5. Does a woman have periods while she is pregnant?

No

Explanation:

A period is when your body produces a layer of tissue and blood to protect the baby. But the period is when your body is like "oops, false alarm" and disposes of the tissue and blood. During pregnancy, the baby is kept safe by the tissue and blood, that is why women don't have periods during pregnancy.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).