Final answer:
In sexual reproduction, each parent contributes one set of chromosomes, and the members of a pair of chromosomes, one from each parent, are called homologous chromosomes. Gametes produced by meiosis are haploid and fuse during fertilization to form a diploid zygote. Meiosis is necessary in the reproductive cycle to maintain chromosome number.
Step-by-step explanation:
During sexual reproduction, each parent contributes one set of chromosomes to the offspring. The members of a pair of chromosomes, with one originating from each parent, are called homologous chromosomes.
During the process of meiosis, gametes (haploid cells) are produced by each parent. These gametes contain only half the number of chromosomes found in the body cells of the organism, which are called diploid cells. When a sperm and an egg combine during fertilization, they form a zygote, a cell that contains two sets of chromosomes and is diploid.
To ensure the continuation of the reproductive cycle, the diploid zygote must undergo meiosis to produce haploid gametes. This is necessary to maintain the number of chromosomes in the species without doubling them in each generation, which would occur if gametes were diploid.