Eukaryotic, multicellular, chlorophyll containing and having cell wall, are grouped under the kingdom Plantae. It is popularly known as plant kingdom.

Transcription

1 XI CLASS BIOLOGY NOTES CHAPTER 3 PLANT KINGDOM Eukarytic, multicellular, chlrphyll cntaining and having cell wall, are gruped under the kingdm Plantae. It is ppularly knwn as plant kingdm. Different systems f classificatin Artificial classificatin ldest classificatin and it is based n few vegetative and sexual characters. Natural classificatin system it is based n natural affinities amng the rganisms in their external and internal features. Phylgenetic classificatin system it is based n evlutinary relatinship Numerical taxnmy by using cmputers numbers and cdes are assigned t all the characters and data are prcessed. Cyttaxnmy it is based n cytlgical infrmatin like chrmsme number, structure and behavir. Chemtaxnmy it is based chemical cnstituents f the plants. 1.ALGAE : Simple, thallid, auttrphic, aquatic rganisms. Habitats grw inmist sil and wd. Symbitic( Lichens) grw n ther animals (slth bear) Size ranges frm Unicellular clnial (vlvx),filamentus ( spirgyra) and Massive bdies (kelp) Reprduce vegetatively, asexually and sexually Spres are Zspres (male) isgamus / anisgamus; Ospres (egg). Ecnmic imprtance: 1. Prphyra, Laminaria, Sargassum are used as fd. 2. Marine brwn algae (Algin) and red algae (Carrageen) are used as Hydrcllids, 1

2 which is a fibrus structure hlds water and used t transprt seedling. 3. Gelidium, Graularia are usedtgrw micrbes, makeice creams and jellies. 4. Chlrella and Spirullina are rich in prteins and used as fd supplements. Algae are divided int 3 main classes; a) Chlrphycease (Green algae): Clnial / filamentus / unicellular Vegetative reprductin is by fragmentatin / spres Asexual reprductin is byflagellated Zspres Sexual reprductin is by isgamus / anisgamus / gamus Examples : - Vlvx, Spirgyra, Chlamydmnas b) Phaephycease (Brwn algae) They are attached t substratum by Hldfast (rt like), Stalk (stipe) and leaf (frnd) Vegetative reprductin by fragmentatin Asexual reprductin is by biflagellated zspres Sexual reprductin is by Isgamus / Anisgamus / Ogamus. Examples: - Laminaria, Srgassum, Ectcarpus, Dictyta, Fucus. c) Rhdphycease ( Red algae) Vegetative reprductin is by fragmentatin. Asexually by nn-mtile spres. Sexually by nn-mtile gametes. 2

3 Examples : - Prphyra, Gracilaria, Gelidium. II.BRYOPHYTES They live in mist shaded areas in the hill. It is knwn as amphibians f plant kingdm. They ccur in damp sil, humid and shaded places. Plant bdy lacks true rts, stem, leaves, they are attached t the substratum by unicellular / multicellular Rhizids. The main plant is haplid and they prduce gametes (Gametphyte dminant). The male sex rgan is Antheridium (antherzids) The female sex rgan is Archegnium (single egg) Antherzids are released in water cme int cntact with Archegnium t frm Zygte. Zygte develps int Sprphyte (diplid) underges meisis t frm haplid spres germinate t prduce Gametphyte. Ecnmic imprtance: Prvide fd fr herbaceus mammals / birds. Sphagnum species (msses) prvide peat, used as a fuel. Due t its water hlding capacity is is used as packing material fr transshipment f living materials. Msses and Lichens frm Pineer cmmunity n bare rcks. Frm dense mats n sil, s reduce the impact f rain and sil ersin. 3

4 Classes: - There are tw classes - Liverwrts, Msses. a) Liverwrts: Mist, shady habitats, damp sil, bark f trees and deep in the wds. Plant bdy is Thallid, have a tiny leaf structures. Asexual reprductin is by fragmentatin / frm gemmae (green, multicellular, asexual bdies) they detach frm parent bdy and frm as a new individual. Sexual reprductin frm male & female sex rgans sprphyte is differentiated int a ft, setae and capsule. Spre germinates t frm gametphyte. Example :- Marchantia b) Msses: Gametphyte shws tw stages Prtnema (spres) and Leafy stage (Secndary prtnema) Attached t the sil by Rhizids Vegetative reprductin is by fragmentatin / budding Sexual reprductin is by antheridia and archegnia Zygte develps int sprphyte and frm capsule and it cntains spres (haplid) Example: - Sphagnum, Funaria III.PTERIDOPHYTES (first land plants): They are used fr medical purpse, rnamental and as sil binders and first terrestrial plants. They grw in cl, damp, shady places Pssess vascular tissues (xylem and phlem) Main plant bdy is Sprphytes The bdy is differentiated int true rts, stem and leaves. Leaves may be small (micrphylls selaginella) r large (macrphylls ferns) and bear sprangia and frm sprphylls (leaf carrying spres). Sprangia prduce spres by meisis. Spre germinatest frm gametphyte,called Prthallus. They need water fr fertilizatin. Gametphyte bear male & female sex rgans called Antheridia and Archaegnia respectively. Gamete fusin results in zygte frmatin. Zygte develps int sprphytes (dminant phase). If all the spres are similar kind, it is called Hmspres. Selaginella prducetw kinds f spres, Macr and micr spres, hence knwn as Hetersprus. Macr and micr spres develp int female and male gametphytes respectively. 4

5 Female gametphyte retained n sprphyte. It leads t the develpment f seed habit. Classes: - There are fur classesin Pteridphtae; a) Psilpsida Ex. Psiltum b) Lycpsida Ex. Selaginella c) Sphenpsida Ex. Equisetum d) Pterpsida Ex. Pteris IV. GYMNOSPERMS (Naked seeds) They are seed bearing plants. The vules are nt enclsed in an vary, s n fruits. Tallest gymnsperm is Sequia (red wd tree) Plant bdy is differentiated int rts, stems and leaves Rts are tap rt assciated with ther rganisms like Pinus rts with Mycrrhizae and Cycas rts with Cyanbacteria like Nstc and Anabaena (nitrgen fixing micrbes) Stem canbebranched / unbranched Leaves are simple / needle like leaves shw Xerphytic adaptatin Gymnsperms are hetersprus, prduce micrspres and megaspres 5

6 They frm male cnes & female cnes Bth cnes can ccur n sme plant / different. Fertilizatin results in Zygteand embry develps. Ovules frm seeds. Gymnsperms shw diplntic life cycle. They shw Alternatin f generatin. Examples ; - Pinus, Cycas, Cedrus V. ANGIOSPERMS (flwering plants) They are flwering plants Seeds are cvered by fruits live in wide range f habitats. Size variesfrm tiny micrscpic Wlfia t tall trees Eucalyptus. Prvide fd, fdder, fuel and medicine. There are tw classes - Dictyledns and Mnctyledns. 6

7 Male sex rgan is Stamen and female is Pistil. Ovules have embry sac; it underges meisis and frm egg apparatus with ne egg and 2 synergids, 3 antipdal cells and 2 plar nuclei. Duble fertilisatin- Each pllen grain prduce tw male gametes. One gametes fuse with egg t frm embry. This is called Syngamy. Other gametes fuse with tw plar nuclei t frm endsperm, triple fusin. Since fertilisatin takes place twice, it is called duble fertilisatin. Plar nuclei fuses t frm secndary plar nucleus. Pllen dispersal is by pllinatin pllen tube grws in t stigma and style f pistil, ne male gamete fuses with egg and frm zygte and ther male gamete fuses with secndary plar nucleus (2n) t frm Primary Endsperm Nucleus (PEN - 3n). Due t tw fusins, it is called Duble fertilizatin. Zygte - Embry PEN - Endsperm (and nurishes embry) Synergids and antipdal cells - degenerate Ovules seeds Ovary - Fruits 7

8 Alternatin f generatin Different plant grups cmplete their life cycles in different patterns. Angisperms cmplete their life cycle in tw phases- a diplid sprphytes and haplid gametphyte. The tw fllws each ther. This phenmenn is called alternatin f generatin. Haplntic- Saprphytic generatin is represented by nly the ne-celled zygte. Meisis in zygte results int haplid spres t frm gametphytes, which is the dminant vegetative phase. Example- Vlvx, Spirgyra etc. Diplntic- Diplid sprphytes is dminant, independent, phtsynthetic plants. The gametphyte is represented by single t few celled. All seed bearing plants fall under this categry. Hapl-diplntic- Bth phases are multicellular and intermediate cnditin is present. It is present in Bryphytes and Pteridphytes. Life cycle patterns : (a) Haplntic (b) Diplntic (c) Hapl-diplntic 8

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