A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
The given information is not enough to determine the traits- blood group A or O is dominant. In ABO blood grouping blood type A is always dominant whereas, the blood type O is always recessive. Here the father's blood group is A hence, it can either be homozygous (AA) or heterozygous (AO). The mother's blood group is O and it is only possible if it is heterozygous (OO). For the daughter to have blood group O the father must be heterozygous (AO) and mother must be (OO).
