When two unlike unit factors responsible for a single character are present in a single individual, one unit factor is dominant to the other, which is said to be recessive.
Two factors for tall stems
Two factors for dwarf stems
If an individual contains unlike unit factors (e.g., one for tall and one for dwarf), then each gamete has a 50 percent probability of receiving either the tall or the dwarf unit factor.
The trait not expressed is controlled by the recessive unit factor.
If an individual contains a pair of like unit factors (e.g., both specific for tall), then all its gametes receive one of that same kind of unit factor
During the formation of gametes, the paired unit factors separate, or segregate, randomly so that each gamete receives one or the other with equal likelihood.
One of each factor
The trait expressed in the F1 generation is controlled by the dominant unit factor
Genetic characters are controlled by unit factors existing in pairs in individual organisms.