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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 .
For example, in the green alga, Chlamydomonas reinhardtii, there are so-called "plus" and "minus" gametes. A few types of organisms, such as many fungi and the ciliate Paramecium aurelia, [11] have more than two "sexes", called mating types. Most animals (including humans) and plants reproduce sexually.
Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes , resulting in offspring genetically different from either parent.
It is important in ferns and in flowering plants, but is very rare in other seed plants. In flowering plants, the term "apomixis" is now most often used for agamospermy, the formation of seeds without fertilization, but was once used to include vegetative reproduction. An example of an apomictic plant would be the triploid European dandelion ...
Among all living organisms, flowers, which are the reproductive structures of angiosperms, are the most varied physically and show a correspondingly great diversity in methods of reproduction. [27] Plants that are not flowering plants (green algae, mosses, liverworts, hornworts, ferns and gymnosperms such as conifers) also have complex ...
About 94% of flowering plant species are either hermaphroditic (all flowers produce both male and female gametes) or monoecious, where both male and female flowers occur on the same plant. There are also mixed breeding systems , in both plants and animals, where hermaphrodite individuals coexist with males (called androdioecy ) or with females ...
In both plants and animals, gamete size difference is the fundamental difference between females and males. [2] Anisogamy most likely evolved from isogamy. [3] Since the biological definition of male and female is based on gamete size, the evolution of anisogamy is viewed as the evolutionary origin of male and female sexes.
About 10–15% of flowering plants are predominantly self-fertilizing. [9] Self-pollination is an example of autogamy that occurs in flowering plants. Self-pollination occurs when the sperm in the pollen from the stamen of a plant goes to the carpels of that same plant and fertilizes the egg cell