Blood Genes Name A is dominant + O is recessive. AB is a codominant blood type. Rh+ is dominant over Rh-. Rh is a separate gene from ABO.
Blood Type Problem: The following are possible blood types for the offspring in a Punnett square:
a. A+O+
b. A+AO+ or A+O-
c. A+ARh+O+ or A+ARh+O-
d. A+ARhO- or A+OARhO-
Multiple Alleles: In blood typing, there are three alleles involved - A, B, and O. A and B are dominant over O. Any combination of A and B results in type AB blood. Type O is recessive and does not have any dominant alleles. A person with type AB blood can physically carry both A and B alleles. A person with type B blood can only carry the B allele. A person with type A blood can only carry the A allele. A person with type O blood does not carry any A or B alleles.
Blood Type Inheritance:
12. A man with type AB blood marries a woman with type O blood, but whose father was type A blood. The possible genotypes for their first child are A+O+ or A+O-.
13. A man with type B blood marries a woman with type A blood. They have a child with type A blood. The genotypes of the father, mother, and child are B+AO+, A+AO+, and A+AO+ respectively.
14. A man whose father is type B and whose mother is type A marries a type A woman whose parents had the same blood types as his parents. The possible genotypes for their child are A+AO+ or A+AO-.