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Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. [6] [7] Sexual reproduction also occurs in some unicellular eukaryotes. [2] [8] Sexual reproduction does not occur in prokaryotes, unicellular organisms without cell nuclei, such as bacteria and archaea.
In zoology, copulation is animal sexual behavior in which a male introduces sperm into the female's body, especially directly into her reproductive tract. [ 1 ] [ 2 ] This is an aspect of mating . Many aquatic animals use external fertilization , whereas internal fertilization may have developed from a need to maintain gametes in a liquid ...
In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. Fertilization is the fusion of two gametes. [1] Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization. [2]
Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism.
Anisogamy is the form of sexual reproduction that involves the union or fusion of two gametes which differ in size and/or form. [12] The smaller gamete is considered to be male (a sperm cell), whereas the larger gamete is regarded as female (typically an egg cell, if non-motile).
Evolution of sexual reproduction describes how sexually reproducing animals, plants, fungi and protists could have evolved from a common ancestor that was a single-celled eukaryotic species.
Sexual systems play a key role in genetic variation and reproductive success, and may also have led to the origin or extinction of certain species. [4] In flowering plants and animals, sexual reproduction involves meiosis, an adaptive process for repairing damage in the germline DNA transmitted to progeny. [5]
Meiosis is a key event of the sexual cycle in eukaryotes. It is the stage of the life cycle when a cell gives rise to haploid cells each having half as many chromosomes as the parental cell. Two such haploid gametes, ordinarily arising from different individual organisms, fuse by the process of fertilization, thus completing the sexual cycle.