It has its own laws of biological science, and at the same time it contains and follows the laws of physics and chemistry. Therefore, biological science is closely related to physics and chemistry. Living things are distributed on the earth's surface, which is an important factor to constitute the earth's landscape. Therefore, biological science and earth science also permeate and cross each other. Early biological sciences mainly observed and described nature, and studied natural history and morphological classification. Therefore, biological sciences were originally divided into disciplines according to groups, such as botany, zoology, microbiology and so on. Due to the diversity of biological species and people's more and more understanding of biological sciences, the division of disciplines is becoming more and more detailed. A discipline is often divided into several disciplines, such as botany, which can be divided into phycology, bryology and pteridology. Zoology is divided into protozoology, entomology, ichthyology and ornithology. Microorganisms are not a natural biological group, but an artificial division. Bacteria, unicellular fungi, algae, protozoa and all other micro-organisms can be called microorganisms, and viruses without cell morphology can also be included in microorganisms. Therefore, microbiology is further divided into bacteriology, mycology, virology and so on.
Dividing disciplines according to biological groups is conducive to understanding the biological characteristics and regularity of a natural group from all sides. But no matter what the specific object is, the research topics are nothing more than classification, morphology, physiology, biochemistry, ecology, heredity, evolution and so on. In order to emphasize that disciplines classified by type include not only classical contents such as morphology and taxonomy, but also other processes and levels, people tend to call botany plant bioscience and zoology animal bioscience.
Biology has a history of about 4 billion years in the history of the earth. About 6.5438+0.5 million species of organisms have become extinct, and some of their remains are preserved in the strata to form fossils. Paleontology specializes in studying organisms in geological history through fossils. Early paleontology mainly focused on the classification and description of fossils. In recent years, various branches of biological science have been introduced into paleontology, resulting in paleoecology, paleogeography and other branches. Now it is proposed to replace paleontology with paleontology in a broad sense, which was originally limited to the classification and description of fossils.
There are so many groups of organisms that a special subject is needed to study the division of groups. This subject is taxonomy. The classification in Linnaeus period is guided by the theory of species invariance, and it is only classified according to some distinguishable characteristics, which is called artificial classification. Modern classification is based on the theory of evolution, and it is called natural classification according to the evolutionary distance of species. Modern taxonomy not only compares morphological structures, but also absorbs the achievements of biochemistry and molecular biology, and compares them at the molecular level, thus revealing the evolutionary relationship of organisms more deeply. Modern taxonomy can be defined as a science that studies the systematic classification of organisms and the evolutionary relationship between organisms.
There are many branches of biological science, which are divided according to the attributes, characteristics or life processes of life movements.
Morphology is a subject that studies the morphological structure of animals and plants in biological science. Before the invention of microscope, morphology was limited to macroscopic observation of animals and plants, such as human anatomy and comparative anatomy of vertebrates. Comparative anatomy is to study the structural similarities and differences of vertebrates by comparative and historical methods, so as to find out the genetic relationship and historical development of these categories. After the invention of microscope, histology and cytology were established accordingly. With the use of electron microscope, morphology goes deep into the field of ultrastructure. However, the study of morphological structure cannot be completely divorced from the study of function. Now morphology has jumped out of the circle of simple description and used various advanced experimental means.
Physiology is a subject that studies biological functions, and the research method of physiology is mainly experiment. According to the research object, it is divided into plant physiology, animal physiology and bacterial physiology. Plant physiology is established during the development of agricultural production. Physiology can also be divided into cell physiology, organ physiology and individual physiology according to the structural level of organisms. Early plant physiology mostly took seed plants as the research object; Animal physiology is mostly related to medicine, with people, dogs, rabbits and frogs as the research objects; Later, it gradually extended to the physiological research of lower organisms, thus developing comparative physiology.
Genetics is a subject that studies the inheritance and variation of biological characters and expounds their laws. Genetics is developed under the impetus of breeding practice. 1900, Mendel's genetic law was rediscovered and genetics began to be established. Later, due to the work of T.H. Morgan and others, a complete cytogenetic system was established. From 65438 to 0953, the molecular structure of genetic material DNA was revealed and genetics went deep into the molecular level. At present, the transmission of genetic information and the regulation mechanism of genes have been gradually understood. The theory and technology of genetics are playing an important role in the practice of agriculture, industry and clinical medicine, and occupy an important position in all branches of biological science. Many problems in biological science, such as the mechanism of individual development and biological evolution, the formation of species and the concept of population, must be deeply understood by applying the results of genetics.
Embryology is a subject that studies the individual development of organisms, which originally belongs to the category of morphology. /kloc-the publication of Darwin's theory of evolution in 859 greatly promoted the study of embryology. /kloc-in the second half of the 9th century, the morphology of embryo development and fertilization process was described in detail and accurately. Since then, animal embryology has developed from observation and description to experimental study of development mechanism, thus establishing experimental embryology. At present, the research on individual development adopts biochemical methods, absorbs the achievements of molecular biology, further analyzes the mechanism of development and character differentiation at the molecular level, and expands the research on development from embryo to the whole life history of organisms, forming developmental biology.
Ecology is a subject that studies the relationship between organisms and between organisms and the environment. The research scope includes individuals, populations, communities, ecosystems and biosphere. Revealing the relevant laws of food chain, productivity, energy flow and material circulation in ecosystem is not only of great theoretical significance, but also closely related to human life. The biosphere is the home of mankind. Human production activities continue to consume natural resources and destroy the natural environment. Especially after entering the 20th century, due to the rapid growth of population and the rapid development of industry, the natural environment has suffered an unprecedented destructive impact. Protecting resources and maintaining ecological balance is an urgent task for mankind at present. Ecology is an important part of environmental science, so it can also be called environmental biological science. Human ecology involves human society, which is beyond the scope of biological science and related to social science.
Life activities are nothing more than the transformation and transmission of matter, energy and information. Therefore, it is necessary and effective to study life by physical, chemical and mathematical methods. This is how interdisciplinary subjects such as biochemistry, biophysics and biomathematics came into being.
Biochemistry is a subject that studies the chemical composition of organisms and various chemical processes of organisms, and has developed rapidly since the 20th century. The achievements of biochemistry have improved people's understanding of the nature of life. The contents of biochemistry and molecular biology are different, but there are also similarities. Generally speaking, biochemistry mainly studies the chemical process of life and the action mechanism of reagents, products and enzymes involved in this process. For example, the conversion, transmission and feedback mechanism of matter and energy in the process of cell respiration and photosynthesis are all biochemical research contents. Molecular bioscience developed from the study of the structure of biological macromolecules, and now more attention is paid to the relationship between the structure and function of biological macromolecules and the mechanism of gene expression and regulation.
Biophysics is a subject that studies the structure and function of organisms and the physical and physicochemical processes of life activities with the concepts and methods of physics. Early biophysical research began with bioluminescence, bioelectricity and other issues. Since then, with the development of biological science, the emergence of new physical concepts such as quantum physics and information theory, and the use of new technologies such as X-ray diffraction, spectroscopy and spectroscopy, the research scope and level of biophysics have been broadened and deepened. Some important life phenomena, such as the reaction of capturing light energy at the initial moment of photosynthesis, the structure and mechanism of biofilm, are all research topics in biophysics. Crystal structure of biological macromolecules, quantum bioscience and biological cybernetics also belong to biophysics.
Biomathematics is the product of the combination of mathematics and biological science. Its task is to study the mathematical laws of biological science problems and life processes by mathematical methods. In the early days, people only used statistics, geometry and some elementary analysis methods to make a static and quantitative analysis of biological phenomena. After the 1920s, people began to build mathematical models to simulate various life processes. At present, biomathematics plays an important role in various fields of biological sciences such as physiology, genetics, ecology and taxonomy, which makes the research level in these fields improve rapidly. On the other hand, biomathematics itself has developed into an independent discipline in solving biological science problems.
A few biological sciences are divided by methods, such as descriptive embryology, comparative anatomy and experimental morphology. Disciplines classified by methods are often included in the above-mentioned disciplines classified by attributes and types as sub-disciplines at a lower level.
The biological world is a multi-level complex system. In order to reveal the law of a certain level and its relationship with other levels, disciplines divided by levels have emerged and attracted more and more attention.
Molecular bioscience is a subject that studies the life process at the molecular level. Its task is to reveal the material basis of various life processes from the structure and function of molecules and the interaction between molecules. One of the main branches of modern molecular biology science is molecular genetics, which studies the replication of genetic material, the transmission and expression of genetic information and its regulation.
Cell biology is a subject that studies the process of life at the cellular level. In the early stage, cytology was mainly based on morphological description. Since then, cytology has absorbed the achievements of molecular biological science and reached the level of ultrastructure, mainly studying the biological processes such as cell growth, metabolism and inheritance, and cytology has developed into cell biological science.
Individual bioscience is a subject that studies the process of life at the individual level. Before the invention of compound microscope, biological science mainly focused on individuals and organ systems. To study the individual process, it is necessary to analyze the organ system process, cellular process and molecular process that make up this process. But the individual process is different from the simple addition of organ system process, cell process or molecular process. Individuals have a self-regulation mechanism in this process. Through this mechanism, highly complex organisms are integrated into a highly coordinated unity and respond to the stimulation of external factors with coordinated behavior. Personal bioscience has been established for a long time, and it is still very important until now.
Population bioscience is to study the structure of biological population, the relationship between individuals in the population, the relationship between population and environment, the self-regulation and genetic mechanism of population. There is a great overlap between population bioscience and ecology, and population bioscience can be said to be the basic part of ecology.
The above is only the main pattern of the current branches of biological sciences, and there are more actual disciplines than the above. For example, as humans enter space, cosmic biological science is already developing. For another example, with the continuous improvement of experimental accuracy, the requirements for experimental animals are becoming more and more strict, and the biological science of studying aseptic organisms and understanding ecology is also established because of the need. In short, some new disciplines are constantly dividing and some disciplines are moving towards integration. This differentiation of biological sciences reflects the extremely rich content and vigorous development of biological sciences.