Reproduction is the ability of living organisms to reproduce their own kind.
There are two main forms of reproduction – asexual and sexual.
Asexual reproduction is called reproduction, which occurs without the formation of gametes. One individual participates in it, and the genotype of the offspring is the same as that of the parent.
With asexual reproduction, you do not need to look for a partner, any individual can leave offspring anywhere. A huge number of descendants emerge.
The disadvantage of this form of reproduction is the identity of all offspring. With a sharp change in conditions, all organisms can die.
Cell division is typical for unicellular organisms. Bacteria divide by simple binary fission, and protists (amoeba, euglena, ciliates, etc.) divide by mitosis.
Multiple division (schizogony) leads to the formation of a large number of daughter cells from one original. It is observed in sporozoans, for example, in the malaria plasmodium. Schizogony follows immediately after the entry of Plasmodium into the liver. About a thousand cells are quickly formed, each of which can penetrate into erythrocytes.
Spore formation is the reproduction of some unicellular and multicellular organisms using spores.
A spore is a specialized cell, consisting of a small amount of cytoplasm and a nucleus with a minimum supply of nutrients, capable of giving rise to a new organism.
Many protists, fungi and plants reproduce by spores.
Spores are formed in normal cells of the mother’s body or in special organs – sporangia – and germinate into a new organism.
Spores of bacteria are not involved in reproduction. Their function is to endure unfavorable conditions.
Budding is characteristic of some multicellular organisms. A small outgrowth (kidney) is formed on the body of the parent, from which a new organism then develops. In yeast and hydroids, the daughter organism separates and becomes independent. In sponges, coral polyps, daughter individuals do not separate, and colonies appear.
Fragmentation is the multiplication of multicellular organisms by body parts. In fungi, lichens, algae, a new organism develops from areas of the mycelium or thallus. Fragmentation is based on regeneration – the ability of living organisms to restore lost body parts. Fragmentation is also observed in some animals (coelenterates, sponges, echinoderms, flatworms and some annelids).
Vegetative reproduction is the formation of new individuals from vegetative organs. It is also based on regeneration.
Most typical for flowering plants.
A special type of asexual reproduction is polyembryony. In this case, several embryos are formed from one diploid zygote.
Blastomeres formed during division of the zygote separate, and each of them develops as an independent zygote. Descendants are genetically identical and always of the same sex.
This type of asexual reproduction is found in armadillos.
Polyembryony also includes the formation of identical twins in humans.