Biology is the study of life and living organisms. Biology includes topics that religious fundamentalists don't like such as Evolution. Or, indeed, evidence, fact and logic. It is known as the natural science. Biology is a very vast subject and below are some of the subdivisions, topics, and disciplines. The most important thing in biology is the hierarchy of life.

Cells: the building blocks and hierarchy of life

1. Atoms that come together in order to make life, become Cells, one type of cell is a Eucarote.

2. Cells come together to make tissue of an organism.

3. The tissue comes together to make an organ.

4. The organs come together in a constructed manor to make and organ system.

5. Many different organ systems come together in conjunction with one-another to make an organism.

Subdivisions of biology

There are also many different subdisciplines of biology that are recognized on the basis of the scale at which organisms are studied and the methods used to study them:

1. Biochemistry- examins the rudimentary chemistry of life (like the hierarchy above).

2. Molecular biology- examins the complex interactions of systems of biological molecules.

3. Cellular biology- examines the building blocks of life; cells, and how they continue to carry on lifeforms.

4. Physiology- examines the physical and chemical functions of the tissues, organs, and organ systems of an organism.

5. Ecology- examines how various organisms interact and associate with their environment.


The term biology is derived from the Greek word bios, which means life and the suffix , -logia, which mean the "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-. The name is believed to have first been used by Karl Burdach (1776-1847) to denote the study of man.

The foundations of modern biology:

The Cell theory

The Cell theory: The fact that the cell is the fundamental unit of life; all living things are made up of cells. Cells reproduce themselves to make more cells before they die out by cell division. In multicellular organisms, living beings with more that one cell in its body, every cell in the organism's body derives ultimately from a single cell in a fertilized egg. The cell is also considered to be the basic unit in many pathological processes. Additionally, the phenomenon of energy flow occurs in cells in processes that are part of the function known as metabolism. Finally, cells contain hereditary information (DNA) which is passed from cell to cell during cell division.


Evolution: The central organizing concept in biology is that life changes and develops through the adapting and evolving of organisms, and that all life-forms known have a common origin. Introduced into the scientific lexicon by Jean-Baptiste de Lamarck in 1809, evolution was established by Charles Darwin fifty years later as a viable scientific model when he articulated its driving force: natural selection. (Alfred Russel Wallace is recognized as the co-discoverer of this concept as he helped research and experiment with the concept of evolution.) Evolution is now used to explain the great variations of life found on Earth. Darwin theorized that species and breeds developed through the processes of natural selection and artificial selection or selective breeding. Genetic drift was embraced as an additional mechanism of evolutionary development in the modern sythesis of the theory.

The evolutionary history of the species—which describes the characteristics of the various species from which it descended—together with its genealogical relationship to every other species is known as its phylogeny. Widely varied approaches to biology generate information about phylogeny. These include the comparisons of DNA sequences conducted within molecular biology or genomics, and comparisons of fossils or other records of ancient organisms in paleontology. Biologists organize and analyze evolutionary relationships through various methods, including phylogenetics, phenetics, and cladistics.


Genetics: The study of genes, which are are the primary units of inheritance in all organisms. A gene is a unit of heredity and corresponds to a region of DNA that influences the form or function of an organism in specific ways. All organisms, from bacteria to animals, share the same basic machinery that copies and translates DNA into proteins. Cells transcribe a DNA gene into an RNA version of the gene, and a ribosome then translates the RNA into a protein, a sequence of amino acids. The translation code from RNA codon to amino acid is the same for most organisms, but slightly different for some. For example, a sequence of DNA that codes for insulin in humans also codes for insulin when inserted into other organisms, such as plants.


Homeostasis: The ability of an open system to regulate its internal environment to maintain stable conditions by means of multiple dynamic equilibrium adjustments controlled by interrelated regulation mechanisms. All living organisms, whether unicellular or multicellular, exhibit homeostasis.

To maintain dynamic equilibrium and effectively carry out certain functions, a system must detect and respond to perturbations. After the detection of a perturbation, a biological system normally respond through negative feedback. This means stabilizing conditions by either reducing or increasing the activity of an organ or system. One example is the release of glucagon when sugar levels are too low.


Energy: The survival of a living organism depends on the continuous input of energy. Energy is the ability to work. Chemical reactions that are responsible for its structure and function are tuned to extract energy from substances that act as its food and transform them to help form new cells and sustain them. In this process, molecules of chemical substances that constitute food play two roles; first, they contain energy that can be transformed for biological chemical reactions; second, they develop new molecular structures made up of biomolecules.

The organisms responsible for the introduction of energy into an ecosystem are known as producers or autotrphes. Nearly all of these organisms originally draw energy from the sun. Plants and other phototrophes use solar energy via a process known as photosythesis to convert raw materials into organic molecules, such as ATP, whose bonds can be broken to release energy. A few ecosystems, however, depend entirely on energy extracted by chemitrophes from methane, sulfides, or other non-luminal energy sources.

Some of the captured energy is used to produce biomass to sustain life and provide energy for growth and development. The majority of the rest of this energy is lost as heat and waste molecules. The most important processes for converting the energy trapped in chemical substances into energy useful to sustain life are metabolism and cellular respiration.

Branches of biology

There are still many branches of Biology:

  • Aerobiology – the study of airborne organic particles
  • Agriculture – the study of producing crops from the land, with an emphasis on practical applications
  • Anatomy – the study of form and function, in plants, animals, and other organisms, or specifically in humans
  • Arachnology – the study of arachnids
  • Astrobiology – the study of evolution, distribution, and future of life in the universe—also known as exobiology, exopaleontology, and bioastronomy
  • Biochemistry – the study of the chemical reactions required for life to exist and function, usually a focus on the cellular level
  • Bioengineering – the study of biology through the means of engineering with an emphasis on applied knowledge and especially related to biotechnology
  • Biogeography – the study of the distribution of species spatially and temporally
  • Bioinformatics – the use of information technology for the study, collection, and storage of genomic and other biological data
  • Biomathematics (or Mathematical biology) – the quantitative or mathematical study of biological processes, with an emphasis on modeling
  • Biomechanics – often considered a branch of medicine, the study of the mechanics of living beings, with an emphasis on applied use through prosthetics or orthotics
  • Biomedical research – the study of the human body in health and disease
  • Biophysics – the study of biological processes through physics, by applying the theories and methods traditionally used in the physical sciences
  • Biotechnology – a new and sometimes controversial branch of biology that studies the manipulation of living matter, including genetic modification and synthetic biology
  • Building biology – the study of the indoor living environment
  • Botany – the study of plants
  • Cell biology – the study of the cell as a complete unit, and the molecular and chemical interactions that occur within a living cell
  • Conservation biology – the study of the preservation, protection, or restoration of the natural environment, natural ecosystems, vegetation, and wildlife
  • Cryobiology – the study of the effects of lower than normally preferred temperatures on living beings
  • Developmental biology – the study of the processes through which an organism forms, from zygote to full structure
  • Ecology – the study of the interactions of living organisms with one another and with the non-living elements of their environment
  • Embryology – the study of the development of embryo (from fecundation to birth)
  • Entomology – the study of insects
  • Environmental biology – the study of the natural world, as a whole or in a particular area, especially as affected by human activity
  • Epidemiology – a major component of public health research, studying factors affecting the health of populations
  • Epigenetics – the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence
  • Ethology – the study of animal behavior
  • Evolutionary biology – the study of the origin and descent of species over time
  • Genetics – the study of genes and heredity
  • Herpetology – the study of reptiles and amphibians
  • Histology – the study of cells and tissues, a microscopic branch of anatomy
  • Ichthyology – the study of fish
  • Integrative biology – the study of whole organisms
  • Limnology – the study of inland waters
  • Mammalogy – the study of mammals
  • Marine biology (or Biological oceanography) – the study of ocean ecosystems, plants, animals, and other living beings
  • Microbiology – the study of microscopic organisms (microorganisms) and their interactions with other living things
  • Molecular biology – the study of biology and biological functions at the molecular level, some cross over with biochemistry
  • Mycology – the study of fungi
  • Neurobiology – the study of the nervous system, including anatomy, physiology and pathology
  • Oncology – the study of cancer processes, including virus or mutation oncogenesis, angiogenesis and tissues remoldings
  • Ornithology – the study of birds
  • Population biology – the study of groups of conspecific organisms, including
  • Paleontology – the study of fossils and sometimes geographic evidence of prehistoric life
  • Pathobiology or pathology – the study of diseases, and the causes, processes, nature, and development of disease
  • Parasitology – the study of parasites and parasitism
  • Pharmacology – the study and practical application of preparation, use, and effects of drugs and synthetic medicines
  • Physiology – the study of the functioning of living organisms and the organs and parts of living organisms
  • Phytopathology – the study of plant diseases (also called Plant Pathology)
  • Psychobiology – the study of the biological bases of psychology
  • Sociobiology – the study of the biological bases of sociology
  • Structural biology – a branch of molecular biology, biochemistry, and biophysics concerned with the molecular structure of biological macromolecules
  • Virology – the study of viruses and some other virus-like agents
  • Zoology – the study of animals, including classification, physiology, development, and behavior (branches include: Entomology, Ethology, Herpetology, Ichthyology, Mammalogy, and Ornithology)