Biology terminology

Animals are multicellular, eukaryotic organisms belonging to the biological kingdom Animalia (). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Animals form a clade, meaning that they arose from a single common ancestor. Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77&

Bacteria are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit the air, soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition

The eukaryotes () are the domain of Eukaryota or Eukarya, organisms whose cells have a membrane-bound nucleus. All animals, plants, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of life forms alongside the two groups of prokaryotes: the Bacteria and the Archaea. Eukaryotes represent a small minority of the number of organisms, but given their generally much larger size, their collective global biomass is much larger than that of prokaryotes.

Archaea ( ) is a domain of organisms. Traditionally, Archaea included only its prokaryotic members, but has since been found to be paraphyletic, as eukaryotes are known to have evolved from archaea. Even though the domain Archaea cladistically includes eukaryotes, the term archaea ( ; ) in English still generally refers specifically to prokaryotic members of Archaea.

In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the population during that process. Thirdly, it is a phenotypic trait or adaptive trait, with a functional role in each individual organism, that is maintained and has evolved through natural selection.

In biology, homeostasis (British also homoeostasis; ) is the state of steady internal physical and chemical conditions maintained by living organisms. This is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits (homeostatic range). Other variables include the pH of extracellular fluid, the concentrations of sodium, potassium, and calcium ions, as well as the blood sugar level, and these need to be regulated despite changes in the environment, diet, or level of activity. Each of t

thumb|300px|Cycle between autotrophs and heterotrophs. Autotrophs use light, [[carbon dioxide (CO2), and water to form oxygen and complex organic compounds, mainly through the process of photosynthesis (green arrow). Both types of organisms use such compounds via cellular respiration to generate ATP and again form CO2 and water (two red arrows).]]

offspring of cross-species reproduction

thumb|336x336px|The Amanita muscaria mushroom, an iconic toxic mushroom.

thumb|Mixed-species tangle of lianas in tropical Australia thumb|Lianas in Udawattakele, Sri Lanka thumb|A canopy of Entada gigas that has formed over a monkey ladder vine ([[Bauhinia glabra) on Kauai, Hawaii]] thumb|Liana tangle across a forest in the Western Ghats

thumb|300px|Overview of cycle between autotrophs and heterotrophs. [[Photosynthesis is the main means by which plants, algae and many bacteria produce organic compounds and oxygen from carbon dioxide and water (green arrow).]]

organism that thrives in an oxygenated environment

Photoperiod is the change of day length over the seasons. Earth's rotation around its axis produces 24-hour changes in light (daytime) and dark (night) cycles on Earth. The length of the light and dark in each phase varies across the seasons due to the axial tilt of Earth. The photoperiod defines the length of the light. For example, in summer the length of light could be 16 hours while the dark is 8 hours, whereas in winter the length of day could be 8 hours, while the dark is 16 hours. Importantly, the axial tilt of the Earth causes the opposing seasons in the Northern and Southern Hemispher

Acclimatization or acclimatisation (also called acclimation or acclimatation) is the process in which an individual organism adjusts to a change in its environment (such as a change in altitude, temperature, humidity, photoperiod, or pH), allowing it to maintain fitness across a range of environmental conditions. Acclimatization occurs in a short period of time (hours to weeks), and within the organism's lifetime (compared to adaptation, which is evolution, taking place over many generations). This may be a discrete occurrence (for example, when mountaineers acclimate to high altitude over hou

thumb|The light from the lamp (1.) functions as a detectable change in the plant's environment. As a result, the plant exhibits a reaction of phototropism—directional growth (2.) toward the light stimulus. thumbnail|Auxin distribution controls phototropism. 1. Sunlight strikes the plant from directly above. Auxin (pink dots) encourages growth straight up. 2, 3, 4. Sunlight strikes the plant at an angle. Auxin is concentrated on one side, stimulating growth at an angle from the preceding stem. thumb|Phototropism in Solanum lycopersicum.

right|thumb|Terrestrial and aquatic phototrophs: plants grow on a fallen log floating in algae-rich water

plant that produces wood as its structural tissue

A chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototrophs, which use photons. Chemotrophs can be either autotrophic or heterotrophic. Chemotrophs can be found in areas where electron donors are present in high concentration, for instance around hydrothermal vents.

thumb|Lesser celandine (Ficaria verna) on forest floor in spring

In biomedical contexts, a biomarker, or biological marker, is a measurable indicator of some biological state or condition. Biomarkers are often measured and evaluated using blood, urine, or soft tissues to examine normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Biomarkers are used in many scientific fields.

dead plant material that has fallen to the ground

The principle of individuation, or '''''''''', describes the manner in which a thing is identified as distinct from other things.

original landscape formed by nature

A biosignature is a phenomenon that can be explained by biological processes where all possible abiotic causes of this phenomenon have been eliminated. This term is mainly used in the field of astrobiology in the search for past or present extraterrestrial life, from planets and moons in the Solar System to exoplanets. Candidate biosignatures strongly indicate some of the earliest known life forms, aid studies of the origin of life on Earth as well as the possibility of life on Mars, Venus and elsewhere in the universe.

thumb|upright=2|right| Red arrows indicate the likely point of origin of phototaxis in a given group. Question marks indicate uncertainties regarding independent or common origin.

A xerophile (from Ancient Greek ξηρός (xerós), meaning "dry", and φίλος (phílos), meaning "loving") is an extremophilic organism that can grow and reproduce in conditions with a low availability of water, also known as water activity.

state of animals well outside their normal range

surface on which an organism lives

thumb|upright=1.1|Aerial roots of a [[maize landrace, Sierra Mixe corn, grown in nitrogen-depleted soils in the Sierra Mixe, known for aerial roots with a bacterial gel that contributes substantially to the plant's nitrogen supply]]

putative fossilized microorganisms found near hydrothermal vents

stem produced by grass plants

part of an organism targeted by a ligand or drug to affect behavior

thumb|230px|Paratype of Lepidothrix vilasboasi (Sick, 1959) in [[Museum für Naturkunde, Berlin]] thumb|230px|Paratype of Cadurcotherium nouleti – MHNT

thumb|300x300px|Embryonic oophagy occurs in shortfin mako. Oophagy ( ) or ovophagy, literally "egg eating", is the practice of embryos feeding on eggs produced by the ovary while still inside the mother's uterus. The word oophagy is formed from the classical Greek (, "egg") and classical Greek (, "to eat"). In contrast, adelphophagy is the cannibalism of a multi-celled embryo.

name of a taxon, at a rank lower than species

thumb|Winogradsky column showing Photoautotrophs in purple and green Photoautotrophs are organisms that can utilize light energy from sunlight, and elements (such as carbon) from inorganic compounds, to produce organic materials needed to sustain their own metabolism (i.e. autotrophy). Such biological activities are known as photosynthesis, and examples of such organisms include plants, algae and cyanobacteria.

ability of a cell to alter its genetics by taking up extracellular DNA from its environment

thumb|A prehensile tail Prehensility is the quality of an appendage or organ that has adapted for grasping or holding. The word is derived from the Latin term prehendere, meaning "to grasp". The ability to grasp is likely derived from a number of different origins. The most common are tree-climbing and the need to manipulate food.

viable seed present in the soil

part of a plant specifically modified for storage of energy (generally in the form of carbohydrates) or water

thumb|right|Klepton genetic inheritance in frogs In biology, a klepton (abbreviated kl.) and synklepton (abbreviated sk.) is a species that requires input from another biological taxon (normally from a species which is closely related to the kleptonic species) to complete its reproductive cycle. Specific types of kleptons are zygokleptons, which reproduce by zygogenesis; gynokleptons which reproduce by gynogenesis, and tychokleptons, which reproduce by a combination of both systems.

thumb|Desert spider, Stegodyphus lineatus, one of the best-described species that participates in matriphagy

A molluscivore is a carnivorous animal that specialises in feeding on molluscs such as gastropods, bivalves, brachiopods and cephalopods. Known molluscivores include numerous predatory (and often cannibalistic) molluscs, (e.g. octopuses, murexes, decollate snails and oyster drills), arthropods such as crabs and firefly larvae, and vertebrates such as fish, birds and mammals. Molluscivory is performed in a variety of ways with some animals highly adapted to this method of feeding. A similar behaviour, durophagy, describes the feeding of animals that consume hard-shelled or exoskeleton bearing o

Photoheterotrophs (Gk: photo = light, hetero = (an)other, troph = nourishment) are heterotrophic phototrophs—that is, they are organisms that use light for energy, but cannot use carbon dioxide as their sole carbon source. Consequently, they use organic compounds from the environment to satisfy their carbon requirements; these compounds include carbohydrates, fatty acids, and alcohols. Examples of photoheterotrophic organisms include purple non-sulfur bacteria, green non-sulfur bacteria, and heliobacteria. These microorganisms are ubiquitous in aquatic habitats, occupy unique niche-spaces, and

thumb|alt=three plants of different species grow in deep sand|Psammophytes of three different species in the Sahara desert A psammophyte is a plant that grows in sandy and often unstable soils. Psammophytes are commonly found growing on beaches, deserts, and sand dunes. Because they thrive in these challenging or inhospitable habitats, psammophytes are considered extremophiles, and are further classified as a type of psammophile.

A relict is a surviving remnant of a natural phenomenon.

Thanatocoenosis (from Greek language thanatos - death and koinos - common) are all the embedded fossils at a single discovery site. This site may be referred to as a "death assemblage". Such groupings are composed of fossils of organisms which may not have been associated during life, often originating from different habitats. Examples include marine fossils having been brought together by a water current or animal bones having been deposited by a predator. A site containing thanatocoenosis elements can also lose clarity in its faunal history by more recent intruding factors such as burrowing

Psammon (from Greek "psammos", "sand") is an ecological community of organisms inhabiting coastal sand. It consists of biota buried in moist sediments. Psammon is also sometimes considered a part of benthos due to its near-bottom distribution. Psammon term is commonly used to refer to freshwater reservoirs such as lakes.

Proteostasis is the dynamic regulation of a balanced, functional proteome. The proteostasis network includes competing and integrated biological pathways within cells that control the biogenesis, folding, trafficking, and degradation of proteins present within and outside the cell. Loss of proteostasis is central to understanding the cause of diseases associated with excessive protein misfolding and degradation leading to loss-of-function phenotypes, as well as aggregation-associated degenerative disorders. Therapeutic restoration of proteostasis may treat or resolve these pathologies.

thumb|This diagram shows the monogastric digestive system of a human and rabbit. Notice the difference in cecum size between the two species. A monogastric organism defines one of the many types of digestive tracts found among different species of animals. The defining feature of a monogastric is that it has a simple single-chambered stomach (one stomach). A monogastric can be classified as an herbivore, an omnivore (facultative carnivore), or a carnivore (obligate carnivore). Herbivores have a plant-based diet, omnivores have a plant and meat-based diet, and carnivores only eat meat. Examples

300px|thumb|Sample synchronized biosignals from a human subject. A biosignal is any signal in a living organism that can be continually measured and monitored. The term biosignal is often used to refer to bioelectrical signals, but it may refer to both electrical and non-electrical signals. The usual understanding is to refer only to time-varying signals, although spatial parameter variations (e.g. the nucleotide sequence determining the genetic code) are sometimes subsumed as well.

Mycobiota (plural noun, no singular) are a group of all the fungi present in a particular geographic region (e.g. "the mycobiota of Ireland") or habitat type (e.g. "the mycobiota of cocoa"). An analogous term for Mycobiota is funga.

vegetation in tropical latitudes

In biology, monoclonality refers to the state of a line of cells that have been derived from a single clonal origin. Thus, "monoclonal cells" can be said to form a single clone. The term monoclonal comes .

modularity of biological systems

digestive process seen in monogastric herbivores with a simple, single-chambered stomach