The Great African Lion, an organism that is studied in a branch of biology, zoology

Biology is a natural science that concerns the study of life and organisms, involving the deep analysis of their structure, function, growth, origin, evolution, distribution, and taxonomy. Because it is such a broad and subject, it has been divided into individual topics that have captured the minds of billions over centuries. Numerous sub disciplines have involved other scientific fields such as chemistry, physics, mathematics, and engineering. However, there are five fundamental principles (listed below) that are key to a complete understanding of this science.

1. Cells are the basic unit of life (cell theory).

2. New species and inherited traits are the product of evolution (evolution).

3. Genes are the basic unit of heredity (genetics).

4. An organism regulates its internal environment to maintain a stable and constant condition (homeostasis).

5. Living organisms consume and transform energy (energy).



Antonie Van Leeuwenhoek, the inventor of the microscope

The word “biology” originates from the Greek word βίος , bios meaning life, and –λογία, which translates as the study of. With the study of life being an interest to numerous scientists in Ancient Egypt and Persia, it was not until Aristotle that the science was truly beginning to become defined, with his many zoological texts (such as the ‘History of Animals’) surviving the Middle Ages into the era of Scientific Revolution (see Aristotle).

When Antonie van Leeuwenhoek invented the microscope in the decade surrounding 1676, when he was the first to truly observe micro organisms, leading to the scientific community to name him the first ever microbiologist, due to his studies regarding micro-organisms, gaining him a fine reputation that stands to this day. He went on to be the first ever human to observe red blood cells, bacteria, and protozoa (see Antonie van Leeunwenhoek). The rapid advances in optical microscopy influenced the biologists of the period, including Matthias Schleiden and Theodor Schwann, who together formulated the cell theory, which is studied to this day due to the important conclusions made (see article regarding Cell Theory). In Sweden, Carolus Linnaeus became the father of taxonomy by composing a system for naming every single organism after their part in the animal kingdom and their species in Latin. Eventually, evolutionary thinking began to arise after this when the idea of humans as primates spread throughout the community at the time. Jean Baptiste Lamarck, a French naturalist and academic, made a theory regarding adaptation, stating that physiological changes acquired over the life of an organism may be transmitted to offspring. However, Charles Darwin, an English naturalist, developed a theory (concluded to be correct but shunned by many as a defiance to religion) that all species of life have descended over time from common ancestry, proposing the theory that this pattern of evolution was the result of natural selection, in his book ‘On the Origin of Species’ (see Evolutionary Theory). The Austrian geneticist and friar Gregor Mendel soon discovered the new field of genetics after observing different pea plants, establishing his laws of inheritance, which are remembered today (see genetics). The physical representation of heredity brought by many scientists soon lead the way for more complicated biological topics such as a detailed study of evolution and population genetics. In the modern age, the work of the founding fathers of biology has continuously been expanded, and the processes and the anatomy of life are being studied in institutions across the globe.

Fundamentals of Modern BiologyEdit

The five principles listed above are the unifying axioms of biology, serving as a foundation for modern research and education.

Cell Theory (See Cell Theory)Edit

The study of cells began the educational revolution for biological discoveries. The term “Cell Theory” generally refers to the idea that cells are the foundations of the structures of organisms (being the most basic unit of life), It was a conjecture that was concluded after significant developments on microscopy. The theory is generally attributed to 3 scientists: Matthias Schleiden, Theodor Schwann, and Rudolf Virchow, although many other biologists made significant discoveries which aided in the finding of cell theory.

Evolution (See Evolutionary Theory)Edit

Evolution is another central concept in biology that dictates the changes and developments of life through

Charles Darwin, English biologist known for his work with Evolutionary theory and Ethology

evolution, and the sharing of a common ancestor with others. First proposed by Jean Baptiste Lamarck in 1809, it was not until the publication of Charles Darwin’s marvelous papers on evolution that the idea began to be truly considered by the scientific community when he introduced the driving forces behind the interesting process: natural selection and selective breeding.

In short, the theory postulates that all organisms on Earth, both living and extinct, descended from a common ancestor (known today by many as the Missing Link).

Genetics (See Genetics)Edit

Genes are the primary units of hereditary in all organisms, from tigers to penguins. They correspond to a region of DNA that influences the form or function of the organism in specific ways. The DNA is also transferred into proteins via RNA (which is one of the three major macromolecules, along with DNA and proteins, that are vital to all life). The translation from RNA to amino acid/protein uses a genetic code that is similar for all organisms. A genome is the entirety of an organism’s hereditary information in all locations of a cell. The genetic information within a genome is held within genes, and the complete assemblage of this information in an organism is called a genotype.

Homeostasis (See Homeostasis)Edit

Homeostasis is the ability of a system (that continuously interacts with the environment) to regulate its internal environment to maintain stable conditions by means of equilibrium in all cells using diffusion and other phenomena. A system must detect perturbations in order to execute homeostasis; e.g. the release of glucagon (a hormone created by the pancreas to increase blood sugar levels) when sugar levels are too low.

Energy (See Food Chain, Cellular Respiration, Photosynthesis)Edit

The health and survival of any given organism highly depends on the input of energy. Chemical reactions within organisms (namely Cellular Respiration and Photosynthesis) help generate energy for the organism using basic necessities such as sunlight, water and food. The organisms bringing in energy to an ecosystem are known as the autotrophs, drawing energy from the sun. The phototrophs, on the other hand, generate their own energy from the sun using photosynthesis, converting raw materials into organic molecules, such as ATP (the body’s “energy currency”), which can be broken to release energy. Nevertheless, some animals gain their energy from chemotrophs, who extract the energy needed by some organisms, bringing methane, sulfides, or non-luminal energy sources. When the energy is consumed, the remaining energy is used as heat and waste molecules. The most important processes for converting energy trapped in chemicals into energy are chemical respiration and metabolism, which are therefore used by many organisms to gain energy.



Molecular biology deals with the study of biology at a molecular level. Anatomy deals with the study of the

The anatomical drawings of Andreas Vesalius

structure of organisms. Cell biology involves the in depth study of cells with unicellular and multicellular organisms, where many microbiologists search for new processes and organelles in cells. Genetics is the science of genes, hereditary, and the variation of organisms; likewise, genes play an extremely large role in influencing the final phenotype of the organism. Development biology studies the processes by which organisms grow and develop.

Physiology (See Physiology)Edit

One of the most basic but key topics in biology are the shared characteristics of living things:

  • All living things have a level of complexity and organization not exhibited in lifeless objects
  • All living things exhibit a rapid turnover of chemical materials, referred to as metabolism
  • All living things are able to respond to a stimulus in their environment (where a stimulus is anything that can cause a living thing to respond)
  • All living things grow
  • All living things reproduce
  • All living things evolve
  • All living things are influenced by their environments, ultimately adapting to them and changing them

Physiology studies the mechanical, physical, and biochemical processes of living things by trying to understand how all of the structures within any given organism function as a whole. Physiology is generally divided into two subtopics (Animal Physiology and Plant Physiology) but some principles (such as those listed above) are universal to all organisms. More detailed studies in physiology will involve the observation of (e.g.) the circulatory or nervous systems, and how they work together at a biological and chemical point of view. The study of the organ systems may coincide with medical disciplines such as neurology and cardiology.

Evolution (See Evolutionary Theory)Edit

Research in fields with relevance to the Theory of Evolution are generally concerned with the origin and descent of species, as well as their change over time. Many other scientists from other fields aid this field, and their help usually answers questions dealing with evolution. However, today evolutionists enlist the help of paleontologists to uncover fossils and bone structure that help describe the mode and tempo of evolution. It is a field that has its critics, but is continuously gaining popularity.

Systematics (See Systematics)Edit

Systematics is the study of the differences and similarities between species and groups of species. Even though it seems to be based around the theory of evolution, it was an active field of research long before evolutionary thinking was common. This field of biology generally deals with the classification of organisms, resolving issues on naming disputes.

Ecology (See Ecology and Ethology/Behaviour)Edit


In a (symbiotic) situation, the clownfish feeds on small invertebrates which otherwise potentially could harm the sea anemone, and the faecal matter from the clownfish provides nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone's stinging cells, to which the clownfish is immune. This is an example of how organisms can cooperate together in an environment.

Ecology is the study of the interactions between an organism and its environment. A habitat of an organism can be described as the non-living chemical and physical factors in an environment such as climate, in addition to the other organisms and living factors in the environment.

Ecological systems are studied at many different levels from individuals and populations to ecosystems and the biosphere.

Ethology is a branch of biology that deals with animal behavior (typically in social primates), and is considered by many to be a branch of zoology (which is the study of animals). Ethologists are mainly interested in the evolution of behaviour and natural selection. The first known ethologist to exist is Charles Darwin, who wrote a book ‘The Expressions of the Emotions of Man and Animals’ which would influence many ethologists to come.