Q2 of 53 Page 33

Can a child have blood group O if his parents have blood group ‘A’ and ‘B’. Explain.

Yes it is possible for a child to have blood group O if his parents have blood groups A and B. ABO blood grouping in humans is controlled by the gene I. The gene (I) has three alleles IA,IB and i. The genotype of blood group A is IAIA or IAi; blood group B is IBIB or IBi and that of blood group O is ii.

So for a child to have O blood group, his parents should be with blood group genotype as IAi and IBi . Hence when the allele from parent 1 is”i” and allele from parent 2 is “i” the genotype of offspring becomes “ii” which means the blood group is O.


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