Question

Which of the following pairs of genotype a result in the same phenotype?
A IAIA and IBIB
B. IAIA and IAi
C. IBIB and ii
D. IBi and ii

Answer 1

Often the genotype is just written as AA, AO for blood type A, etc. The I with superscript A is referring to a gene that creates the A antigen, the I with superscript B is referring to the allele creating the B antigen, and the allele that cannot create an A or B antigen is denoted lowercase i. Thus: I^AI^A is equivalent to AA I^AI^B is equivalent to AB I^BI^B is equivalent to BB I^Bi is equivalent to BO and so on... So: a) genotype AA (or I^AI^A) is blood type A, genotype AB (or I^AI^B) is blood type AB b) genotypes BB (or I^BI^B) and BO (or I^Bi) are blood type B c) genotypes BB (or I^BI^B) and AB (or I^AI^B) are blood types B and AB, respectively d) BO (or I^Bi) and OO (or ii) are blood types B and O, respectively Therefore, answer b is the only combination of two genotypes that both result in the same phenotype.