+ AS we go higher from species to kingdom, the number of common characterises goes on decreasing. Lower the taxa, more ae the characteristics that the members within the axon co [Organisms with their taxonomic categories share Higher the category oreaterste dificult of determining the relationship to other taxa at the same level. Hence, the problem of cassifiation becomes more complex Common Name |Biological Name| Genus | Family | Order Class___| Phylum/Division Men Home sapiens | Homo Hominidae |Primata | Mammalia Chordata Housefly Musca domestica |Musca [Muscidae [Diptera Insecta Arthropoda Mango Mangitera indica | Mangitera | Anacardiaceae |Sapindales |Dicotyiedonae _| Angiospermae Wheat Titicum aestivum |Tticum _|Poaceze _|Poales __| Monocotyledonae | Angiospermae ‘Who gave the Binomial Nomenclature? InTexT Practice Questions Name the highest category of classification system. Biological Classification + The scientific procedure of arranging organisms into ‘groups and subgroups on the basis of their simiarties ‘and issimilartes and placing them in taxonomic hierarchy, is known as biological Cassifcation. +A dasifcaton system helps in identification of organisms ‘and understanding the relationships amongst different ‘groups of organisms. ‘+The organisms ofthe past can be studied only with 2 proper system of classification and evolutionary tendencies can be known on the basis of relationship and simplicity or ‘compiexity found in the members of various taxa TYPES OF CLASSIFICATION SYSTEM + Depending upon the type of system of classification, ‘organisms are cassfid into two kingdoms, three kingdoms, four kingdoms, five kingdoms and now into six kingdoms. ‘Two Kingdom Classification + Two kingdom classification system was suggested by Carolus Linnaeus the father of taxonomy) in 1758, ‘The organisms were divided into two kingdoms - Kingdom Plantae and Kingdom Animalia + Two kingdom system of classification did not distinguish between the eukaryotes and prokaryote, unicellular and mmuttceluiar and photosynthetic (green algze) and non- photosynthetic (fungi) organisms. Hence, two kingdom classification was found inadequate ® \wB10Logy Tooay | AP. Three Kingdom Classification + Haeckel (1866) separated unicelular animals, algae and fungi from other organisms on the basis of lack of tissue differentiation. The new gioup was called Kingdom Protista. + Later on fungi and multicelular algae were taken out from the group so that Kingdom Protista came to have only unicellular organisms. The organisms were divided into three Kingdoms : Plantze,Protista and Animalia, Four Kingdom Classification + With the discovery of electron micoscope, it became clear that bacteria and elated organisms have a efferent nuclear structure 2s compated ta others + They are prokaryotes in contrast to others which have a ‘rue nucleus and are caled eukaryotes. + Copeland (1956) ceated a separate Kingdom Monera for them, + Ths divided the ling world into four Kingdoms : Monera, Protista, Plantae and Animals + In this sytem, fungi continued to remain with the plantae. Five Kingdom Classification ‘+ Five kingdom classification was proposed by an Ametican ‘taxonomist, R.H. Whittaker (1969). + Thekingdoms were named Moneta, Potsta, Fungi, Pantae and Animalia+The main criteria for classification used by him include cell structure, thallus organisation, mode of nutrition, mode of reproduction and phylogenetic reationships. Characteristics ofthe five kingdoms Characters Five Kingdoms | Monera Protista Fungi Plantae Animalia Celitype | Prokayotic Eukaryotic Eukaryotic | Eukaryotic | Eukaryotic Cellwal | Non-celuosic Present in Present (with | Present (wth | Absent (Polysaccharide + amino acid) _| some Chitin) cellulose) Nuclear | Absent Present Present | Present Present ‘membrane Body Caluar Celuar Muticelular! | Tssuelorgan | Tissue/organ’ ‘organisation loose tissue organ system Mode of | Autotrophic (chemosynthetic and | Autotophic Heterotrophic | Autotrophic | Heterotrophic ‘nutrition | photosynthetic) and heterotrophic | (photosytheti) | (saprophytic! | (photosynthetic) | (holozoic! (Saprophytioparsitic) andheterotophic | parasitic) saprophytic, etc) Mode of | Conjugation ‘Gametic fusion | Fetlisation [Fertilisation | Fertilisation reproduction and conjugation Shortcomings of five kingdom classification +The Kingdoms Monera and Protista ate still heterogenous groups. Both inciude photosynthetic (autotrophic) and non- Photosynthetic (heterotrophic, walled and wa-ess organisms. + Phylogenetic relationships, particularly of lower organisms, ate not fully reflected. For example, certain green algae and some photosynthetic bacteria get hydrogen from sources, other than water but these are assigned to different kingdoms + A distinction between unicellular and multicellular organisms is not possible in case of algze. Due to this, Uniceluiar green aigae such as Chlamydomonas, Volvox, etc., have not been inciuded in the Kingdom Protista, + Viruses have not been included in this system of assification. + Archaebectera difer from other bacteria in structure, composition and physiology Three Domains of Life (Six Kingdom Classification) + The three-domain system was introduced by Carl Woese (1990) that divides cel war life forms into archaea, bacteria and eukarya domains. + It emphasises the separation of prokaryotes into two ‘groups, originally called Eubacteria (now Bacteria) and ‘Archaebactetia (now Archaea), + Thus, the three-domain system divides the moners into two ‘domains’, leaving the remaining eukeryotic kingdoms in the third domain + tis actualy a sic kingdom classification _ === Domain Archaea Domain Bacteria Domain Eukarya (Contains single kingdom) (Contains a single kingdom) (Corti four kingdoms) p l Kingdom Archaebacteria Kingdom Eubactera Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia KINGDOM MONERA Itis a kingdom of prokaryotes, therefore, 'so known as prokaryota ‘+ Two mejor groups of monera include: Archaebacteria and Eubacteria. Eubacteri is further of two types : bacteria and cyanobacteria (blue green algae), + The true nucleus with nuclear membrane is absent in bacteria! cell. The nuclear material consisting of naked DNA molecule is called as nucleoid. +A layer of sie over the cell wall is present in bacterial cell itis usually composed of polysaccharides + Bacterial cell wall consists of acety! glucosamine, acty ‘1oLosy TooAy [7m 24muramic acid and @ peptide chain of four or five amino acid. Al these chemica's together form a polymer called peptidoglycan + A thin elastic and selectively permeable plasma membrane issituated just internal tothe cell wal in each bacterial cell + In many bacteria the plasma membrane gives rise to infoldings called mesosomes which participate in the separation of replicated nucleoid and formation of septa during cell division + The ribosomes in bacteria are of 705 type. + Many bacteria (e.g. E.cal) have accessory rings of DNA called plasmids in addition to bacterial chromosomes. The pasmid DNA replicates independently and maintain independent integrity + Bacteria reproduce asenually by binary fission. Sometimes Under unfavourable conditions, they produce spores. + Sexual reproduction or genetic recombination in bacteria takes place by three methods: conjugation, ‘transformation and transduction, ‘Based on theit shape bacteria are grouped under four categories :the spherical coceus, the rod shaped bacillus, the comma shaped vibrio and the spire spirillum. ‘+ Bacteria show both autotrophic and heterotrophic nuttion, + Autotrophic nutrition is of two types : chemosynthesis and photosynthesis, The bacteria performing these modes of nutition are called chemoautotrophs end photoautotrophs respectve'y + Heterotrophic nutrition is of three types symbiotic and parasitic, ‘Some of them can fx atmospheric nitrogen in specialised cell called heterocysts, eg., Nastoc and Anabaena, + Archaebacteria are group of most primitive prokaryotes characterised by the absence of peptidog\ycan in their cel wall. + Aichaebecteta are of three major types: methanogens, halophiles and thermoacidophiles. Methanogens are present in the gut of several ruminant animals such a5 cows and buffaloes and they are responsibe for production of methane from dung ofthese animals. Methanagens are obligate anaerobes and produce methane in biogas fermenters, e.g., Methanobacterium, Methanococcus. Halophiles ae’ sat cving” bacteria asthey ae found in envionment with a very high sat concentration. Thermoaeidophies (hot springs) live in extremely acidic environment that have extremely high temperatures. saptotrophic, © © wor0sy toon so 4 WHO AM I... “1 am the simplest and the smallest of free living prokaryotes, can survive in the absence of oxygen.” They are found in hot sulphur springs + Cyanobacteria (blue-green algze) are photosynthetic prokaryotes that have evolved more than 3 bilion years back and paved the path for evolution of aerobic forms, including aerobic bacteria, Mycoplasma (PPLO) ‘+ Mycoplasmas are the simplest and the smallest of the free iving prokaryotes. The organisms are often called PPLOs (Pleuro pneumonia ike organisms). cell wal is absent and plasma membrane fms the outer boundary ofthe cel, Due to ‘the absence of cel wal the organisms can change ther shape and are called pleomorphic. Mycoplasmas are heterotrophic in their nutrition and can survive without oxygen KINGDOM PROTISTA Kingdom Protista includes all the unicellular eukaryotic organisms. Phy;ogeneticay, the Kingdom Protista acts as @ connecting ink between the prokaryotic Kingdom Moneta none hand and the complex multcel ular Kingdoms Fungi, Plantae and Animaia on the other hand. + These are microscopic unicellular and eukaryotic organisms with cosmopo'itan habitat. Many protists are found in water bodies inthe form of plankton. + The cell body contains wel defined nucleus + The cell is surrounded by plasma membrane and wel developed membrane bound organelles are present inside the ce. + Mode of nutrition may be photosynthetic, holozoic, saprottophic, parasitic and symbiotic ete ‘+ Most of fee living protists perform aerobic respiration, however, the parasitic protistsrespire anaerobically. + Protiss reproduce by both asenual and sexual methods invoving cel fusion and zygote formation. + The major groups of protists incude chrysophytes, dinoflagellates, euglenoids, slime moulds and protozoans, + Chrysophytes include diatoms and golden algae. They are found in fresh water as well as in marine environments. + The cel wails of chrysophytes are embedded with silica and thus ate indestructible. + Chiysophytes produce diatomaceous earth and are the chief ‘producers’ in the oceans Dinoflagellates are mostly marine and photosynthetic. They appear yellow, green, brown and ..search me ©biue or red depending on the main pigment present in their cells, Majority of euglenoids are fresh water organisms found in, stagnant water A protein ich ayer called peliceis present instead ofa cell wall which makes ther body flexible. Euglencis are photosynthetic inthe presence of sunlight, however, when deprived of sunlight they behave lke heterotrophs Slime moulds are saprophytic protiss. They form an aggregate called plasmodium which may move and spread over several feet under favorabie conditions. Protozoans are heterotraphs and live as predators or parasites. They are considered to be primitive relatives of animals heterotrophs when deprived of sunlight? How does archaebacteria differ from eubacteri CHEMISTRY 6 Ps on PHYSICS Chemistry Today (sew - Dace Mathematics Today INTExT Practice ‘Which group of protista is photosynthetic in Four major groups of protozcans are as follows ‘Amoeboid protozoans : Tey livin feshwatey, sea water or moist soil. They move and capture their prey with the help of pseudopadiz. Some of them such as Enlamoeba are parasites Flagellated protozoans : Te members ofthis group are either feelving or patesitc. They have fagela. The parasitic forms such as Trypanosoma cause disease called steeping sickness. ited protozoans : These ate aquetic and actively ‘moving organisms because of presence of thousands of ci, 49, Paramecium, Sporozoans : These include diverse organisms that have an infectious spore-lke stage in ther life ce, eg, Plasmodium Questions «... the presence of sunlight and behave like Co Physics For You aeuary- December) How to order : Send money by ‘demand éraftmoney ordet. Dean Draft should be drawn in favour of MTG Learning Media (P) Ltd Mention the volume you require along wth your name an adress OR buyonine Fem mtgin Uaeuay-Decenbe) Biology Today (aeuary- December) = ‘Add ® 90 as postal charges ‘Oder issues can be accessed on digital.mtg.in in digital form, Mathematics Today aeuary- December Biology Today eur - December) oo Mathematics Today (aeuay-Decenbr Pon e ‘Mail your order to: Girewaton Manages, MIG teaming Mela). Plot 99,Sector a4 IrsttuonaArea, Gurvgram, HR) “els (0124 6601200, Emal:ifoe@mtgin Wieb:wnutgin sematoer oom Hem QDKINGDOM FUNGI They are achlorophyllous, heterotrophic, spre-forming, non: vascular, eukaryotic organisms which often contain chitin or fungal celulose in their cell walls and possess glycogen as. food reserve, ‘They have absorptive type of nutrition and are parasites or saprotrophs. ‘The body of fungus is filamentous and is called mycelium. The flaments ate known a5 hyphae. Hyphae are either multicellular or multnuclate. + Reproduction is of three types asewial + Vegetative reproduction occurs by budding, fission, fragmentation, sclerotia and rhizomorphs. + Asenval reproduction occurs through the formation of different ype of spores, + Sexual reproduction occurs by plznogametic copulation, gametangia contact, gametangial copulation, spermatogamy and somatogamy. + Kingdom Fung} is cassiied as follaws sexual, vegetative and = Sexual reproduction Mycelium aseptate not known Phyconycota lower or ala fun) Fungi pares ra Aygonlcetes (ogameus unc) (Cougation fur) + In oomycetes the mycelium is coenocytic (multinucleate and eseptate) ‘Asexual reproduction involves the formation of spore containing sacs oF sporangia which produce zoospores in aquatic environment. In terrestrial environment, the sporangia often behave as spores and equivalent to conidia, Zoospores are usualy bilagelate Gametes are usualy nor-fagallate Sexual reproduction takes place by gametangial contact and the product of sexual reproduction is oospore. Some examples are Abugo candida, Phytophthora infestans, ythium debaryanum. Zygomycetes is a cass of terestrial fungi which are mostly saprotrophic, rately parasitic The mycelium is coenocytic. Moti cls are absent, Sexual reproduction occurs through gametangial copulation or conjugation. The gametes are multinucleateand are caled coenogametes. Sexual reproduction produces 2 dip oid spore called zygospore Some examples are Rhizopus stoloniter, Mucor pusitus, Pilobolus crystalinus Ascomycetes include pigmented moulds, yeasts, morels, ‘ruffles, cup fungi and powdery mildews. The mycelium consists of septate hyphae. Moti structures do not occur inthe life cycle ‘The common mode of asexual reproduction i through the formation of conidia, However inyeasts asexual reproduction, ‘occurs through budsing and fission. Oia stage is found in some other ascomycetes. Sexual reproduction takes place through gametangil contact. ® ‘BIOLOGY ToDAY | APi."24 Sexual reproduction known (Mycelium septate Eumycoa (higher fg ‘Ascomycetes Basidiomycetes (Sac fngd (club fungi) + Fertilisation takes place in two steps plasmogamy and karyogamy. + Karyogamyis delayed afterp asmogamy and anew tanstona phase called dikaryophase appe inthe life cjcle + The cells of cikaryophase are called dikaryotc cells. Each cell possesses two nucie (n+ n), Later the two nucei fuse and the cells become diploid ‘+The fungi form fruiting bodies, in which reduction division occurs leading to formation of hapioid spores. + Some examples are yeast, Aspergilus, Penicillum, Clavicens and Neurospora. ‘+ Basidiomycetes grow in sil on logs and in living plant bodies as parasites. + The mycelium is septate and branched. Septa have dbolipores (pores with barrel shaped outgrowths). Vegetative reproduction occurs by fragmentation. The asexvai spores are not found. The sex organs ate absent but plasmogamy isbrought about by fusion of two vegetative or somaticcelis, of different stains or genotypes. The resutant structure is dikaryotic which gives rise to basiium. ‘SERS MARCH 2028 I= = 1. Erythropoietin. 2. Neem 3. Uttafitration 4. Protozoa 5. Troponin 6. Alley 7. Analogous 8. Operculum erate Se et eng+ Karyogamy ard meiosis takes place in the basidium producing four basidiospores. ‘+ Some exampies are Agaricus, Ustilago and Puccinia + Deuteromycetes are commoniy known as imperfect fungi because oniy the aserual or vegetative phases of these fungi are known + Some members of deuteromycetes are saprophytes or parasites whie a arge number of them are decomposers, of iter and help in mineral cycling, + The myceliumis septate and branched, The deuteromycetes reproduce oniy by asexual spores known as conidia, + Some examples ae Tichoderma, Ateraria and Colettichum ‘Most fungi are heterotrophic and zbsorb soluble organicmatter from dead substrates and hence are caled saprophytes Those fungi depend on ring pants and animals are caled parasites. They can aso live as symbionts Ze, in association with aigae a lichens and with roots of higher plants as mycorrhiza mNGnoM PLANTAE It incudes all eukaryotic chlorophy' containing organisms commonly called plants. +A few members such as biadderwort and Venus fy tap ate insectivorcus while few others such as Cuscuta are parasitic. + Kingdom Plantae includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms. + Two distinct phases are present in fe cycle of plants the dipoid sporophytic phase and the haploid gametophytic phase that aterate with each other. + These two phases follow each other rigidly but indifferent patterns in different plant groups. This phenomenon is, ¢a/ed alternation of geners KINGDOM ANIMALIA + This kingdom is characterised by heterotrophic, eukaryotic organisms that are multicellular and their cels lack cell wal’ + They depend directly or indirectly on plants for food. The mode of nutrition is by ingestion of food, ie, holozoic. + The food reserves are stored as glycogen or fat. Most of them are capable of locomotion. They have a definite shape and size and follow a definite growth pattem also, ‘The serual reproduction takes place by copulation of male and female fo owed by embryo\agical development. MIRUSES, VIROIDS AND LICHENS LB wore Practice Questions 7. Name the scientist who crystallised Tobacco Mosaic Virus (TMV) for the first time. ‘Why deuteromycetes are called imperfect fungi? ‘The name virus was given by Pasteur. DJ. Wanowsky (1892) is credited with the discovery of virus. Beijerinck (1896), called it contagium vivum fuidum. The viruses ate uiltamicoscopic, highly infectious agents and non-cellar organisms characterised by having an inert nstallne structure outside the ving cel Once they infect a cal they take over the machinery of the host cel to replicate themselves, Kling the host. Viruses contain capsid, the proteinaceous covering and ‘genetic material that could be either DNA or RNA. ‘Vises that infect plants have single stranded RNA while those that infect animals have either single or double stranded RNA or double stranded DNA. Bacteriophages are usualy double standed DNA viruses. In humans, viruses cause diseases like mumps, smallpox, herpes, influenza and AIDS. In plants, the symptoms of vitus infection can be mosaic formation ieafrolng, yellowing, ef cuing and stunted growth Stanley (1935) crystalised Tobacco Mosaic Virus (TMV) for the fist time An inert virus is called viion that can be crystalised and. stored indefinite Viroids are the smallest sf replicating partces discovered by Diener (1971), Voids ae infectious RNA partices devoid of protein coat. Like viruses, they ae obligate parasites. Viroids are known to cause diseases in pants only, eg, Potato spindle tuber chrysanthemum stunt Prions are highly resistant glycoprotein particles which function as infectious agents. Prions are not affected by proteases, nucleases, temperature upto 800°C, UV radiation and formaldehyde. Prions accumu ate in nervous tissue and, bring about its degeneration, Common diseases caused by them are mad cow disease, scrapie of sheep, kuru, Creutzfeldt-lakob disease (CJD). Prions were discovered by Prusiner (1983). Lichens are dual organisms or entities which contain 2 permanent association of a fungus or mycabiont and an aga ot phycobiont. ‘The alga! component is autotrophic while fungal component isheterotrophic. ‘Algge prepare food for fungi and fungi provide shelter and absorb minera|nutients and water fo algae Lichens cannot tolerate air polution especially due to suiphur dioxide ‘1oLosy TooAy [7m 24