A living organism is the main subject 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.
Wildlife Science
The term "biology" was introduced by J. B. Lamarck, a French naturalist, in 1802. Around the same time, and independently of him, this name was given to the science of the living world by the German botanist G. R. Treviranus.
Numerous sections of biology consider the diversity of not only currently existing, but also already extinct organisms. They study their origin and evolutionary processes, structure and function, 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 are significantlydifferent from those currently in existence. 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 ate only organic components that arose from primary carbohydrates. At the dawn of their history, both animals and plants were the smallest single-celled creatures. They were similar to today's amoebas, 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 s alts. Organic substances found 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 in the ratio of these elements. Living organisms are those whose composition is ninety-eight percent hydrogen, oxygen, carbon and nitrogen.
Classification
The organic world of our planet today has almost one and a halfmillion diverse animal species, half a million plant species, and ten million micro-organisms. Such diversity cannot be studied without its detailed systematization. The classification of living organisms was first developed by the Swedish naturalist Carl Linnaeus. He based his work on the hierarchical principle. The unit of systematization was the species, the name of which 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.
A set of living organisms that have a common origin, the same chromosome set, adapted to similar conditions, living in a certain area, freely interbreeding and producing offspring capable of reproduction, and is a species.
There is another classification in biology. This science divides all cellular organisms into groups according to the presence or absence of a formed nucleus. These are prokaryotes and eukaryotes.
The first group is represented by nuclear-free primitive organisms. A nuclear zone stands out in their cells, but it contains only a molecule. It's bacteria.
The true nuclear representatives of the organic world are eukaryotes. The cells of living organisms of this group have all the main structural components. Their core is also clearly defined. This group includes animals, plants and fungi.
The structure of the livingorganisms 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 systematics, there is a rank of hierarchical classification, which scientists consider one of the main ones. He distinguishes classes of living organisms. The main ones include the following:
- bacteria;
- mushrooms;
- animals;
- plants;
- algae.
Class descriptions
Bacteria is a living organism. It is a unicellular organism that reproduces by division. A cell in a bacterium is enclosed in a shell and has a cytoplasm.
Mushrooms belong to the next class of living organisms. In nature, there are about fifty thousand species of these representatives of the organic world. However, biologists have studied only five percent of their total. Interestingly, fungi share some characteristics of both plants and animals. 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 great variety. Representatives of this class can be found in such zones 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 they feed their offspring. All mammals are dividedon ungulates (giraffe, horse) and carnivores (fox, wolf, bear).
Insects are representatives of the animal world. There are a huge number of them on Earth. They swim and fly, crawl and jump. Many of the insects are so small that they cannot withstand even water pressure.
Amphibians and reptiles were one of the first vertebrates that came to land in distant historical times. 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 lungs. The larvae breathe through gills and swim in the water. Currently, there are about seven thousand species of this class of living organisms on Earth.
Birds are unique representatives of the fauna of our planet. Indeed, unlike other animals, they are able to fly. Almost eight thousand six hundred species of birds live on Earth. This class is characterized by plumage and oviposition.
Fish belong to a huge group of vertebrates. 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 types of fish.
Inside the class of plants there is its own gradation. Representatives of the flora are divided into dicots and monocots. In the first of these groups, the seed contains an embryo consisting of two cotyledons. You can identify representatives of this species by the leaves. They are pierced by a mesh of veins(corn, beets). The embryo of a monocotyledonous plant has only one cotyledon. On the leaves of such plants, the veins are parallel (onion, wheat).
The algae class has more than thirty thousand species. These are water-dwelling spore plants that do not have vessels, but have chlorophyll. This component contributes to the implementation of the process of photosynthesis. Algae do not form seeds. Their reproduction occurs vegetatively or by spores. This class of living organisms differs from higher plants in the absence of stems, leaves and roots. They have 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 matter exchange. In a living organism, there is a constant transformation of various substances into energy, as well as physical and chemical changes.
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 the inorganic. Yes, in inanimate objects there are also changes in matter and the transformation of energy. However, these processes have their fundamental differences. The metabolism that occurs in inorganic objects destroys them. At the same time, living organisms without metabolic processes cannot continue their existence. The consequence of metabolism is the renewal of the organic system. The termination of the exchange processes entails death.
The functions of a living organism are diverse. But they allare directly related to the metabolic processes occurring in it. This can be growth and reproduction, development and digestion, nutrition and respiration, reactions and movement, excretion of waste products and secretion, etc. The basis of any function of the body is a set of processes of transformation of energy and substances. Moreover, this equally applies 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 with the help of photosynthesis. A living organism in the implementation of metabolism 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. Light and food are examples of this.
Properties inherent in living organisms
Any biological unit has in its composition separate 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 the chaotic molecular motion. This creates a certain order in time and space for all living things. Structural organization is a whole complex of the most complex self-regulating metabolic processes that proceed in a certain order. This allowsmaintain the constancy of the internal environment at the required level. For example, the hormone insulin reduces the amount of glucose in the blood when it is in excess. With a lack of this component, it is replenished by adrenaline and glucagon. Also, warm-blooded organisms have numerous mechanisms of thermoregulation. This is the 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 included in the process of self-reproduction, because the existence of any biological system has a time limit. Only self-reproduction can sustain life. This function is based on the process of 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 beings gives birth to their own kind. Through heredity, living organisms transmit their developmental features, properties and signs. 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 react to internal and external changes (impacts). As for the irritability of the human body, it is inextricably linked with the properties inherent in muscle, nervous, and also glandular tissue. These components are able to give impetus to the response after muscle contraction, the departure of a nerve impulse, as well as the secretion of varioussubstances (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 s alt 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 systems can respond to a 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 are deprived of 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 space invariably surrounds a living organism or a whole group. This is the habitat.
In the life of any organism, organic and inorganic components of nature play a significant role. They have an effect on him. Living organisms are forced to adapt to existing conditions. So, some of the animals can live in the Far North at very low temperatures. Others can only exist in the tropics.
There are several habitats on planet Earth. 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 have evolved, changed, settled and at the same time affected their environment.
The influence of organic systems on the atmosphere caused more oxygen to appear. This significantly reduced the amount of carbon dioxide. Plants are the main source of oxygen production.
Under the influence of living organisms, the composition of the waters of the World Ocean has also changed. Some rocks are of organic 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. With the loss of at least a single link from this chain, an imbalance of the ecological system as a whole will occur. That is why it is important for the circulation of energy and substances on the planet to preserve all the existing diversity of representatives of the organic world.
