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The cloning of an organism is a form of asexual reproduction. By asexual reproduction, an organism creates a genetically similar or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of sexual reproduction is that only 50% of organisms reproduce [1] and organisms only pass on 50% ...
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.
Human reproduction naturally takes place as internal fertilization by sexual intercourse. During this process, the man inserts his erect penis into the woman's vagina and then either partner initiates rhythmic pelvic thrusts until the man achieves orgasm , which leads to ejaculation of semen containing sperm into the vaginal canal.
Individual organisms participating in a biological life cycle ordinarily age and die, while cells from these organisms that connect successive life cycle generations (germ line cells and their descendants) are potentially immortal. The basis for this difference is a fundamental problem in biology.
Sexually reproducing animals, plants, fungi and protists are thought to have evolved from a common ancestor that was a single-celled eukaryotic species. [1] [2] [3] Sexual reproduction is widespread in eukaryotes, though a few eukaryotic species have secondarily lost the ability to reproduce sexually, such as Bdelloidea, and some plants and animals routinely reproduce asexually (by apomixis ...
The three traditional modes of reproduction are: [1] Oviparity, taken to be the ancestral condition, where either unfertilised oocytes or fertilised eggs are spawned. [1] Viviparity, including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body. [1]
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction.Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. [1]
Meiosis is ubiquitous among eukaryotes. It occurs in single-celled organisms such as yeast, as well as in multicellular organisms, such as humans. Eukaryotes arose from prokaryotes more than 2.2 billion years ago [1] and the earliest eukaryotes were likely single-celled organisms. To understand sex in eukaryotes, it is necessary to understand ...