Question

$ABO$ blood groups in human beings are controlled by the gene $I$. has three alleles - $I^A$, $I^B$ and $i$. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur ?

• A. three
• B. one
• C. four
• D. two.

Answer 1

Answer: (C)

four

Answer 2

In human beings $ABO$ blood groups are controlled by gene $I$ which has three alleles $I^A$, $I^B$ and $I$. The six possible genotypes are $I^AI^A$, $I^AI^B$, $I^Ai$, $I^BI^B$, $I^Bi$ and $ii$. The phenotypes which occur by these genotypes are $A \,(I^AI^A$, $I^Ai)$, $B \,(I^BI^B$, $I^Bi)$, $AB\,(I^AI^B)$ and $O\, (ii)$.