Give reasons for the appearance of new combinations
of characters in the `F_2 progeny.

Explanation

During the cross between two true breeding parents (RRYY and rrYY), the resultant offspring (F1) is heterozygous for the dominant trait. The recessive traits remain masked by the dominant trait in heterozygous condition, Eg: RrYy. When the Fl offsprings are let to self fertilize, they give rise to new combinations as the recessive traits reappear in homozygous conditions in some of the F2 offsprings. Eg: Rryy, ryy.