All the diversity of the living world is almost impossible to express in quantitative terms. For this reason, taxonomists grouped them into groups based on certain features. In our article, we will consider the main properties, the basics of classification and the levels of organization of living organisms.
Diversity of the living world: in brief
Each species that exists on the planet is individual and unique. However, many of them have a number of similar structural features. It is on these grounds that all living things can be combined into taxa. In the modern period, scholars distinguish five Kingdoms. The diversity of the living world (the photo shows some of its representatives) includes Plants, Animals, Mushrooms, Bacteria and Viruses. The last of them do not have a cellular structure and, on this basis, belong to a separate kingdom. A virus molecule consists of a nucleic acid, which can be either DNA or RNA. Around them is a protein shell. With such a structure, these organisms are able to carry out only the only sign of livingcreatures - to multiply by self-assembly inside the host organism. All bacteria are prokaryotes. This means that their cells do not have a formed nucleus. Their genetic material is represented by a nucleoid - circular DNA molecules, clusters of which are located directly in the cytoplasm.
Plants and animals differ in the way they eat. The former are able to synthesize organic substances themselves during photosynthesis. This type of nutrition is called autotrophic. Animals absorb ready-made substances. Such organisms are called heterotrophs. Mushrooms have characteristics of both plants and animals. For example, they lead an attached lifestyle and unlimited growth, but are not capable of photosynthesis.
Properties of living matter
And on what basis, in general, are organisms called living? Scientists identify a number of criteria. First of all, it is the unity of the chemical composition. All living matter is formed by organic substances. These include proteins, lipids, carbohydrates and nucleic acids. All of them are natural biopolymers, consisting of a certain number of repeating elements. The signs of living beings also include nutrition, respiration, growth, development, hereditary variability, metabolism, reproduction, and the ability to adapt.
Each taxon is characterized by its own characteristics. For example, plants grow indefinitely, throughout their lives. But animals increase in size only up to a certain time. The same goes for breathing. It is believed that this process takes placeonly in the presence of oxygen. Such respiration is called aerobic. But some bacteria can oxidize organic matter even without oxygen - anaerobically.
Diversity of the living world: levels of organization and basic properties
Both a microscopic bacterial cell and a huge blue whale have these signs of life. In addition, all organisms in nature are interconnected by a continuous metabolism and energy, and are also necessary links in food chains. Despite the diversity of the living world, the levels of organization suggest the presence of only certain physiological processes. They are limited by structural features and species diversity. Let's consider each of them in more detail.
Molecular level
The diversity of the living world, along with its uniqueness, is determined precisely by this level. The basis of all organisms are proteins, the structural elements of which are amino acids. Their number is small - about 170. But only 20 are included in the composition of the protein molecule. Their combination causes an endless variety of protein molecules - from the reserve albumin of bird eggs to the collagen of muscle fibers. At this level, the growth and development of organisms as a whole, the storage and transfer of hereditary material, metabolism and energy conversion take place.
Cellular and tissue level
Moleculesorganic matter forms cells. The diversity of the living world, the basic properties of living organisms at this level are already fully manifested. Single-celled organisms are widely distributed in nature. It can be both bacteria, and plants, and animals. In such creatures, the cellular level corresponds to the organism.
At first glance it may seem that their structure is rather primitive. But that's not the case at all. Just imagine: one cell performs the functions of the whole organism! For example, the ciliate shoe performs movement with the help of a flagellum, breathing through the entire surface, digestion and regulation of osmotic pressure through specialized vacuoles. Known in these organisms and the sexual process, which occurs in the form of conjugation. Multicellular organisms form tissues. This structure consists of cells that are similar in structure and function.
Organism level
In biology, the diversity of the living world is studied precisely at this level. Each organism is a single entity and works in harmony. Most of them are composed of their cells, tissues and organs. The exceptions are lower plants, fungi and lichens. Their body is formed by a collection of cells that do not form tissues and is called the thallus. The function of roots in organisms of this type is performed by rhizoids.
Population-species and ecosystem level
The smallest unit in taxonomy is the species. This is a collection of individuals with a number ofcommon features. First of all, these are morphological, biochemical features and the ability to freely interbreed, allowing these organisms to live within the same range and produce fertile offspring. Modern taxonomy has more than 1.7 million species. But in nature they cannot exist separately. Within a certain area, several species live at once. This is what determines the diversity of the living world. In biology, a set of individuals of the same species that live within a certain range is called a population. They are isolated from such groups by certain natural barriers. It can be reservoirs, mountains or forests. Each population is characterized by its diversity, as well as sex, age, ecological, spatial and genetic structure.
But even within a single range, the species diversity of organisms is quite large. All of them are adapted to living in certain conditions and are closely related trophically. This means that each species is a food source for the other. As a result, an ecosystem, or biocenosis, is formed. This is already a collection of individuals of different species, connected by habitat, circulation of matter and energy.
Biogeocenosis
But factors of inanimate nature constantly interact with all organisms. These include air temperature, salinity and chemical composition of water, the amount of moisture and sunlight. All living beings are dependent on them and cannot exist without certainconditions. For example, plants feed only in the presence of solar energy, water and carbon dioxide. These are the conditions for photosynthesis, during which the organic substances they need are synthesized. The combination of biotic factors and inanimate nature is called biogeocenosis.
What is the biosphere
The diversity of the living world on the widest scale is represented by the biosphere. This is the global natural shell of our planet, uniting all living things. The biosphere has its limits. The upper one, located in the atmosphere, is limited by the planet's ozone layer. It is located at an altitude of 20 - 25 km. This layer absorbs harmful ultraviolet radiation. Above it, life is simply impossible. At a depth of up to 3 km is the lower boundary of the biosphere. Here it is limited by the presence of moisture. Only anaerobic bacteria can live so deeply. In the water shell of the planet - the hydrosphere, life was found at a depth of 10-11 km.
So, living organisms inhabiting our planet in different natural shells have a number of characteristic properties. These include their ability to breathe, feed, move, reproduce, etc. The diversity of living organisms is represented by different levels of organization, each of which differs in the level of complexity of the structure and physiological processes.
