Biological Terms | Science & Technology for UPSC CSE PDF Download

Agar-agar : A polysaccharide, obtained from cell-walls of red-algae which remains semisolid at room temperature, used as an emulsifying agent in pharmaceuticals, and also to solidify the synthetic media for artificial cultural work.

Allopolyploid : An organism containing more than two genomes derived from two or more different species.

Ascus : A sac-like structure produced as a result of sexual reproduction in ascomycetes (Fungi) and containing eight ascospores.

Autotrophic : organisms which can manufacture their food on their own.

Bacteriophage : A virus which multiplies in a bacterial cell and lyses the cell in which it multiplied.

Biocoenosis : A community of pl ants and animals.

Biome : A group of sim ilar types o f co mmuniti es, unified in the types of organisms they contain and their responses to environment.

Biosphere : The envelop e containing all liv ing th ings on earth.

Cambium : A l ateral m eristem atic z one in highe r plants which adds cells in a radial manner in stems and roots increasing the final diameter of the latter.

Cephalization : The development of the head bearing the brain.

Cerebellum : The fourth part of the brain in  vertebrates which governs the muscular coordination.

Chyle : The part of f ood in ali mentary c anal, whi ch consists largely of emulsified fats and is absorbed through walls of small intestine and then collected by lymphatic vessels.

Chyme : The f ood re pres ent in g th e li qui d st at e af te r digestion of solid matter.

Dendron : A branched fibre from a nerve cell which carries impulses towards the cell body.

Dormancy : A period of in activity in seeds, buds , bulbs, and other modified plant organs.

Ecdysis : The shedding of the cuticle of an arthropoda or of the horny scales of a snake or lizard.

Ecotone : Transitional zone between two vegetational types or regions.

Epicalyx : A whor ls o f leaf-l ike stru ctur es external to calyx and resembling it.

Epizoic : organisms which grow on the surface of other animals.

Eugenics : The sc ience whi c h deal s with the improvement of the inborn or hereditary qualities in a series of generation of the human race.

Euthenics : The science dealing with the betterment of living conditions.

Exocarp : The outermost layer of the pericarp (fruit wall) generally the mere skin of the fruit.

Facultative parasite : An organi s m whi ch is basically a saprophyte but can live as a parasite, if it gets a suitable host.

Gemma : A mul tic ell ular, asex ual re-producti ve structure, which after detachment from the parent, is capable of growing into a new plant.

Ganglion : A collec tion of nerve cel ls out side t he central nervous system.

Gizzard : A portion of the alimentary canal in annelids and birds, the function of which is to grind food.

Gibberellins : A group of gro wth hormones hav ing a property of overcoming genetically controlled dwarfism in plants.

Glume : An outer and low ermost bract of a grass spikelet.

Guttation : Ex udation of l iquid water containing nutrients from plant leave.

Haustorium : A s pecial ized organ us ed by parasites to drive nutrition from host plants.

Heterothallism : Proc ess in which tw o diffe rent thalli or plants of the same species are required for sexual reproduction.

Heterospory : Production of morphologically   different types of spores.

Hormogonium : A mul tic ell ular fragment of a filament capable of growth into a new plant in  blue-green algae.

Identical twins : Twins tha t are derived from a single zygote after the first division.

Insulin : the hor mone s ecre ted by pa ncrea s wh ich regulates sugar metabolism in vertebrates.

Isomorphic : a li fe-cycle in which gametophyte and sporophyte are morphologically similar.

Karyotype : Charact eristi c size and shape of chromosomes of a organism at mitotic metaphase.

Keratin : A structural protein which forms the chemical basis of horn hair nails, feathers and epidermal scales.

Labium : An exoske leta l m ass, composed of s everal pieces which forms the posterior boundary of the pre-oral cavity in insects.

Lanugo : The hairy covering on the human foetus before birth.

Lithotroph : An organis m that manufac tures food by utilizing energy derived from the oxidation of inorganic raw materials.

Meninges : A membrane which surrounds the brain and spinal cord.

Mutagen : A chemical or physical factor which causes mutation.

Nucellus : Tissue comprising chief part of the young ovule in which the embryo-sac develops.

Ontogeny : The developmental stages in the life of an individual from fertilized egg to the adult stage.

Operon : A group of genes c ons ist in g of an operator gene and the structural genes under its control.

Pepsin : An enzyme produc ed in the stomach of vertebrates which changes proteins to peptones.

Pericardium : A membranou covering enclosing the heart.

Prostrate glands : A gland connected with the male reproductive system and producing a secretion that stimulates the activity of sperm cells.

Petrification : A type of plant fossil in which the original cellular tissues are retained and impregnated with mineral compounds.

Phytochrome : A protein contai ning pigment associated with responses to durations of light and dark periods in plants.

Placenta : The region within the ovary where one or more ovules are attached.

Quantosome : A photosyn thetic unit compri sing 200-300 chlorophyll molecules, located on photosynthetic lamella in chloroplasts, and capable of capturing one quantum of light at a time.

Recessive gene : That member of a pair of genes, when both the members of the pair are present, in subordinate or suppressed by the other, dominant gene.

Recon : The smallest length of DNA that is capable of recombination, which sometime can represent only one nucleotide.

Recessive gene : That member of a pair of genes, when both the members of the pair are present, in subordinate or suppressed by the other, dominant gene.

Recon : The smallest length of DNA that is capable of recombination, which sometimes can represent only one nucleotide.

Reflex Arc : A chain of nerve cells numbering three-a receptor neuron on the surface which receives a stimulus and passes the effect as an impulse to an adjustor neurons; this in turn passes it on to an effector cell that performs the appropriate activity.

Sebaceous glands : The oil glands connected with the hair of mammals.

Siliqua : The characteristic frui to fcruciferae, the valves splitting from the bottom and leaving the placenta with false portion stretched between.

Sinus venosus : Chamber of vertebrate heart between veins and auricle, it is absent in birds and mammals.

Systole : Heart beat in which its muscles contract to pump blood into the arteries or contraction of contractile vacuole in protozoa.

Tassel : Staminate inflorescence in maiza.

Tepal : Unit structure of a perianth that is not differentiated into sepals and petals.

Umbilical cord : Stalk arisi ng from ventral side of embryo of mammal and joining the placenta,  contains mesoderm blood vessels and parts of yolk sac and allantois, it breaks at birth.

Vitelline membrane : Membrane surrounding ovum of animals.

Wandering Cell : A leucocyte that moves about in the tissue of the body.

Yolk : Stored food in the form of protein and fats in eggs.

Xeromorphic : Term referring to anatomi cal modifications of the leaf of Xerophytes.

Zooid : A colony of a small animal t hat has been produced by asexual reproduction.

Zygomorphic : Flowers which can be divided into two equal halves only in one plane.