Biology, abbreviated as biology, is one of the six basic disciplines of natural science. Study the structure, function, occurrence and development of living things. And the relationship between living things and their surroundings. Biology originated from natural history, experienced experimental biology and molecular biology, and entered the period of systematic biology.
I. Classification of disciplines
Biological taxonomy is a branch of biology, which studies the methods and principles of biological taxonomy. Classification refers to following the principles and methods of taxonomy to name and grade all kinds of organisms. After the Swedish biologist Linnaeus named creatures, later biologists classified them by domain, realm, phylum, class, order, family, genus and species. The top boundary, the five boundaries proposed by Whittaker, is accepted by many people; They are animal kingdom, protozoa kingdom, fungi kingdom, plant kingdom and animal kingdom. From the highest "boundary" to "species", the lower the level, the more similar the characteristics of the creatures they belong to. * * * There are seven categories, namely: phylum, family, genus and species.
Second, the research significance
Biology is closely related to many aspects of human life. Biology, as a basic science, is traditionally the basis of agronomy and medicine, involving agriculture, animal husbandry, fisheries, medical care, pharmacy, health and so on. With the continuous development of biological theory and method, its application field is also expanding. The influence of biology has broken through the above-mentioned traditional fields and extended to food, chemical industry, environmental protection, energy and metallurgical industries and so on. If bionics is considered, it will also affect electronic technology and information technology.
Population, food, environment and energy are global issues that attract worldwide attention. The annual growth rate of the world population is about 20%, and the population will double every 35 years. The population on the earth is increasing at an unprecedented rate. The population problem is a social problem as well as an ecological problem. People must make a thorough quantitative study of the complex relationship between human beings and the environment, so as to have a clear understanding of the fate of the earth and human beings, so as to learn to control themselves and keep the population at a reasonable level. Biology should and may make its own contribution in this respect. The achievements of endocrinology and reproductive biology led to the invention of oral contraceptives and promoted the popularization of family planning in the world. On the population issue, in addition to the rapid growth of population, genetic diseases also seriously threaten the quality of the population. Some data show that the proportion of newborns suffering from various genetic diseases is between 3% ~ 10.5%. In some mountainous areas of China, mental retardation accounts for 2% ~ 3%, and in some areas it is more than 10%. It is undoubtedly another important task of biology to reveal the causes of genetic diseases and find ways to control and conquer them. Carry out family analysis to determine whether patients have genetic diseases and provide beneficial genetic guidance and suggestions for patients; By chromosome analysis of fetal desquamation cells and biochemical analysis of various enzymes, it can be diagnosed whether the future baby has congenital genetic diseases. These methods can avoid or reduce the birth of babies with genetic diseases, thus reducing the heavy burden on families and society. The application of genetic engineering to the treatment of genetic diseases is called gene therapy, and some progress has been made in gene therapy of several genetic diseases in experimental animals. With the development of genetic engineering technology, gene therapy will open up broad prospects for controlling and treating human genetic diseases.
Closely related to the population problem is the food problem. Food shortage is a serious problem that developing countries have not solved for a long time. At present, hundreds of millions of people in the world are malnourished. By the beginning of 2 1 century, the grain output must increase by at least 3% ~ 8% every year to improve the grain shortage. The ultimate source of human food is photosynthesis of plants, but the land area for expanding agricultural production on land is limited, and the main way to increase food production is to improve plants themselves. In the past, biology has made great contributions to the development of scientific agriculture and the "green revolution". Today, it is not an unrealistic dream for human beings to directionally transform plants to a certain extent through genetic engineering and cell engineering, and cultivate excellent varieties with high quality, high yield, drought resistance, cold tolerance, waterlogging tolerance, salt tolerance and pest resistance. Some key technologies of plant genetic engineering were broken through, and some transgenic plants were obtained. In addition, protein-rich algae, bacteria or fungi were used for large-scale culture to obtain single-cell protein. Due to the successful application of genetic engineering and the technical experience of large-scale continuous fermentation engineering, single cell protein technology has made a major breakthrough. Amino acids are monomers of protein, and plant proteins often lack some essential amino acids. If certain amino acids are added to food, the biological value of plant protein will be greatly improved. Microbial fermentation, immobilized cells or immobilized enzymes to produce amino acids have gradually formed a relatively complete system. It can be predicted that the production of amino acids will play an increasingly important role in malnutrition. The combination of modern biological achievements and food industry makes the food industry become a new industry and flourish.
The research on the relationship between man and nature in the 20th century aroused people's concern about the ecological environment on which they lived. A large number of industrial wastewater, waste gas and solid waste are discharged, and agricultural pesticides and herbicides are widely used, which pollutes a large area of land and waters and threatens human production and life. This requires people to study the ecological laws of matter and energy cycle in the biosphere more deeply, and apply these laws correctly to human economic life and other social life, so that organisms can better serve human beings. Modern biology has proved that the biocatalytic activity of microorganisms is extremely extensive. Microorganisms that degrade almost any toxic organic matter can be found through enrichment culture, and their degradation ability can be continuously improved through genetic engineering and other technologies. Therefore, degrading microorganisms and their enzyme preparations has become a powerful means to eliminate pollution. It is also promising to use microorganisms to control pests and partially replace seriously polluted organic pesticides. It is an important event related to the restoration of natural ecological balance and the general trend of agricultural development to apply new technologies such as biological control and biological nitrogen fixation in agriculture as soon as possible to change the situation that agriculture relies too much on petrochemical industry. Traditional agriculture, which consumes a lot of resources, is bound to change to ecological agriculture based on biotechnology.
Reserves of chemical energy (oil, coal, etc.). The resources in the world are always limited and will be exhausted one day. Therefore, the renewable biological resources (biomass) in nature are once again concerned. Most of the biomass in nature is cellulose, hemicellulose and lignin. By combining chemical, physical and biological methods, cellulose can be converted into alcohol and used as energy. It is estimated that by the end of the 20th century, about 35% of cars in the world will use biomass (alcohol). Biogas is another product that uses biomass to develop energy. China and India have made remarkable achievements in biogas production by anaerobic fermentation of rural wastes. Industrial biogas anaerobic reactors using immobilized cell technology have appeared in the world. Some unicellular algae contain oil with similar structure to crude oil, which can be as high as 70% of the total weight. This is another extraordinary renewable bioenergy. Solar energy is the most powerful energy that human beings can use, and biological photosynthesis is the most important way to fix solar energy. It can be predicted that it is promising to solve energy problems with biological theories and methods.
In addition, the comprehensive study of population, food, environment, energy and other issues, as well as the rise of agricultural ecological engineering with various comprehensive solutions to these problems will eventually develop new and large-scale modern agriculture.
Only from the relationship among population, food, environment, energy problems and biology, the above description is still insufficient. But we can see that the development of biology is closely related to the future of mankind.