A living organism is ... Classification of living organisms. Set of living organisms

A living organism is the main subject, which is studied by such a science as biology. It is a complex system consisting of cells, organs and tissues. A living organism is one that has a number of characteristic features. He breathes and eats, moves or moves, and also has offspring.

The science of living nature

The term "biology" was introduced by J.B. Lamarck - the French naturalist - in 1802. Around the same time and independently of him, the German botanist GR gave such a title to the science of the living world. Treviranus.

Numerous sections of biology consider the diversity of not only existing, but already extinct organisms. They study their origin and evolutionary processes, structure and functioning, as well as individual development and links with the environment and with each other.

Sections of biology consider the particular and general patterns that are inherent in all living things in all properties and manifestations. This applies to reproduction, and metabolism, and heredity, and development, and growth.

The beginning of the historical stage

The first living organisms on our planet were very different in structure from those at the present time. They were incomparably simpler. Throughout the entire formation of life on Earth, natural selection took place . He helped to improve the structure of living beings, which allowed them to adapt to the conditions of the surrounding world.

At the initial stage, living organisms in nature were fed only by organic components originating from primary carbohydrates. At the dawn of their history, both animals and plants were the smallest single-celled creatures. They looked like the current amoeba, blue-green algae and bacteria. In the course of evolution, multicellular organisms began to appear, which were much more diverse and more complex than their predecessors.

Chemical composition

A living organism is one that is formed by molecules of inorganic and organic substances.

The first of these components is water, as well as mineral salts. Organic substances in the cells of living organisms are fats and proteins, nucleic acids and carbohydrates, ATP and many other elements. It is worth noting the fact that living organisms in their composition contain the same components that exist in non-living objects . The main difference is the correlation of these elements. Living organisms are those, ninety-eight percent of which are hydrogen, oxygen, carbon, and nitrogen.

Classification

The organic world of our planet today has almost one and a half million different species of animals, half a million plant species, and ten million microorganisms. Such diversity can not be studied without its detailed systematization. Classification of living organisms was first developed by the Swedish naturalist Karl Linnaeus. In the basis of his work he laid down a hierarchical principle. The unit of classification was a species whose name was offered only in Latin.

The classification of living organisms, used in modern biology, indicates kinship ties and the evolutionary interrelationships of organic systems. At the same time, the principle of hierarchy is preserved.

The totality of living organisms having a common origin, the same chromosome set, adapted to similar conditions, living in a certain area, freely interbreeding with each other and giving offspring, capable of reproduction, and is a species.

There is one more classification in biology. By this science all cellular organisms are divided into groups according to the presence or absence of a formed nucleus. These are prokaryotes and eukaryotes.

The first group is denuclearized primitive organisms. In their cells a nuclear zone is allocated, but it contains only a molecule. It's bacteria.

The true nuclear representatives of the organic world are eukaryotes. Cells of living organisms of this group possess all the basic structural components. Clearly decorated with them and the core. This group includes animals, plants and mushrooms.

The structure of living organisms can be not only cellular. Biology studies other forms of life. These include non-cellular organisms, such as viruses, as well as bacteriophages.

Classes of living organisms

In biological taxonomy there is a rank of hierarchical classification, which scientists consider one of the main. He distinguishes classes of living organisms. The main ones are the following:

- bacteria;

- mushrooms;

- animals;

- plants;

- seaweed.

Description of classes

The bacterium is a living organism. It is a single-cell that multiplies by division. The cell in the bacterium is encased and has a cytoplasm.

To the next class of living organisms are mushrooms. In nature, there are about fifty thousand species of these representatives of the organic world. However, biologists studied only five percent of their total number. Interestingly, fungi are characterized by some signs of both plants and animals. An important role of living organisms of this class is in the ability to decompose organic material. That is why mushrooms can be found in virtually all biological niches.

The fauna can boast a great variety. Representatives of this class can be found in such areas, where, it would seem, there are no conditions for existence.

The most highly organized class are warm-blooded animals. They got their name from the way the offspring feed them. All representatives of mammals are divided into ungulates (giraffe, horse) and predatory (fox, wolf, bear).

Representatives of the animal world are insects. There are a lot of them on Earth. They swim and fly, crawl and jump. Many of the insects are so small that they can not withstand even the water tension.

One of the earliest vertebrate animals that left in distant historical times on land was amphibians and reptiles. Until now, the life of representatives of this class is connected with water. So, the habitat of adults is dry land, and their breathing is carried out by the lungs. The larvae breathe in the gills and swim in the water. At present, there are about seven thousand species of this class of living organisms on Earth.

The unique representatives of the fauna of our planet are birds. In fact, unlike other animals, they are able to fly. On Earth, there are almost eight thousand six hundred species of birds. Representatives of this class are characterized by feathering and laying of eggs.

To a huge group of vertebrate animals belong fish. They live in ponds and have fins and gills. Biologists divide fish into two groups. These are cartilaginous and bony. At present, there are about twenty thousand different kinds of fish.

Within the class of plants there is a proper gradation. Representatives of the flora are divided into dicots and monocotyledons. The first of these groups in the seed is the embryo, consisting of two cotyledons. Identify representatives of this species can be on the leaves. They are permeated with a mesh of veins (corn, beet). The embryo of monocotyledonous plants has only one cotyledon. On the leaves of such plants veins are located in parallel (onions, wheat).

The class of algae has more than thirty thousand species. These are spore plants that live in water, which do not have blood vessels, but possess chlorophyll. This component contributes to the process of photosynthesis. Algae do not form seeds. Their reproduction occurs vegetatively or spores. From higher plants this class of living organisms is distinguished by the absence of stems, leaves and roots. They possess only the so-called body, which is called the thallus.

Functions inherent in living organisms

What is fundamental for any representative of the organic world? This is the implementation of the processes of energy and substance exchange. In a living organism there is a constant transformation of various substances into energy, and also physical and chemical changes occur.

This function is an indispensable condition for the existence of a living organism. It is thanks to metabolism that the world of organic beings differs from inorganic ones. Yes, in non-living objects, there are also changes in matter and the transformation of energy. However, these processes have their own fundamental differences. The metabolism that occurs in inorganic objects, destroys them. At the same time, living organisms without metabolic processes can not continue their existence. The consequence of the metabolism is the renewal of the organic system. Termination of the processes of exchange entails death.

The functions of a living organism are diverse. But they are all directly related to the metabolic processes taking place in it. It can be growth and reproduction, development and digestion, nutrition and respiration, reactions and movement, allocation of waste products and secretion, etc. At the heart of any function of the body is a set of processes for the transformation of energy and substances. And equally it has to do with the possibilities of both tissue, cell, organ, and the whole organism.

The metabolism of humans and animals includes processes of nutrition and digestion. In plants it is carried out by means of photosynthesis. A living organism, when metabolizing, supplies itself with substances necessary for existence.

An important distinctive feature of the objects of the organic world is the use of external energy sources. Light and food can serve as an example.

Properties inherent in living organisms

Any biological unit has in its composition separate elements, which, in turn, form an inseparably linked system. For example, in aggregate, all the organs and functions of a person are his organism. The properties of living organisms are diverse. In addition to a single chemical composition and the possibility of carrying out exchange processes, the objects of the organic world are capable of organization. From a chaotic molecular motion, certain structures are formed. This creates for all living things a certain order in time and space. Structural organization is a whole complex of complex self-regulating metabolic processes that take place in a certain order. This allows you to maintain the necessary consistency of the internal environment. For example, the hormone insulin reduces the amount of glucose in the blood with its excess. With a lack of this component, it replenishes adrenaline and glucagon. Also, warm-blooded organisms possess numerous mechanisms of heat regulation. This is the expansion of skin capillaries, and intense sweating. As you can see, this is an important function performed by the body.

The properties of living organisms, characteristic only of the organic world, are also contained in the process of self-reproduction, because the existence of any biological system has a temporary limitation. Only self-reproduction can support life. This function is based on the process of the formation of new structures and molecules, due to the information that is embedded in the DNA. Self-reproduction is inextricably linked with heredity. After all, each of the living beings gives birth to similar ones. Through heredity, living organisms transmit their characteristics of development, properties and attributes. This property is due to constancy. It exists in the structure of DNA molecules.

Another property characteristic of living organisms is irritability. Organic systems always respond to internal and external changes (impacts). As for the irritability of the human body, it is inseparably linked with the properties inherent in the muscular, nervous, and glandular tissue. These components are able to give a push response after muscle contraction, the departure of the nerve impulse, as well as the secretion of various substances (hormones, saliva, etc.). And if the living organism is devoid of the nervous system? The properties of living organisms in the form of irritability are manifested in this case by movement. For example, the protozoans leave solutions in which the salt concentration is too high. As for plants, they are able to change the position of shoots in order to absorb light as much as possible.

Any living systems can respond to the action of the stimulus. This is another property of the objects of the organic world - excitability. This process is provided by muscle and glandular tissues. One of the final reactions of excitability is movement. The ability to move is a common property of all living things, despite the fact that outwardly some organisms do not have it. After all, the cytoplasmic movement occurs in any cell. Moved and attached animals. Growth movements due to the increase in the number of cells are observed in plants.

Habitat

The existence of objects of the organic world is possible only under certain conditions. Some part of space invariably surrounds a living organism or a whole group. This is the habitat.

In the life of any organism, the organic and inorganic components of nature play a significant role. They produce a certain impact on it. Living organisms are forced to adapt to existing conditions. So, some of the animals can live in the regions of the Far North at very low temperatures. Others can only exist in the tropics.

On Earth, several habitats are distinguished. Among them are:

- water;

- land-water;

- ground;

- soil;

- living organism;

- ground-air.

The role of living organisms in nature

Life on planet Earth has been around for three billion years. And during all this time, organisms developed, changed, settled and simultaneously influenced their habitat.

The influence of organic systems on the atmosphere caused the appearance of more oxygen. At the same time, the volume of carbon dioxide significantly decreased. The main source of oxygen production are plants.

Under the influence of living organisms, the composition of the waters of the World Ocean has also changed. Some rocks have organic origin. Minerals (oil, coal, limestone) - this is also the result of the functioning of living organisms. In other words, the objects of the organic world are a powerful factor that transforms nature.

Living organisms are a kind of indicator that indicates the quality of the human environment. They are connected by the most complex processes with vegetation and soil. With the loss of even a single link from this chain, there will be an imbalance in the ecological system as a whole. That is why it is important for the cycle of energy and matter on the planet to preserve all the existing diversity of representatives of the organic world.