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Use a double square (dihybrid cross) to determine the possible genotypes and phe

ID: 211156 • Letter: U

Question

Use a double square (dihybrid cross) to determine the possible genotypes and phenotypes for this couple’s child. Give percentages and show your work. Remember that blood type A and B are dominant, and blood type O is recessive. The Rh factor is inherited as dominant, and you should use (D, d) to track this. So, Rh+ is either DD or Dd, and Rh- is dd. Glenn has blood type A- and is heterozygous for A, Maggie has blood type O-. What are the possible genotype and phenotype outcomes for their child? In this case, is it possible that the child could have a phenotype different than at least one of its parents?

Explanation / Answer

For Glen the blood group is A-, genotype is IAIO dd

maggie has bllod group O.- , genotype=IOIO dd

IAIO dd X IOIO dd

IAd

IA d

IO d

IO d

IO d

IA IO d d

IA IO d d

IO IO d d

IO IO d d

IO d

IA IO d d

IA IO d d

IO IO d d

IO IO d d

For the chilldren the genotype will be either IAIO dd or IOIO

the phenotype will be A- or O-

there is no possibility that the child will have a phenotype different from any one of its parent.

IAd

IA d

IO d

IO d

IO d

IA IO d d

IA IO d d

IO IO d d

IO IO d d

IO d

IA IO d d

IA IO d d

IO IO d d

IO IO d d