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Home >>Biology Dictionary >> Biennial - Bio-assay
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Berry. Many-seeded fleshy fruit in which wall (pericarp) consists of outer skin (epicarp), comparatively thick fleshy mesocarp and inner membranous endocarp e.g. gooseberry currant, tomato.
Biennial. A plant that requires two years to complete its life cycle, from seed germination to seed production and death. During the first season biennials, e.g. carrot, cabbage, store up food which is used in the second season when they produce flowers and seed.
Bilaterally symmetrical. Of organisms or their parts, capable of being halved in one, and only one, plane in such a way that the two halves are approximately mirror-images of each other. Usually this plane lies anteroposteriorly and dorsoventrally, thus separating similar right and left halves.
Almost all freely moving animals are bilaterally symmetrical, e.g. all vertebrates, arthropods, and worm shaped animals. Similar condition in flowers, e.g. snapdragon, is often called zygomorphy.
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Bile. Secretion of liver cells (hepatocytes) or vertebrates, passed through bile duct to duodenum. Important in digestion of fats, which , through action of bile salts, are converted into minute droplets (emulsified). Contains also pigments which are waste products of hemoglobin destruction.
Bile duct. Duct from liver to duodenum of vertebrates. Conveys bile.
Bile Juice. It is a secretion of lever. It contains bilirubin, biliverdin, pigments, cholesterol and traces of some other substances.
Bile Salts. The sodium salts secreted in bile, sodium taurocholate and sodium glycocholate which greatly lower surface tension and are important in emulsifying fats.
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Binary system. Any system where two alternatives occur as in some taxomomic keys.
Binomial nomenclature. The system of naming organisms using a two part Latinized (or scientific) name that was devised by the Swedish botanist Linnaeus (Cart Linne; 1707-78); it is also known as the Linnaean system. The first part is the generic name (see genus), the second is the specific or trivial name (see species).
The Latin name is usually printed in italics, starting with a capital letter. For example, in the scientific name of the common frog, Rana temporaria Rana is the generic name and temporaria the species name. The name of the species may be followed by an affreviated form of the name of its discoverer; for example, the common daisy is Bellis perennis L. (for Linnaeus).
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There are several International Codes of Taxonomic Nomenclature that lay down the rules for naming organisms.
Bio-assay. Quantitative estimation of amount of biologically active substances by the measurement of their actions in standardized conditions on living organisms or parts of organisms, e.g. androgen estimation on capon’s comb.
Biochemical mutant. A mutant which has a defect in a biochemical pathway, such as an Auxotroph.
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Biochemistry. Study of chemical substances and chemical processes of living things.
Biogenesis. Production by living organisms.
Biogenesis, principle of. The theory that a living thing can originate only from a parent or parents of the whole similar to itself. It denies both spontaneous generation (q.v.) and such fanciful notions current 300 years ago as the origin of geese from barnacles. If allowance is made for alternation of generation, complex life cycles, extreme sexual dimorphism, castes, and hybridization, it is substantantially true.
Biological classification. The arrangement of organism into taxa on the basis of their genetic relationships.
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Biological control. An artificial control of pests and parasites by use of other organism, e.g. of mosquitoes by fishes or by insectivorous plants which feed on the larvae.
Biological clock. It refers to the internal mechanism of an organism that regulates circadian rhythms and various other periodic cycles.
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