How did Gregor Mendel’s experiments support the law of segregation?

Gregor Mendel’s experiments with the common pea plant (Pisum sativum) provided the quantitative data necessary to formulate the law of segregation. By tracking single, distinguishable traits—such as seed color or plant height—across successive generations, Mendel observed patterns that contradicted the idea of blending inheritance.12

When Mendel crossed "pure" parent varieties (P generation) that differed in a single trait, the first-generation hybrids (F1) displayed only the dominant trait. However, when he allowed these F1 hybrids to self-pollinate, the recessive trait reappeared in the second generation (F2) in a consistent 3:1 ratio.12

Mendel inferred that each plant carries two "factors" (now known as genes) for every trait. His experiments demonstrated that these factors do not blend; instead, they remain distinct and separate during the formation of gametes. This process, where the two alleles of a gene pair separate so that each gamete receives only one, constitutes the law of segregation.13