Organism Concept – Types, Examples, Human

We explain what an organism is, how it is classified, autotrophic and heterotrophic organism. Also, human organism and examples.

Organism - bird - animal kingdom
Organisms have a metabolism that allows them to guarantee their existence.

What is an organism?

In biology, it is called an organism or living being a singular and differentiated individual, composed of a set of hierarchical and specialized organic matter. It is constituted by biochemical transmission and communication systems, which allow it to preserve its internal balance while exchanging matter and energy with the environment that surrounds it. In other words, an organism is a living entity, endowed with the ability to nurture, grow, reproduce and die.

All known organisms, with the exception of viruses, are made up of 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 are distinguished 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 in a very different way from the inorganic molecules of inert matter.

Organism types

Organism - flower - Kingdom plantae
Organisms of the plantae kingdom are capable of photosynthesis.

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

  • Prokaryota domain. The most primitive known organisms are found in this domain, all unicellular and devoid of a cell nucleus, that is, with circular, simple and loose DNA molecules in the cell cytoplasm. They are the oldest living beings evolutionarily and the simplest and smallest. In this domain two kingdoms are identified:
    • Bacteria kingdom. In this kingdom are the most abundant prokaryotes on the planet, bacteria, adapted to almost all habitats and to various life models based on photosynthetic, chemosynthetic, parasitic metabolisms, etc.
    • Archaea kingdom. Archaebacteria 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 equipped with a cell nucleus in which DNA resides, in the shape of a double helix, as well as other similar organelles. They are an evolutionary step forward with respect to prokaryotes and, thanks to this, they allowed the existence of multicellular beings. In this domain four kingdoms are identified:
    • Protist kingdom. Protists are eukaryotic unicellular organisms, which would become the link between prokaryotes and multicellular organisms. In this kingdom there are various types of living beings, both autotrophic and heterotrophic, that is, that photosynthesize or that feed on other living beings, including parasites that cause disease.
    • Kingdom plantae. 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 their characteristic green color.
    • Fungi kingdom. The kingdom of fungi, which share cellular characteristics with plants (such as the presence of the cell wall, but of chitin instead of cellulose) and with animals (such as their heterotrophic nutrition, from decomposing organic matter). Except for yeasts, which are unicellular, they are always multicellular and reproduce by means of spores.
    • Animalia 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 air or water (using lungs or gills).

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 the one that distinguishes between living beings capable of synthesizing their own nutrients (autotrophs) and those that are not capable of doing so and must consume the organic matter of other living beings (heterotrophs) .

Among living beings of the first type, we find the plants and those 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 found at the base of the food pyramid.

The living beings with heterotrophic metabolism, on the other hand, are the most diverse and make up various trophic levels above the 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, in the third level are the large predators that feed on other predators and herbivores, and are the end of the chain.

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

Human organism

The human organism He is the only one of known nature who is fully aware of himself. and an intelligence that allows him to modify the environment in his favor, instead of adapting himself to the challenges of the environment. The human being is the product of billions of years of continuous evolution, which produced the first Homo sapiens about 2 million years ago.

Our body is multicellular (it is made up of almost 100 trillion cells) and it is made up 50% of water. We are mammalian, biped, bilaterally symmetric and vertebrate living beings, with oxygen-dependent metabolisms (respiration) and glucose, which we ingest from an omnivorous diet.

Examples of organism

Any living being on the planet is a perfect example of an organism or living being. This includes plants such as algae, ferns, fruit trees or shrubs in the plains, and cacti in the desert; also the fungi that we see on the forest floor or on the roots of trees (mycorrhizae), or those so annoying that afflict athletes between their toes; also 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. Wherever there is life, we can identify an organism.