The whole diversity of the living world is almost impossible to express in quantitative terms. For this reason, taxonomists combined them into groups based on certain characteristics. In our article, we will consider the basic properties, the basics of classification and the organization levels of living organisms.
The diversity of the living world: briefly
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, scientists distinguish five kingdoms. The diversity of the living world (photo shows some of its representatives) includes Plants, Animals, Mushrooms, Bacteria and Viruses. The last of them do not have a cellular structure and, by this sign, belong to a separate Kingdom. A virus molecule consists of a nucleic acid, which can be represented by both DNA and RNA. Around them is the protein shell. With such a structure, these organisms are able to carry out only the only sign of living things - to reproduce by self-assembly inside the host organism. All bacteria are prokaryotes. This means that in their cells there is no formed nucleus. Their genetic material is represented by a nucleoid - ring DNA molecules whose clusters are located directly in the cytoplasm.
Plants and animals differ in the way they eat. The former are capable of synthesizing organic matter themselves during photosynthesis. This method of nutrition is called autotrophic. Animals absorb ready-made substances. Such organisms are called heterotrophs. Mushrooms possess the 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 by what signs, in general, are organisms called living? Scientists identify a number of criteria. First of all, this 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 creatures 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 unlimitedly throughout life. But animals increase in size only until a certain time. The same goes for breathing. It is generally accepted that this process occurs only with the participation of oxygen. Such breathing is called aerobic. But some bacteria can oxidize organic matter even without oxygen - anaerobically.
The diversity of the living world: levels of organization and basic properties
The microscopic bacterial cell and the huge blue whale possess the indicated signs of the living. In addition, all organisms in nature are interconnected by a continuous exchange of substances and energy, and are also necessary links in the food chain. Despite the diversity of the living world, 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 by this level. The basis of all organisms is proteins, the structural elements of which are amino acids. Their number is small - about 170. But the composition of the protein molecule includes only 20. Their combination causes an infinite variety of protein molecules - from reserve albumin of bird eggs to collagen of muscle fibers. At this level, the growth and development of organisms as a whole, the storage and transmission of hereditary material, metabolism and energy conversion are carried out.
Cell and Tissue Level
Organic molecules form cells. The diversity of the living world, the basic properties of living organisms at this level are already fully manifested. Unicellular organisms are widespread in nature. It can be both bacteria, and plants, and animals. In such creatures, the cellular level corresponds to the body level.
At first glance, it may seem that their structure is quite primitive. But this is not at all true. Just imagine: one cell performs the functions of a whole organism! For example, the ciliates shoe moves with a flagellum, breathes through the entire surface, digests and regulates the osmotic pressure through specialized vacuoles. The sexual process that occurs in the form of conjugation is also known in these organisms. Multicellular organisms form tissues. This structure consists of cells similar in structure and function.
Body level
In biology, the diversity of the living world is studied at this level. Each organism is a single whole and works in concert. Most of them are composed of 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 the 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 of common features. First of all, these are morphological, biochemical features and the ability to cross freely, allowing these organisms to inhabit within the same range and produce prolific offspring. Modern taxonomy has more than 1.7 million species. But in nature, they cannot exist separately. Within a certain territory several species live at once. This determines the diversity of the living world. In biology, the totality of individuals of one species that live within a specific area is called a population. They are isolated from similar groups by certain natural barriers. It can be ponds, mountains or forests. Each population is characterized by its diversity, as well as gender, age, environmental, spatial and genetic structure.
But even within a single range, the species diversity of organisms is quite large. All of them are adapted to live in certain conditions and are closely related trophically. This means that each species is a source of nutrition for the other. As a result, an ecosystem, or biocenosis, is formed. This is a collection of individuals of different species, connected by habitat, the circulation of substances and energy.
Biogeocenosis
But with all organisms factors of inanimate nature constantly interact . These include the temperature regime of air, salinity and chemical composition of water, the amount of moisture and sunlight. All living things are dependent on them and cannot exist without certain conditions. For example, plants only eat in the presence of solar energy, water, and carbon dioxide. These are the conditions of photosynthesis, during which the necessary organic substances are synthesized. The totality of biotic factors and inanimate nature are 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 life. The biosphere has its borders. The upper one, located in the atmosphere, is limited by the ozone layer of the planet. 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 3 km is the lower boundary of the biosphere. Here it is limited by moisture. Only anaerobic bacteria can dwell so deeply. In the water shell of the planet - the hydrosphere, life is found at a depth of 10-11 km.
So, the living organisms that inhabit our planet in different natural shells have a number of characteristic properties. These include their ability to breathe, eat, 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.