Unit 3 biodiversity of plants

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Unit 3 biodiversity of plants

  1. 1. UNIT 3:BIODIVERSITYOF PLANTSCampbell & Reece (2010);Chapter 29 and 30http://en.wikipedia.org/wiki/File:Diversity_of_plants_image_version_2.png
  2. 2. 290, 000 known plant speciesLand plants enabled survival of other lifeforms on land – including animalsRoots provide habitats, stabilize landscapesOxygen supplyUltimate provider of food eaten by terrestrialanimals
  3. 3. Common (derived) traits of land plants –separate them from ancestral plants (algalrelatives):Alteration of generations & multicellular,dependent embryo’sWalled spores produced in sporangiaMulticellular gametangiaApical meristems
  4. 4. Alteration of GenerationsThe life cycle includes bothmulticellular haploid (n) &multicellular diploid (2n)organisms
  5. 5. Multicellular, Dependent EmbryosAfter fertilization zygote develops intoa multicellular embryo within maternalstructures.Maternal tissues provide nutrients.Embryo is dependentLand plant called embryophytes.
  6. 6. Walled Spores Produced in SporangiaSporophyte produces spores in organs calledsporangiaDiploid cells called sporocytes undergomeiosis – generate (n) sporesSpore walls containsporopollenin:resistant to harshenvironments
  7. 7. Multicellular GametangiaGametes produced in multicellular organs – gametangia.Female gametangia – archegonia – produce single eggMale gametangia – antheridia - produce & release sperm– fertilize egg internallywithin the archegonium
  8. 8. Apical MeristemsPlants sustain continual growth inapical meristemsCells from apical meristems differentiate into varioustissues1) Elongation of the rootsNutrients & water from soil2) Growth of stems & leavesMore area for photosynthesis
  9. 9. GROUPING OF LAND PLANTS• Ancestral species gave rise to a vast diversity ofmodern plants• Land plants informally grouped based onpresence or absence of vascular tissue• Most plants have vascular tissue; these constitutethe vascular plants• Nonvascular plants are commonly calledbryophytessites.google.com
  10. 10. GROUPING OF LAND PLANTS• Seedless vascular plants can be divided:– Lycophytes (club mosses and their relatives)– Pterophytes (ferns and their relatives)contrib.andrew.cmu.eduquizlet.comen.wikipedia.orgbiology.iastate.edu
  11. 11. GROUPING OF LAND PLANTS• Seed plants• A seed is an embryo and nutrients surrounded bya protective coat• Seed plants can be divided into:– Gymnosperms, the “naked seed” plants, includingthe conifers– Angiosperms, the flowering plants
  12. 12. GYMNOSPERMS ANGIOSPERMSvisual.merriam-webster.combluebellnursery.com• Conifers (seeds not enclosed)• “Naked seed”• All flowering plants• 90% of living plant species• Seeds develop in ovaries –originate within flowers & matureinto fruitsbiology.iastate.eduucadia.com
  13. 13. Bryophyta (non-vascular plants)(p. 606 – 609)• Phylum includes all mosses (Bryophyta)• Bryophytes: all non-vascular plants– Include liverworts, hornworts & mosses• Mosses show alternation of generations– i.e. have sporophyte & gametophyte generationtolweb.orgflickrhivemind.netbryophytes.plant.siu.edu anbg.gov.au forums.gardenweb.com
  14. 14. Bryophyta• In all bryophytes gametophytes are dominantin life cycle• Larger & longer living than sporophytetolweb.orgflickrhivemind.netbryophytes.plant.siu.edu forums.gardenweb.combotany.hawaii.edu
  15. 15. KeyHaploid (n)Diploid (2n) Protonemata(n)“Bud”“Bud”Malegametophyte(n)Femalegametophyte (n)GametophoreRhizoidSporesSporedispersalPeristomeSporangiumMEIOSIS SetaCapsule(sporangium)FootMaturesporophytesCapsule withperistome (SEM)Femalegametophytes2mmRaindropSpermAntheridiaEggArchegoniaFERTILIZATION(within archegonium)Zygote(2n)EmbryoArchegoniumYoungsporophyte(2n)THE MOSS LIFE CYCLED:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_08MossLifeCycle_A.html
  16. 16. KeyHaploid (n)Diploid (2n) Protonemata(n)“Bud”“Bud”Malegametophyte(n)Femalegametophyte (n)GametophoreRhizoidSporesSporedispersalPeristomeSporangiumMEIOSIS SetaCapsule(sporangium)FootMaturesporophytesCapsule withperistome (SEM)Femalegametophytes2mmTHE MOSS LIFE CYCLE
  17. 17. KeyHaploid (n)Diploid (2n) Protonemata(n)“Bud”“Bud”Malegametophyte(n)Femalegametophyte (n)GametophoreRhizoidSporesSporedispersalPeristomeSporangiumMEIOSIS SetaCapsule(sporangium)FootMaturesporophytesCapsule withperistome (SEM)Femalegametophytes2mmRaindropSpermAntheridiaEggArchegoniaFERTILIZATION(within archegonium)THE MOSS LIFE CYCLE
  18. 18. KeyHaploid (n)Diploid (2n) Protonemata(n)“Bud”“Bud”Malegametophyte(n)Femalegametophyte (n)GametophoreRhizoidSporesSporedispersalPeristomeSporangiumMEIOSIS SetaCapsule(sporangium)FootMaturesporophytesCapsule withperistome (SEM)Femalegametophytes2mmRaindropSpermAntheridiaEggArchegoniaFERTILIZATION(within archegonium)Zygote(2n)EmbryoArchegoniumYoungsporophyte(2n)THE MOSS LIFE CYCLED:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_13FernLifeCycle_A.html
  19. 19. VASCULAR PLANTSLIVING VASCULAR PLANTS CHARACTERISED BY:• Life cycles with dominant sporophytes– Fern life cycle• Transport in vascular tissues– Xylem and phloem• Well-developed roots and leaves– Including spore bearing leaves called sporophylls
  20. 20. Pterophyta(p. 610 – 615)• Phylum includes all ferns, horsetails & whisk ferns• Vascular seedless plants– Vascular means plants could grow taller than bryophytes• Ferns show alternation of generations (dominant sporophyte)• Sperm flagellated – must swim through water to reach eggsi.e. found in damp environmentstolweb.orgflickrhivemind.netbryophytes.plant.siu.edu forums.gardenweb.combotany.hawaii.edu
  21. 21. KeyHaploid (n)Diploid (2n)MEIOSISSporedispersalSporangiumSporangiumMaturesporophyte(2n)SorusFiddleheadSpore(n)YounggametophyteMaturegametophyte(n) ArchegoniumEggAntheridiumSpermFERTILIZATIONNewsporophyteGametophyteZygote(2n)THE FERN LIFE CYCLED:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_13FernLifeCycle_A.html
  22. 22. KeyHaploid (n)Diploid (2n)MEIOSISSporedispersalSporangiumSporangiumMaturesporophyte(2n)SorusFiddleheadTHE FERN LIFE CYCLE
  23. 23. KeyHaploid (n)Diploid (2n)MEIOSISSporedispersalSporangiumSporangiumMaturesporophyte(2n)SorusFiddleheadSpore(n)YounggametophyteMaturegametophyte(n) ArchegoniumEggAntheridiumSpermFERTILIZATIONTHE FERN LIFE CYCLE
  24. 24. KeyHaploid (n)Diploid (2n)MEIOSISSporedispersalSporangiumSporangiumMaturesporophyte(2n)SorusFiddleheadSpore(n)YounggametophyteMaturegametophyte(n) ArchegoniumEggAntheridiumSpermFERTILIZATIONNewsporophyteGametophyteZygote(2n)THE FERN LIFE CYCLED:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_13FernLifeCycle_A.html
  25. 25. Transport in Vascular Tissues• Two types of vascular tissue:• Xylem and phloem• Xylem conducts water & minerals• Dead cells called tracheids• Phloem distributes sugars, amino acids, & other organicproducts• Consists of living cells• Water-conducting cells are strengthened by ligninand provide structural support
  26. 26. Evolution of Roots• Benefits of lignified vascular tissue belowground• Instead of rhizoids, roots evolved– May have evolve from subterranean stems• Roots: organs to absorb water & nutrientsfrom soil• Also anchor vascular plants
  27. 27. Evolution of Leaves• Leaves increase surface area of plant body• Main photosynthetic organ of vascular plants• Classified as:– Microphylls (only lycophytes) – leaves with asingle vein– Megaphylls (all vascular plants) – highly branchedvascular system• Greater photosynthetic productivity
  28. 28. Sporophylls and Spore Variations• Sporophylls are modified leaves withsporangia• Sori are clusters of sporangia on theundersides of sporophylls• Strobili are cone-like structuresformed from groups of sporophylls
  29. 29. • Most seedless vascular plants are homosporous• Produce one type of spore that develops into a bisexualgametophyte• All seed plants (and some seedless vascular plants)are heterosporous• Produce megaspores that give rise to femalegametophytes• And microspores that give rise to male gametophytesSporophylls and Spore Variations
  30. 30. SEED PLANTS• Seeds changed the course of plant evolution– Plants with seeds would become dominantproducers in most terrestrial ecosystems• Living seed plants can be divided into two:– Gymnosperms– Angiosperms• A seed consists of an embryo and nutrientssurrounded by a protective coat
  31. 31. SEED PLANTS5 DERIVED TRAITS:(COMMON TO ALL SEED PLANTS)1. Reduced gametophytes– Develop in walls of spores that are retained in tissues ofparent sporophyte2. Heterospory– Megasporangia produce megaspores (femalegametophytes)– Microsporangia produce microspores (male gametophytes)
  32. 32. SEED PLANTS3. Ovules– An ovule consists of a megasporangium, megaspore, andone or more protective integuments• Gymnosperm megaspores have one integument• Angiosperm megaspores usually have two integuments
  33. 33. SEED PLANTS4. Pollen– Microspores develop into pollen grains – contain malegametophytes– Pollination is the transfer of pollen to the part of a seedplant containing the ovules Pollen eliminates need for film of water Can be dispersed great distances by air or animals If a pollen grain germinates, it gives rise to a pollen tubethat discharges two sperm into the female gametophytewithin the ovule
  34. 34. SEED PLANTS5. Seeds• Evolutionaryadvantages overspores:– May remain dormant fordays to years, untilconditions are favorablefor germination– Transported longdistances by wind oranimals
  35. 35. Seed coat(derived fromintegument)(c) Gymnosperm seedEmbryo (2n)(new sporophyte)Food supply(femalegametophytetissue) (n)(b) Fertilized ovule(a) Unfertilized ovuleIntegumentImmaturefemale coneSpore wallMegasporangium(2n)Male gametophyte(within a germinatedpollen grain) (n)Megaspore (n) Micropyle Pollen grain (n)Egg nucleus (n)Dischargedsperm nucleus (n)Femalegametophyte (n)
  36. 36. SUMMARY
  37. 37. Gymnosperms(p. 618 – 625)• Plants with ‘naked seeds’ not enclosed inovaries• Include conifers (pine tree) and cycads• Three key features of the gymnosperm life cycleare:1. Dominance of the sporophyte generation2. Development of seeds from fertilized ovules3. The transfer of sperm to ovules by pollen• The life cycle of a pine provides an exampletolweb.orgflickrhivemind.netbryophytes.plant.siu.edu forums.gardenweb.combotany.hawaii.edu
  38. 38. Microsporangium (2n)Microsporocytes(2n)Pollengrains (n)PollenconeMicrosporangiaMEIOSISMaturesporophyte(2n)Haploid (n)Diploid (2n)KeyMEIOSISSurvivingmegaspore (n)PollengrainMegasporocyte (2n)OvuleIntegumentOvulateconeFERTILIZATIONPollentubeFemalegametophyteSpermnucleus (n)Egg nucleus (n)ArchegoniumSeedlingSeedsSeed coat(2n)Foodreserves(n)Embryo(2n)Megasporangium(2n)THE PINE LIFE CYCLED:Chapter_30A_PowerPoint_Lectures30_Lecture_Presentation30_06PineLifeCycle_A.html
  39. 39. Microsporangium (2n)Microsporocytes(2n)Pollengrains (n)PollenconeMicrosporangiaMEIOSISMaturesporophyte(2n)Haploid (n)Diploid (2n)KeyOvulateconeTHE PINE LIFE CYCLE
  40. 40. Microsporangium (2n)Microsporocytes(2n)Pollengrains (n)PollenconeMicrosporangiaMEIOSISMaturesporophyte(2n)Haploid (n)Diploid (2n)KeyMEIOSISSurvivingmegaspore (n)PollengrainMegasporangium(2n)Megasporocyte (2n)OvuleIntegumentOvulateconeTHE PINE LIFE CYCLE
  41. 41. Microsporangium (2n)Microsporocytes(2n)Pollengrains (n)PollenconeMicrosporangiaMEIOSISMaturesporophyte(2n)Haploid (n)Diploid (2n)KeyMEIOSISSurvivingmegaspore (n)PollengrainMegasporocyte (2n)OvuleIntegumentOvulateconeFERTILIZATIONPollentubeFemalegametophyteSpermnucleus (n)Egg nucleus (n)ArchegoniumMegasporangium(2n)THE PINE LIFE CYCLE
  42. 42. Microsporangium (2n)Microsporocytes(2n)Pollengrains (n)PollenconeMicrosporangiaMEIOSISMaturesporophyte(2n)Haploid (n)Diploid (2n)KeyMEIOSISSurvivingmegaspore (n)PollengrainMegasporocyte (2n)OvuleIntegumentOvulateconeFERTILIZATIONPollentubeFemalegametophyteSpermnucleus (n)Egg nucleus (n)ArchegoniumSeedlingSeedsSeed coat(2n)Foodreserves(n)Embryo(2n)Megasporangium(2n)THE PINE LIFE CYCLED:Chapter_30A_PowerPoint_Lectures30_Lecture_Presentation30_06PineLifeCycle_A.html
  43. 43. Angiosperms(p. 625 – 634)• Most widespread and diverse of all plants• Are seed plants with reproductive structurescalled flowers and fruits• Characterised by enclosed seeds• The flower is an angiosperm structurespecialized for sexual reproduction• Pollinated by insects, animals or wind
  44. 44. Angiosperms(p. 625 – 634)• A flower is a specialized shoot with up to fourtypes of modified leaves:– Sepals, which enclose the flower– Petals, which are brightly colored and attractpollinators– Stamens, which produce pollen on their terminalanthers– Carpels, which produce ovules• A carpel consists of an ovary at the base and a styleleading up to a stigma, where pollen is received
  45. 45. Angiosperms(p. 625 – 634)• A fruit typically consistsof a mature ovary butcan also include otherflower parts• Fruits protect seeds andaid in their dispersal• Mature fruits can beeither fleshy or dry
  46. 46. Angiosperms(p. 625 – 634)• Various fruitadaptations helpdisperse seeds• Seeds can be carried bywind, water, or animalsto new locations
  47. 47. MEIOSISKeyMicrosporangiumMicrosporocytes (2n)Generative cellAntherTube cellPollengrainsMicrospore(n)Male gametophyte(in pollen grain)(n)Mature flower onsporophyte plant(2n)Haploid (n)Diploid (2n)MEIOSISOvule (2n)OvaryMegasporangium(2n)Megaspore(n)Female gametophyte(embryo sac)Antipodal cellsCentral cellSynergidsEgg (n)PollentubePollentubeStigmaSperm(n)Discharged sperm nuclei (n)FERTILIZATIONGerminatingseedEmbryo (2n)Endosperm (3n)Seed coat (2n)SeedNucleus ofdevelopingendosperm(3n)Zygote (2n)Eggnucleus (n)StyleSpermTHE ANGIOSPERM LIFE CYCLE
  48. 48. MEIOSISKeyMicrosporangiumMicrosporocytes (2n)Generative cellAntherTube cellPollengrainsMicrospore(n)Male gametophyte(in pollen grain)(n)Mature flower onsporophyte plant(2n)Haploid (n)Diploid (2n)THE ANGIOSPERM LIFE CYCLE
  49. 49. MEIOSISKeyMicrosporangiumMicrosporocytes (2n)Generative cellAntherTube cellPollengrainsMicrospore(n)Male gametophyte(in pollen grain)(n)Mature flower onsporophyte plant(2n)Haploid (n)Diploid (2n)MEIOSISOvule (2n)OvaryMegasporangium(2n)Megaspore(n)Female gametophyte(embryo sac)Antipodal cellsCentral cellSynergidsEgg (n)THE ANGIOSPERM LIFE CYCLE
  50. 50. MEIOSISKeyMicrosporangiumMicrosporocytes (2n)Generative cellAntherTube cellPollengrainsMicrospore(n)Male gametophyte(in pollen grain)(n)Mature flower onsporophyte plant(2n)Haploid (n)Diploid (2n)MEIOSISOvule (2n)OvaryMegasporangium(2n)Megaspore(n)Female gametophyte(embryo sac)Antipodal cellsCentral cellSynergidsEgg (n)PollentubePollentubeStigmaSperm(n)Discharged sperm nuclei (n)FERTILIZATIONEggnucleus (n)StyleSpermTHE ANGIOSPERM LIFE CYCLE
  51. 51. MEIOSISKeyMicrosporangiumMicrosporocytes (2n)Generative cellAntherTube cellPollengrainsMicrospore(n)Male gametophyte(in pollen grain)(n)Mature flower onsporophyte plant(2n)Haploid (n)Diploid (2n)MEIOSISOvule (2n)OvaryMegasporangium(2n)Megaspore(n)Female gametophyte(embryo sac)Antipodal cellsCentral cellSynergidsEgg (n)PollentubePollentubeStigmaSperm(n)Discharged sperm nuclei (n)FERTILIZATIONGerminatingseedEmbryo (2n)Endosperm (3n)Seed coat (2n)SeedNucleus ofdevelopingendosperm(3n)Zygote (2n)Eggnucleus (n)StyleSpermTHE ANGIOSPERM LIFE CYCLE
  52. 52. Angiosperm DiversityMonocots (one cotyledon)¼ of angiosperm speciesEudicots (“true” dicots)More than 2/3 angiospermspeciesTWO MAIN GROUPS OF ANGIOSPERMS
  53. 53. HUMAN WELFARE• No group of plants is more important tohuman survival than seed plants• Plants are key sources of food, fuel, woodproducts, and medicine• Our reliance on seed plants makespreservation of plant diversity critical
  54. 54. PRODUCTS FROM SEED PLANTS• Most of our food comes from angiosperms• Six crops (wheat, rice, maize, potatoes, cassava, andsweet potatoes) yield 80% of the calories consumedby humans• Modern crops are products of relatively recentgenetic change resulting from artificial selection• Many seed plants provide wood• Secondary compounds of seed plants are used inmedicines
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