Biology | Definition, History, Concepts, Branches, & Facts

What is Biology? 

Biology is the study of the life sciences. While this is a large body of science, many interconnected disciplines come together as a unified field. For example, all living things have cells that process genetic information stored in genes that can be passed on to future generations. Another important point is evolution, which explains the unity and biodiversity. Energy systems are essential to life because they allow organisms to move, grow and reproduce. But all organisms have the ability to control their internal environment.

What is Biology, Definitions, Types and Facts-min

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All organisms share certain biological, chemical, and physical characteristics, regardless of their specificity. For example, there are basic units called cells that are chemically similar and, when analyzed, show striking similarities even in organisms as diverse as bacteria and humans.

Moreover, since the function of an organism is determined by the function of its cells and the interaction of all cells, all organisms have the same basic function.

Not only the unity of the basic substance and function of living things but the unity of origin of all living things. According to the theory of the German pathologist Rudolf Virchow in 1855: “All living cells arise from pre-existing living cells”. That principle seems to apply to all organisms under current environmental conditions.

But if life originated on Earth long ago, the fact that all living things are created, built, and function the same means that only one original species has succeeded.


In his theory of natural selection, which will be discussed in more detail later, Charles Darwin proposed that “survival of the fittest” was the basis of organic evolution. Evolution itself is a biological phenomenon that all organisms have in common, regardless of their differences. Evidence supporting the theory of evolution comes mainly from fossil records, structure and function comparisons, embryological development studies, and DNA and RNA (ribonucleic acid) studies.


Although organisms, organisms, and organisms are similar to all organisms, there are biological differences not only between organisms but also within entire populations. The phenomenon of diffraction has a long history of research because most of the differences in nature are visible to the eye. The fact that organisms have changed in prehistoric times and that new variations are constantly appearing can be proven from paleontological data and from laboratory experiments. Long after Darwin assumed that there was variation; biologists discovered that it was caused by genetic variation (DNA).

Such changes can be small changes in the sequence of DNA molecules (nucleotides), large changes such as changes in chromosome structure, or complete changes in the number of chromosomes. In any case, changes in the genetic makeup of the reproductive system manifest as some type of genetic or chemical change in the offspring. The effects of this mutation depend on the interaction of the mutated child with its environment.

Behavior and Interrelationships

The study of the relationship between organisms and their environment is known as ecology. Because these relationships are so essential to life on Earth and because they can be so disrupted by human activity, the environment has become an important branch of biology.


Whether an organism is a human or a bacterium, the ability to reproduce is one of the most important characteristics of life. Since life only arises from pre-existing life, subsequent generations can only continue the characteristics of the species through reproduction.

Tissues and Organs

Early biologists considered their work biological. This organ ism, then considered the essence of life, remains a central concern of some modern biologists, and understanding how organisms affect their internal environment

is an important area of biological research. To understand biology, researchers study the cells and organs that makeup living things. The key to this work is the ability to preserve and grow cells in vitro (“in vitro”), called cell culture.

The History of Biology

There has been a period in the history of all sciences when extraordinary progress was made in a relatively short period of time. The leap in knowledge is generally due to two factors: one is the presence of a creative mind – a mind that is perceptive and original enough to reject hitherto accepted ideas and formulate new hypotheses; Without the proper research tools, the most original and inquiring mind is severely limited; Conversely, the most advanced technological tools alone cannot provide insight into the scientific process.


An example of the relationship between these two factors is cell detection. There has been speculation about the basic structure of plants and animals for hundreds of years. But the light machinery was not developed enough to explain cells until a general hypothesis, the cell theory, was clearly formed about how plants and animals were organized. And automatic DNA sequencing machines, resulting in the biological evolution of much of the descriptive science — dealing with all cells and organisms — attempt to equate structure with function at all levels. The Greco-Roman world

Although the Babylonians, Assyrians, Egyptians, Chinese, and Indians amassed much biological information, they lived in a world believed to be dominated by unpredictable demons and spirits. Hence, learned individuals in those early cultures directed their studies toward an understanding of the supernatural, rather than the natural, world. Anatomists, for example, dissected animals not to gain an understanding of their structure but to study their organs in order to predict the future. With the emergence of the Greek civilization, however, those mystical attitudes began to change. Around 600 BCE there arose a school of Greek philosophers who believed that every event has a cause and that a particular cause produces a particular effect.

That concept, known as causality, had a profound effect on subsequent scientific investigation. Furthermore, those philosophers assumed the existence of a “natural law” that governs the universe and can be comprehended by humans through the use of their powers of observation and deduction. Although they established the science of biology, the greatest contribution the Greeks made to science was the idea of rational thought.

Post-Grecian Biological Studies

With Aristotle and Theophrastus, the great Greek period of the scientific investigation came to an end. The most famous of the new centers of learning were the library and museum in Alexandria. From 300 BCE until around the time of Christ, all significant biological advances were made by physicians at Alexandria. One of the most outstanding of those individuals was Herophilus, who dissected human bodies and compared their structures with those of other large mammals.

He recognized the brain, which he described in detail, as the center of the nervous system and the seat of intelligence. On the basis of his knowledge, he wrote a general anatomical treatise, a special one on the eyes, and a handbook for midwives.

His Experiment

Erasistratus, a younger contemporary and reputed rival of Herophilus who also worked at the museum in Alexandria, studied the valves of the heart and the circulation of blood. Although he was wrong in supposing that blood flows from the veins into the arteries, he was correct in assuming that small interconnecting vessels exist. He thus suspected (but did not see) the presence of capillaries; he thought, however, that the blood changed into the air, or pneuma, when it reached the arteries, to be pumped throughout the body.

Perhaps the last of the ancient biological scientists of note was Galen of Pergamum, a Greek physician who practiced in Rome during the middle of the 2nd century CE. His early years were spent as a surgeon at the gladiatorial arena in biology, which gave him the opportunity to observe details of human anatomy. At that time in Rome, however, it was considered improper to dissect human bodies, and, as a result, a detailed study of human anatomy was not possible. Thus, though Galen’s research on animals was thorough, his knowledge of human anatomy was faulty. Because his work was extensive and clearly written, Galen’s writings, nevertheless, dominated medicine for centuries.





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