UCMP Glossary: B

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bacteriophage -- Virus which infects and destroys a bacterial host. Some phages, however, will incorporate their DNA into that of their host, and remain dormant for an extended period. For this reason, they have become essential tools of genetic engineers.

Baltica -- n. A separate continental plate of the Early Paleozoic composed of the United Kingdom, Scandinavia, European Russia and Central Europe; named for the Baltic Sea.

Banded Iron Formation -- n. Rock consisting of alternating light and dark layers of iron-rich chert (the dark layers have more iron minerals) formed from 3.8 to 1.7 billion years ago.

barachois -- n. - A lagoon separated from the ocean by a sandbar, which was deposited in a delta after the last glaciation. The term is used in Atlantic Canada, where the landform is common.

barrier island -- n. A long, narrow island that runs parallel to the mainland and is separated from it by a lagoon.

basal group -- The earliest diverging group within a clade; for instance, to hypothesize that sponges are basal animals is to suggest that the lineage(s) leading to sponges diverged from the lineage that gave rise to all other animals.

basalt -- Highly mafic igneous volcanic rock, typically fine-grained and dark in color; rough volcanic equivalent of gabbro.

basement rock -- n. The oldest rocks in a given area; a complex of metamorphic and igneous rocks that underlies the sedimentary deposits. Usually Precambrian or Paleozoic in age.

basin -- n. Any large depression in which sediments are deposited.

Basin and Range Province -- n. One of the most extensive systems of fault-bounded mountains separated by sediment-filled valleys, extending across Idaho, Oregon, Nevada, Utah, Arizona, New Mexico, California, and northern Mexico. Basin and Range topography The surface features typical of the Basin and Range Province.

bedrock -- n. The general term referring to the rock underlying other unconsolidated material, i.e. soil.

benthic -- Organisms that live on the bottom of the ocean are called benthic organisms. They are not free-floating like pelagic organisms are.

Bering Land Bridge -- n. The vast tundra plain that was exposed between Asia and North America during the Last Glacial Maximum, about 21,000 years ago; it served as a migration route for people, animals, and plants. Also known as Beringia.

binomial nomenclature -- n. A method of identifying and naming organisms using two names. The first name is the genus name, and the second is the species name. Names are usually Latin or Greek in origin.

biochemistry -- the study of those molecules used and manufactured by living things.

biological/biotic factors -- Living factors such as decomposers, scavengers and predators.

bioluminescence -- the production of light by a chemical reaction within an organism. The process occurs in many bacteria and protists, as well as certain animals and fungi.

biomes -- The world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment. MORE?

biostratigraphy -- n. The study of rock layers (e.g., distribution, environment of deposition, age) based on their fossils; biostratigraphic- adj.

biostratinomy -- The study of what happens between the death of an organism and burial. Part of taphonomy.

bioturbation -- n. The disturbance of sediment by organisms, e.g. burrows, trails, or complete mixing.

bipedal -- adj. Describes an animal that walks on two legs.

bipinnate -- Describing a pinnate leaf in which the leaflets themselves are further subdivided in a pinnate fashion.

biramous -- Arthropod appendages that are biramous have two branches, an outer branch and an inner branch. These branches may have separate functions; in crustaceans, for instance, the inner branch of a leg is used for walking, while the outer branch may be paddle-shaped or feathery and often functions as a gill. Contrast with uniramous.

bisporangiate -- When a flower or cone produces both megaspores and microspores, it is said to be bisporangiate. Most flowers are bisporangiate.

blade -- Any broad and flattened region of a plant or alga, which allows for increased photosynthetic surface area.

blood -- Fluid which circulates throughout the body of an animal, distributing nutrients, and often oxygen as well.

blueschist -- Metamorphic rock formed under great pressures, but not so great temperatures.

book lung -- A set of soft overlapping flaps, covered up by a plate on the abdomen, through which oxygen is taken up and carbon dioxide given off. Characteristic of many terrestrial arachnids such as scorpions and spiders.

boreal -- adj. Describes the northern biotic area that is dominated by tundra, taiga, and coniferous forests.

brackish -- adj. Slightly salty.

bract -- Any reduced leaf-like structure associated with a cone or flower.

braided river -- n. A river characterized by a network of channels that split and entwine, rather than a single channel for water and sediment. Braided rivers are common in upland areas closer to mountain fronts where the slope, and consequently water velocity, lessens and the river begins to deposit sediment. Braiding is the result of the channel becoming clogged with sediment.

brain -- Collection of nerve cells usually located at the anterior end of an animal, when present at all. The nerves coordinate information gathered by sense organs, locomotion, and most internal body activities.

breccia -- n. A rock composed of angular fragments of older rocks; distinguished from a conglomerate in that the component rocks are not rounded and worn.

brevitoxin -- neurotoxin produced by the dinoflagellate Ptychodiscus brevis.

bryophyte -- Plants in which the gametophyte generation is the larger, persistent phase; they generally lack conducting tissues. Bryophytes include the Hepaticophyta (liverworts), Anthocerotophyta (hornworts), and Bryophyta (mosses).

Last updated:2009-11-12