The 7 most important characteristics of living beings

The 7 most important characteristics of living beings
Posted on 10-02-2022

Characteristics of living beings

All living beings, whether unicellular organisms, plants, fungi, or animals, including humans, share certain common characteristics: they are all capable of feeding, growing, and reproducing, which distinguishes them from the non-living elements of nature. Next, we will explain each of these characteristics in more detail.

1. They have a cellular organization

Living things are made up of cells, the basic unit of life. These have a complex internal composition and can form structures of higher levels of complexity when joined together. Unicellular or multicellular living organisms can exist.

Unicellular organisms are made up of a single cell and have a simple internal organization. For example, bacteria.


Unicellular organism. It is a paramecium, from the kingdom Protista.

Multicellular organisms have a higher level of cellular organization. To the extent that cells group together, they form tissues, and these, in turn, form the vital organs that give rise to a complex living being. For example, plants, animals, and humans.


Tissues that form organisms of multicellular structures. In this case, we see the human being, an example of the Animalia kingdom.


2. They perform various vital functions

Each and every one of the living beings fulfills a series of vital functions during their life cycle, which are breathing, feeding, metabolizing, and excreting.

Breathing. All living beings need to breathe, a mechanism that they fulfill in different ways and in different environments according to their ecosystem.

  • Aerobic respiration: when oxygen is taken from the air or water. For example, land animals and aquatic animals.
  • Anaerobic respiration: when another element, such as sulfur, is used to replace oxygen. For example, bacteria.

Nutrition. Food is the process by which living beings obtain the necessary nutrients to survive. It can be heterotrophic or autotrophic.

  • Heterotrophic nutrition or feeding: when nutrients are obtained from other living beings. For example, herbivorous animals (such as sheep, cattle), carnivorous animals (such as lions, tigers, and spiders), and omnivorous animals (such as humans).
  • Autotrophic nutrition or feeding: when they do not depend on other living beings for nourishment, that is, they produce their own food. For example, plants.

Metabolization. It refers to the chemical reactions produced by cells. Metabolism is done through two processes, which are anabolism and catabolism.

  • Anabolism: synthesizes new compounds from simple molecules.
  • Catabolism: breaks down compounds into simple products.

Excretion. Excretion is the process through which living beings eliminate useless or toxic substances from the body. That is, it is the process to expel waste.


3. They grow, develop and die science

Example: life cycle of a hen or a rooster.

All living beings have a life cycle limited in time, according to their particular characteristics. In this period, living beings undergo a process of growth in size, development of their potentialities (including reproduction), aging, and death.

In other words, all living things follow a life cycle that begins with gestation, followed by birth, growth or development, reproduction, and death.


4. They reproduce

Living beings are capable of reproducing. In this way, they transmit their genes to new generations and achieve the survival of the species. The reproduction of living beings can be sexual or asexual.

  • Sexual reproduction: occurs when the presence of two parents (male and female) is necessary for fertilization. For example, mammals like lions and dolphins.
  • Asexual reproduction: occurs when only one individual is capable of generating other identical individuals. For example, bacteria or starfish do not need a partner in order to procreate.

5. They react to stimuli

Living beings need to interact with the environment to live and, therefore, react to the stimuli they receive from it. This ability to react is called irritability. This characteristic allows living beings to react to chemical, physical and sensory stimuli essential for their development. For example, living beings respond to aromas, sounds, textures, visual stimuli, etc.

6. They are able to regulate their internal environment

regulate internal environment

Living things carry out a process called homeostasis. Homeostasis specifically consists of the ability of living beings to keep their environment or internal condition stable in the face of certain changes in the environment.

An example of homeostasis is the process of sweating in humans, whose purpose is to regulate the interior temperature when there is excess heat in the environment.

Dogs are also able to regulate their temperature when it is very hot. That is the reason why dogs pant with their tongues out.


7. They adapt to the environment

adapt to environment

Chameleon. Example of adaptation by mimesis or camouflage with the environment.

Living beings are capable of adapting to certain changes in the conditions of the ecosystem. This ability allows them to guarantee subsistence and survival, by adopting different characteristics.

For example, some animals are able to camouflage or blend in with the environment to protect themselves. This is the case of chameleons, which change their color according to the tone of nearby elements. This is also the case for some insects such as stick insects, certain varieties of butterflies, etc.


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