A living thing is something that needs food, water, air, and shelter. Some examples are plants, since they need water; food, which they get from the sun; fresh air; and shelter Just like humans clearly need water, food air, and shelter.
When we talk about living things, we immediately remember animals, however, plants, fungi, protozoa, algae and bacteria are also considered living beings. Although quite distinct, they all have characteristics that allow you to classify them, these characteristics are:
Reproduction: Living beings are able to leave offspring, that is, they are able to reproduce. Initially, it was believed that microorganisms, like bacteria, arose through abiogenesis. Today, however, it is known that even these small organisms reproduce. In the case of bacteria, the main type of reproduction is binary division or cissiparity, a type of asexual reproduction.
Evolution: Evolution is a process that acts on all living beings, changing them over time. At this point, it is important to highlight natural selection, which ends up selecting the organisms that are most likely to survive in a given environment. The most adapted organisms survive longer in the environment and, consequently, pass on their advantageous characteristics to their descendants. As an example, we can highlight the horses, which through evolution have adapted their paws and can run long distances, escape from predators and establish their survival, while short-legged horses ended up being disadvantaged and dying.
Metabolism: Living beings present metabolism, that is, inside their cells, chemical reactions occur that guarantee their survival. This metabolism ensures, for example, that living beings acquire energy to perform activities, such as reproduction and locomotion.
Response to stimulus: Living beings are able to respond to stimuli, which ensures that they interact with the environment. A pain stimulus, for example, can cause an animal to move away from an area. Another example is the light stimulus, which makes plants grow towards the light.
Cell: It is customary to accept that living beings have cells, which are considered the structural and functional unit of an organism. Some beings are formed by several cells (multicellular); others, however, have only one (single-celled).
Genetic material: All living beings have DNA and / or RNA, the material responsible for controlling their metabolism and ensuring that characteristics are passed on to the next generation (heredity).
