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 information provided is not sufficient to determine which blood group trait (A or O) is dominant. The ABO blood group system is inherited through multiple alleles, and the determination of dominance is not solely based on the blood types of the parents and offspring.

In the ABO blood group system, there are three main alleles: A, B, and O. The A and B alleles are codominant, while the O allele is recessive. The possible combinations of alleles that result in the ABO blood groups are:

» Blood Group A: AA or AO (codominant)
» Blood Group B: BB or BO (codominant)
» Blood Group AB: AB (codominant)
» Blood Group O: OO (recessive)

Given that the daughter has blood group O, it means that both parents must have contributed an O allele. The father with blood group A could contribute either an A or an O allele, and the mother with blood group O would contribute an O allele. Therefore, the father could be AO or AA.

The information about the daughter having blood group O only tells us about the recessive phenotype (OO), but it does not provide information about the dominant phenotype in the father. It could be either blood group A (if the father is AO) or blood group O (if the father is AA).

In summary, based on the information provided, we cannot determine the dominance relationship between blood group A and O. Additional information about the genotype of the father is needed to make a conclusive determination about dominance.