The word biology is derived from the greek words /bios/ meaning /life/ and /logos/ meaning /study/ and is defined as the science of life and living organisms. An organism is a living entity consisting of one cell e.g. bacteria, or several cells e.g. animals, plants and fungi. Aspects of biological science range from the study of molecular mechanisms in cells, to the classification and behaviour of organisms, how species evolve and interaction between ecosystems.
The study of biology can be divided into different disciplines –
Ethology (from Greek: ήθος, ethos, “character”; and λόγος, logos, “knowledge”) is the scientific study of animal behavior, and a branch of zoology (not to be confused with ethnology).
Although many naturalists have studied aspects of animal behavior through the centuries, the modern discipline of ethology is usually considered to have arisen with the work in the 1960s of Dutch biologist Nikolaas Tinbergen and Austrian biologist Konrad Lorenz, joint winners of the 1973 Nobel Prize in Biology. Ethology is a combination of laboratory and field science, with strong ties to certain other disciplines — e.g., neuroanatomy, ecology, evolution. Ethologists are typically interested in a behavioral process rather than in a particular animal group and often study one type of behavior (e.g., aggression) in a number of unrelated animals.
The desire to understand the animal world has made ethology a rapidly growing field, and since the turn of the 21st century, many prior understandings related to diverse fields such as animal communication, personal symbolic name use, animal emotions, animal culture and learning, and even sexual conduct, long thought to be well understood, have been revolutionized, as have new fields such as neuroethology.
Evolutionary biology is an interdisciplinary field because it includes scientists from a wide range of both field and lab oriented disciplines. For example, it generally includes scientists who may have a specialist training in particular organisms such as mammalogy, ornithology, or herpetology, but use those organisms as case studies to answer general questions in evolution. It also generally includes paleontologists and geologists who use fossils to answer questions about the tempo and mode of evolution, as well as theoreticians in areas such as population genetics and evolutionary psychology. Experimentalists have used selection in Drosophila to develop an understanding of the evolution of ageing, and experimental evolution is a very active subdiscipline.
In the 1990s developmental biology made a re-entry into evolutionary biology from its initial exclusion from the modern synthesis through the study of evolutionary developmental biology.
Its findings feed strongly into new disciplines that study mankind’s sociocultural evolution and evolutionary behavior. Evolutionary biology’s frameworks of ideas and conceptual tools are now finding application in the study of a range of subjects from computing to nanotechnology.
Artificial life is a sub-field of bioinformatics that attempts to model, or even recreate, the evolution of organisms as described by evolutionary biology. Usually this is done through mathematics and computer models.
Physiology (from Greek: φυσις, physis, “nature, origin”; and λόγος, logos, “speech” lit. “to talk about the nature (of things)”) is the study of the mechanical, physical, and biochemical functions of living organisms.
Physiology has traditionally been divided between plant physiology and animal physiology but the principles of physiology are universal, no matter what particular organism is being studied. For example, what is learned about the physiology of yeast cells may also apply to human cells.
The field of animal physiology extends the tools and methods of human physiology to non-human animal species. Plant physiology also borrows techniques from both fields. Its scope of subjects is at least as diverse as the tree of life itself. Due to this diversity of subjects, research in animal physiology tends to concentrate on understanding how physiological traits changed throughout the evolutionary history of animals. Other major branches of scientific study that have grown out of physiology research include biochemistry, biophysics, paleobiology, biomechanics, and pharmacology.
Genetics (from Ancient Greek γενετικός genetikos, “genitive” and that from γένεσις genesis, “origin”[1][2][3]), a discipline of biology, is the science of heredity and variation in living organisms.[4][5] The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the process of inheritance, only began with the work of Gregor Mendel in the mid-nineteenth century.[6] Although he did not know the physical basis for heredity, Mendel observed that organisms inherit traits in a discrete manner—these basic units of inheritance are now called genes.
DNA, the molecular basis for inheritance. Each strand of DNA is a chain of nucleotides, matching each other in the center to form what look like rungs on a twisted ladder.
Genes correspond to regions within DNA, a molecule composed of a chain of four different types of nucleotides—the sequence of these nucleotides is the genetic information organisms inherit. DNA naturally occurs in a double stranded form, with nucleotides on each strand complementary to each other. Each strand can act as a template for creating a new partner strand—this is the physical method for making copies of genes that can be inherited.
The sequence of nucleotides in a gene is translated by cells to produce a chain of amino acids, creating proteins—the order of amino acids in a protein corresponds to the order of nucleotides in the gene. This is known as the genetic code. The amino acids in a protein determine how it folds into a three-dimensional shape; this structure is, in turn, responsible for the protein’s function. Proteins carry out almost all the functions needed for cells to live. A change to the DNA in a gene can change a protein’s amino acids, changing its shape and function: this can have a dramatic effect in the cell and on the organism as a whole.
Although genetics plays a large role in the appearance and behavior of organisms, it is the combination of genetics with what an organism experiences that determines the ultimate outcome. For example, while genes play a role in determining a person’s height, the nutrition and health that person experiences in childhood also have a large effect.
Molecular biology is the study of biology at a molecular level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interactions between DNA, RNA and protein biosynthesis and learning how these interactions are regulated.
Writing in Nature, William Astbury described molecular biology as:
“… not so much a technique as an approach, an approach from the viewpoint of the so-called basic sciences with the leading idea of searching below the large-scale manifestations of classical biology for the corresponding molecular plan. It is concerned particularly with the forms of biological molecules and ….. is predominantly three-dimensional and structural – which does not mean, however, that it is merely a refinement of morphology – it must at the same time inquire into genesis and function.” [1]
Morphology is the field of linguistics that studies the internal structure of words. (Words as units in the lexicon are the subject matter of lexicology.) While words are generally accepted as being (with clitics) the smallest units of syntax, it is clear that in most (if not all) languages, words can be related to other words by rules. For example, English speakers recognize that the words dog, dogs, and dog-catcher are closely related. English speakers recognize these relations from their tacit knowledge of the rules of word-formation in English. They intuit that dog is to dogs as cat is to cats; similarly, dog is to dog-catcher as dish is to dishwasher. The rules understood by the speaker reflect specific patterns (or regularities) in the way words are formed from smaller units and how those smaller units interact in speech. In this way, morphology is the branch of linguistics that studies patterns of word-formation within and across languages, and attempts to formulate rules that model the knowledge of the speakers of those languages.
Biological systematics is the study of the diversity of life on the planet Earth, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic trees, phylogenies). Phylogenies have two components, branching order (showing group relationships) and branch length (showing amount of evolution). Phylogenetic trees of species and higher taxa are used to study the evolution of traits (e.g., anatomical or molecular characteristics) and the distribution of organisms (biogeography). Systematics, in other words, is used to understand the evolutionary history of life on Earth.
A comparison of phylogenetic and phenetic concepts
The term “systematics” is sometimes used synonymously with “taxonomy” and may be confused with “scientific classification.” However, taxonomy is properly the describing, identifying, classifying, and naming of organisms, while “classification” is focused on placing organisms within groups that show their relationships to other organisms. All of these biological disciplines can be involved with extinct and extant organisms. However, systematics alone deals specifically with relationships through time, requiring recognition of the fossil record when dealing with the systematics of organisms.
Systematics uses taxonomy as a primary tool in understanding organisms, as nothing about an organism’s relationships with other living things can be understood without it first being properly studied and described in sufficient detail to identify and classify it correctly. Scientific classifications are aids in recording and reporting information to other scientists and to laymen. The systematist, a scientist who specializes in systematics, must, therefore, be able to use existing classification systems, or at least know them well enough to skillfully justify not using them.
Phenetic systematics was an attempt to determine the relationships of organisms through a measure of similarity, considering plesiomorphies (ancestral traits) and apomorphies (derived traits) to be equally informative. From the 20th century onwards, it was superseded by cladistics, which considers plesiomorphies to be uninformative for an attempt to resolve the phylogeny of Earth’s various organisms through time. Today’s systematists generally make extensive use of molecular biology and computer programs to study organisms.
Systematics is fundamental to biology because it is the foundation for all studies of organisms, by showing how any organism relates to other living things.
Systematics is also of major importance in understanding conservation issues because it attempts to explain the Earth’s biodiversity and could be used to assist in allocating limited means to preserve and protect endangered species, by looking at, for example, the genetic diversity among various taxa of plants or animals and deciding how much of that it is necessary to preserve.
Ecology (from Greek: οίκος, oikos, “household”; and λόγος, logos, “knowledge”) is the scientific study of the distribution and abundance of life and the interactions between organisms and their environment. The environment of an organism includes physical properties, which can be described as the sum of local abiotic factors such as insolation (sunlight), climate, and geology, and biotic factors, which are other organisms that share its habitat.
The word “ecology” is often used more loosely in such terms as social ecology and deep ecology and in common parlance as a synonym for the natural environment or environmentalism. Likewise “ecologic” or “ecological” is often taken in the sense of environmentally friendly.
The term ecology or oekologie was coined by the German biologist Ernst Haeckel in 1866, when he defined it as “the comprehensive science of the relationship of the organism to the environment.”[1] Haeckel did not elaborate on the concept, and the first significant textbook on the subject (together with the first university course) was written by the Danish botanist, Eugenius Warming. For this early work, Warming is often identified as the founder of ecology.[2]
