Question

The number of phenotypes in ABO Blood group is
A) 1
B) 4
C) 6
D) 8

Answer 1

Hint: Blood group is determined by the antigen present on the surface of RBC’s. For example, If antigen A is present, the blood group is A and the blood contains antibodies against antigen B i.e anti - B antibodies.

Complete answer: ABO Blood grouping is the method to classify RBCs on the basis of antigens present on their cell surfaces. There are mainly four types of blood groups namely A, B, O and AB. These blood groups were founded by Karl Landsteiner in 1901. Type A blood groups have A antigens on RBC’s and B antibodies in plasma. Type B blood groups have B antigens on RBC’s and antibodies in plasma. Type O groups have both A and B antigens on RBC’s but the antibodies are absent in plasma. Lastly, O blood groups have both A and B antibodies in plasma but none of the antigens on RBC’s. There are 3 alleles responsible for blood groups I^A, I^B and i. ii genotype gives O blood group phenotype, I^AI^A gives A phenotype, I^BI^B gives B blood group phenotype, and I^AI^B gives AB blood group phenotype.
Hence, the correct answer is option B.

Additional information: Agglutination method is used to determine the blood group. In this method, antisera containing antibodies are present. This antisera is added to the blood. If agglutination happens with A antibodies then the blood group is A-type, and similarly, it is done to test other blood groups as well.

Note: I^A and I^B are dominant alleles and I^O is recessive to both .I^A and I^B together show co-dominance and give AB genotype. O blood group is also known as a universal donor as it can donate blood to type A, B and O, whereas type AB is a universal recipient and can receive blood from A, B and O.