Glossary of Biology

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abiotic component

Any non-living chemical or physical part of the environment that affects living organisms and the functioning of ecosystems, such as the atmosphere and water resources.

abscission

The shedding of flowers, leaves, and/or fruit following formation of scar tissue in a plant.

absorption

A process in which one substance permeates another. A fluid permeates or is dissolved by a liquid or solid. Skin absorption is a route by which substances can enter the body through the skin.

absorption spectrum

The spectrum of electromagnetic radiation that has passed through a medium which absorbs radiation of certain wavelengths.

acclimatization

Adaptation to a new climate, as with a new temperature or altitude or environment.

acetyl-CoA

A molecule that participates in many biochemical reactions in protein, carbohydrate, and lipid metabolism, notably the citric acid cycle.

acoelomate

A type of animal, such as a flatworm or a jellyfish, with a body plan that lacks a fluid-filled cavity between the body wall and the digestive tract. Rather, semi-solid mesodermal tissues between the gut and body wall hold the animal's organs in place. Contrast coelomate and pseudocoelomate.

action potential

The local change in voltage that occurs when the membrane potential of a specific location along the membrane of a cell rapidly depolarizes, such as when a nerve impulse is transmitted between neurons.

activation energy

The energy that an atomic system must acquire before a process (such as an emission or reaction) can occur.

active site

The part of an enzyme or antibody at which substrate molecules bind and undergo a chemical reaction.

active transport

Transport of a substance (such as a protein or drug) across a cell membrane against a concentration gradient. Unlike passive transport, active transport requires an expenditure of energy.

adaptive radiation

The process by which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new niches.

adenine

A purine-derived organic compound which is one of the four canonical nucleobases used in the nucleic acids DNA and RNA. Its derivatives are involved in a wide variety of biochemical reactions, including cellular respiration.

adenosine triphosphate (ATP)

An organic compound derived from adenine that functions as the major source of energy for chemical reactions inside living cells. It is found in all forms of life and is often referred to as the "molecular currency" of intracellular energy transfer.

adipose tissue

A type of loose connective tissue made of mostly adipocytes and found in human and animal tissue, where it is colloquially known as body fat.

aerobic

Capable of surviving and growing in the presence of oxygen.

aerobiology

The study of organic particles which are passively transported by the air, including bacteria, fungal spores, very small insects, pollen grains, and viruses.

agriculture

The practice of cultivating land, growing food, and/or raising livestock.

agrobiology

The study of plant nutrition and growth, especially as a way to increase crop yield.

alga

(pl.) algae

Any member of a diverse polyphyletic group of photosynthetic, eukaryotic, mostly aquatic organisms ranging from simple unicellular microalgae to massive colonial or multicellular forms such as kelp. Algae may reproduce sexually or asexually, and are often compared to plants, though they lack most of the complex cell and tissue types that characterize true plants.

allopatric speciation

A form of speciation which occurs when biological populations of the same species become isolated from each other to an extent that prevents or interferes with genetic interchange.

amino acid

A class of organic compounds containing an amine group and a carboxylic acid group which function as the fundamental building blocks of proteins and play important roles in many other biochemical processes.

amniote

An organism which produces an egg composed of a shell and membranes that creates a protected environment in which the embryo can develop out of water.

analogous structures

A set of morphological structures in different organisms which have similar form or function but were not present in the organisms' last common ancestor. The cladistic term for the same phenomenon is homoplasy.

anatomy

The branch of biology that studies the structure and morphology of living organisms and their various parts.

animal

Any member of a clade of multicellular eukaryotic organisms belonging to the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, reproduce sexually, and grow from a blastula during embryonic development. An estimated 7 million distinct animal species currently exist.

antibiotic

Also called an antibacterial.

A type of antimicrobial drug used in the treatment and prevention of bacterial infections.

apoptosis

A highly regulated form of programmed cell death that occurs in multicellular organisms.

arachnology

The scientific study of spiders, scorpions, pseudoscorpions, and harvestmen, collectively called arachnids.

artificial selection

Also called selective breeding.

The process by which humans use animal breeding and plant breeding to selectively control the development of particular phenotypic traits in organisms by choosing which individual organisms will reproduce and create offspring. While the deliberate exploitation of knowledge about genetics and reproductive biology in the hope of producing desirable characteristics is widely practiced in agriculture and experimental biology, artificial selection may also be unintentional and may produce unintended (desirable or undesirable) results.

asexual reproduction

A type of reproduction involving a single parent that results in offspring that are genetically identical to the parent.

astrobiology

The branch of biology concerned with the effects of outer space on living organisms and the search for extraterrestrial life.

autoimmunity

The system of immune responses of an organism directed against its own healthy cells and tissues.

autotroph

Sometimes used interchangeably with primary producer.

An organism capable of producing complex organic compounds from simple substances present in its surroundings, generally by using energy from sunlight (as in photosynthesis) or from inorganic chemical reactions (as in chemosynthesis). Autotrophs do not need to consume another living organism in order to obtain energy or organic carbon, as opposed to heterotrophs.

B cell

A type of lymphocyte in the humoral immunity of the adaptive immune system.

bacteria

An enormous and diverse clade of microscopic, prokaryotic, single-celled organisms which lack a true nucleus. They represent one of the three fundamental biological domains.

bacteriophage

A virus that infects and multiplies within bacteria.

Barr body

The inactive X chromosome in a female somatic cell, rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y (including humans) or W chromosome rather than the diploidy of the X or Z.

basal body

An organelle formed from a centriole, and a short cylindrical array of microtubules. Also called a basal granule, a kinetosome, and in older cytological literature, a blepharoplast.

behavioral ecology

The study of the evolutionary basis for animal behavior due to ecological pressures.

bile

A dark green to yellowish-brown fluid, produced by the liver of most vertebrates, which aids the digestion of lipids in the small intestine. Also called gall.

binary fission

The process by which one prokaryotic cell divides into two identical daughter cells.

binomial nomenclature

A formal system of classifying species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages.

biocatalysis

The process of catalysis in biological systems. In biocatalytic processes, natural catalysts, such as protein enzymes, perform chemical transformations on organic compounds.

biochemistry

The branch of biology that studies the chemical properties, compositions, reactions, and processes related to living organisms.

biodiversity

A contraction of "biological diversity" generally referring to the variety and variability of life on Earth.

bioengineering

The application of concepts and methods of biology to solve real-world problems related to the life sciences or the application thereof.

bioenergetics

The study of the transformation of energy in living organisms.

biogeography

The study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, isolation and habitat area.

bioinformatics

The application of computer technology to the management of biological information.

biological organization

The hierarchy of complex biological structures and systems, designed to define life through a reductionist approach.

biology

The study of life and living organisms.

biomass

Organic matter derived from living or recently living organisms. Biomass can be used as a source of energy and it most often refers to plants or plant-based materials which are not used for food or feed, and are specifically called lignocellulosic biomass.

biomathematics

The theoretical use of mathematical models and abstractions of living systems to understand and predict biological problems.

biome

Any very large ecological area on the Earth's surface containing fauna and flora (animals and plants) adapting to their environment. Biomes are often defined by abiotic factors such as climate, topographical relief, geology, soils, and water resources.

biomechanics

The study of the structure and function of biological systems by means of the methods of "mechanics", which is the branch of physics involving analysis of the actions of forces.

biomedical engineering

The application of engineering principles and design concepts to medicine and biology for healthcare purposes (e.g. diagnostic or therapeutic).

biomedical research

The pursuit of answers to medical questions. These investigations lead to discoveries, which in turn lead to the development of new preventions, therapies, and cures for problems in human and veterinary health. Biomedical research generally takes two forms: basic science and applied research.

biomolecule

Molecules and ions that are present in organisms, essential to some typically biological process such as cell division, morphogenesis, or development.

biophysics

The application of approaches traditionally employed in physics to study biological systems.

biotechnology

Biotechnology is the use of living systems and organisms to develop or make products, or "any technological application that uses biological systems, living organisms or derivatives thereof, to make or modify products or processes for specific use" (UN Convention on Biological Diversity).

bipedal

A form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs.

blastocyst

A mammalian blastula in which some differentiation of cells has occurred.

blood

A body fluid that circulates in humans and other vertebrate animals and is generally responsible for delivering necessary substances such as oxygen and nutrients between the cells and tissues of the body and transporting metabolic waste products away from those same cells and tissues.

blood-brain barrier

A semipermeable membrane separating the blood from the cerebrospinal fluid, and constituting a barrier to the passage of cells, particles, and large molecules.

botany

The branch of biology that studies plants.

building biology

A science that leads to natural healthy ecological homes, schools, and workplaces that exist in harmony with the environment.

Calvin cycle

The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle[[1]](https://en.wikipedia.org/wiki/Glossary_of_biology#cite_note-1) of photosynthesis are the chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the stroma, the fluid-filled area of a chloroplast outside the thylakoid membranes. These reactions take the products (ATP and NADPH) of light-dependent reactions and perform further chemical processes on them. There are three phases to the light-independent reactions, collectively called the Calvin cycle: carbon fixation, reduction reactions, and ribulose 1,5-bisphosphate (RuBP) regeneration.

carbon fixation

The conversion process of inorganic carbon (carbon dioxide) to organic compounds by living organisms.

carbonate

Any member of two classes of chemical compounds derived from carbonic acid or carbon dioxide.

carotenoid

One of a class of organic pigments produced by algae and plants, as well as certain bacteria and fungi.

catalase

An enzyme found in nearly all living organisms exposed to oxygen, including bacteria, plants, and animals.

cell

The basic structural and functional unit of all living organisms, and the smallest functional unit of life. A cell may exist as an independent, self-replicating unit (as in the case of unicellular organisms), or in cooperation with other cells, each of which may be specialized for carrying out particular functions within a larger multicellular organism. Cells consist of cytoplasm enclosed within a cell membrane and sometimes a cell wall, and serve the fundamental purpose of separating the controlled environment in which biochemical processes take place from the outside world. Most cells are visible only under a microscope.

cell biology

Also called cytology.

The branch of biology that studies the structure and function of living cells, including their physiological properties, metabolic processes, chemical composition, life cycle, the organelles they contain, and their interactions with their environment. This is done at both microscopic and molecular levels.

cell cycle

The ordered series of events which take place in a cell leading to duplication of its genetic material and ultimately the division of the cytoplasm and organelles to produce two or more daughter cells. These events can be broadly divided into phases of growth and division, each of which can vary in duration and complexity depending on the tissue or organism to which the cell belongs. Cell cycles are essential processes in all unicellular and multicellular organisms.

cell division

Any process by which a parent cell divides into two or more daughter cells. Examples include binary fission, mitosis, and meiosis.

cell membrane

The semipermeable membrane surrounding the cytoplasm of a cell.

cell nucleus

The "control room" for the cell. The nucleus gives out all the orders.

cell plate

Grown in the cell's center, it fuses with the parental plasma membrane, creating a new cell wall that enables cell division.

cell theory

The theory that all living things are made up of cells.

cell wall

A tough, often rigid structural barrier surrounding certain types of cells (such as in fungi, plants, and most prokaryotes) that is immediately external to the cell membrane.

cellular

Of or relating to a cell.

central dogma of molecular biology

A framework for understanding the movement of genetic information between information-carrying biopolymers within biological systems. Popularly (though simplistically) stated as "DNA makes RNA and RNA makes protein", the principle attempts to capture the notion that the transfer of genetic information only naturally occurs between certain classes of molecules and in certain directions.

centriole

A cylindrical cell structure[1] composed mainly of a protein called tubulin that is found in most eukaryotic cells.

centrosome

An organelle that is the main place where cell microtubules get organized, occurring only in plant and animal cells and regulating the cell division cycle.

chemical compound

A chemical substance consisting of two or more different chemically bonded elements, with a fixed ratio determining the composition. The ratio of each element is usually expressed by a chemical formula.

chemical equilibrium

The state in which both reactants and products are present in concentrations which have no further tendency to change with time in a chemical reaction.

chemical reaction

A process that leads to the transformation of one set of chemical substances to another.

chemistry

A branch of the physical sciences that studies the composition, structure, properties, and change of matter. Chemical interactions underlie all biological processes.

chlorophyll

Any of several photosynthetic pigments found in cyanobacteria, algae, or plants.

chloroplast

Organelles, specialized subunits, in plant and algal cells, main role of which is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight and converts and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water.

cholesterol

An organic molecule, a sterol, a type of lipid molecule, and biosynthesized by all animal cells because it is an essential structural component of all animal cell membranes—essential to maintain both membrane structural integrity and fluidity.

chromosome

A threadlike strand of DNA in the cell nucleus that carries the genes in a linear order.

citric acid cycle

Also called the Krebs cycle and tricarboxylic acid cycle (TCA).

A series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats and proteins into carbon dioxide and chemical energy in the form of guanosine triphosphate (GTP). In addition, the cycle provides precursors of certain amino acids as well as the reducing agent NADH that is used in numerous other biochemical reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest established components of cellular metabolism and may have originated abiogenically.

clonal selection

Clonal selection theory is a scientific theory in immunology that explains the functions of cells (lymphocytes) of the immune system in response to specific antigens invading the body. The theory has become the widely accepted model for how the immune system responds to infection and how certain types of B and T lymphocytes are selected for destruction of specific antigens.[[2]](https://en.wikipedia.org/wiki/Glossary_of_biology#cite_note-Rajewsky1996-2)

cloning

The process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually.

conservation biology

The scientific study of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions.

convergent evolution

The independent development of similar characteristics in species of different lineages.

countercurrent exchange

A mechanism that happens in nature and is mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other.

crista

A fold in the inner membrane of a mitochondrion.

cryobiology

The branch of biology that studies the effects of low temperatures on living things within Earth's cryosphere or in laboratory experiments.

cytology

See cell biology.

cytoplasm

All of the material within a cell and enclosed by the cell membrane, except for the nucleus. The cytoplasm consists mainly of water, the gel-like cytosol, various organelles, and free-floating granules of nutrients and other biomolecules.

cytosine

One of the four main nucleotide bases found in DNA and RNA, along with adenine, guanine, thymine, and uracil (in RNA); it is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at position 2).

cytoskeleton

A cytoskeleton is present in the cytoplasm of all cells, including bacteria, and archaea. It is a complex, dynamic network of interlinking protein filaments that extends from the cell nucleus to the cell membrane.[[3]](https://en.wikipedia.org/wiki/Glossary_of_biology#cite_note-Hardin-3) The cytoskeletal systems of different organisms are composed of similar proteins. In eukaryotes, the cytoskeletal matrix is a dynamic structure composed of three main proteins, which are capable of rapid growth or disassembly dependent on the cell's requirements.[[4]](https://en.wikipedia.org/wiki/Glossary_of_biology#cite_note-4)

Darwinian fitness

The genetic contribution of an individual to the next generation's gene pool relative to the average for the population, usually measured by the number of offspring or close kin that survive to reproductive age.

deciduous

Deciduous means "falling off at maturity" or "tending to fall off", and it is typically used in order to refer to trees or shrubs that lose their leaves seasonally (most commonly during autumn) and to the shedding of other plant structures such as petals after flowering or fruit when ripe.

dehydration reaction

A chemical reaction that involves the loss of a water molecule from the reacting molecule.

denaturation

A process in which proteins or nucleic acids lose the quaternary, tertiary and secondary structure which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, or an organic solvent.

dendrite

A short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.

denitrification

A microbially facilitated process of nitrate reduction (performed by a large group of heterotrophic facultative anaerobic bacteria) that may ultimately produce molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Part of the nitrogen cycle.

deoxyribonucleic acid (DNA)

A nucleic acid polymer that serves as the fundamental hereditary material in all living organisms. A set of four bases is used in the nucleotide sequences which comprise each DNA molecule: adenine (abbreviated A), cytosine (C), guanine (G), and thymine (T); these four bases are individually attached to a sugar-phosphate complex to form a complete nucleotide.

depolarization

The process of reversing the charge across a cell membrane (such as that of a neuron), thereby causing an action potential. In depolarization, the inside of the membrane, which is normally negatively charged, becomes positive and the outside becomes negative. This is brought about by positive sodium ions rapidly passing into the axon.

desmosome

Also called macula adhaerens.

A cell structure specialized for cell-to-cell adhesion.

developmental biology

The branch of biology that studies the processes by which living organisms grow and develop over time. The field may also encompass the study of reproduction, regeneration, metamorphosis, and the growth and differentiation of stem cells in mature tissues.

DNA

See deoxyribonucleic acid.

DNA replication

The replication of a DNA molecule; the process of producing two identical copies from one original DNA molecule, in which the double helix is unwound and each strand acts as a template for the next strand; nucleotide bases are matched to synthesize the new partner strands.

DNA sequencing

The process of determining the precise order of nucleotides within a DNA molecule.

dynein

A motor protein (also called molecular motor or motor molecule) in cells which converts the chemical energy contained in ATP into the mechanical energy of movement.

dimorphism

The existence among animals of same species of two distinct forms that differ in one Or more characteristics such as colour ,size etc

ecological efficiency

The efficiency with which energy is transferred from one trophic level to the next. It is determined by a combination of efficiencies relating to organismic resource acquisition and assimilation in an ecosystem. Primary production occurs in autotrophic organisms of an ecosystem.

ecological pyramid

An ecological pyramid (also trophic pyramid, eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bio productivity at each trophic level in a given ecosystem. Biomass is the amount of living or organic matter present in an organism.

ecological succession

The more or less predictable and orderly set of changes that occurs in the composition or structure of an ecological community over time.

ecology

The scientific analysis and study of interactions between organisms and their environment. It is an interdisciplinary field that includes biology, geography, and Earth science.

ecophysiology

A biological discipline that studies the adaptation of an organism's physiology to environmental conditions.

ecosystem

A community of living organisms in conjunction with the non-living components of their physical environment, interacting as a system.

ecotype

Sometimes called an ecospecies.

In evolutionary ecology, a genetically distinct geographic variety, population, or race within a species which is adapted to specific environmental conditions.

ectoderm

The outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis, nerve tissue, and nephridia.

ectotherm

An organism in which internal physiological sources of heat are of relatively small or quite negligible importance in controlling body temperature. Colloquially, these organisms often referred to as "cold-blooded".

effector

A small molecule that selectively binds to a protein and regulates its biological activity. In this manner, effector molecules act as ligands that can increase or decrease enzyme activity, gene expression, or cell signaling.

efferent

Conducted or conducting outwards or away from something (for nerves, the central nervous system; for blood vessels, the organ supplied). Contrast afferent.

egg

The organic vessel containing the zygote in which an animal embryo develops until it can survive on its own, at which point the developing organism emerges from the egg in a process known as hatching.

electrochemical gradient

A gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts: the electrical potential and the difference in chemical concentration across the membrane.

electromagnetic spectrum

The range of all possible frequencies of electromagnetic radiation. When referring to an object, the electromagnetic spectrum is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.

electron

A negatively charged subatomic particle, symbolized by e− or β−.

electron acceptor

An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. It is an oxidizing agent that, by virtue of its accepting electrons, is itself reduced in the process.

electron carrier

electron carrier. Any of various molecules that are capable of accepting one or two electrons from one molecule and donating them to another in the process of electron transport. As the electrons are transferred from one electron carrier to another, their energy level decreases, and energy is released.

electron donor

An electron donor is a chemical entity that donates electrons to another compound. It is a reducing agent that, by virtue of its donating electrons, is itself oxidized in the process.

electron microscope

The electron microscope is a type of microscope that uses a beam of electrons to create an image of the specimen. It is capable of much higher magnifications and has a greater resolving power than a light microscope, allowing it to see much smaller objects in finer detail.

electron transport chain

The site in a mitochondrion of oxidative phosphorylation in eukaryotes. The NADH and succinate generated by the citric acid cycle are oxidized, providing energy to power ATP synthase. Photosynthetic electron transport chain of the thylakoid membrane.

embryo

A developing stage of a multicellular organism.

embryology

The branch of biology that studies the development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology involves the study of congenital disorders that occur before birth.

endangered species

Endangered species are threatened by factors such as habitat loss, hunting, disease and climate change, and usually, endangered species, have a declining population or a very limited range.

endemism

The ecological state of an organism or species being unique to a defined geographic location, such as an island, nation, country, habitat type, or other defined zone. Organisms are said to be endemic to a place if they are indigenous to it and found nowhere else.

endergonic reaction

Also called a nonspontaneous reaction or unfavorable reaction.

A type of chemical reaction in which the standard change in free energy is positive, and energy is absorbed.

endocrine gland

A gland of the animalian endocrine system that secretes hormones directly into the blood rather than through a duct. In humans, the major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus, and adrenal glands.

endocrine system

The collection of glands that produce hormones which regulate metabolism, growth and development, tissue function, and a wide variety of other biological processes.

endocytosis

A form of active transport in which a cell transports molecules such as proteins into the cell's interior by engulfing them in an energy-consuming process.

endoderm

One of the three primary germ layers in the very early human embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer), with the endoderm being the innermost layer.

endogenous

(of a substance or process) Originating from within a system (such as an organism, tissue, or cell), as with endogenous cannabinoids and circadian rhythms. Contrast exogenous.

endoplasmic reticulum

A type of organelle found in eukaryotic cells that forms an interconnected network of flattened, membrane-enclosed sacs or tube-like structures known as cisternae.

endosperm

The tissue produced inside the seeds of most of the flowering plants following fertilization.

endosymbiotic theory

An evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms, first articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lynn Margulis in 1967.

endotherm

An organism that maintains its body at a metabolically favorable temperature, largely by the use of heat set free by its internal bodily functions instead of relying almost purely on ambient heat.

entomology

Entomology is the study of insects, but etymology is the study of words.

environmental biology

the branch of biology concerned with the relations between organisms and their environment. bionomics, ecology. biological science, biology - the science that studies living organisms. palaeoecology, paleoecology - the branch of ecology that studies ancient ecology.

enzyme

Enzymes are biological molecules (proteins) that act as catalysts and help complex reactions occur everywhere in life. Let's say you ate a piece of meat. Proteases would go to work and help break down the peptide bonds between the amino acids.

epidemiology

Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in defined populations. It is the cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare.

epigenetics

A sub-field of genetics that studies cellular and physiological phenotypic trait variations caused by external or environmental factors which affect how cells express genes, as opposed to those caused by changes in the DNA sequence.

epiphyte

An organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, marine environments or from debris accumulating around it.

estrogen

The primary female sex hormone.

ethology

The scientific study of non-human animal behaviour (i.e. excluding human behaviour) and usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait.

eukaryote

Organisms whose cells have a nucleus enclosed within membranes, unlike Prokaryotes (Bacteria and other Archaea).

evolution

The change in the heritable characteristics of populations of biological organisms over successive generations, which may occur by mutation, gene flow, natural selection, or random chance.

evolutionary biology

Evolutionary biology is the subfield of biology that studies the evolutionary processes that produced the diversity of life on Earth starting from a single origin of life. These processes include the descent of species, and the origin of new species.

exocytosis

A form of active transport and bulk transport in which a cell transports molecules out of the cell by expelling them through an energy-dependent process.

exogenous

(of a substance or process) Originating outside of or external to a system (such as an organism, tissue, or cell), as with drugs and many pathogens. Contrast endogenous.

exponential growth

It is exhibited when the rate of change of the value of a mathematical function is proportional to the function's current value, resulting in its value at any time being an exponential function of time.

external fertilization

A type of fertilization in which a sperm unites with an egg external to the body or bodies of the parent organisms. Contrast internal fertilization.

extracellular

Of or occurring in the space outside the plasma membrane of a cell. Contrast intracellular.

extranuclear inheritance

A transmission of genes that take place outside the nucleus.

facultative anaerobe

An organism which is capable of producing energy through aerobic respiration and then switching to anaerobic respiration depending on the amounts of oxygen and fermentable material in the environment.

fermentation

A metabolic process that consumes sugar in the absence of oxygen.

fetus

Also spelled foetus.

An animal embryo after eight weeks of development.

flagellum

(pl.) flagella

A lash-like appendage that protrudes from the cell body of certain bacterial and eukaryotic cells.

flavin adenine dinucleotide (FAD)

A redox cofactor, more specifically a prosthetic group of a protein, involved in different important enzymatic reactions in metabolism.

food chain

The chain of eating and getting nutrition which starts from a small herbivores animal and ends up at a big carnivorous organism.

founder effect

A loss of genetic variation that takes places when a new population is established by a very small number of individuals from a larger population.

G protein

A family of proteins that act as molecular switches inside cells, and are implicated in transmitting signals from a diversity of stimuli outside a cell to its interior.

gene

Any segment of DNA that contains the information necessary to produce a functional RNA and/or protein product in a controlled manner. Genes are often considered the fundamental molecular units of heredity. The transmission of genes from a parent cell or organism to its offspring is the basis of the inheritance of phenotypic traits.

gene pool

A set of all genes, or genetic information, in any population, usually of a particular species.

genetic code

A set of rules used by living cells to translate information encoded within genetic material (DNA or mRNA sequences) into proteins.

genetic drift

An alteration in the frequency of an existing gene variant in a population due to random sampling of organisms.

genetic variation

Variations of genomes between members of species, or between groups of species thriving in different parts of the world as a result of genetic mutation. Genetic diversity in a population or species is a result of new gene combinations (e.g. crossing over of chromosomes), genetic mutations, genetic drift, etc.

genetics

The study of heredity.

genome

The entire set of genetic material contained within the chromosomes of an organism, organelle, or virus.

genotype

Part of the genetic makeup of a cell, and therefore of an organism or individual, which determines one of its characteristics (phenotype).

gizzard

An organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, and dinosaurs, including birds), earthworms, some gastropods, some fish, and some crustaceans.

guanine

One of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA).

habitat

A place for animals, people, and plants and non-living things.

habituation

A form of learning in which an organism decreases or desists its responses to a stimulus after repeated or prolonged presentations .

heredity

The passing on of phenotypic traits from parents to their offspring, either through sexual or asexual reproduction. Offspring cells and organisms are said to inherit the genetic information of their parents.

hermaphrodite

A sexually reproducing organism with both male and female reproductive organs.

herpetology

The branch of zoology that studies reptiles and amphibians.

heterosis

The improved or increased function of any biological quality in a hybrid offspring.

histology

The study of the microscopic anatomy of cells and tissues of plants and animals.

hormone

Any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.

host

Any living organism that harbors another living organism (known as a "guest" or symbiont), whether the guest is parasitic, mutualistic, or commensalist in its interactions with the host. The guest typically receives shelter and nourishment from the host.

hydrocarbon

An organic compound consisting entirely of hydrogen and carbon atoms. Hydrocarbons from which one hydrogen atom has been removed are functional groups called hydrocarbyls.

ichthyology

The branch of biology devoted to the study of fish, including bony fishes (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha).

+151 fiszek więcej