Blood groups
1. Humans can have one of four possible blood types: O, A, B. and AB. These are the result of three
alleles for blood proteins (multiple alleles) that are inherited as a single gene trait of two alleles. The
possible genotypes and phenotypes are as follows: ii is type O; IAIA and IAi are type A; IBIB and IBi
are type B; AB is type AB. A young man has type AB blood and his sister has type O blood. What
are their genotypes and the genotypes of the parents?
2. A woman with type A blood marries a man with type O blood. They have six children, all of whom
have type A blood. What are the probable genotypes of the parents? Could they possibly have a
child with type O blood?
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7. A man homozygous for type A blood marries a woman who is heterozygous for type B blood. What
will be the possible genotypes and phenotypes of their children?
8.
Suppose a blood type B boy, has blood type A mother.
a. What are the possible genotypes of the father? (Hint: there are 3 possibilities)
b. What must the mother’s genotype be?
9. A man with type B blood marries a woman with type A blood. They have the first child with blood
type O.
a. What are the genotypes of the father and the mother?
b. What is the genotype and phenotype of the baby?
10. A man with type B blood marries a woman with type A blood. They have the first child with blood
type O.
a. What are the genotypes of the father and the mother?
b. What is the genotype and phenotype of the baby?
11. A man with type O blood marries a woman with type AB blood. What is the predicted genotypic
and phenotypic ratios of their children?
12. Mr. Cash died and left all his money to his two children. A young man claiming to be a lost third
child sued for his share of the estate. The judge ordered blood tests for all family members and for
the young man. Mr. Cash’s blood type was AB. His wife had type A. Using a Punnett square,
diagram the offspring that could be produced if Mrs. Cash had genotype AA and Mr. Cash had
genotype AB.
a. Which phenotypes could result among the offspring of this marriage?
b. Using another punnett square diagram the possible offspring if Mrs. Cash had genotype AO and Mr.
Cash had genotype AB.
a. Which phenotypes could result among the offspring of this marriage? The man claiming to be the
long-lost son then went for his blood test. He had type O blood.
b. What is the genotype of the young man claiming to be Mr. Cash’s long lost son?
c. Could this young man have been Mr. Cash’s son?