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.
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.
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.
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.
biomes -- The world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment. MORE?
biostratinomy -- The study of what happens between the death of an organism and burial. Part of taphonomy.
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.
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.
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).