The ability to reproduce itself is one of the hallmarks of living organisms. In nature, there are several methods of reproduction that ensure the continuity of generations on the planet.
Self-reproduction of organisms
Without the process of reproduction, living organisms would cease to exist. But the most important thing is the essence of this process. The transfer of information about all the structural features fixed in the genetic material of organisms is ensured precisely by self-reproduction. This is the most important condition for the existence of life. After all, if a new organism appears with other signs, it simply will not survive in certain environmental conditions and will die. For example, imagine: a fish is born with lungs instead of gills. Several generations of such animals are doomed. They simply do not have time to adapt to the aquatic environment and die. But this does not happen in nature due to the presence of several methods of reproduction at once.
Asexual reproduction
Self-reproduction of cells can occur without the participation of germ cells. In plants, it is carried out with the help of vegetative organs. Atmany mushrooms, club mosses, horsetails, ferns and mosses form spores - cells of asexual reproduction. In some organisms, a protrusion forms on the body, which grows and, over time, turns into a new organism. Consider these methods of reproduction in more detail.
Sporulation
Self-reproduction of organisms with the help of spores can be found for the first time in the most primitive plants - algae. For example, spores of a single-celled chlamydomonas, leaving the cell membrane of the mother's organism, go outside and quickly grow to its size. Already after one week, young individuals are able to form cells of asexual reproduction. This process is repeated many times.
Higher spore plants in the cycle of their development alternate between sexual and asexual generation. Their disputes are formed in special organs. For example, in mosses, they are represented by a box on a leg, inside which there are asexual cells. The significance of this process lies in the fact that an exact copy of the mother organism is formed from the spores.
Vegetative propagation
Stem, leaves and root are the organs by which self-reproduction is also carried out. These are the vegetative parts of the plant. The essence of this process is to restore the missing parts of the body. For example, in the presence of water, heat and solar radiation, a root grows on the petiole of a leaf of an uzambara violet.
Woody leafy plants are often propagated using petioles - parts of shoots of a certain length. Whereinthey can exist in different life forms. This is how grapes, currants, gooseberries are planted. The most important thing is that there are viable buds on the petiole.
Use for reproduction and modification of vegetative organs. Potato tubers, strawberry whiskers, tulip bulbs, lily of the valley rhizomes are examples of plants that have transformed shoots. A modification of the root, which is used for vegetative propagation, is the root tuber. Dahlia and sweet potato reproduce precisely with the help of it.
Budding
Self-reproduction is the process of creating one's own kind. Another way this happens is called budding. This is how yeast, freshwater hydra, scyphoid polyps and corals reproduce. In most cases, the kidney, which is formed on the mother's body, splits off from it and begins an independent existence. But this is not the case with corals. The result is bizarre reefs.
Forms of the sexual process
Generative reproduction occurs with the participation of gametes - sex cells. The most primitive forms of the sexual process are conjugation and parthenogenesis. The first of them can be considered on the example of ciliates-shoes. A cytoplasmic bridge is formed between the cells of animal organisms, through which the exchange of sections of the genetic material contained in DNA molecules takes place.
Parthenogenesisalso represents self-reproduction. This is the process of developing a new organism from an unfertilized egg. The existence of parthenogenesis as a method of reproduction is of great biological importance. After all, a situation may arise in the absence of a male for a long time. And then the existence of the species will be threatened. And the appearance of an individual from the female germ cell without the fertilization process solves this problem.
In higher angiosperms, the generative organ is a flower. Its main functional parts - stamen and pistil - contain gametes: sperm and egg, respectively. The process of fertilization is necessarily preceded by pollination - the transfer of pollen from the stamen to the stigma of the pistil. This happens with the help of wind, insects or humans. Further, the germ cells, when merged, form an embryo and a reserve nutrient - the endosperm. Together, a seed is formed, which is also an organ of sexual reproduction.
In animals, gametes are located in the glands, coming out along the excretory pathways. According to the type of structure of the reproductive system, they are dioecious and hermaphrodites - organisms in which both female and male germ cells are simultaneously formed. They are mainly parasitic animals that feed at the expense of the host and do not have their own digestive system, living in the ducts of its intestines.
Meaning of self-reproduction
Self-reproduction is the preservation of one's life. The ability to reproduce, along with nutrition, respiration,growth and development is a sign of living organisms. There are also representatives of the organic world for whom this process is the only one. These are viruses - non-cellular forms of life. They consist of nucleic acid molecules (DNA or RNA) and a protein shell. With such a structure, the ability to reproduce is the only possible process that determines belonging to living organisms. Penetrating into the host organism, they begin to produce their own nucleic acid and protein. This method of reproduction is called self-assembly. At the same time, similar processes in the host organism are suspended. The virus is starting to take over. This is how influenza, herpes, encephalitis and other diseases with a similar genesis begin. Viral particles die due to the action of colorless blood cells - leukocytes. They capture pathogens, destroying them.
Thus, representatives of all kingdoms of wildlife are capable of self-reproduction. And the process of reproduction itself is very important, since it determines the continuity of generations and the provision of life on Earth.
