A living organism is the main subject that science such as biology studies. 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 feeds, moves or moves, and also has offspring.
Wildlife science
The term "biology" was introduced by J. B. Lamarck - a French naturalist - in 1802. At about the same time and independently of it, the German botanist G.R. gave this name to the science of the living world. Treviranus.
Numerous sections of biology consider the diversity of not only currently existing, but also extinct organisms. They study their origin and evolutionary processes, structure and functioning, as well as individual development and relationships with the environment and with each other.
Sections of biology consider 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 in their structure were significantly different from those currently existing. They were incomparably simpler. Throughout the entire stage of the formation of life on Earth, natural selection took place . He contributed to the improvement of 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 arising from primary carbohydrates. At the dawn of their history, both animals and plants were tiny unicellular creatures. They looked like current amoebas, blue-green algae and bacteria. In the course of evolution, multicellular organisms began to appear, which were much more diverse and 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 are found in objects of inanimate nature. The main difference is the ratio 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 diverse species of animals, half a million species of plants, as well as ten million microorganisms. Such a variety cannot be studied without a detailed systematization. The classification of living organisms was first developed by the Swedish naturalist Karl Linnaeus. He laid the foundation for his work on the hierarchical principle. The systematization unit was a species whose name was proposed to be given only in Latin.
The classification of living organisms used in modern biology indicates family ties and evolutionary relationships 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 and giving offspring capable of reproduction, is a species.
There is another classification in biology. With this science, all cellular organisms are divided into groups by the presence or absence of a formed nucleus. These are prokaryotes and eukaryotes.
The first group consists of nuclear-free primitive organisms. A nuclear zone is released in their cells, but it contains only a molecule. These are bacteria.
The true nuclear representatives of the organic world are eukaryotes. The cells of living organisms of this group possess all the basic structural components. Their core is clearly framed. This group includes animals, plants and mushrooms.
The structure of living organisms can be not only cellular. Biology studies other life forms. These include non-cellular organisms, such as viruses, as well as bacteriophages.
Classes of living organisms
In biological systematics, there is a rank of hierarchical classification, which scientists consider one of the main. He identifies classes of living organisms. The main ones include the following:
- bacteria;
- mushrooms;
- animals;
- plants;
- seaweed.
Class Description
A bacterium is a living organism. It is a unicellular that multiplies by division. A cell in a bacterium is encapsulated and has a cytoplasm.
The next class of living organisms includes fungi. In nature, there are about fifty thousand species of these representatives of the organic world. However, biologists studied only five percent of their total. Interestingly, some characteristics of both plants and animals are inherent in mushrooms. An important role of living organisms of this class lies in the ability to decompose organic material. That is why mushrooms can be found in almost all biological niches.
The animal world boasts a wide variety. Representatives of this class can be found in 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 that offspring are fed. All mammals are divided into ungulates (giraffe, horse) and carnivores (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 are not able to withstand even water tension.
Amphibians and reptiles were one of the first vertebrates that went to land in distant historical times. Until now, the lives of representatives of this class are connected with water. So, the habitat of adults is dry land, and their breathing is carried out by the lungs. Larvae breathe with gills and swim in the water. Currently, there are about seven thousand species of this class of living organisms on Earth.
Unique representatives of the fauna of our planet are birds. Indeed, unlike other animals, they are able to fly. Almost eight thousand six hundred species of birds live on Earth. Representatives of this class are characterized by plumage and egg laying.
A huge group of vertebrates includes fish. They live in water bodies and have fins and gills. Biologists divide fish into two groups. These are cartilage and bone. Currently, there are about twenty thousand different species of fish.
Inside the class of plants, there is its own gradation. Representatives of the flora are divided into dicotyledons and monocotyledons. The first of these groups contains a seed in the seed, consisting of two cotyledons. Representatives of this species can be identified by leaves. They are penetrated by a mesh of veins (corn, beets). The embryo of monocotyledonous plants has only one cotyledon. On the leaves of such plants, the veins are located in parallel (onion, wheat).
Algae class 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 by 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 exchange of energy and substances. In a living organism there is a constant conversion of various substances into energy, and physical and chemical changes also 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 is different from inorganic. Yes, in non-living objects, changes in matter and the conversion of energy also occur. 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 cannot continue to exist. The consequence of metabolism is the renewal of the organic system. The cessation of metabolic processes entails death.
The functions of a living organism are diverse. But all of them are directly related to the metabolic processes taking place in it. This can be growth and reproduction, development and digestion, nutrition and respiration, reactions and movement, isolation of waste products and secretion, etc. At the heart of any body function is a combination of processes of energy and substance conversion. Moreover, this is equally related to the capabilities of both tissue, cell, organ, and the whole organism.
Metabolism in humans and animals includes the processes of nutrition and digestion. In plants, it is carried out using photosynthesis. During the metabolism, a living organism supplies itself with the substances necessary for existence.
An important distinguishing feature of the objects of the organic world is the use of external energy sources. An example of this is light and food.
Properties inherent in living organisms
Any biological unit has in its composition individual elements, which, in turn, form an inextricably linked system. For example, in the aggregate, all organs and functions of a person represent his body. The properties of living organisms are diverse. In addition to a single chemical composition and the possibility of implementing metabolic processes, objects of the organic world are capable of organization. Certain structures are formed from random molecular motion. This creates a certain order for all living things in time and space. Structural organization is a whole complex of complex self-regulating metabolic processes that occur in a certain order. This allows you to maintain at the required level the constancy 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 is replaced by adrenaline and glucagon. Also, warm-blooded organisms have numerous mechanisms of heat regulation. This is an expansion of skin capillaries, and intense sweating. As you can see, this is an important function that the body performs.
The properties of living organisms, characteristic only for the organic world, are also concluded in the process of self-reproduction, because the existence of any biological system has a time limit. Life can only be supported by self-reproduction. The basis of this function is the formation of new structures and molecules, due to the information that is embedded in DNA. Self-reproduction is inextricably linked with heredity. After all, each of the living creatures gives birth to their own kind. Through heredity, living organisms convey their developmental features, 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 (effects). As for the irritability of the human body, it is inextricably linked with the properties inherent in muscle, nervous, and glandular tissue. These components are able to give an impetus to the response after muscle contraction, the sending of a nerve impulse, as well as the secretion of various substances (hormones, saliva, etc.). And if a living organism is deprived of the nervous system? The properties of living organisms in the form of irritability are manifested in this case by movement. For example, protozoa leave solutions in which the salt concentration is too high. As for plants, they are able to change the position of the shoots in order to absorb light as much as possible.
Any living system 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 lack it. After all, the movement of the cytoplasm occurs in any cell. Attached animals also move. Growth movements due to an 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 the space invariably surrounds a living organism or an entire 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 effect on him. Living organisms are forced to adapt to existing conditions. So, some of the animals can live in areas of the Far North at very low temperatures. Others are able to exist only in the tropic zone.
On planet Earth, several habitats are distinguished. Among them are:
- water;
- ground 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 throughout this time, organisms developed, changed, settled, and simultaneously affected their environment.
The influence of organic systems on the atmosphere caused the appearance of more oxygen. At the same time, the volume of carbon dioxide decreased significantly. The main source of oxygen production are plants.
Under the influence of living organisms, the composition of the waters of the oceans has changed. Some rocks are organic in origin. Minerals (oil, coal, limestone) are 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, indicating the quality of the human environment. They are connected by complex processes with vegetation and soil. If at least one link in this chain is lost, an imbalance of the ecological system as a whole will occur. That is why for the cycle of energy and substances on the planet, it is important to preserve the entire existing diversity of representatives of the organic world.