| biological assessment | A specific process required as part of an environmental assessment. An evaluation of potential effects of a proposed project on proposed, endangered, threatened, and sensitive animal and plant species and their habitats. (05 Dec 1998) |
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| biological availability | The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action. (12 Dec 1998) |
| biological chemistry | The scientific study of the chemistry of living cells, tissues, organs and organisms. (09 Oct 1997) |
| biological clock | <biology, physiology> An internal biological mechanism which controls certain biological rhythms and biocycles, such as metabolism, sleep cycles, photosynthesis. (21 Mar 1998) |
| biological clocks | The physiological mechanisms that govern the rhythmic occurrence of certain biochemical, physiological, and behavioural phenomena in plants and animals. The pineal gland, which receives input from the optic nerves and connects to the hypothalamus, may be the biological clock in humans. (12 Dec 1998) |
| biological coefficient | Rarely used term denoting the energy expended by the body at rest. (05 Mar 2000) |
| biological containment | <molecular biology> Refers to any number of methods to contain genetically engineered organisms by creating biochemical barriers to prevent them from growing outside the laboratory. In the case of bacteria and yeasts, genes in the organisms may be altered so that they need to have a supply of a nutrient that is normally found only in the laboratory. (21 Mar 1998) |
| biological control | <agriculture> The agricultural use of living things, such as parasites, diseases, and predators, to control or eliminate others, such as weeds and pests, rather than by using chemicals (herbicides and pesticides). (21 Mar 1998) |
| biological dressings | Human or animal tissue used as temporary wound coverings. (12 Dec 1998) |
| biological engineering | <agriculture> A type of artificial selection, the creation of plant or animal breeds that are agriculturally or industrially useful. Compare: natural selection. (21 Mar 1998) |
| biological factors | Compounds made by living organisms. They have biological or physiological activities. (12 Dec 1998) |
| biological half-life | <biochemistry, biology> This is the time required for one-half of the total amount of a particular substance in a biological system to be consumed or broken down by biological processes when the rate of removal is approximately exponential. Toxic chemicals with a long biological half-life (such as some pesticides) will tend to accumulate in the body and are, therefore, more likely to be harmful. A substance with a short biological half-life may still accumulate if a portion of it it becomes tightly bound to bone or other tissues, even if most of it is quickly cleared from the body. (21 Mar 1998) |
| biological hazard potential | <radiobiology> Measure of the hazard posed by a given quantity of radioactive material in which the variation in biological effects of the various elements are accounted for. See: integrated biological hazard potential. (21 Mar 1998) |
| biological immunotherapy | <immunology> Treatment of disease by stimulating the bodys own immune system. This is a type of therapy currently being researched as a treatment for cancer. (16 Dec 1997) |
| biological magnification | <biology, zoology> The process by which toxins such as pesticides build up in each successive link in the food chain. For instance, a given population of beetles may have very low levels of a fat-soluble pesticide, but the pesticide will build to much greater levels in the fat of a bird that eats those beetles, and the pesticide will reach greater levels still in a human or panther that eats the beetle-eating birds. (21 Mar 1998) |