Biology
Overview
Biology is a natural science
concerned with the study of life
and living organism
s, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines. Among the most important topics are five unifying principles that can be said to be the fundamental axioms of modern biology:
Subdisciplines of biology are recognized on the basis of the scale at which organisms are studied and the methods used to study them: biochemistry
examines the rudimentary chemistry of life; molecular biology
studies the complex interactions of systems of biological molecules; cellular biology examines the basic building block of all life, the cell
; physiology
examines the physical and chemical functions of the tissues
, organs
, and organ systems of an organism; and ecology
examines how various organisms interact and associate with their environment.
The term biology is derived from the Greek
word , bios, "life
" and the suffix , -logia, "study of." It appears in German (as biologie) as early as 1791, and may be a back-formation
from the older word amphibiology (meaning the study of amphibians) by deletion of the initial amphi-.
Although biology in its modern form is a relatively recent development, sciences related to and included within it have been studied since ancient times.
Natural science
The natural sciences are branches of science that seek to elucidate the rules that govern the natural world by using empirical and scientific methods...
concerned with the study of life
Life
Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not, either because such functions have ceased , or else because they lack such functions and are classified as inanimate...
and living organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines. Among the most important topics are five unifying principles that can be said to be the fundamental axioms of modern biology:
- CellsCell theoryCell theory refers to the idea that cells are the basic unit of structure in every living thing. Development of this theory during the mid 17th century was made possible by advances in microscopy. This theory is one of the foundations of biology...
are the basic unit of life - New species and inherited traits are the product of evolutionEvolutionEvolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
- GeneGeneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s are the basic unit of heredityHeredityHeredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve... - An organism regulatesHomeostasisHomeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
its internal environment to maintain a stable and constant condition - Living organisms consume and transform energyEnergyIn physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
.
Subdisciplines of biology are recognized on the basis of the scale at which organisms are studied and the methods used to study them: biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
examines the rudimentary chemistry of life; molecular biology
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...
studies the complex interactions of systems of biological molecules; cellular biology examines the basic building block of all life, the cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
; physiology
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
examines the physical and chemical functions of the tissues
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
, organs
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...
, and organ systems of an organism; and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
examines how various organisms interact and associate with their environment.
The term biology is derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
word , bios, "life
Life
Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not, either because such functions have ceased , or else because they lack such functions and are classified as inanimate...
" and the suffix , -logia, "study of." It appears in German (as biologie) as early as 1791, and may be a back-formation
Back-formation
In etymology, back-formation is the process of creating a new lexeme, usually by removing actual or supposed affixes. The resulting neologism is called a back-formation, a term coined by James Murray in 1889...
from the older word amphibiology (meaning the study of amphibians) by deletion of the initial amphi-.
Although biology in its modern form is a relatively recent development, sciences related to and included within it have been studied since ancient times.
