What is the essence of sexual reproduction and what are its advantages? This question has long been of interest to many scientists, because the reproduction by organisms of their own kind is a necessary condition for life on planet Earth.
What is breeding?
The essence of this process is to reproduce their own kind. And this is not about eye color or hair structure. It is important that the body, which was just born in a certain habitat, could survive in it. This can be ensured only by the characteristic species features of the structure inherited from the ancestors. Otherwise, everyone would have experienced torment, like an amphibian man from a movie of the same name.
Methods of reproduction of organisms
Are there any fundamental differences between asexual and sexual reproduction? Of course. In the first case, gametes do not take part; in the second, their presence is simply necessary. There are several ways of asexual reproduction. The simplest of these is cell division in two. So bacteria, unicellular animals and algae multiply. For malarial plasmodium, multiple division is characteristic, as a result of which several dozen daughter cells are immediately formed from one mother cell. Due to the ability of cells to divide, damaged tissues and organs are restored, and many animals are capable of rapid regeneration. For example, a freshwater hydra, which is a representative of the type of Enterocarpal, can recover from 1/200 part.
This organism propagates by budding. At the same time, a protrusion is first formed on the body, which grows, acquires the features of the mother's body, and then splits off and begins to exist independently.
Everyone used nutritional yeast. So, an increase in their number is nothing but the process of budding mushrooms.
Plants are capable of vegetative propagation. This method consists in separating from the whole organism its multicellular part. In violets, leaves are used for this, in potatoes - modified underground shoots (tubers), in grapes - cuttings.
What is the essence of sexual reproduction
This process occurs only with the participation of gametes - specialized germ cells: male - sperm, and female - egg cells. They contain in their nuclei hereditary information contained in DNA molecules.
The essence of the process of sexual reproduction is the recombination of this material. And for this, gametes are not always needed. So, conjugation occurs in the ciliates of the shoe . In this case, the two organisms come together, and a cytoplasmic bridge is formed between them, along which the nuclei exchange their contents.
Benefits of Sexual Reproduction
Thanks to the recombination of genes - sections of DNA molecules - the body can acquire new useful traits. The main significance of sexual reproduction is precisely in this. Indeed, with the division of the mother cell, its exact copy is formed. Other signs are simply nowhere to come from. When environmental conditions change, such organisms fail to adapt, which will inevitably lead to their death and a decrease in species diversity in general.
New traits are formed only with a change in genetic material. Then they can be inherited and fixed in a number of generations.
Sexual process in plants and animals
What is the essence of sexual reproduction of plants, you can consider the example of fern, which is the highest spore plant. On the underside of its green leaves, special structures ripen - soruses. They contain spores - asexual reproduction cells. Once in moist soil, they germinate, forming a small green sprout. In it, eggs and sperm are generated, which, pairwise merging, give rise to a new leafy plant. This is how the alternation of the sexual generation - the gametophyte, and the asexual - sporophyte occurs.
In flowering plants, a flower is used for generative propagation. In its pistil, the female gamete matures, and in the anther of the stamen, the male. As a result of fertilization, a seed embryo is formed. For future development and protection, it has a large number of spare substances, juicy or leathery membranes of the fetus.
Animals also have specialized cells and organs in which they are located - glands. Representatives of this kingdom have several types of fertilization. With external fusion of gametes occurs outside the female’s body, as in fish or amphibians, when the female spawns eggs in the water and the male sprinkles it with seminal fluid. Why are there so many eggs? This is a biological mechanism for maintaining the adult population, because the cells are defenseless, and most of them are eaten by predators. In the case of internal fertilization, the future organism is in the maternal body for a certain time. Therefore, the number of eggs capable of fertilization will not be so impressive.
This is the essence of sexual reproduction, as a result of which new varieties of plants and animal species arise, and also thanks to which it becomes possible to create hybrid and cloned organisms.