Living beings

What are living things?

Living beings or organisms are all complex structures that fulfill functions such as food, development, reproduction and interactions with other organisms, including energy exchange with the environment that surrounds them. That is, they are all organisms such as cells, animals, plants and fungi.

Among other traits, living beings are characterized by having a cellular organization, responding to stimuli, adapting to the environment and fulfilling vital functions such as nutrition and reproduction.

The life cycle of living things encompasses birth, growth, reproduction, and death. To survive, they need to obtain energy through nutrition.

The structure of living beings is formed with cells. There are unicellular and multicellular living beings. Unicellular ones are made up of a cell, like bacteria. Multicellular cells are made up of many cells. These form tissues; the tissues form the organs, and the organs give rise to a living being, like animals.

The basic difference between living and non-living beings is precisely that the former are made up of cells, while non-living elements do not have them at all. Some examples of non-living elements are water, sand, metals, and rocks.

Characteristics of living beings

Although there is a wide diversity of living beings, they all share certain characteristics:

They have various levels of cellular organization. Some organisms are unicellular, while others are multicellular. According to this, the structure has several levels of organization, which can range from biomolecules to the formation of tissues, bones and organs of more complex living beings.

They develop and reproduce. Organisms go through a life cycle that encompasses birth, development, reproduction, and death. This involves a series of internal and external changes (increase in size, weight, shape, etc.). At one point in their development they are ready to reproduce, either sexually or asexually.

They fulfill vital functions. All living beings carry out the functions of nutrition, metabolism and excretion. This means that after eating, they do a process called metabolism, which consists of the absorption, transformation and release of energy necessary for their essential activities. Then, the body is responsible for expelling toxic waste through excretion.

They respond to stimuli. Every living being has the ability to receive stimuli from the environment, process it and take that information to generate a short or long-term response.An animal that runs away when listening to its predators is responding to a stimulus.

They are capable of self-regulation. All organisms have the ability to self-regulate to compensate internally for changes that occur in the environment. This ability is known as homeostasis and is vital for survival. An example of homeostasis is human perspiration, which allows to maintain the internal temperature of the body.

They adapt to the environment. Any living organism has the ability to adapt to the environment that surrounds it. In this way, it ensures its own survival and that of its species.

It may interest you:

  • Characteristics of living beings
  • Reproduction
  • Metabolism

Classification of living things

1. Kingdom Animalia. 2. Kingdom Plantae. 3. Kingdom Fungi. 4. Kingdom Protozoa. 5. Chromist Kingdom. 6. Kingdom Archaea. 7. Kingdom Bacteria.

At present, living beings are classified into seven large groups called kingdoms of nature. Let's see what they are and what they consist of.

Kingdom Animalia (animals)

In this kingdom are all multicellular organisms with a defined cell nucleus that breathe oxygen, feed on other organisms, move autonomously and reproduce sexually.

For example, birds, fish, reptiles, mammals and, among the latter, humans.

Kingdom Plantae (plants)

They are multicellular organisms with a defined cell nucleus that, unlike those of the Animalia kingdom, do not need to feed on other organisms, they do not have autonomy of movement and their reproduction can be sexual or asexual. In short, we mean plants as a whole.

For example, the orchid (Orchidaceae) or the cherry tree (Prunus).

Kingdom Fungi (mushrooms)

It brings together multicellular organisms which, like plants, have a defined cell nucleus, breathe oxygen, and are immobile. However, their diet can be parasitic or come from the waste of other species. They also reproduce by spores, either sexually or asexually.

For example, him Penicillium chrysogenum and brewer's yeastSaccharomyces cervisiae)

Chromista Kingdom (Chromists)

They are organisms with a defined cell nucleus and capable of photosynthesis. They have a cellular layer that protects them, and in it they have a structure of cilia, which allows them to move.

For example, diatoms, a type of single-celled algae.

Kingdom Protozoa (protozoa)

It groups together certain microscopic unicellular organisms that cannot be considered chromist. They normally breathe oxygen and feed on other single-celled organisms, although there are some exceptions. They can reproduce sexually or asexually.

For example, amoebas and protozoa.

Archaea Kingdom (archaea)

This kingdom is made up of organisms whose cells do not have a differentiated nucleus (prokaryotic cells). They can feed on other living beings or be autonomous. They reproduce asexually by binary fission. Archaea are never pathogenic.

For example, methanogenic archaea found in the intestines of certain animals.

Kingdom Bacteria (bacteria)

It is made up of prokaryotic organisms whose cells do not have a differentiated nucleus. Bacteria are covered by a wall that protects them from the outside environment, which contains peptidoglycan, which archaea do not. Some bacteria are pathogens.

For example, the bacteria Escherichia coli.

See also:

  • Kingdoms of nature
  • Classification of living things
  • animal Kingdom

chemical composition of living being

Living beings share a chemical composition made up of bioelements or biogenic elements. Bioelements are divided into two large groups:

  • Primary chemical elements: they receive this name because they are present in all known forms of life and, in addition, their proportion reaches 96%. These are: carbon, oxygen, hydrogen, phosphorus, sulfur, and nitrogen.
  • Secondary chemical elements: they are called secondary because they are found in a lower proportion than the primary ones. Although there are many, among them we can name the following: sodium, calcium, potassium, iodine, iron, magnesium, silicon, copper, fluorine, manganese, boron and chlorine.

Bioelements form biomolecules, that is, organic and inorganic compounds that are present in living beings. Organic compounds include carbohydrates, lipids, proteins, and nucleic acids. Inorganic compounds include water and mineral salts.

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