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Home >>Biology Dictionary >> Aggulutination - Alimentary Canal
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Affinity
The relationship of one organism to another in terms of its evolution.
After-ripening
A doomant period, after the seed is formed, needed by the embryo to undergo certain chemical and physical changes before it can grow.
Agamospermy
All types of apomixes in which embryos and seeds are formed by asexual means; excludes vegetative reproduction.
Agar
Mixture of polysaccharides, some sulphated obtained from certain seaweeds; forms a gel with water, melting at a higher temperature than it solidifies at; is used to solidify culture media on which micro-organisms are grown.
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Agglutinin
Substance producing agglutination, usually antibody or lectin.
Aggregate fruit
A fruit consisting of a collection of simple fruits, derived from a flower with several free carpels. An example is the black berry.
Aggressins
Enzymes that are produced by parasitic bacteria. The aggressins dissolve tissues and enable the bacteria to enter the host tissues.
Agronomy
The study of the cultivation of field crops, with particular emphasis on improving their productivity and qualitative features.
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Agonistic behaviour
Aggressive behaviour towards another member of the same species, involving threat or fighting.
Air-bladder
Swim-bladder or lung of fish.
Air Sac
A thin walled extension to the lings present in the thorax, abdomen and bones of birds. Air sacs also occur as diverticula of the trachea in insects where as in birds, they are important in respiration.
Albinism. Hereditary lack of pigmentation in an organism. In mammals, including man, commonly due to an autosomal recessive gene.
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Alcyonaria
Soft corals, sea pens, etc. an order of Coelenterates class. Actinozoa. Have eight pinnate tentacles and eight mesenteries.
Aldosterone
A hormone produced by the adrenal glands (see corticosteroid) that controls excretion of sodium by the kidneys and thereby maintains the balance of salt and water in the body fluids. See also Angiotensin.
Algae
A large and diverse group of simple, photosynthetic plants with unicellular organs of reproduction. Plant body (thallus, q.v.) unicellular; or multicellular, filamentous or flattened, ribbon-like, with relatively complex internal organization in higher forms but non-vascular. Aquatic plants, marine or freshwater or plants of damp situations, e.g. damp walls, tree trunks, in soil.
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Algae has been abandoned as a formal taxon in recent classifications, component group being now considered as sufficiently distinctive to merit recognition as division.
These are based on structure, pigments, chemical nature of cell wall, flagella, assimilatory products: and comprise Bacillariophyta, Charophyta, Chlorophyta, Chrysophyta, Cryptophyta, Cyanophyta. Euglenophyta, Phaeophyta, Pyrrophyta, Rhodophyta, Xanthophyta.
Alimentary (Enteric) Canal
The gut; a tube concerned with digestion and absorption of food. In some animals it has one opening only (Coelenterates, flatworms), but in most it has an opening (mouth) into which food is taken and another (anus) from which unassimilated material is rejected.
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Alisphenoid
The bone forming in the middle region of the cranium of mammals. Alkaline tide. A period when the alkaline of the body and winary system is affected by excessive recreation of digestive hydrochloric acid.
Albumin
A protein without a prosthetic group, and is soluble in water and in dilute salt solution. The main protein constituent blood serum in vertebrates.
Alkaloids
A group of nitrogen-containing, basic organic compounds present in plants of a few families of Dicotylendons, e.g. Solanaceae, Papaveraceac; possibly end-products of nitrogen metabolism. Of great importance because of their poisonous and medicinal properties, e.g. atropine cocaine, morphine, nicotine, quinine, strychnine.
Agnatha
A group of vertebrates (sometimes made a subphylum the other vertebrate classes then being grouped as the sub-phylum Gnathostomata). Represented now by very few species, order Cyclo-stomata, i.e. the lampreys and hag fishes.
Agave.
A semi woody perennial native of the American continent. Pulque and aquamiel are produced from it as fermented beverages and mescal and tequila may in turn be distilled from these.
Agglutination
The clumping together, e.g. of bacteria (one of the effects of antibodies); or of red blood corpuscles (as when blood of incompatible blood-groups is mixed.).
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