Question

In Snapdragon, a cross between true-breeding red flowered (RR) plants and true breeding white flowered (rr) plants showed a progeny of plants with all pink flowers. (a) The appearance of pink flowers is not known as blending. Why? (b) what is this phenomenon known as.

Answer 1

In snapdragon a cross between true breeding red flowered plant (RR) and true breeding white flowered plant (rr) will result in the progeny being heterozygous (Rr) and having pink flowers. Neither of the traits are dominant over the other and one allele does not mask the effect of the other. As a result, the phenotypic result is a blend in expression of the two phenotypes resulting in pink flowered plants (a third different phenotype). It is therefore a form of intermediate inheritance.
(a) However, only blending of phenotypes is seen and there is no actual blending of alleles or genetic material. Therefore, it cannot be said to be blending inheritance.
(b) This phenomenon is called incomplete dominance.