Great Migration: Life for Migrants in the City. By the end of 1919, some 1 million blacks had left the South, usually traveling by train, boat or bus; a smaller number had automobiles or even horse-drawn carts.
Genetic variation is increased by meiosis During fertilisation, 1 gamete from each parent combines to form a zygote. Because of recombination and independent assortment in meiosis, each gamete contains a different set of DNA.
B. Mendel's second law, the law of independent assortment, says that alleles of different genes assort independently of one another during gamete formation. The second law describes the outcome of dihybrid (two character) crosses, or hybrid crosses involving more than two traits. 1.. Mendel's second law, the law of independent assortment, says that alleles of different genes assort independently of one another during gamete formation. The second law describes the outcome of dihybrid (two character) crosses, or hybrid crosses involving more than two traits. 1.