Q.6.  The person having genotype Ia  Ibwould show the blood group as AB. THis is because of 

a.  pleiotropy

b.  codominance

c.  segregation

d.  incomplete dominance

(b)  A B O blood grouping in humans is an example of codominance. A B O blood groups are controlled by gene I. Gene I has three alleles IA, IB and Ioi.       lA and IB are the dominant alleles. When IA and IB are present together, both express equally and produce the surface antigen.

Pleiotropy referred to the genetic effect of a single gene on multiple phenotypic traits.

Incomplete dominance is a genetic term in which gene does not completely dominate another allele.

Segregation is the separation of allele during the process pf gametogenesis. This is the basis of the reappearance of recessive character in F2-generation.