What did Mendel discover about genetic factors in pea plants

Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits. For instance, In a Punnett Square, which shows the predicted results of a breeding, it's easy to see why.

T - - - t

T TT Tt

t Tt tt

The top row shows the genotype, or genetic makeup of one tall F1 parent, Tt. The side shows the other tall Tt F1 parent. See how one allele is passed from each parent? This gives you the expected ratios from the F1 cross!