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Systems of Biological Classification, , 1. Artificial System, 2. Natural System, 3. Phylogenetic, System, , JSS PU COLLEGE DHARWAD
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Systems of Biological Classification, 1. Artificial Classification Systems, Carl Linnaeus, , Earliest systems of classification., They were based on vegetative, characters or superficial, morphological characters such as, habit, colour, number and shape of, leaves, etc., , Linnaeus’s artificial system of, classification was based on the, androecium structure., JSS PU COLLEGE DHARWAD
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Systems of Biological Classification, 1. Artificial Classification Systems, Carl Linnaeus, , Drawbacks:, They separated the closely related, species since they were based on a few, characteristics., , Equal weightage to vegetative &, sexual characteristics. This is not, acceptable since the vegetative, characters are more easily affected by, environment., JSS PU COLLEGE DHARWAD
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Systems of Biological Classification, 2. Natural Classification Systems, These are based on natural, , affinities among organisms., It considers external features and, , internal features (ultrastructure,, anatomy, embryology &, phytochemistry)., E.g. Classification for flowering plants, given by George Bentham & Joseph, , Dalton Hooker., JSS PU COLLEGE DHARWAD
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Systems of Biological Classification, 3. Phylogenetic Classification Systems, , These are based on evolutionary, , relationships among the, organisms., This assumes that organisms in the, same taxa have a common, ancestor., , JSS PU COLLEGE DHARWAD
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Systems of Biological Classification, Other sources to resolve the problems in, classification, Numerical Taxonomy: It is based on all, , observable characteristics. It is carried, out using computers. Number & codes are, assigned to all the characters and the data, are processed. Thus hundreds of, characters can be equally considered., , Cytotaxonomy: It is based on, cytological information like, chromosome number, structure, behaviour, etc., , Chemotaxonomy: It uses the chemical, constituents of the plant., , JSS PU COLLEGE DHARWAD
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ALGAE, Simple, thalloid, autotrophic,, chlorophyll-bearing and aquatic, Algae, , (fresh water & marine) organisms., Lichen, , They also occur in moist stones,, soils & wood., Some occur in association with, fungi (lichen) and animals (e.g. on, sloth bear)., , Sloth bear green fur is due, to presence of certain algae, , JSS PU COLLEGE DHARWAD
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ALGAE, , Reproduction, Vegetative reproduction:, By fragmentation. Each fragment, develops into a thallus., , Asexual reproduction:, By the production of spores., E.g. zoospores (most common)., They are flagellated (motile). They, germinate to give rise to new plants., , Sexual reproduction:, Through fusion of two gametes., JSS PU COLLEGE DHARWAD
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ALGAE, , Reproduction, , Sexual reproduction is many types:, Isogamous: Fusion of gametes, similar in size. They may be, , flagellated (e.g. Ulothrix) or nonflagellated (non-motile, e.g., , Spirogyra)., Anisogamous: Fusion of two gametes, dissimilar in size., E.g. Some species of Eudorina., , Oogamous: Fusion between one large,, non-motile (static) female gamete, JSS PU COLLEGE DHARWAD, , and a smaller, motile male gamete.
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Benefits of algae, , ALGAE, 1., , Through photosynthesis, they fix, , half of the total CO2 on earth and, increase the level of dissolved, oxygen., , 2., , They are primary producers and, the basis of the food cycles of all, aquatic animals., , JSS PU COLLEGE DHARWAD
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ALGAE, , 1. Chlorophyceae (green algae), , Unicellular, colonial or filamentous., Usually grass green due to the, pigments chlorophyll a & b in, chloroplasts., The chloroplasts may be discoid,, , plate-like, reticulate, cupshaped, spiral or ribbon-shaped, in different species., Chloroplasts of, Chlamydomonas, , JSS PU COLLEGE DHARWAD
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ALGAE, , 2. Phaeophyceae (brown algae), They are mostly marine forms., , Ectocarpus, , Kelps (Macrocystis), , They show great variation in size &, form. They range from simple branched,, filamentous forms (E.g. Ectocarpus ) to, profusely branched forms (e.g. kelps100 m in height)., They have chlorophyll a, c ,, carotenoids & xanthophylls., They vary in colour from olive green to, brown depending upon the amount of a, xanthophyll pigment, fucoxanthin., , JSS PU COLLEGE DHARWAD
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ALGAE, , 3. Rhodophyceae (red algae), They have red thalli due to the red, pigment, r-phycoerythrin., Majority are marine especially in, warmer areas., They occur in both well-lighted, regions close to the surface of water, and at great depths in oceans where, relatively little light penetrates., , JSS PU COLLEGE DHARWAD
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ALGAE, , 3. Rhodophyceae (red algae), Reproduction, Vegetative reproduction:, By fragmentation., , Asexual reproduction:, By non-motile spores., , Sexual reproduction:, Oogamous. By non-motile, gametes. It has complex post, Life cycle of Polysiphonia, JSS PU COLLEGE DHARWAD, , fertilisation developments.
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ALGAE: A COMPARISON, Chlorophyceae, , Phaeophyceae, , Rhodophyceae, , Common name, , Green algae, , Brown algae, , Red algae, , Major pigments, , Chlorophyll a, b, , Chlorophyll a, c,, Fucoxanthin, , Chlorophyll a, d,, Phycoerythrin, , Stored food, , Starch, , Mannitol, laminarin, , Floridean Starch, , Cell wall, , Cellulose, , Cellulose and algin, , Cellulose, , Flagellar number, & position of, insertion, , 2-8, equal, apical, , 2, unequal, lateral, , Absent, , Habitat, , Fresh water, salt water, & brackish water, , Fresh water (rare), salt, water & brackish water, , Fresh water (some), salt, water (most) & brackish, water, , JSS PU COLLEGE DHARWAD
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BRYOPHYTES, They are called, amphibians of the plant, kingdom because they can, live in soil but need water, for sexual reproduction., They occur in damp, humid, and shaded localities., , JSS PU COLLEGE DHARWAD
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BRYOPHYTES, Body is more differentiated than that of, algae. It is thallus-like and prostrate or, erect, and attached to the substratum by, unicellular or multicellular rhizoids., They lack true roots, stem or leaves., They may possess root-like, leaf-like or, stem-like structures., The main plant body is haploid. It, produces gametes, hence is called a, gametophyte ., JSS PU COLLEGE DHARWAD
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BRYOPHYTES, , Zygotes do not undergo meiosis, immediately. They produce a, multicellular body called a, , sporophyte., Sporophyte is not free-living but, attached to the photosynthetic, gametophyte and derives, nourishment from it. Some cells of, the sporophyte undergo meiosis to, produce haploid spores. These, spores germinate to form, JSS PU COLLEGE DHARWAD, , gametophyte.
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BRYOPHYTES, Importance of Bryophytes, 1., , Some mosses provide food for, herbaceous mammals, birds etc., , 2., , Species of Sphagnum (a moss), provide peat. It is used as fuel. It, has water holding capacity so, that used as packing material for, trans-shipment of living material., , Sphagnum, , JSS PU COLLEGE DHARWAD, , Sphagnum Peat
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BRYOPHYTES, Importance of Bryophytes, 3., , They are ecologically important, because of their role in plant, , succession on bare rocks/soil., Mosses along with lichens, Primary succession, , decompose rocks making the, substrate suitable for the growth, of higher plants., 4., , Since mosses form dense mats, on the soil, they can prevent soil, , Dense mat of mosses on soil, JSS PU COLLEGE DHARWAD, , erosion.
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BRYOPHYTES, , 1. Liverworts, They grow usually in moist, shady, habitats such as banks of streams,, marshy ground, damp soil, bark of, trees and deep in the woods., Their plant body is thalloid. E.g., , Marchantia., Thallus is dorsi-ventral and closely, appressed to the substrate., The leafy members have tiny leaf-like, appendages in two rows on the stemlike structures., JSS PU COLLEGE DHARWAD
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BRYOPHYTES, , 1. Liverworts, Reproduction, Sexual reproduction, Male and female sex organs are, produced on the same or different thalli., , Sporophyte is differentiated into a foot,, seta and capsule., , After meiosis, spores are produced, within the capsule., , These spores germinate to form freeJSS PU COLLEGE DHARWAD, , living gametophytes.
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BRYOPHYTES, , 2. Mosses, , The predominant stage of the life, cycle of a moss is the, , gametophyte., It consists of two stages:, , JSS PU COLLEGE DHARWAD, , ❑, , First stage: Protonema stage, , ❑, , Second stage: Leafy stage
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BRYOPHYTES, , 2. Mosses, 1., , Protonema stage: It develops, directly from a spore. It is a creeping,, green, branched and frequently, filamentous stage., , 2., , Leafy stage: It develops from the, secondary protonema as a lateral, bud. They consist of upright, slender, axes bearing spirally arranged leaves., They are attached to soil through, multicellular and branched rhizoids., This stage bears the sex organs., , JSS PU COLLEGE DHARWAD
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BRYOPHYTES, , 2. Mosses, Reproduction, Sexual reproduction, The antheridia & archegonia are, produced at the apex of leafy shoots., After fertilisation, zygote develops to, a sporophyte having a foot, seta &, capsule., The sporophyte in mosses is more, elaborate than that in liverworts., The capsule contains spores. Spores, are formed after meiosis., Mosses have an elaborate mechanism, of spore dispersal., , JSS PU COLLEGE DHARWAD
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PTERIDOPHYTES, They include, horsetails, and ferns., They are found in cool, damp, shady places. Some flourish well in, sandy-soil conditions., Evolutionarily, they are the first terrestrial plants to possess, vascular tissues (xylem & phloem)., JSS PU COLLEGE DHARWAD
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PTERIDOPHYTES: ECONOMIC, IMPORTANCE, , Rattlesnake Fern, , Ostrich Fern, , Bracken Fern, , Some ferns having medicinal value, , They are used for, medicinal purposes., They are used as soilbinders., They are grown as, ornamentals., , Asparagus Fern, , Dryopteris erythrosora, , Actinopteris, , Some ornamental ferns, JSS PU COLLEGE DHARWAD
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PTERIDOPHYTES: REPRODUCTION, , Prothallus requires cool, damp, shady places to grow. Also, it needs water, for fertilization. So, the spread of pteridophytes is limited and restricted, to narrow geographical regions., The gametophytes (prothallus) bear male and female sex organs called, , antheridia and archegonia, respectively., JSS PU COLLEGE DHARWAD
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PTERIDOPHYTES: REPRODUCTION, , The megaspores & microspores, germinate and give rise to female, and male gametophytes,, respectively. The female, gametophytes are retained on the, parent sporophytes for variable, periods., Within female gametophytes,, zygotes develop into young, embryos. This event is a precursor, to the seed habit. It is considered, , JSS PU COLLEGE DHARWAD, , as an important step in evolution.
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GYMNOSPERMS, Gymnosperms (gymnos:, naked, sperma: seeds) are, plants in which the ovules, , are not enclosed by ovary, Cycas, , Cycas- ovules, , wall and remain exposed, before and after fertilization., , Seeds that develop postfertilization are not covered, , (naked)., JSS PU COLLEGE DHARWAD
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GYMNOSPERMS, Gymnosperms (gymnos:, naked, sperma: seeds) are, plants in which the ovules, , are not enclosed by ovary, wall and remain exposed, before and after fertilization., , Seeds that develop postGymnosperm ovule, , Angiosperm ovule, , See the comparison of gymnosperm, ovule and Angiosperm ovule, JSS PU COLLEGE DHARWAD, , fertilization are not covered, , (naked).
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GYMNOSPERMS, They include mediumsized trees or tall trees, and shrubs., The gymnosperm,, , Sequoia (giant, redwood) is the tallest, tree species., , JSS PU COLLEGE DHARWAD
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GYMNOSPERMS, , Stems are unbranched (Cycas ) or branched, (Pinus, Cedrus)., Leaves are simple or compound. They are, well-adapted to withstand extreme, temperature, humidity and wind., In Cycas, the pinnate leaves persist for a, few years., In conifers ( Pinus, Cedrus etc.), the needle-, , like leaves reduce the surface area. Their, Cycas pinnate, leaf, , Pinus, needle-like leaves, , JSS PU COLLEGE DHARWAD, , thick cuticle & sunken stomata also help to, reduce water loss.
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GYMNOSPERMS, , Reproduction, a. Microsporophylls, They are arranged to male strobili, , (microsporangiate)., They bear microsporangia., The microspores develop into male, gametophytes. It is highly reduced, and confined to only a limited, number of cells. This gametophyte is, called a pollen grain ., The pollen grains are developed, JSS PU COLLEGE DHARWAD, , within the microsporangia.
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GYMNOSPERMS, , Reproduction, The male or female cones may be, borne on the same tree (Pinus) or on, different trees (Cycas )., Unlike bryophytes and pteridophytes,, in gymnosperms, the male and the, female gametophytes do not have an, independent free-living existence., They remain within the sporangia, retained on the sporophytes., , JSS PU COLLEGE DHARWAD
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GYMNOSPERMS, , Reproduction, The pollen grain released from, the microsporangium are, carried in air currents and meet, the opening of the ovules., The pollen tube carrying the, male gametes grows towards, archegonia in the ovules and, discharges their contents near, the mouth of the archegonia., , LIFE CYCLE OF GYMNOSPERMS, , JSS PU COLLEGE DHARWAD, , After fertilization, zygote, develops into an embryo and, the ovules into seeds.
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ANGIOSPERMS (FLOWERING PLANTS), Exceptionally large group of, plants., They range in size from tiny,, Wolffia, , almost microscopic Wolffia to tall, trees of Eucalyptus (over 100, metres)., They are divided into two classes:, , Eucalyptus, JSS PU COLLEGE DHARWAD, , ❖, , Dicotyledons, , ❖, , Monocotyledons
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Monocotyledons, ANGIOSPERMS (FLOWERING PLANTS), , ❖, , Have only one cotyledon., , ❖, , Parallel venation in leaves., , ❖, , Trimerous flowers (3 members in, each floral whorl)., , JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), Flower is the reproductive structure., Male sex organ in a flower is the, stamen., Each stamen consists of a filament, with an anther at the tip., Within the anthers, the pollen, mother cell divides by meiosis to, produce microspores which matures, into pollen grains., , JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), , Female sex organ in a flower is the, pistil., It consists of a swollen ovary at its, base, a long slender style & stigma., Ovary contains ovules., , JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), An ovule has a megaspore mother, cell that undergoes meiosis to form, 4 haploid megaspores., 3 of them degenerate and one, divides to form embryo sac., , JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), Each embryo-sac has a threecelled egg apparatus (one egg cell, & two synergids), three antipodal, cells and two polar nuclei., The polar nuclei eventually fuse to, produce a secondary nucleus (2n)., , JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), Pollen grains are dispersed from, the anthers and carried by wind, or other agencies to the stigma, of a pistil. It is called pollination., , The pollen grains germinate on, the stigma and the resulting, pollen tubes grow through the, tissues of stigma and style and, reach the ovule., JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), The pollen tubes enter, the embryo sac where, two male gametes are, discharged. One male, gamete fuses with egg, cell to form zygote, (syngamy)., The other male gamete, fuses with diploid, secondary nucleus to, produce triploid, primary endosperm, JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), Because of the involvement of, two fusions, this event is called, double fertilisation. It is an, event unique to angiosperms., Zygote develops into an embryo, (with 1 or 2 cotyledons)., PEN develops into endosperm, which provides nourishment to, the developing embryo., Synergids & antipodals, degenerate after fertilization., JSS PU COLLEGE DHARWAD
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Reproduction, ANGIOSPERMS (FLOWERING PLANTS), During these events, ovules, develop into seeds and ovaries, develop into fruit., The seeds are enclosed by fruits., , JSS PU COLLEGE DHARWAD
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PLANT LIFE CYCLES & ALTERNATION OF, GENERATIONS, In plants, both haploid & diploid cells can, divide by mitosis. This forms haploid and, diploid plant bodies., Haploid plant body (gametophyte) produces, gametes by mitosis., After fertilization, the zygote also divides by, mitosis to produce diploid plant body, (sporophyte). This produces haploid spores, by meiosis. Spores divide by mitosis to form a, haploid plant body., Thus, during the life cycle of any sexually, reproducing plant, there is an alternation of, generations between gametophyte (n) and, sporophyte (2n)., , JSS PU COLLEGE DHARWAD, , Haplontic, , Patterns of Plant, life cycles, , Diplontic, Haplo-diplontic
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PLANT LIFE CYCLES & ALTERNATION OF, GENERATIONS, 1. Haplontic, In this, sporophytic generation is, represented only by the zygote., Zygote undergoes meiosis to form, , haploid spores. They divide, mitotically to form gametophyte., The dominant, photosynthetic phase, is the free-living gametophyte., E.g. Algae such as Volvox, Spirogyra, and some species of, , Chlamydomonas., JSS PU COLLEGE DHARWAD
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PLANT LIFE CYCLES & ALTERNATION OF, GENERATIONS, 2. Diplontic, In this, the diploid sporophyte is the, dominant, photosynthetic,, independent phase., , Gametophytic phase is represented, by the single to few-celled haploid, gametophyte., E.g. An alga, Fucus sp., all seed, bearing plants (gymnosperms &, angiosperms - the gametophytic, phase is few to multi-celled).)., JSS PU COLLEGE DHARWAD
