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?

From the given information above, the answer would be that type O blood is not dominant. To explain this, all blood types consist of genotypes and these genotypes consist of two letters. For blood type A (A, i) and (A, A); for blood type B (B, i) and (B, B); For blood type AB, there is only one which is (A, B) as well as for O which is (i, i). The capital letters are considered as the dominant whereas, the lowercase letters are recessive. So to conclude, blood type O is a recessive blood type. Going back to the information given, the father is blood type A which is (A, i) whereas the mom has a blood type O (i, i) and the daughter is also blood type O (i, i). Therefore, what the daughter got from his dad is i, and another i from the mother, which makes her having a blood type O.