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                                BIOLOGICAL CLASSIFICATION


·            Turril (1938) divided taxonomic studies into three phases α, β and ⱳ.

         α Taxonomy- based on gross morphological features.

βTaxonomy – based on morphology, anatomy, cytology, embryology, biochemistry and other branches of study.

     ⱳTaxonomy- Neosystematics or biosystematics which is based on all types of evidences including experimental, genetic and evolutionary.

·         Twort (1915): Discovered virus-infecting bacteria. They were named bacteriophages by Herelle (1917).

·         Delbruck (1938): Discovered that viruses to undergo mutations.

·         Lwoff(1953): Discovered temperate cycle in viruses.

·         Saffarman and Morris (1963): Discovered cyanophages.

·         SARS (Severe Acute Respiratory Syndrome) , caused by Corona RNA virus, similar to that causes cold.

·         Bird Flu: Avian influenza which spreads to humans as well.

·         Gastric or Peptic Ulcers: Mostly due to bacterium Helicobacter pyroli.

·         Bolello Vibrio: A small sized bacteria that attack other bacteria, multiply inside their bodies and cause lysis of host cells. Bdellovibrio bacteriovorous  is believed to help maintain purity of Ganges.

·         Death Factors: Three types-VFDF (Very Fast Death Factor), FDF (Fast Death Factor) and SDF (Slow Death Factor). Toxins from cyanobacteria like Aphanizomenon, Anabaena and Microcystis.

·         Phytoalexins: Chemicals produced by plant tissues in response to attack by a parasite for inhibiting the growth of the later.

·         Primary Host: Host in which sexual stage of a parasite is passed. Also called definitive host and final host.

·         Secondary Host: Host in which parasite passes its asexual phase. Also called intermediate host.

·         Reservoir’s Host: An alternate or passive host or carrier that harbours the pathogen without being harmed and serves as a source of infection to others.

·         Collateral Host: A substitute host in which the parasite can subsist with or without any apparent harm.

·         Autoecious: Parasite passing its different stages in the same single host.

·         Digenetic: Requirement of two alternate hosts for completion of life cycle of a parasite.

·         Heteroecious: A parasite passing different stages of life history in different hosts.

Mr. A. KINGSLIN M.Sc, BEd, Phd,(doing)
Post Graduate Teacher in Botany
St. Mary Goretty Hr. Sec School, Manalikarai 
Kanyakumari district

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