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4.Principles of Inheritance and Variation
medium
$ABO$ blood groups in humans are controlled by the gene $I$. It 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
(AIPMT-2010)
Solution
(c) : The three alleles $I^A$, $I^B$ and $i$ of gene $I$ in $ABO$ blood group system can produce six different genotypes and four different phenotypes as shown below :
| Genotypes | Phenotypes |
|
$I^AI^B$ $I^Ai$ |
Blood group $A$ |
|
$I^BI^B$ $I^Bi$ |
Blood group $B$ |
| $I^AI^B$ | Blood group $AB$ |
| $i\ i$ | Blood group $O$ |
Standard 12
Biology
