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Home >>Biology Dictionary >> Antibiotic - Antigibberllins
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Anthrax
A fever of the spleen in cattle and sheep caused by toxins released from the Bacillus anthracis. The disease can spread to humans when infected animal products such as wool and bristles are handled, giving rise to malignant skin lesions and pustules.
Anthropoid apes
The most nearly related to man of all living animals; gibbons, organ, chimpanzee, gorilla. They are catarrhine Primates, forming the family Pongidae, all in habiting Old world.
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Antibiotic
Substance obtained from living organisms which diffuses into its surroundings and is toxic to individuals belonging to other species. Antibiotics have been obtained from many micro-organisms that inhabit the soil and may be an important factor in the competition amongst microorganisms that is a characteristic of their life in this environment.
Antibody
A protein produced by certain white blood cells (Lymphocytes) in response to entry into the body of a foreign substance (antigen) in order to render it harmless. An antibody – antigen reaction is highly specific. Antibody production is one aspect of the immune response and is stimulated by such antigens as invading bacteria, foreign red blood cells, inhaled pollen grains or dust, or foreign tissue grafts.
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Anticlinal
Division of cells situated approximately at right angles to outer surface of plant part.
Anticoagulant
Substance which prevents the clotting of blood, e.g. heparin.
Anticodon
A group of three adjacent nucleotides of transfer RNA matching three nucleotides of Messenger RNA. See Codon.
Antidiuretic Hormone (Adh, Vasopressin)
Hormone secreted from posterior lobe of pituitary. A peptide of nine amino-acid residues, in chemical structure very similar to Oxytocin. Synthesized in certain hypothalamus. In mammals, stimulates water reabsorption by uriniferous tubule and hence diminishes volume of urine, and indirectly increases blood pressure. Deficiency cause diabetes insipidus.
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Antigen
Substance capable of stimulating formation of an antibody.
Antigibberellins
Organic compounds ranging widely in structure that cause plants to grow with short and thick stems or with appearance opposite to that obtained with gibberellin. Of agricultural importance are such compounds as phosphon and maleic hydrazide (used, e.g., to retard growth of grass, reducing frequency of cutting).
Antihaemophilic Globulin
It i an important protein tha
t is needed for blood clotting.
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Antitranspirants
These are chemical substances that are sprayed on the plants to reduce the rate of transpirations.
Antler
Bony projection from skull of deer (cervids). Unlike horns, they are often branched, are shed annually, and are confined to males (except reindeer).
Anuar (Salientia)
An order of the class Amphibia including frogs and toads. Long hind legs for jumping; not tail; soft, moist skin important in respiration, with no scales.
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Anti-toxin
Anti body that neutralizes a specific toxin
Aorta
In man and other mammals, the major artery which leaves the heart (from the left ventricle), and through which passes the arterial blood supply for the whole body (about four litres per minute in man) to be distributed via the numerous arteries which branch off the aorta.
Anthropoidea
(Pithecoidea). Sub-order of the order Primates. Includes monkeys, anthropoid apes, and man. Divided into two groups, Platyrrhini and Catarrhini. Large eyes, facing forwards; strong tendency to use hands for manipulation; relatively large brain.
Antiauxins
Chemicals which can prevent the action of auxins (q.v.) in plants, e.g. 2. 6-dichlorophenoxyacetic acid; 2,3, 5-triodobenzoic acid.
Anus
Posterior opening of the alimentary canal to the exterior through which undigested remains of food, is expelled. This is its only function, except in some aquatic animals which use hind-end of gut for respiration (e.g. some dragon-fly larvae). Present in most metazoan but absent in all Platyhelminthes and Coelenterata.
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