The diversity of the world is simply amazing in its splendor. Whatever creatures you meet! After all, there are about a million different species of insects, not to mention animals and representatives of other taxonomic units of nature. However, scientists have created a theory that speaks of the unity of origin of all biomass on the planet. This means that the ancestor was alone. Evidence of this is the similarity between the creatures. What is common in the structure of all living organisms? Why is this theory considered universally accepted? Let's try to figure it out.
What is common in the structure of all living organisms?
The answer to this question is actually simple. This is said to students from the fifth grade in biology and nature studies. The general properties of living organisms are repelled by the structure, which is based on all the only structure - the cell. No wonder it is called the brick of life.
The cells of the bodies of plants, fungi, animals, lichens and humans are composed of cells. The smallest creatures on the planet are bacteria, but they are also cells. But note that the structure of the cells of living organisms is not the same. And this is natural. After all, evolution took place over many millennia, which led to the emergence and consolidation of differences. As a result, we have that world, that biomass of the planet that is now.
What is common in the structure of all living organisms? The answer is quite clear. The presence of a cell, be it the only one, or there are millions of them. If you look even deeper, then you can indicate the commonality of the biochemical composition of this structure. After all, it is known that protein molecules are the basis of life.
According to the Oparin-Haldane theory, life was born from a coacervate droplet, a protein molecule. Over time, it was transformed into a cell, and then all other levels of organization of life followed . Therefore, to the question: "What is common in the structure of all living organisms?" can be answered in a few words:
- cell-based structure;
- cell-based protein;
- nucleic acids at the heart of the hereditary apparatus.
These are the very similarities on which the theory of the unity of the origin of life on Earth is based.
The main signs of living
The main properties of living organisms, clearly allowing to distinguish them from inanimate objects and bodies, are as follows:
- reproduction, that is, leaving behind offspring to maintain and maintain numbers;
- irritability - the ability to respond to external influences of any kind (physical, chemical, mechanical);
- metabolism (as well as energy), which includes nutrition and excretion;
- breath;
- growth and development.
The totality of these signs allows you to judge whether the body is alive or not. And the analysis of its morphological, genetic and physiological features, anatomical structure, allows attributing to one or another kingdom of wildlife.
They, in turn, are known today for five.
- Animals.
- Plants.
- Mushrooms.
- Bacteria.
- Viruses.
The latter relate to non-cellular life forms; their systematic position in the general system of nature is rather ambiguous.
Levels of life organization of living systems
The hierarchy in the construction of life has already been designated above. Let's consider it in more detail. Each living creature becomes a part of the planet, another element of biomass. However, where does it all begin, what stages does it go through? This question has been studied by scientists for a long time. It is customary to distinguish several levels of organization of life.
- Molecular.
- Cellular.
- Tissue.
- Organ.
- Organized.
- Population and species.
- Biogeocenotic.
- Biosphere.
Each level has its own characteristics, processes that indicate the presence of life. Let's consider them in more detail.
Molecular and cellular
These levels are the very first, fundamental. So, on the molecular one, numerous chemical reactions occur between various organic and inorganic compounds. As a result, the structures of the future cell are formed. From here smoothly begins the rise one step higher - the cellular level. He is one of the most important and speaks of the unity of all life on the planet.
What are the most important molecules in a cell? Without which of them its existence is impossible? These are such as:
- carbohydrates;
- proteins;
- enzymes;
- hormones;
- vitamins;
- amino acids;
- nucleic acids;
- some inorganic complex compounds;
- water;
- lipids;
- micro and macro elements.
Of course, the meaning of each of them is different. However, with a prolonged absence of any organism undergoes irreversible changes, and ultimately the end of the life cycle.
Tissue and organ
The next level beyond the cellular is tissue. After all, any tissue in itself is a collection of cells that are united by a common origin, anatomical features and the role played.
In turn, tissues form various organs. If we are talking about plants, then this is the root system and all the structures of the shoot. If about animals, then you can list the organs for a long time, because there are a lot of them. For example, the heart, kidneys, lungs, intestines, skin and others.
At these levels, the general properties of living organisms related to multicellular ones are manifested.
Levels for multicellular
The next highest level is organismic. It implies that in the body of multicellular creatures, organs are combined into systems that, together and in coordinated work, ensure the normal functioning of the whole organism.
However, all biomass elements are different. The population-species step is the result of innovations in the organization of various types of creatures. These changes are due to environmental influences. That is, in essence, this is the level at which evolutionary changes occur as a result of fitness.
Biosphere
The main properties of living organisms, which we have listed above, underlie such a global concept as the biosphere. This is the highest, most comprehensive level of organization of nature. All participants in the biosphere are only living things. It is from them that biomass is formed. Also an important part is what creatures produce. It makes up the biocosal substance of the biosphere.
There are several types of substances that make up this level. It:
- living;
- biogenic;
- inert;
- biokosny;
- space origin;
- radioactive decay;
- simple atoms.
The founder of the doctrine of the biosphere was V.I. Vernadsky. His merit in the development of this concept is simply enormous.
Prokaryotic organisms
A special place among the taxa of nature is occupied by bacteria. The thing is that their cell is arranged somewhat differently than all the others. The position of microorganisms in the living world system is indicated in one word - prokaryotes. This term refers to creatures whose cell is deprived of a formed nuclear membrane. This means that nucleic acids are located within the entire cavity.
For bacteria, the levels of organization of nature are slightly different. They can be listed in this order:
- molecular;
- cellular;
- species;
- biosphere.
All other steps are not available to them. But the microscopic nature and simple structure did not prevent microorganisms from becoming the most common and numerous representatives of our planet. No other kingdom of wildlife counts such a number of representatives.