The ability to reproduce itself is one of the hallmarks of living organisms. In nature, there are several methods of reproduction, ensuring 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 structural features fixed in the genetic material of organisms is ensured 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 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.
Asexual reproduction
Self-reproduction of cells can occur without the participation of germ cells. In plants, it is carried out using vegetative organs. Many fungi, crowns, horsetails, ferns and mosses spores form - asexual reproduction cells . 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.
Spore formation
Self-reproduction of organisms using spores can be found for the first time in the most primitive plants - algae. For example, spores of unicellular chlamydomonas, leaving the cell membrane of the mother’s body, go outside and quickly grow to its size. After one week, young individuals are able to form asexual reproduction cells. This process is repeated many times.
Higher spore plants in the cycle of their development alternate sexual and asexual generation. Disputes in them are formed in special organs. For example, in mosses they are represented by a box on a leg, inside of which there are asexual cells. The significance of this process is that an exact copy of the maternal organism is formed from spores.
Vegetative propagation
The stem, leaves and root are organs with the help of 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, a root grows on the petiole of a leaf of uzambar violet in the presence of water, heat and solar radiation.
Tree leafy plants are often propagated with petioles - parts of shoots of a certain length. Moreover, they can exist in different life forms. So plant grapes, currants, gooseberries. The most important thing is that there are viable kidneys on the petiole.
Used for the reproduction and modification of vegetative organs. Potato tubers, strawberry mustaches, 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 your own kind. Another way this happens is called budding. This is how yeast, freshwater hydra, scyphoid polyps and corals breed. In most cases, the kidney that forms on the mother’s body, splits off from it and begins to exist independently. But this does not happen in corals. As a result, bizarre reefs form.
Forms of the sexual process
Generative reproduction occurs with the participation of gametes - germ 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, along which there is an exchange of parts of the genetic material contained in the DNA molecules.
Parthenogenesis also 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 has a very important biological significance. After all, a situation may arise when a male is absent for a long time. And then the existence of the species will be in jeopardy. And the appearance of an individual from a female reproductive cell without the process of fertilization solves this problem.
In higher angiosperms, a generative organ is a flower. Its main functional parts - stamen and pestle - contain gametes: sperm and egg, respectively. The fertilization process is necessarily preceded by pollination - transfer of pollen from the stamen to the stigma of the pestle. This happens with the help of wind, insects or humans. Further, the germ cells at fusion form the embryo and the reserve nutrient - the endosperm. In aggregate, a seed is formed, which is also the organ of sexual reproduction.
In animals, gametes are located in the glands, coming out through the excretory tract. By the type of structure of the reproductive system, they are dioecious and hermaphrodites - organisms in which female and male reproductive cells are simultaneously formed. These are mainly parasitic animals that feed on the host and do not have their own digestive system, living in the ducts of his intestines.
The value 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 such representatives of the organic world for which this process is the only one. These are viruses - non-cellular life forms. They consist of nucleic acid molecules (DNA or RNA) and a protein coat. With this structure, the ability to reproduce is the only possible process that determines the membership of living organisms. Penetrating into the host, they begin to produce their own nucleic acid and protein. This method of reproduction is called self-assembly. In this case, similar processes in the host organism are suspended. The virus begins to dominate. So begins the flu, herpes, encephalitis and other diseases with a similar genesis. Viral particles die due to the action of colorless blood cells - white blood cells. They capture pathogens, destroying them.
Thus, representatives of all the kingdoms of wildlife are capable of self-reproduction . And the process of reproduction itself is very important, because it determines the continuity of generations and the provision of life on Earth.