Reproduction :: essays research papers

THE REPRODUCTIVE SYSTEMThe ability to regreen groceries is one of the unifying characteristics of on the whole living things. Sexual facts of life produces offspring that are genetically different from their parents. Asexual reproduction produces offspring genetically identical to their parent. Asexual ReproductionFission, budding, fragmentation, and the institution of rhizomes and stolons are some of the mechanisms that allow organisms to reproduce asexually. The hydra produces buds starfish squeeze out regenerate an entire body from a fragment of the original body. Asexual reproduction allows an organism to rapidly produce many offspring without the time and resources committed to courtship, finding a mate, and mating. The lack of genetic variability in asexually reproducing populations can be detrimental when environmental conditions change quickly.Sexual ReproductionIn sexual reproduction new individuals are produced by the partnership of haploid gametes to attain a diploi d zygote. Sperm are male gametes, ova are female gametes. Meiosis produces cells that are genetically distinct from each other fertilization is the fusion of two such distinctive cells that produces a unique new combination of alleles, thus increasing variation on which natural selection can operate. Rotifers result reproduce asexually when conditions are favorable by having females produce eggs by mitosis. When conditions deteriorate, rotifers will reproduce sexually and encase their zygotes inside a revolting shell. Once conditions improve, these eggs hatch into diploid individuals. Rotifers thus use sexual reproduction as way to survive a deteriorating environment.Sexual reproduction offers the eudaimonia of generating genetic variation among offspring, which enhances the chances of the populations survival. Costs of this process include the need for two individuals to mate, courtship rituals, as well as a number of basic mechanisms describe later. Human Reproduction and Devel opmentHuman reproduction employs internal fertilization, and depends on the integrated action of hormones, the nervous system, and the reproductive system. Gonads are sex organs that produce gametes. Male gonads are the testes, which produce sperm and male sex hormones. Female gonads are the ovaries, which produce eggs and female sex hormones. The Male Reproductive governanceTestes are suspended outside the abdominal cavity by the scrotum, a pouch of skin that keeps the testes close or far from the body at an best temperature for sperm development. Seminiferous tubules are inside each testis, and are where sperm are produced by meiosis. About 250 meters (850 feet) of tubules are packed into each testis. Spermatocytes inside the tubules apportion by meiosis to produce spermatids that in turn develop into mature sperm.