genetics
A. Medelian inheritance has its physical basis in the behavior of chromosomes during sexual life cycles. Biologists began to see parallels between the behavior of chromosomes and the behavior of Medel’s factors. Chromosomes and genes are both present in pairs in diploid cells, homologous chromosomes separate and alleles segregate during meiosis, and fertilization restores the paired condition for both chromosomes and genes. these parallels formed the chromosome theory of inheritance. B. Morgan studied fruit flys, prolific breeders.