Have you ever thought about what life is? What does it mean to be alive?
I'm alive, and so are you. The birds chirping is alive, and so is the tree outside my home.
However, the snow falling from the clouds is not alive. The computer or mobile you are using right now and reading this article from is not alive, nor is the chair or table. The parts of that chair or table made of wood were once alive but are no longer.
What is something that defines life? How can you tell that one thing is alive and the other is not? Most people have an intuitive understanding and knowledge of what it means for something to be alive. However, it’s surprisingly hard and impossible to come up with a precise definition of life.
Because of that, many definitions of life are operational—they allow us to differentiate living things from nonliving ones. Still, they don’t define or pin down what life is. To make this differentiation, one must get to know a list of properties that are, as a group, unique characteristics of all living organisms.
Characteristics of life
The main characteristics of living things differentiate them from nonliving things and will be present in all living things.
All the living things on earth can move in some way. It may be evident in animals that can walk or even run. Or it can be less evident for plants that can not move freely but have specific parts that move in the sun's direction.
Thus, plants and animals can move any way without outside help. Although, some external factors might affect their rate of movement or growth (in plants).
The movement may consist of the flow of materials within the organism (diffusion), external movement of the organism, or some parts of the organism.
Do you know: Muscles are the driving force behind the movement - these are approximately 650 in number within the body. In comparison, there are just over 200 bones in the skeleton.
Living things are born with the ability to respond to changes or conditions around them. For example, green plants grow toward the sunshine, and certain microorganisms shrink into tiny balls or structures when something touches them. If we talk about human beings, they blink when light shines into their eyes.
So, in short words, you can define sensitivity as the ability to detect changes in the surrounding environment.
Do you know that our skin is the body's largest sensory organ?
All living things can breathe naturally. Respiration or breathing means the exchange of gasses between the organism and the surrounding or external air.
Respiration is a cellular-level process or a chemical reaction that happens within the cells of an organism to release energy from food.
In aerobic respiration, oxygen is taken up, and carbon dioxide is given off. Every living organism must breathe in oxygen, which travels to the lungs and is transferred to the blood flow of the body’s arteries.
Do you know: When our brain senses a shortage of oxygen, it triggers us to take a long deep breath…or to YAWN.
All living things require energy to survive. This energy, which is necessary for survival, is derived from nutrients or food. Some nutrients that are taken may be used to provide energy. The organism then uses this energy to function.
The process mentioned above can be compared to when an engine burns oil or coal and gets the energy to move a train. However, an engine does not use coal or oil to make itself larger or mend parts, as living things do with food.
Do you know: One cup of cooked spinach has 5 grams of protein, and 1 cup of cooked broccoli has 4 grams of protein.
You May also read this: Complete overview of Food Chain
Living things grow by making new cells and parts and changing or replacing old ones. It happens when a seed grows into a whole new plant or a chick matures into a hen. Moreover, as human beings grow, they add new structures, such as teeth, and change the proportions of others.
A special kind of growth heals injuries. For example, shrubs and trees mend wounds by covering them with bark and adding new layers of wood. Crabs can grow new legs when old ones are lost. Human beings can heal cut skin and wounds and mend broken bones.
All living things can reproduce, make new offspring, and continue their generation. It is true even for the simplest microorganisms, which may reproduce by simply dividing into two parts e.g. archaea and eubacteria. Each new part can function independently; it can move, feed, grow, and perform other living functions. This type of reproduction is called asexual because it can be performed without a mating partner.
Another form of reproduction is called sexual reproduction, which requires a partner. This reproduction occurs in complex organisms, like plants, large animals, and humans.
All living organisms produce waste products throughout their lives. Much of the waste comes from the food they consume. The rest is produced by movement, growth, and other living functions.
If this waste remained in living things, it would soon cause illness and even death. Thus, living things must have a way to dispose off excess water and waste matter. The process that removes waste products from the body is called excretion.
Populations of living organisms can undergo evolution, meaning that the genetic makeup of a population may change over time. In some cases, evolution involves natural selection. A heritable trait, such as darker fur color or narrower beak shape, enables organisms to survive and reproduce better in a particular environment.
Over generations, a heritable trait that provides a fitness advantage may become more and more common in a population, making it better suited and adapted to its environment. This process is called adaptation.
Thus, we can say that all living things must have these characteristics. In the above article, we have provided a comprehensive idea of living things, which will give you a better understanding of them and help you differentiate them from nonliving things.