B
B CellA lymphocyte that produces antibodies in response to antigens.
BacillusA rod-shaped bacterium.
Background extinction rateNormal rate of extinction -- as a natural part of the evolutionary process -- of various species as a result of changes in local environmental conditions and the actions of natural evolutionary forces. Extinctions not caused or contributed to by the actions of humans.
BacteriaMicroorganisms that break down organic materials in the first stages of composting. It is bacteria that generate the heat associated with hot composting. The three types of bacteria are psychrophilic, mesophyllic, and thermophilic.
BacteriophageA virus that infects bacteria.
BaleenOne of the keratinous plates that function to filter food from water in some whales.
BarbA branch of a vane in the feather of a bird.
BarbuleA branch of a barb in the feather of a bird.
BaseAny substance that increases the concentration of hydroxide (OH – ) ions when added to a water solution.
Base UnitOne of seven fundamental units of SI measurement that describe length, mass, time, and other quantities.
Base-Pairing RuleThe rule stating that in DNA, cytosine pairs with guanine and adenine pairs with thymine and in RNA, adenine pairs with uracil.
BasidiocarpThe fruiting body of a basidiomycete.
BasidiumA specialized club-shaped reproductive structure that forms on the gills of mushrooms.
BateTo flutter off the fist or perch; an abortive attempt to fly when the bird is restrained by the leash.
Benign TumorAn abnormal but nonthreatening cell mass.
Benthic ZoneThe ocean bottom.
BiennialA plant having a two-year life cycle.
Bilateral SymmetryIn animals, a body plan in which the left and right sides mirror each other.
BileA yellowish fluid secreted by the liver that functions as a fat emulsifier in digestion.
Binary FissionAn asexual cell division of prokaryotes that produces identical offspring.
BindTo grab and hold onto quarry (or volunteers) with the feet.
Binomial NomenclatureA system of naming organisms that uses the genus name and a species identifier.
Binomial nomenclatureThe two-name system, developed by Carolus Linnaeus (the founder of modern taxonomy), used to assign scientific names to all living things. Homo sapiens, for example, is the scientific name for humans. The first name is the genus name and is always capitalized. This is sort of like your last name... it belongs to several of your close relatives, too, and it shows that you are all closely related. The second name is the species name is always lower case. This is like your first name, which no one else in your circle of relatives posseses and so it uniquely identifies you. Memory tool: you probably know the meanings of the terms generic (i.e. general, broad) and specific (i.e. precise, exact). These terms come from the same origins as genus and species, so recalling their meaning will help you recall the relationship between the two portions of a scientific name.
BioaccumulationThe absorption of toxic chemicals in plants and animals; some time referred to as bioconcentration.
Biochemical PathwayA series of chemical reactions in which the product of one reaction is consumed in the next reaction.
Biochemical PathwayA series of chemical reactions in which the product of one reaction is consumed in the next reaction.
BiocideAn agent that kills many organisms in the environment.
Biodegradable Able to be broken into simpler chemical compounds by microorganisms. Organic materials are biodegradable.
Biodegradable materialMaterials that can be broken down by micro organisms into simple stable compounds such as carbon dioxide and water. Most organic material such as food scraps and paper are biodegradable
Biodegradation Biodegradation or biotic degradation or biotic decomposition
is the chemical dissolution of materials by bacteria or other
biological means. The term is often used in relation to ecology, waste
management, biomedicine, and the natural environment and is now commonly associated with environmentally friendly products
that are capable of decomposing back into natural elements.
BiodieselBiodiesel is registered with the Environmental Protection Agency as a pure fuel or as a fuel additive and is a legal fuel in commerce. It is typically produced through the reaction of a vegetable oil or animal fat with methanol in the presence of a catalyst to yield glycerin and biodiesel (chemically called methyl esters). It is an alternative fuel that can be used by itself or blended with petroleum diesel for use in diesel engines. Its use can result in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter.
BiodiversityIt refers to the variety and the variability among living organisms. These include diversity within species, between species, ecosystems etc.
BiogenesisThe theory that living organisms come only from other living
organisms.
Biogeochemical CycleThe process by which materials necessary for organisms are circulated through the environment.
BiogeographyStudy of the geographical distribution of fossils and living organisms.
BiogeographyA branch of geography that deals with the geographical distribution of animals and plants.
Biological control Controlling plants’ diseases, and animal pests using natural enemies; or inhibiting the reproduction of pests by methods that result in the laying of infertile eggs, etc. Bio-control method may be an alternative or compliment to chemical pest control methods.
Biological resourcesIncludes genetic resources, organisms or parts thereof, populations, or any other biotic component of ecosystems with actual or potential use or value for humanity.
Biological Species ConceptThe principle that defines a species as those organisms that can produce offspring together.
Biologically unique speciesA species that is the only representative of an entire genus or family.
BioluminescenceThe production of light by means of a chemical reaction in an organism.
BiomagnificationThe accumulation/magnification of a substance as it
moves through the food.
BiomassThe dry weight of organic material in an ecosystem.
BiomeA geographic area characterized by specific kinds of plants and animals.
BiomeA major portion of the living environment of a particular region (such as a fir forest or grassland), characterized by its distinctive vegetation and maintained largely by local climatic conditions.
Biopesticide A pesticide that is biological in origin (i.e., viruses, bacteria, pheromones, natural plant compounds) in contrast to synthetic chemicals. Transgenic Bt cotton and corn are biopesticides because Bacillus thuringiensis (Bt) is a naturally occurring soil bacterium that has been genetically engineered into the plants.
Bioregion (bioregional planning)A territory defined by a combination of biological, social, and geographic criteria, rather than geopolitical considerations; generally, a system of related, interconnected ecosystems.
BiosphereThe portion of the earth and its atmosphere in which living organisms exist or that is capable of supporting life.
BiosphereThe area on and around Earth where life exists.
BiosphereThe area on and around Earth where life exists.
Biosphere reservesBiosphere reserves are a series of protected areas linked through a global network, intended to demonstrate the relationship between conservation and development, established under UNESCO's Man and the Biosphere (MAB) Program.
BiotaThe living organisms of a region.
BioticPertaining to any aspect of life, especially to characteristics of entire populations or ecosystems.
Biotic FactorA living component of an ecosystem.
BipedalismThe ability to walk upright on two legs.
BipinnariaThe larva of echinoderms.
Birth RateThe number of births occurring in a period of time.
BivalveAn aquatic mollusk with a shell divided into two halves connected by a hinge, such as a clam, oyster, or scallop.
BladeThe broad, flat portion of a typical leaf.
BlastocoelThe central cavity of a blastula.
BlastoporeA depression formed when cells of the blastula move inward.
BlastulaA hollow ball of cells formed when a zygote undergoes repeated cycles of cell division.
BlightA disease of plants characterized by quickly developing decay and discoloring of leaves, stems, and flowers.
Blood Alcohol Concentration (BAC)A measurement of the amount of alcohol in a person’s blood.
Blood PressureThe force that blood exerts against the walls of a blood vessel.
Blood TypeA specific characteristic of the blood of an individual; A, B, AB, or O, depending on the type of antigen present on the surface of the red blood cell.
BoltingThe rapid lengthening of internodes caused by gibberellic acid.
Bone MarrowThe soft tissue in the center and ends of long bones where blood cells are produced.
Book LungIn the abdomen of an arachnid, an organ for gas exchange with parallel folds that resembles the pages of a book.
Botanical pesticidesPesticides whose active ingredients are plant-produced chemicals such as nicotine, rotenone, or strychnine. Also called plant-derived pesticides.Being "natural" pesticides, as distinct from synthetic ones, they are typically acceptable to organic farmers.
BotanyThe scientific study of plants.
Bowman’s CapsuleCup-shaped structure of the nephron of a kidney which encloses the glomerulus and in which filtration takes place.
Brain StemThe region of the brain that lies posterior to the cerebrum and that connects the cerebrum to the spinal cord.
Breed
A group of animals descended from common
ancestors and possessing similar characteristics.
BreedA group of animals or plants related by descent from common ancestors and visibly similar in most characteristics. Taxonomically, a species can have numerous breeds.
Breeder
A male or female kept for reproduction.
Breeding lineGenetic lines of particular significance to plant or animal breeders that provide the basis for modern varieties.
BronchioleA small tube that branches from the bronchi within the lungs.
BronchusOne of the two branches of the trachea that enter the lungs.
BryophyteA plant that has no vascular tissue and does not form true roots, stems, and leaves.
BudA structure that develops on the stem at the point of attachment of each leaf.
Bud ScaleA modified leaf that forms a protective covering for a bud until it opens.
BuddingIn fungi, a form of asexual reproduction in which a part of a cell pinches off to produce an offspring cell.
BufferChemical that neutralizes small amounts of acids or bases added to a solution.
Buffer zoneThe region near the border of a protected area; a transition zone between areas managed for different objectives.
Buffer zonesAreas on the edge of protected areas that have land use controls and allow only activities compatible with protection of the core area, such as research, environmental education, recreation, and tourism.