB in any case hand down one factor, either A or B. People without a factor (group 0) can't hand down A or B. Given those rules, a child with griup 0 did not inherit factor A nor B. So the parents of this child don't have group AB, but can have any of the other three groups.
The rhesus-system is about having (being positive, +) or lacking (being negative, -) an other factor, the so called Rhesus factor. A rhesus- positive person either does or doesn't hand down this factor to his/her children. A rhesus-negative person has nothing to hand down. Thus, knowing that the child in your example is rhesus-positive, it did inherit this factor from at least one of its parents. This, one can assume that one or both parents also carry this factor.
- There can be rare exceptions from the above mentioned rules.
- There are more details about this topic worth reading. However, I skipped them to keep the answer readable.