In genes at one locus mask the effect of genes at another l

In ____, genes at one locus mask the effect of genes at another locus.

In the following list, pick the one that is not a source of genetic variability from meiosis and fertilization.

Solution

1)

In epistasis genes at one locus mask the effect of genes at another locus. Thus, the correct option is epistasis. For example, the A is dominant over a and B is dominant over b. The allele A can express itself only in the presence of ‘B’ or b allele, whereas B expresses only in the presence ‘aa.’ In this condition, the traits won’t express typical medalian ratio, namely 9:3:3:1, instead the ratio would be 12:3:1.

2)

Physical arrangement of chromosomes along the metaphase plate in preparation for anaphase is the one that is not a source of genetic variability from meiosis and fertilization. Thus, the correct option is (a).