Answer: 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).
By the end of meiosis, the resulting reproductive cells, or gametes, each have 23 genetically unique chromosomes. The overall process of meiosis produces four daughter cells from one single parent cell.
Explanation:
During meiosis, homologous chromosomes (1 from each parent) pair along their lengths. The chromosomes cross over at points called chiasma. At each chiasma, the chromosomes break and rejoin, trading some of their genes. This recombination results in genetic variation.
The drift explanation states that the people with higher socio-economic status (SES) tend to have better lives. It further states that genetics and biology plays an important role in the socio-economic status so that healthier people can enjoy their SES for longer period of time.
Cancer: An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some cases, to metastasize (spread). Cancer is not one disease. It is a group of more than 100 different and distinctive diseases. Cancer can involve any tissue of the body and have many different forms in each body area.
im pretty sure it is the first one