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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.
Asexual reproduction in animals (1 C, 10 P) B. Bird breeding (3 C, 27 P) Birth (5 C, 4 P) ... Animal sexual behaviour; Apophallation; Arrhenotoky; B. Bimodal ...
Sexual reproduction has many drawbacks, since it requires far more energy than asexual reproduction and diverts the organisms from other pursuits, and there is some argument about why so many species use it. George C. Williams used lottery tickets as an analogy in one explanation for the widespread use of sexual reproduction. [36]
A sex organ, also known as a reproductive organ, is a part of an organism that is involved in sexual reproduction. Sex organs constitute the primary sex characteristics of an organism. Sex organs are responsible for producing and transporting gametes , as well as facilitating fertilization and supporting the development and birth of offspring.
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 ...
The term "gonochorism" is usually applied to animals while "dioecy" is applied to plants. [20] Gonochorism is the most common sexual system in animals, occurring in 95% of animal species. [21] Gynodioecy: females and hermaphrodites coexist in the same population. [10] Gynomonoecy
Animals make use of a variety of modes of reproduction to produce their young. Traditionally this variety was classified into three modes, oviparity (embryos in eggs), viviparity (young born live), and ovoviviparity (intermediate between the first two).
Another theory is that sexual reproduction originated from selfish parasitic genetic elements that exchange genetic material (that is: copies of their own genome) for their transmission and propagation. In some organisms, sexual reproduction has been shown to enhance the spread of parasitic genetic elements (e.g. yeast, filamentous fungi). [79]