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.
Physical change only change the appearances of a substance, not it’s chemical composition. Chemical changes cause an entirely new substance with new chemical formula.
Mendel observed that a heterozygote offspring can show the same phenotype as the parent homozygote, so he concluded that there were some traits that dominated over other inherited traits. However, the relationship of genotype to phenotype is rarely as simple as the dominant and recessive patterns described by Mendel.
