Q46. The number of phenotypes in ABO blood groups is:
(a) 3
(b) 4
(c) 5
(d) 6

Question

FirstInTest · Accepted Answer

Correct answer: b. The ABO blood group system in humans is an excellent example of multiple allelism and co-dominance. It is controlled by three alleles: I^A, I^B, and i. These alleles can combine to form six different genotypes (I^A I^A, I^A i, I^B I^B, I^B i, I^A I^B, ii). However, these genotypes result in only **four** distinct phenotypes:
1.  **Blood group A:** Genotypes I^A I^A or I^A i
2.  **Blood group B:** Genotypes I^B I^B or I^B i
3.  **Blood group AB:** Genotype I^A I^B (due to co-dominance of I^A and I^B)
4.  **Blood group O:** Genotype ii (recessive to both I^A and I^B)
Therefore, there are 4 phenotypes in ABO blood groups.

Related Questionsin Biology / Genetics

Practice More CUET UG Questions