2017 Principles of Inheritance and VariationMultiple alleles - ABO blood groups Medium Question 3 of 4 in Multiple alleles - ABO blood groups

The genotypes of a Husband and Wife are $I^AI^B$ and $I^Ai$. Among the blood types of their children, how many different genotypes and phenotypes are possible?

A 3 genotypes ; 3 phenotypes
B 3 genotypes ; 4 phenotypes
C 4 genotypes ; 3 phenotypes
D 4 genotypes ; 4 phenotypes

The answer is C.

Solution

Four genotypes collapse into three phenotypes (A, AB, B).

Husband $I^AI^B$ × Wife $I^Ai$ Offspring: $I^AI^A$, $I^AI^B$, $I^Ai$, $I^Bi$ Number of genotypes = 4 $I^AI^A$ and $I^Ai$ = A; $I^AI^B$ = AB; $I^Bi$ = B Number of phenotypes = 3

Concept abo-cross-genotypes-phenotypes

Multiple alleles - ABO blood groups in past papers

4 questions from this chapter have appeared across 4 exam years.