A cross between two heterozygous F1 plants produces a 15:1 ratio in the F2 generation. What type of ratio is this?

A 15:1 ratio in the F2 generation typically arises from a modified dihybrid cross. This specific ratio results from the phenotypic expressions of two genes where one trait is dominant and the other does not express as often due to epistatic interactions.

In this case, when two heterozygous plants are crossed, the expected ratios of traits demonstrate that one of the traits is dominant, overwhelming the other to create fewer observable phenotypes. The 15:1 ratio indicates that there is one phenotype for the dominant traits that collectively outweighs the one phenotype for the recessive traits. Enhanced interaction between two genes leads to this unusual distribution, hence identifying it as a modified dihybrid ratio rather than a standard monohybrid or dihybrid ratio.

The other ratios mentioned, like the normal monohybrid or normal dihybrid ratios, do not fit because they generally reflect outcomes of one gene pair or two independently assorting gene pairs without any interaction effects that cause such a skewed distribution. Therefore, the observation of a 15:1 ratio signifies a more complex relationship, characteristic of a modified dihybrid scenario where genetic interactions significantly alter expected outcomes.