Biology Dictionary B

Meanings of biological terminology

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b (1) base; (2) buccal.

B Boron.

Ba Barium.

Babesia /bə-BEEZH-yə or -ee-ə/ n. A genus of protozoan blood parasites transmitted by ticks; infects humans, cattle, dogs, and many other vertebrates. The resulting disease is babesiosis /bah-bə-zee-ō-səs/. LIFE CYCLE OF BABESIA MICROTI

BAC See: bacterial artificial chromosome.

Online Biology Dictionary (BACILL-)

bacillemia /bass-əl-EEM-ee-yə or -ee/ n. Presence of bacilli in the blood.

bacilli /bə-SILL-ī, -ee/ n. Plural of bacillus.

bacilliform /bə-SILL-ə-form/ adj. Rod-shaped.

bacillus (pl bacilli) /bə-SILL-əs; pl: ī, -ee/ n. Any rod-shaped bacterium.

Bacillus anthracis /bə-SILL-əs AN-thrə-kiss/ n. A bacilliform bacterium; causative agent of anthrax.

backcross (1) n. a cross between a hybrid individual obtained by crossing two parental types and a second individual belonging one of those parental types; (2) v. to create a backcross individual or generation.

back mutation /myoo-TĀ-shən/ (also reverse mutation) n. A change in a mutant gene that allows it to once again produce its normal (wild type) product. See: forward mutation.

Online Biology Dictionary (BACTER-)

bacteremia /back-ter-EEM-ee-yə/ n. Presence of bacteria in the blood.

bacteria (sing bacterium) /back-TEER-ee-ə; sing: -əm/ n. (1) broadly: prokaryotes; (2) strictly: one of the two major types of prokaryotes, the other type being archaeans (more information >>) — bacterial. AGENTS OF COMMON BACTERIAL INFECTIONS

bacterial artificial chromosome (BAC) n. A vector used to clone DNA fragments in Escherichia coli cells. The fragments are typically 100- to 300-kb long (mean ~150 kb). The fragments are inserted in an F-factor plasmid found in E. coli. See also: cloning vector.

bactericide /back-TEER-ə-side/ n. Any agent that destroys bacteria. — bactericidal /back-TEER-ə-side-əl/ (also bacteriocidal /back-TEER-ee-ə-SIDE-əl/)

bacteriochlorophyll /back-TEER-yō-CHLORE-ə-fill/ (BChl) Any one of the six types (a, b, c, d, e, and g) of chlorophyll found in bacteria.

bacteriostat /back-TEER-yə-stat/ n. A substance preventing bacterial growth.

bacteriophage (or simply phage) /back-TEER-ee-əh-fayj/ n. A virus that infects bacteria.

bacteriophage lambda /back-TEER-ee-əh-fayj/ (also phage lambda /FĀJ LAM-də/) n. A DNA virus, which infects E. coli , much used for the purpose of introducing genes into that bacterium.

bacteriophagy /back-TEER-ee-əh-PHAJE-ee/ (also bacteriophagia /back-TEER-ee-ə-FĀ-zhə/) n. Consumption of bacteria, as by a bacteriophage.

Online Biology Dictionary (BAL-)

Balanidae n. The family composed of the acorn barnacles.

balanopreputial /bə-LAN-ō-pree-PYOO-shəl/ adj. Of or pertaining to the glans penis and prepuce.

Balbiani ring /BALB-ee-ahn-ee/ n. A very large puff at a particular band on a polytene chromosome.

baleen whales /BAL-een/ n. Whales that have within their mouths a sieve-like structure (the baleen) with which they obtain food by filtering small organisms from the water.

Baltica /BALT-ick-ə/ n. A separate continental plate (named for the Baltic Sea) that existed in the the Early Paleozoic. It later became part of Euramerica, then part of Pangea, and still later, part of Laurasia. Today it underlies parts of modern Scandinavia, European Russia and central Europe and the northern United Kingdom.

Online Biology Dictionary (BAR-)

barium (Ba) /BEAR-ee-əm/ n. Soft metallic element (atomic weight 137.34, atomic number 86); member of alkaline earth group. PERIODIC TABLE

barium sulphate /BEAR-ee-əm SƏL-fate/ n. Compound used in x-ray examinations. When ingested, it allows visualization the gastrointestinal tract.

barospirator /BAR-ō-spear-ə-ter/ n. A device that causes respiration by means of the application of alternating high and low air pressures.

barotactic /BAR-ō-TACK-tick/ adj. Pertaining to barotaxis.

barotaxis /BAR-ō-TAX-əs/ (pl barotaxes /BAR-ō-TAX-eez/) n. A taxis in which the stimulus is pressure.

Barr body n. An inactivated X chromosome. Under the microscope it is seen as a dense body lying near the nuclear envelope.

Online Biology Dictionary (BAS-)

basal metabolism /BĀ-səl/ n. The quantity of energy required to maintain an organism when at complete rest.

basalt /bə-SALT/ n. Dark igneous rock (cools from a hot fluid lava or magma), which usually originates as a lava flow; contains a high percentage of magnesium and iron, and low amounts of potassium, silica, and sodium.

base n. (1) in connection with DNA and RNA, one of the purine or pyrimidine nucleotide bases of which RNA and single-stranded RNA is composed. See: adenine, cytosine, guanine, thymine, and uracil); (2) any substance that reduces a solution's hydrogen ion concentration. See: acid.

basic /BĀ-sick/ adj. Chemistry: Tending to reduce a solution's hydrogen ion concentration. See: acid.

base pair (bp) n. A pair of hydrogen-bonded nitrogenous bases that join the two strands of the DNA double helix. A base pair is composed of a purine and a pyrimidine (guanine and cytosine or adenine and thymine).

base-pair substitution n. The substitution, in duplex DNA, of one pair of nucleotides for another, or the reversal of a pair of nucleotides with respect to the strands in which the two individual nucleotides reside. There are two types of base-pair substitutions: transitions, in which a purine substitutes for a purine in one strand and a pyrimidine substitutes for a pyrimidine in the other; and transversions in which a pyrimidine substitutes for a purine in one strand and a purine substitutes for a pyrimidine in the other.

base sequence n. The ordered sequence of nucleotide bases present in a particular DNA or RNA molecule.

base sequence analysis n. Any method for identifying the bases present in a particular nucleotide sequence.

basophil /BASE-ə-fill/ (also basophile /BASE-ə-file/) n. A leukocyte that stains dark purple with base dyes; appear in many types of inflammations, particularly allergic reactions.

Batesian mimicry /BĀT-see-ən/ n. A type of mimicry where a harmless organism looks like some other type of organism that is poisonous or harmful in some other way.

Online Biology Dictionary (BATHY-)

bathypelagic /bath-ə-pə-LAJ-ik/ adj. Pertaining to ocean levels that are deep but above the abyssal zone.

batrachoid /BAT-rə-koid/ (also batrachian /bə-TRACK-ee-ən/) adj. Similar to, or characteristic of, a frog or toad.

batrachophagous /bat-trə-KAWF-ə-gəs/ Frog-eating.

batrachotoxin /bə-TRACK-ō-TAWX-ən, BAT-rə-kō-/ n. A potent toxin exuded by frogs of the family Dendrobatidae, most notably by the Golden Poison Frog. MORE INFORMATION

B cell or B lymphocytes n. A type of lymphocyte that differentiates in the bone marrow in mammals and in bursa of Fabricius in birds (the B in B cell originally stood for bursa since these cells were discovered in birds, but now generally under stood to refer to bone marrow); after contact with an antigen, B cells differentiate into antibody-secreting plasma cells.

BChl Bacteriochlorophyll.

Beagle (H.M.S.) The ship on which Darwin took a five-year round-the-world voyage. ABOUT THE VOYAGE OF THE BEAGLE | PLAN OF THE BEAGLE

Before Present (BP) years is a time scale used in geology, archaeology, and other branches of science to indicate the number of years back to past events. Since the present time changes, this system of time measurement has been standardized to use January 1, 1950 as the zero mark on the scale. For example, 1200 BP means 1200 years before 1950 (i.e., the year 850).

behavioral genetics n. The study of genes influencing behavior.

Beijing Man See: Homo erectus .

belemnite /bə-LEM-night/ (or belemnoid /bə-LEM-noid/) n. A member of the extinct group Belemnoidea composed of certain cephalopods similar to the modern squid and cuttlefish. They are abundant as fossils. The portion of a belemnite usually fossilized is the rear portion of the internal skeleton, the guard or rostrum, which is cylindrical and rounded or pointed on one end. Fossil range: Early DevonianLate Cretaceous

benthic zone /BEN-thick/ The seafloor, as an environment or habitat.

beta-lactam antibiotics n. Penicillin-related antibiotics (e.g., dicloxacillin, methicillin, nafcillin, oxacillin).

bezoar /BEE-zore/ n. A solid indigestible mass forming in the intestines or stomach of an animal (including humans).

Online Biology Dictionary (BIL-)

bile n. A substance produced by the liver. It contains bile salts (sodium glycocholate and sodium taurocholate) and aids in the absorption of fats by facilitating their digestion and emulsification.

bilirubin /bill-ee-ROOB-ən/ n. An orangish-yellow pigment in bile. A catabolite of hemoglobin breakdown, bilirubin is carried to the liver where it is chemically converted and excreted in the bile into the duodenum.

binary fission /BINE-er-ee/ n. The method of reproduction used by prokaryotes, in which a single parent cell divides into two daughter cells, each of which receives a single, complete copy of the parental chromosome. MORE INFORMATION

binomial /bī-NOME-ee-əl/ n. A taxonomic name, composed of two separate words, usually of Greek or Latin origin, used to indicate that the organism in question is treated as a species. MORE INFORMATION

Online Biology Dictionary (BIO-)

biochemistry /BĪ-ō-KEM-ə-stree/ n. The study of living things at the chemical level, in particular the chemistry of proteins, carbohydrates, and nucleic acidsbiochemist /BĪ-Ī-KEM-ist/

bioclimatology /BĪ-ō-KLĪM-ə-TAWL-ə-jee/ n. The study of the influence of climate on living organisms — bioclimatologist /BĪ-ō-KLĪM-ə-TAWL-ə-jist/

bioengineering (also biological engineering) /Bī-ō-en-jə-NEAR-ing/ A hybrid field of scientific research that uses the principles of biology and the techniques of engineering to produce useful products — bioengineer /BĪ-ō-EN-jə-near/

biogeography /BĪ-ō-jee-AWG-rə-fee/ n. The study of the geographic distributions of living organisms — biogeographist /BĪ-ō-jee-AWG-rə-fist, -fəst/

bioinformatics /BĪ-ō-in-fer-MAT-iks/ n. The use of computers to manage and analyze biological data — bioinformaticist /BĪ-ō-in-fer-MAT-ə-sist/

biologist /bī-AWL-ə-jəst, -jist/ n. An expert specializing in some aspect of biology. MORE ABOUT BIOLOGISTS

biology /bī-AWL-ə-jee/ n. (1) the scientific study of living things and vital processes; (2) the life processes of a particular organism or class of organisms (e.g., the biology of plants); (3) the organisms living in a particular geographic region or type of environment, taken as a whole MORE INFORMATION | BRANCHES OF BIOLOGY

biomass /BĪ-ō-mass/ Material derived from living organisms, usually plants,particularly material used for the production of biofuel.

biomathematics (also mathematical biology) /BĪ-ō-math-MAT-iks/ n. An interdisciplinary field of study that attempts to model biological processes using mathematical techniques — biomathematician /BĪ-ō-math-mə-TISH-ən/

biome /BĪ-ōme/ n. A major type of ecological community (as savanna, sahel, or taiga).

biophysics /BĪ-ō-FIZZ-icks/ n. An interdisciplinary science that applies the theories and methods of physics to biological questions — biophysicist /BĪ-ō-FIZZ-ə-sist/

biota /bī-Ō-tə/ n. The flora and fauna of a particular era, geographic region, or biome, taken as a whole.

biotechnology /BĪ-ō-tek-NAWL-ə-jee/ n. The practical application of biological science; particularly applied research and product development that uses recombinant DNA, cell fusion, and various other modern bioprocessing techniques — biotechnological /BĪ-ō-tek-nə-LAWJ-ə-kəl/ — biotechnologist /BĪ-ō-tek-NAWL-ə-jist/

biotic /bī-AWT-ick/ adj. Of, pertaining to, or being living things.

Online Biology Dictionary (BI-)

biparous /BIP-ə-rəs/ adj. Producing two offspring per birth.

biped /BĪ-ped/ n. An animal (as a human or a bird), employing bipedalism as its ordinary mode of terrestrial locomotion.

bipedal /bī-PEED-əl/ adj. Walking upright on two legs (as does a human or a bird).

bipedalism /bī-PEED-ə-liz-əm/ n. A form of terrestrial locomotion in which four legs are used.

bird n. A winged, feathered, endothermic, bipedal vertebrate that lays eggs. Like mammals, birds have a complete double circulatory system.

bisetose /bī-SEE-tōs/ adj. Having two bristles.

bisexual /bī-SEX-yoo-əl/ adj. (1) pertaining to or being a type of organism in which two different sexes occur; (2) pertaining to or being an individual having both male and female sexual organs.

bivalent /BĪ-vale-ənt/ n. A pair of synapsed homologous chromosomes; this configration occurs during meiotic prophase I. Also known as a "tetrad."

bivalved /BĪ-valvd/ adj. Having a pair of hard shells that open for feeding and close for protection.

bivalves /BĪ-valvz/ n. Bivalved invertebrates of Class Bivalvia of Phylum Mollusca. Familiar representatives of this class are clams, oysters, and scallops.

bladder See: urinary bladder.

Online Biology Dictionary (BLAST-)

BLAST n. A computer program that finds similar nucleotide or protein sequences in sequence data bases. BLAST stands for Basic Local Alignment Search Tool.

blastema (pl blastemas or blastemata) /blas-TEEM-ə/ n. The bud from which a regenerating limb develops.

blastocoel /BLAST-ə-seal/ n. The cavity within a blastula.

blastocyst /BLAST-ə-sist/ n. Embryo at the time of implantation in the wall of the uterus. PICTURE OF BLASTOCYST

blastula /BLAST-yə-lə/ n. A hollow ball of cells that occurs early in embryonic development.

Online Biology Dictionary (BLATT)

Blattaria /blə-TAR-ee-yə, -TER-/ n. The insect order that consists of the roaches.

blennostatic /blen-ə-STAT-ick/ adj. Reducing mucous secretion.

blepharoplast /BLEF-er-əh-plast/ n. Basal granule of a flagellate.

bond energy n. The amount of energy required to break a given type of chemical bond.

boreal /BORE-ee-əl/ Pertaining to, or located in the cold northern regions of the globe.

boron (B) /BORE-awn/ n. Nonmetallic chemical element; atomic weight 10.811, atomic number 5. Boron is required by plants as a nutrient, in particular for maintenance of their cell walls. It does not, however, appear to be necessary in the diets of animals. PERIODIC TABLE

Borrelia /bore-RELL-yə/ n. A genus of spirochetes, among which are the causative agents of Lyme disease (Borrelia burgdorferi), louse-borne relapsing fever (Borrelia recurrentis), and tick-borne relapsing fever (Borrelia hermsii). PHOTOMICROGRAPH OF BORRELIA BURGDORFERI

botany /BAWT-(ə)-nee/ n. The study of plants — botanist /BAWT-(ə)-nist/

Online Biology Dictionary (BOTRY-)

botryoid /BAWT-ree-oid/ (also botryoidal /bawt-ree-OID-əl/) adj. Shaped like a bunch of grapes.

bp See: Base pair.

BP See: Before Present.

BPG D-2,3-bisphosphoglycerate.

BPheo Bacteriopheophytin (same as bacteriochlorophyll less its magnesium residue).

BPTI Bovine pancreatic trypsin inhibitor; also known as aprotinin.

Online Biology Dictionary (BRACH-)

brachiate /BRACK-ee-ət/ adj. Having arms.

brachiate /BRACK-ee-ate/ v. To move about from one handhold to another by swinging (as does an ape) — brachiation /BRACK-ee-Ā-shən/

brachiopod /BRACK-ee-ə-pawd/ n. An animal belonging to the phylum Brachiopoda.

Brachiopoda /brack-ee-AWP-ə-də/ n. A phylum of hard-shelled invertebrates similar in appearance to bivalved mollusks, but differing from them in internal anatomy, in particular with respect to the presence of a lophophore. BRACHIOPOD MORPHOLOGY

brachydactylous /BRACK-ə-DACK-tə-ləs/ adj. Short-fingered.

brachydont /BRACK-ə-dawnt/ adj. Having short crowns and well-developed roots (said of teeth).

Online Biology Dictionary (BRADY-)

bradytelic /BRAID-ə-tel-ick/ adj. Pertaining to evolution that occurs at a slower than usual rate.

branchiae /BRANK-ee-ī, -ee/ n. Gills.

branchial /BRANK-ee-əl/ adj. Of or pertaining to gills.

branchiate /BRANK-ee-ət, -ate/ (also branchiferous /brang-KIF-er-rəs/) adj. Having gills.

breccia /BRECH-yə/ n. A sedimentary rock composed of coarse rock fragments embedded in a matrix of finer-grained material.

brevicaudate /brehv-ə-CAWD-date/ adj. Short tailed.

brevifoliate /brehv-ə-FŌL-ee-ət/ adj. Short leaved.

bronchitis /brawn-KĪT-əs, -iss/ n. Inflammation of the mucous membrane lining the bronchi.

bronchus /BRAWNK-əs/ (pl bronchi /BRAWNK-ee, -ī/) n. Either of the two tubes into which the trachea divides.

Brownian motion n. Movement, visible under the microscope, of minute particles suspended in liquid; due to collisions with the surrounding molecules. MORE INFORMATION

browser n. An animal that feeds on the twigs, shoots, leaves, and fruits of bushes and trees.

brucellosis /broo-sə-LŌ-səs/ n. Spontaneous abortion in cattle and sheep. A highly infectious and economically important disease caused by the motile bacterium Vibrio fetus.

Online Biology Dictionary (BRYO-)

bryology /bry-AWL-ə-jee/ n. The study of bryophytes.

bryophytes /BRY-ə-fĪts/ n. A group of nonvascular plants comprising the mosses, hornworts, and liverworts.

bubble n. The region where a duplex strand of DNA is separated to admit an enzymeenzyme during initiation of transcription or replication.

Online Biology Dictionary (BUCC-)

buccal /BUCK-əl/ Of or pertaining to the mouth or cheeks.

buccal cavity /BUCK-əl/ n. The mouth.

buccogingival /buck-ə-JIN-jə-vəl/ Of or pertaining to the cheeks and gums.

bucnemia /buck-NEEM-ee-yə, NEEM-yə/ n. Elephantiasis; broadly: inflammation of the leg.

budding n. A form of reproduction in which outgrowths from the parent separate from the parent and live on as separate individuals.

Bufo /BYOO-fō/ A genus of toads.

Online Biology Dictionary (BULBO-)

bulbourethral glands /bulb-ō-yə-REE-thrəl/ n. Cowper's glands.

bullate /BULL-ate/ adj. Like a bubble or blister.

BUN Blood urea nitrogen.

bunodont /BYOON-ə-dawnt/ adj. Being or having molar teeth with rounded cusps.

bursa/BER-sə/ (pl bursae /BER-sigh, BER-see/ or bursas /BER-səs/) n. A cushionlike sac nearby a joint. Bursae contain synovial fluid, a lubricant easing friction between tendons and bone — bursal /BER-səl/

bursate /BER-sate/ adj. Having a bursa.

burst size The mean number of phages released from a lysed bacterial host.

byssus /BISS-əs/ A tough strand of filaments attaching certain bivalves to their substrate.

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