Body Fluids and Circulation Question 27
27. With respect to the $ABO$ group, there are four major blood types because this blood group is determined by
[1998]
(a) three alleles, all of which are recessive.
(b) three alleles, of which, two are recessive and the third is dominant.
(c) three alleles, of which two are co-dominant and the third is recessive.
(d) three alleles, all of which are co-dominant.
Show Answer
Answer : c
Hints & Solutions
(c) Blood group is determined by three alleles - $I^{A}, I^{B}$, and $I^{o}$. Alleles $I^{A}$ and $I^{B}$ are codominant. Blood group $A$ is determined by $I^{A} I^{A}$ or $I^{A} I^{O}$. Blood group $B$ is $I^{B} I^{B}$ or $I^{B} I^{o}$. Blood group $O$ is $I^{\circ} I^{\circ}$. Blood group $AB$ is $I^{A}$ $I^{B}$.
