When we think of an animal, it is clear that it is a living being, Is not it? We don't have the same thinking about a rock, which has no life. But, after all, what characteristics can we analyze when it comes to classifying an organism as living or not?Next, you will better understand the characteristics used to identify a living being.
→ Characteristics of living beings
Chemical composition: All living organisms have some basic chemical elements. The elements found in all living things are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur.
Cell organization: In the presence of cells it is also an important characteristic of living things. With the exception of virus, all living organisms have cells, which are known as the functional and structural units of living organisms. It is noteworthy that living beings can have only one cell (unicellular) or be formed by several cells (multicellular).
Growth: Living organisms have the incredible capacity for growth. Multicellular organisms may have increased cell size or increased cells in your body. The unicellular ones, in turn, only increase the cell volume. It is worth noting that this property is also absent in viruses.
Metabolism: The chemical reactions that take place in an organism and are related to the formation and destruction of molecules are called metabolism. They occur in living beings and are essential for the proper functioning of the body, acting in all activities, such as reproduction.
Ability to react to stimuli: living beings present irritability, that is, they are able to react to a certain stimulus, such as light and temperature. Human beings have, for example, the ability to respond to pain stimuli.
Reproduction: Living beings are capable of generating offspring through reproduction. This reproduction may or may not involve gametes. In the first case, we have the sexual reproduction and, in the second, the asexual reproduction.
Heredity: The characteristics of a living being can be transmitted to its descendants. This ability is known as heredity and is related to the transfer of our genetic material. O DNA it is considered the hereditary stuff of life.
Mutation: Over time, living beings can undergo changes in their genetic material. These modifications, which can affect the entire morphology, physiology and behavior of the living being, are called mutation.
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Evolution: You living beings are subject to evolution, that is, to changes in the organism that occur over time. These modifications can be evaluated mainly through the fossil records and present as one of the main factors natural selection, which selects the fittest to survive in the quite.
Fossils are evidence of the evolutionary process
→ Viruses, a special case
Viruses are worth mentioning. These organisms are not considered by many researchers to be living beings. This is due to the fact that they do not have cells (acellular) or metabolism. Another group of scientists, however, accepts that they are living beings, as they can make a cell work according to their commands, reproduce and also evolve.
By Ma. Vanessa dos Santos
