What is an organism?

We explain to you what an organism is, how it is classified, autotrophic and heterotrophic organism. In addition, human organism and examples.

  1. What is an organism?

In biology , a singular and differentiated individual is called an organism or living being , composed of a set of hierarchical and specialized organic matter . They are biochemical communication and transmission systems , which allow you to maintain your internal balance while exchanging matter and energy with the surrounding environment. In other words, an organism is a living entity, endowed with the ability to nourish, grow, reproduce and die.

All known organisms, with the exception of viruses , are formed by cells , and have a metabolism that allows them to guarantee their existence and give rise to their biological processes in exchange for exchanging energy with the environment . The ultimate goal of every organism seems to be reproduction, that is, the perpetuation of its species and the transmission of its genetic material (inheritance).

Chemically speaking, living beings distinguish themselves from the nature that surrounds them in their almost exclusive composition based on carbon, hydrogen, oxygen and nitrogen , that is, based on organic molecules , structured very differently from the inorganic molecules of the inert matter.

  1. Types of organism

Organism - flower - Kingdom plantae
The organisms of the plantae kingdom are able to perform photosynthesis.

Organisms are classified according to various criteria. The main criterion is body and physiological similarity, and its belonging to a determined evolutionary group that shares a common ancestor (a taxon). According to this criterion, living beings can belong to five different realms of life , grouped in turn into two different domains or super kingdoms :

  • Prokaryota domain. In this domain are the most primitive organisms known, all unicellular and devoid of cell nucleus , that is, with circular, simple and loose DNA molecules in the cell cytoplasm . They are the oldest living beings evolutionarily and the most simple and tiny. In this domain two kingdoms are identified:
    • Kingdom bacteria. In this kingdom are the most abundant prokaryotes on the planet, bacteria , adapted to almost all habitats and various life models from photosynthetic, chemosynthetic, parasitic metabolisms, etc.
    • Archaea kingdom. Archeobacteria or archaea gained their reputation as a separate kingdom in relatively recent times, when it was discovered that they possess metabolic pathways and biochemical characteristics more similar to those of eukaryotes . They are usually adapted to very demanding environments with life , such as extreme niches such as salt flats, hot springs, etc. Depending on the classification used, archaea can constitute, like bacteria, an individual domain.
  • Eukaryota domain. The second domain of life is made up of unicellular and multicellular organisms whose cells, of greater size and complexity, are endowed with a cell nucleus in which the DNA resides, in the form of a double helix, as well as other similar organelles. They are an evolutionary step forward with respect to prokaryotes  and, thanks to that, they allowed the existence of multicellular beings. In this domain four kingdoms are identified:
    • Protist kingdom . Protists are single-celled eukaryotic organisms, which would become the link between prokaryotes and multicellular organisms. In this realm there are various types of living beings, both autotrophic and heterotrophic, that is, who do photosynthesis or feed on other living things, including parasites that cause disease.
    • Kingdom plant . This is the kingdom of plants, that is, of multicellular organisms (with the exception of some algae) that carry out photosynthesis: the transformation of CO2 and solar energy into starches that serve for the growth and maintenance of the organism. For this they are endowed with chlorophyll, a pigment that gives them theircharacteristic green color .
    • Fungi kingdom . The kingdom of fungi, which share cellular characteristics with plants (such as the presence of the cell wall, but chitin instead of cellulose) and with animals (such as their heterotrophic nutrition, from decomposing organic matter). Except for yeasts , which are unicellular, are always multicellular and reproduce by spores.
    • Animal kingdom . The kingdom of animals, the only living beings endowed with voluntary mobility, in its enormous diversity , from insects, worms and snails, to amphibians , reptiles , birds and mammals . Animals reproduce sexually and their metabolisms operate based on the oxidation of glucose, for which they must breathe oxygen from the air or water (using lungs or gills).
  1. Autotrophic and heterotrophic organism

Vulture - heterotroph - organism - animal kingdom
Decomposing organisms are considered heterotrophs.

An important and common differentiation to all types of living beings is that which distinguishes between living beings capable of synthesizing their own nutrients ( autotrophs ) and those who are not able to do so and must consume the organic matter of other living beings ( heterotrophs ) .

Among living beings of the first type, we find plants and microorganisms capable of chemically synthesizing their nutrients (chemosynthesis) using extreme environmental conditions. These organisms are known as producers in their respective ecosystems and are usually at the base of the food pyramid.

The living beings of heterotrophic metabolism, however, are the most diverse and make various trophic levels above producers. In the first level are those herbivores that obtain their raw material from the consumption of plants, their fruits or derivatives. The second level is made up of predators that feed on herbivores, which are generally small in size. And, finally, on the third level are the large predators that feed in turn from other predators and herbivores, and are the end of the chain.

Finally, decomposing organisms (such as fungi, insects, scavengers and bacteria) that serve to help decompose residual organic matter are also heterotrophs , acting as the nature recycling department.

  1. Human organism

Organism - human being
The human being is made up of almost 100 trillion cells and 50% water.

The human organism is the only one of the known nature that has full awareness of itself and an intelligence that allows it to modify the environment in its favor, instead of adapting it to the challenges of the environment. The human being is the product of billions of years of continuous evolution , which threw the first Homo sapiens about 2 million years ago.

Our organism is multicellular (it consists of almost 100 trillion cells) and is composed of 50% water. We are living mammals, bipeds, bilaterally symmetrical and vertebrates , with metabolisms dependent on oxygen ( respiration ) and glucose, which we ingest from an omnivorous diet.

  1. Organism Examples

Any living being on the planet is a perfect example of organism or living being . This includes plants such as algae, ferns, fruit trees or plain shrubs and desert cacti ; also the fungi that we see in the forest floor or in the roots of the trees (mycorrhizae), or those so annoying that they afflict the athletes between the toes of their feet; also the animals of all kinds, marine, terrestrial and flying, the human being himself, and the bacterial flora that makes life in our intestines, in a symbiotic relationship with our organism. Where there is life, we can identify an organism.

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