How did chromosome behavior during meiosis provide evidence for Gregor Mendel’s law of segregation?

The law of segregation, formulated by Gregor Mendel, posits that the two members of a gene pair (alleles) separate during the formation of gametes. While Mendel developed this principle through his experiments with pea plants without knowledge of cellular mechanisms, the behavior of chromosomes during meiosis provides the physical evidence for this law.123

During meiosis, homologous chromosomes—one of maternal origin and one of paternal origin—pair up and then separate into different cells. Because these chromosomes carry the genes, their physical separation ensures that the two alleles for a given trait are segregated into different gametes. Consequently, each gamete receives only one member of each homologous chromosome pair, resulting in half of the gametes carrying one allele and the other half carrying the alternative allele. This chromosomal movement directly mirrors the pattern of inheritance Mendel observed, confirming that genes are distinct units transmitted through the reproductive mechanism.213