Question

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? Explain.

Answer 1

• 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).