Final answer:
Every gamete produced by an organism contains a unique combination of genes, which is a result of meiosis, introducing genetic variation through processes such as crossing-over and random fertilization.
Step-by-step explanation:
Gametes produced by an organism contain a combination of genes from that organism, and in every gamete, this combination is unique due to the process of meiosis. Sexual reproduction involves the formation of male and female gametes, which are haploid cells containing half the number of chromosomes found in normal diploid somatic cells. During meiosis, genetic variation is introduced through mechanisms like crossing-over, independent assortment, and random fertilization, which ensure that each gamete carries a different set of genetic information. When two gametes unite during fertilization, they combine their genetic material to form a zygote with a full set of chromosomes—typically two sets, restoring the diploid state.
For each characteristic, an organism's resulting offspring inherit two alleles, one from each parent, which can be the same or different. This genetic combination contributes to the potential for great genetic variation among sexually reproducing organisms. The genotype of the offspring depends on the specific alleles inherited, which in turn can influence the phenotype, or observable traits of the organism.