Question

Define complete linkage. Give an example of a cross, showing complete linkage.

Answer 1

Complete linkage: Linkage of genes on a chromosome which is not altered and is inherited as such from generation to generation without any crossover. In this type of linkage, genes are closely associated and tend to remain together. For example, male Drosophila and female silk worm(Bombyx mori).
100% Parental combinations indicated that the gene for grey body colour is completely linked with long wings. In this dihybrid, $F_2$ phenotypic ratio is $3:1$ and test cross ratio is $1:1$(like a monohybrid).