Mendel conducted a monohybrid cross with pea plants. He observed that one of the contrasting characters disappears in F1 generation. This character reappears in F2 generation (obtained by selfing F1) in just 25% of the progeny.
Mendel concluded that the character which expresses itself in F1 is the dominant character while the other one which is not able to express though it is present in F1 individuals is recessive. This recessive character is able to express only in its pure form, i.e., in 25% of F2 individuals.
