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The maintenance of sexual reproduction (specifically, of its dioecious form) by natural selection in a highly competitive world has long been one of the major mysteries of biology, since both other known mechanisms of reproduction – asexual reproduction and hermaphroditism – possess apparent advantages over it.
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.
This is an accepted version of this page This is the latest accepted revision, reviewed on 3 December 2024. Union of gametes of opposite sexes during the process of sexual reproduction to form a zygote This article is about fertilisation in animals and plants. For fertilisation in humans specifically, see Human fertilization. For soil improvement, see Fertilizer. "Conceive" redirects here. For ...
The origin and function of meiosis are currently not well understood scientifically, and would provide fundamental insight into the evolution of sexual reproduction in eukaryotes. There is no current consensus among biologists on the questions of how sex in eukaryotes arose in evolution , what basic function sexual reproduction serves, and why ...
These chromosomes have already been replicated and have two sister chromatids which are then separated during the second division of meiosis. [4] Both of these cell division cycles are used in the process of sexual reproduction at some point in their life cycle. Both are believed to be present in the last eukaryotic common ancestor.
This is an accepted version of this page This is the latest accepted revision, reviewed on 19 December 2024. Cell division producing haploid gametes For the figure of speech, see Meiosis (figure of speech). For the process whereby cell nuclei divide to produce two copies of themselves, see Mitosis. For excessive constriction of the pupils, see Miosis. For the parasitic infestation, see Myiasis ...
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).
In contrast to asexual reproduction, sexual reproduction involves two parents. Both the parents produce gametes through meiosis, a special type of cell division that reduces the chromosome number by half. [3] During an early stage of meiosis, before the chromosomes are separated in the two daughter cells, the chromosomes undergo genetic ...