Scientists have long noticed the extreme diversity of our world and therefore they began to study the manifestations, origin and distribution of all life forms on Earth. A science that studies all living organisms, their functions, structure, and also their classification, is called biology. In addition, she explores the relationship of the animate world with the inanimate.
The distinctive properties that only living organisms possess are as follows: the high degree and complexity of their organization; each part has its own meaning and certain functions; the ability to use, extract and convert environmental energy for their life; ability to respond to external stimuli and environmental changes. They are also well adapted to their environment (adaptive properties are developed); can reproduce (multiply), have heredity and a tendency to variability. In addition, evolutionary processes are characteristic of them, as a result of which such a variety of living creatures arose.
There are several levels of organization of life, which are among themselves in a complex subordination. The lowest step is the face that separates living organisms from non-living ones and is a molecular structure. Next comes the cellular level, at which the cells and the main features of the structure are the same for everyone. A more complex organ-tissue level refers only to multicellular organisms, in which parts of the body formed from cells have already developed enough. The next step is a holistic organism, no matter how different the creatures are, they have one common property - they all consist of cells.
Further, the whole diversity of life is classified according to a different principle. In biology, there is even a whole section called systematics, which deals with the description and grouping of all creatures. So, the systematics of living organisms divides them according to their life form into non-cellular (viruses) and cellular. The latter are further subdivided into: simple and complex bacteria, plants, animals and fungi. In order to systematize all these objects, they need to be identified, and for this a number of features are used, which include: morphological, biochemical, physiological and other features.
In biology, much attention is paid to the study of the structure of living beings. They contain a lot of chemical components that form organic and inorganic compounds. Chemical elements in the cells of living organisms contain carbon atoms, which are a hallmark of life. In general, of all organic compounds, only a few classes are important for development. These include nucleic acids, proteins, lipids and carbohydrates. Living organisms can contain up to 70 components of the periodic table in their cells, but only 24 are constantly included in their composition (phosphorus, potassium, sulfur, calcium, iron, magnesium, zinc, aluminum, iodine, etc.)
