Asexual Reproduction

Introduction:


Asexual reproduction is a type of reproduction that does not involve manufacture of sex cells or gametes. Examples of Asexual reproduction are fragmentation, spore formation and budding. It involves only one parent and offsprings that are genetically identical to the parent. Plants that asexually repoduce multiply without the use of genetic seeds to assure an exact copy of the plant being produced. The purpose of asexual reproduction is to establish the stability of the plant. This type of reproduction allows plants to reproduce without using a lot of energy.

Types of Asexual Reproduction


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Binary fission
Many single-celled organisms (unicellular), such as Achaea, bacteria, and protists, reproduce asexually through binary fission



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Budding

Some cells split via budding (for example baker's yeast), resulting in a 'mother' and 'daughter' cell.


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Vegetative reproduction
A type of asexual reproduction found in plants where new independent individuals are formed without the production of seeds or spores.










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Spore formation
Many multicellular organisms form spores during their biological life cycle in a process called sporogenesis.







Fragmentation
A form of asexual reproduction where a new organism grows from a fragment of the parent. Each fragment develops into a mature, fully grown individual.


Parthenogenesis
A form of agamogenesis in which an unfertilized egg develops into a new individual.


Parthenogenesis
Occurs naturally in many plants, invertebrates (e.g. water fleas, aphids, stick insects, some ants, bees and parasitic wasps), and vertebrates (e.g. some reptiles, amphibians, fish, very rarely birds).


Agamogenesis
Any form of reproduction that does not involve a male gamete. Examples are parthenogenesis and apomixis.



Apomixis in plants is the formation of a new sporophyte without fertilization. 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.


Nucellar embryony occurs in some citrus seeds. Male apomixis can occur in rare cases, such as the Saharan Cypress where the genetic material of the embryo are derived entirely from pollen. The term "apomixis" is also used for asexual reproduction in some animals, notably water-fleas, Daphnia.