What is the essence of sexual reproduction (biology, 8th grade)

What is the essence of sexual reproduction and what are its benefits? This question has long been of interest to many scientists, reproducing organisms like themselves is a necessary condition of life on planet Earth.

What is reproduction

The Essence of this process lies in the reproduction of their own kind. And the question here is not about eye color or hair texture. It is important that the body, which only came to light in a certain environment, able to survive in it. To ensure that it may be only the characteristic species features of a structure, inherited from ancestors. Otherwise all experienced a flour-like-man from the eponymous film.

Methods of reproduction of organisms

Is There a fundamental difference between asexual and sexual reproduction? Of course. In the first case, no involvement of gametes, in the second their presence is necessary. There are several ways of asexual reproduction. The easiest of them – dividing into two cells. So the breeding of bacteria, single-celled animals and algae. For of Plasmodium falciparum characterized by multiple divisions, which from one mother cell is formed from a few dozen children. Due to the ability of cells to divide, regenerate damaged tissue and organs, and many animals are capable of rapid regeneration. For example, the freshwater Hydra, which is representative of the type of the Coelenterates, may recover from 1/200 part.

This organism Multiplies by budding. While on the body first forms a protrusion that grows, acquires the traits of the mother's body, and then segregates and begins an independent existence.

Recommended

"Knowledge is light and ignorance is darkness": the value, meaning and alternatives

There are some sayings that would seem to need no explanation, such as “teaching & ndash; light and ignorance – darkness”. But some still do not understand their meaning. But not only for such people is written by our article. I...

What was invented by Mendeleev for the army. The history and fate of the invention

D. I. Mendeleev was a brilliant Russian scientist-polymath, who made many important discoveries in various fields of science and technology. Many people know that he is the author of “Fundamentals of chemistry" and the periodic law of chem...

The origin of the Slavs. The influence of different cultures

Slavs (under this name), according to some researchers, appeared in the story only in 6 century ad. However, the language of nationality bears the archaic features of the Indo-European community. This, in turn, suggests that the origin of the Slavs h...

All used nutritional yeast. So, to increase their number – this is not that other, as a process of budding fungi.

Plants are capable of vegetative reproduction. This method consists in separation from the whole organism to its multicellular parts. In violets for this purpose, leaves of potatoes – modified underground stems (tubers), grape-cuttings.

What is the essence of sexual reproduction

This process occurs only with the participation of gametes-specialized sex cells: male-sperm and female-ovum. They contain in their cores the hereditary information contained in DNA molecules.

The Essence of the process of sexual reproduction is recombination of this material. And this is not always necessary gametes. So, ciliates shoes is conjugation. The two body closer, and between them is formed cytoplasmic bridge in which the nucleus share their content.

Advantages of sexual reproduction

Due to the recombination of genes-sections of DNA molecules – the body may acquire new useful features. The main significance of sexual reproduction. After the division of the parent cells formed an exact copy of it. Other signs simply nowhere to take. When changing environmental conditions, these organisms fail to adapt, which will inevitably lead to their doom and reduction of species diversity as a whole.

New features are formed only by the change in genetic material. Then they can be inherited and fixate in a number of generations.

Sexual reproduction in plants and animals

What is the essence of sexual reproduction of plants, we can consider the example of a fern, which is the higher spore plants. On the underside of its Mature green leaves of special structure – the Sori. They are disputes – cells asexual reproduction. Getting into the wet soil, they germinate, forming a small green sprout. It generates eggs and sperm, which pairs merge to give rise to a new leafy plant. So there is an alternation of sexual generation-the gametophyte and an asexual – the sporophyte.

In Flowering plants for the generative reproduction is the flower. In its pistil Matures female gamete, and the anther of a stamen-the male. As a result of fertilization is formed the embryo of the seed. For the future development and protection he has a large number of spare substances, succulent or leathery shell of the fruit.

Animals also Have specialized cells and organs in which they are located – cancer. The representatives of this Kingdom there are several types of fertilization. For external fusion of gametes occurs outside the body of the female, as in fish or amphibians when the female lays in the water the eggs, and the male pours her seminal fluid. Why are eggs so much? It's a biological mechanism for storing the number of the adult population, because cells vulnerable, and most of them are eaten by predators. In the case of internal fertilization body of the future a certain time is in the mother's body. Therefore, the number of oocytes capable of fertilization, is not so impressive.

That is the essence of sexual reproduction, in which there are new plant varieties and animal species, and by which it becomes possible to createhybrid and cloned organisms.