AP BIOLOGY

Detailed explanation-1: -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).

Detailed explanation-2: -Mutations and sexual reproduction increase genetic variation in a population. Natural selection occurs when environmental pressures favor certain traits that are passed on to offspring.

Detailed explanation-3: -Sexual reproduction also results in genetic variation among siblings. When a parent forms a gamete, only one chromosome from each homologous pair is included at random. So, an offspring might inherit a different combination of chromosomes (and alleles) compared to its siblings.

Detailed explanation-4: -Major causes of variation include mutations, gene flow, and sexual reproduction.

Detailed explanation-5: -Mutation Generates New Alleles Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique. They account for the variation we see in human hair color, skin color, height, shape, behavior, and susceptibility to disease.