Factors that influence biological evolution-paper代写

留学生paper代写精选范文：“Factors that influence biological evolution”，这篇论文讨论了影响生物进化的因素。最开始地球是没有任何生命存在的，后来经过漫长的岁月，那些高分子物质才演变成单细胞生物，再逐渐进化成多细胞生物。而影响生物进化的因素主要有基因突变、自然环境和生态破坏。其中基因突变是随机的，而有益的基因突变才是生物进化的主要因素。

In the course of evolution, species from less increases, the structure and function from simple to complex. In this paper, the author usually learned, describes the genetic condition and Ping Heng several factors influence biological evolution, the final analysis after biological evolution reaction on the environment, put forward their own little superficial understanding.

Primitive Earth was lifeless, initially, in the role of lightning, inorganic substances formed amino acids, after a long chemical reaction forming a polymeric substance gradually amino acid peptide chain, subsequently evolved into single-celled organisms, and then gradually evolved into a multicellular organism. The evolution of the entire organism from a single cell to multicellular process from lower to higher, as a result of internal cell division, is a process of natural selection and biological adaptation to the environment.

Early in 1908, Weinberg made the famous "law of genetic Ping Heng", if the five genetic Ping Heng conditions, gene frequencies population will not change, can achieve stable from generation to generation genetic. The following example illustrates: in a peppered moth population, there are two kinds of bold and white body color thereof, represented by the bold AA genotype, represented by a white body AA genotype, assuming the number of each half thereof, i.e., the individual accounting for 50 AA % AA 50%, of their sexual reproduction results are as follows:

As can be seen from the table: a gene and a frequency of 50% have been, if the genetic Ping Heng condition is satisfied, a, and a gene frequency would not change, indicating that biological evolution will not happen, but these five genetic Ping Heng conditions are difficult to satisfy simultaneously, as long as there is a change in condition, then the gene frequency will change, then biological evolution will occur.

The substance is a gene mutation that under certain conditions there is a sudden change from its original form to another new form of existence. Modern evolutionary theory proposes that biological evolution is to change the substance of gene frequencies population, the probability of mutations that occur in individuals is very small, but the population see the probability of occurrence is relatively large.

In 1859, British biologist Charles Darwin in "Origin of Species" in the proposed natural selection theory of biological evolution. Highlights of the doctrine of individual population has trait differences, the environment in which it has a different adaptation, individuals with favorable traits survive and multiply, an individual will gradually be eliminated unfavorable genes, gene here favorable and unfavorable is favorable and unfavorable mutations on the gene mutation in nature. For example, wingless insects is difficult to foraging on land, and to the beach are well able to avoid being blown into the sea. If the gene copy remains accurate, life on Earth may already perished, because they cannot adapt to drastic changes in the Earth's climate in the past many years what happened. Gene mutations are not directed, random, beneficial mutations are the main factors of biological evolution.

Living organisms in certain circumstances, all the time restricted and the environment. For each biological environmental factors have tolerance range, once exceed the tolerable range, its survival will be affected. Recent developmental biology studies showed that: There is a biological early ability to generate new traits, which is conducive to the variation of organisms. They assumed that the organisms are able to realize before how the environment is changing, and then use this information to form their future evolutionary advantage, such as changing the size and hardness of seed, it will form a birds may be able to adapt the beak of this change. Thus, long-term living organisms in a given area, their genetic structure and properties affected by ecological factors in the region, and can produce good fit. But when environmental conditions change or you move to a new place, their genetic structure and properties will be affected by the new environmental factors, if they can tolerate environmental conditions change, biological evolution will produce oriented.

Associated with the development of human industry, environmental pollution problem is getting worse. It was found that, under the circumstances and conditions of pattern of evolutionary mechanisms and biological contamination of natural stress adaptation is not the same, the environmental pollution is not a general sense of environmental stress, but a kind of ecological damage. Extinction of species in the world today is largely environmental pollution and global proliferation are closely linked, polluted environment makes biological diversity, progressive loss of genetic diversity. For example, China's Kunming Dianchi Lake from the 1950s to the 1990s, due to water pollution leading to eutrophication, higher aquatic species loss of 76%, the species of fish lost 65%. Fowler found that Canada's cloud Sequoia improve the adaptability of air pollution, but the loss of genetic variability section, while resistance to frost is greatly reduced.

Under conditions of environmental pollution, selection factors of biological evolution is not a pollutant but a natural environment, has a global circulation of pollutants, reduce all potential biological evolution, endanger the survival and security of all creatures.

By the native organisms, bacteria, fungi, plants, animals, composed of all the organisms ensures biogeochemical cycling, c AC conversion occurs between organic and inorganic, and biological environment of this communication. So while environmental effects on biological evolution, biological evolution is also on the environment has a very strong reaction.

About 2.7 billion years ago the original algae such as blue-green algae appear, flint algae, which contain chlorophyll, capable of photosynthesis, release oxygen changed the composition of the atmosphere, free oxygen in the atmosphere occurs and increasing the biological the development of anaerobic life to aerobic life, metabolism also will be a fundamental change and promote evolution. As a result, the natural development of a complete water cycle, carbon cycle, atmospheric circulation, to ensure a stable environment biological survival.

In short, the biological traits determined by genetics, but the day after tomorrow environment is also important, and sometimes can lead to mutations, thereby changing the character, the biological survival of the fittest, not those to be eliminated, the environment determines the direction and speed of biological evolution. Variability of genetic material evolution of internal and environmental variability induced by the genetic material has played the role of screening, after the biological evolution of the environment would be counterproductive.

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