|
Home >>Biology Dictionary >> Pantothenic Acid - Passage Cells
|
|
Palps. Of polychaete annelid worms, tactile appendages on the head.
Palynology. Pollen analysis
Pancreas. Sweetbread. Gland of ganthostome vertebrate situated in mesentery near duodenum, into which it discharges through pancreatic duct an alkaline mixture of digestive enzymes (trypsinogen, lipase, amylase, maltase, etc).
Pancreation. An extract of the pancreas that contains pancreatic enzymes.
|
Pandemic. Occurring over a wide geographical area, as with a disease such as malaria.
Papain. A protein-digesting enzyme (see protease) occurring in the fruit of the West Indian papaya tree (Carica papaya). It is used as a digestant and in the manufacture of meat tenderizers.
Papilla. Any cone-shaped protuberance projecting from the surface of an organ or organism. Papillae occur, for example, on the tongue and, in plants, on the surface of many petals.
Panicles. Kind of inflorescence.
Pantothenic Acid. Vitamin of B complex, forming a coenzyme; required by a variety of organism, e.g. some yeasts, some bacteria, insects, vertebrates.
|
Pappus. Ring of fine, sometimes feathery hair, developed from calyx crowing the fruits of flowering plants of family Compositae.
Paraphysis. (Bot.) Sterile filament, numbers of which occur in mosses and in certain algae, interspersed amongst the sex organs; and in the hymenium of ascomycete and basidiomycete fungi.
Parapodium. Paired, segmentally arranged, muscular lateral projection of body of polychaete worms, bearing chaetae and sometimes other structures; locomotor in free-living forms.
Parasite. Organism living in or on another organism (its host) from which it obtains food
Paratonic. (Of plants movements), induced by external stimuli, e.g. mastic movements, taxes nd tropisms. Alternatively described as induced or aitiogenic.
|
|
Parsintercerebrails. The dorsal part of the insect brain containing neurosectetory cell.
Parthenoenesis. The development of an organism from an unfertilized egg. This occurs sporadically in many plants (e.g. dandelions and hawkweeds) and in a few animals, but in some species it is the main and sometimes only method of reproduction. For example, in some species of aphid males are absent or very rare. The eggs formed by the females contains the full (diploid) number of chromosomes and are genetically identical. Variation is consequently very limited in species that reproduce parthenogenetically.
Paratype. Any specimen, other than the type specimen or duplicates of this, cited with original taxonomic description and naming of an organism.
Paturition. The act of giving birth to an offspring.
|
|
|
Passage cells. Cells of endodermis, characteristically of older monocotyledonous roots, opposite protoxylem groups of stele, that remain unthickened, with casparian strips only, after thickening (involving deposition of suberin cellulose, and lignification) of all other endodermis cells; allowing transfer of material between cortex and vascular cylinder.
Parazoa. Grade of organization exemplified only by Porifera which are multicellular animals separately evolved from all others (Metazoa)
Pasteurization. The treatment of milk to destroy of disease causing bacteria, such as those of tuberculosis, typhoid, and brucellosis. Milk is heated to 650 C for 30 minutes or to 720C for 15 minutes followed by rapid cooling to below 100 C.
|
Patella. Knee-cap. A bone (sesamoid bone,) over the front of the knee joint in tenton of (extensor) muscles which straighten the hind-leg, present in most mammals, some birds and reptiles.
Pathogen. Parasite which causes disease.
Pedal. Relating to the foot, particularly those of Molluscus.
Pedicel. Stalk of an individual flower of an inflorescence.
Peduncle. The stall of an inflorescence or a flower.
Pelvic. Pertaining to the posterior girdle and paired appendages of vertebrates; the posterior abdominal region of a mammal.
|
|
