NAME: ____________________________ PERIOD:__________

 

DATE:_________________ DATE DUE:____________________

 

MULTIPLE ALLELES

 

1. In humans, blood type is affected by multiple alleles.  The allele for type A blood (IA) is codominant to the allele for type B blood (IB).  Presence of both of these alleles produces type AB blood. The third allele for type O blood is recessive (i).  Using a Punnett square, cross a person with AB blood with a person with type O blood.

 

___________ X ___________

 

 

 

 

 

 

 

 

 

 

a. What is the genotypic ratio of the offspring?

 

b. What is the phenotypic ratio of the offspring?

 

 

2. Using a Punnett square, cross a person that is heterozygous for type A blood with a person that is heterozygous for type B blood.

 

___________ X ___________

 

 

 

 

 

 

 

 

 

 

 

 

 

a. What is the genotypic ratio of the offspring?

 

b. What is the phenotypic ratio of the offspring?

 

 

2. Using a Punnett square, cross a person that is homozygous for type A blood with a person that has type AB blood.

 

___________ X ___________

 

 

 

 

 

 

 

 

 

 

 

 

a. What is the genotypic ratio of the offspring?

 

b. What is the phenotypic ratio of the offspring?

 

 

The Case of the Long Lost Son?

 

            Mr. Cash dies 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 already on record.  He had type AB blood.  His wife had type A, and the young man who claimed to be the long lost son had type O blood. The judge dismissed the case.

 

1. What is the genotype of Mr. Cash?

 

2. What are the two possible genotypes for Mrs. Cash?

 

3. Using a Punnett square, diagram the offspring that could be produced if Mrs. Cash had genotype IAIA and Mr. Cash had genotype IAIB.

 

 

 

 

 

 

4. What are the genotypes of the possible offspring?

 

 

5. Using a Punnett square, diagram the offspring that could be produced if Mrs. Cash had genotype IAi and Mr. Cash had genotype IAIB.

 

 

 

 

 

 

 

 

 

 

6. What are the genotypes of the possible offspring?

 

 

7. What are the possible genotypes of a person having blood type O?

 

 

8. What is the genotype of the young man claiming to be Mr. Cash’s long lost son?

 

 

9. Do you agree with the judge’s decision?  Why or why not?