question_answer 24)

  In a dihybrid cross, if you get 9 : 3 : 3 : 1 ratio it denotes that (a) the alleles of two genes are interacting with each other (b) it is a multiple inheritance (c) it is a case of multiple allelism (d) the alleles of two genes are segregating independently

Answer:

                    (d) Alleles of two genes are segregating independently. It can be explained as. Suppose crosses are made between a pea plant with round and yellow seeds and one with wrinkled and green ones. All  hybrids give yellow and round seeds. Since yellow colour is dominant over the green and the round shape is dominant over the wrinkled. When the -hybrid plants are crossed to each other or allowed to selffertilize, an-generation form as represented in the following figure The outcome of the dihybrid cross make it very clear that segregation of the seed colour is independent of the seed shape and both the parental and new combinations of the characters appear in the  offspring, i.e., assortment of genes of one pair is independent of the other pair. When the alleles of two genes are interacting with each other one may dominate over other or become recessive. During a multigenic inheritance we describe a characteristics that is specified by a combination of multiple genes. Multipleallelism is a type of non-mendelian inheritance pattern that involves more than just the typical two alleles.