Bio 100 Chapter 18

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Bio 100 Chapter 18

  1. 1. Chapter 18 Evolution of Plants and Fungi Lecture OutlineCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  2. 2. 18.1 Plants have a green algal ancestor Multicellular, photosynthetic eukaryotes Evolved from freshwater green algae some 500 million years ago  Evidence – Both green algae and plants 1. Contain chlorophylls a and b and various accessory pigments 2. Store excess carbohydrates as starch 3. Have cellulose in their cell wall 18-2
  3. 3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. flowers, double fertilization, endosperm, fruit common ancestor seeds Flowering plants Seed megaphylls Gymnosperms Vascular vascular tissue Ferns and allies Seedless apical growth microphylls Lycophytes embryo protection Mosses Nonvascular Bryophytes Hornwortscommongreen Liverwortsalgalancestor Charophytes 550 500 450 400 350 300 250 Million Years Ago (MYA) PRESENT 18-3 Figure 18.1A The evolution of plants
  4. 4. 18.2 Alternation of generations life cycle 2 multicellular stages alternate  Sporophyte represents the diploid generation (2n)  Produces spores by meiosis  A spore undergoes mitosis to become a gametophyte  Gametophyte represents the haploid generation (n)  Produces gametes  In plants, eggs and sperm are produced by mitosis  A sperm and egg fuse, forming a diploid zygote that undergoes mitosis and becomes the sporophyte 18-4
  5. 5. Figure 18.2 Alternation of generations Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. sporophyte (2n) Mi to sis zygote (2n) sporangium (2n) diploid (2n) FERTILIZATION MEIOSIS haploid (n) spore (n) (n) (n) Mi is to tos gametes sis Mi gametophyte (n) 18-5
  6. 6. 18.3 Sporophyte dominance was adaptive to a dry land environment Plants differ as to which generation is dominant Only the sporophyte has vascular tissue for transporting water and nutrients Only plants with a dominant sporophyte generation attain significant height 18-6
  7. 7. Figure 18.3A The size of the gametophyte is progressively reduced as the sporophyte becomes more dominant Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. spores seed seed spores G a S m p e o t roots r o o p roots p h h y rhizoids roots y t t e e(n) rhizoids (2n) Moss Fern Gymnosperm Angiosperm 18-7
  8. 8.  Reproductive Adaptation to Land Environment  Ferns are seedless vascular plants with a dominant sporophyte  Water-dependent gametophyte makes it more difficult for ferns and related plants to spread to and live in dry environments  Flowering plants are seed plants with a dominant sporophyte  All reproductive structures are protected from drying out in the terrestrial environment 18-8
  9. 9. Figure 18.3B a. Archegonium in seedless plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. surface of gametophyte egg becomes sporophyte embryo a. Archegonium in seedless plants © Ed Reschke 18-9
  10. 10. Figure 18.3B b. Ovule in seed plants. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. tissue of sporophyte ovule becomes seed egg becomes sporophyte embryo b. Ovule in seed plants 18-10 © Ed Reschke
  11. 11.  Other Adaptations to the Land Environment  Spophytes have a cuticle  Covering that provides an effective barrier to water loss, but it also limits gas exchange  Leaves have little openings called stomata (sing., stoma) that let carbon dioxide enter while allowing oxygen and water to exit 18-11
  12. 12. Figure 18.3C Leaf structures of vascular plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. cuticle stomata Vascular plant leaves Have a cuticle and stomata. Stained photomicrograph Of a leaf cross section Falsely colored scanning Electron micrograph Of leaf surface (left): © Kingsley Stern; (right): © Andrew Syred/SPL/Photo Researchers, Inc. 18-12
  13. 13. Bryophytes: Non-Vascular Plants Exs: hornworts, liverworts, and mosses First plants to colonize land Successfully reproduce on land because they protect the embryo & produce wind-blown spores No true roots, stems, or leaves – no vascular tissue “Non-vascular” plants 18-13
  14. 14. Figure 18.4A Representative bryophytes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. sporophyte archegonium gametophyte gemma cupHornwort Liverwort female gametophyte Moss gametophyte (hornwort): © Steven P. Lynch; (liverwort): © Harold Taylor/Getty Images; (moss): © Nigel Cattlin/Photo Researchers, Inc. 18-14
  15. 15. In Bryophytes, the Gametophyte is Dominant Bryophyte reproduction  Gametophyte is the dominant generation  Female gametophyte produces eggs in archegonia, and the male gametophyte produces flagellated sperm in antheridia  Following fertilization, the zygote becomes a sporophyte  Sporophyte attached to, and derives its nourishment from, the photosynthetic gametophyte 18-15
  16. 16. Figure 18.4B Moss life cycle, Polytrichum sp. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Developing sporophyte: developing 3 4 sporophyte The sporophyte: The sporophyte embryo The dependent sporophyte has a foot buried in female is retained within the gametophyte tissue, a stalk, and an upper capsule (the archegonium, where sporangium), where meiosis occurs and windblown spores it develops, becoming a are produced. mature sporophyte. Sporangium Mitosis Sporophyte stalk zygote diploid (2n) FERTILIZATION MEIOSIS haploid (n) 2 Fertilization: egg Spores Flagellated sperm sperm Spore dispersal: produced in Mitosis 5 antheridia swim in foot (n) Spores are released external water to when they are most archegonia, each Archegonia likely to be bearing a single egg. archegonium dispersed buds by air currents. Antheridia 1 The mature gametophytes: The immature In mosses, the 6 gametophyte: dominant A spore germinates gametophyte shoots into the first bear either antheridia stage of the male or archegonia, where and the female gametes are antheridium gametophytes. produced by mitosis. Gametophytes 18-16 (top): © Peter Lilja/Getty Images; (bottom): © Steven P. Lynch
  17. 17. Plant Vascular Tissue Vascular tissue in plants:  Xylem transports water & minerals UP in the plant.  Phloem transports nutrients DOWN in the plant. 18-17
  18. 18. Ferns: Seedless vascular plants Ferns, horsetails, and whisk ferns are seedless vascular plants Have megaphylls  Broad leaves with several strands of vascular tissue 18-18
  19. 19. 18.6 Ferns have large leaves called megaphylls Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Horsetails  One genus, strobilus Equisetum, and approximately 25 species  About 300 MYA, horsetails were leaves dominant plants and grew as large as branches modern trees © Gerald & Buff Corsi/Visuals Unlimited 18-19 Figure 18.6B Horsetail (Equisetum)
  20. 20. 18.6 Ferns have large leaves called megaphylls Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Whisk ferns  Psilotum and Tmesipteris  Epiphytes sporangium  Plants that live scale on/in trees aerial stem  No leaves root rhizome (Left): © CABISCO/Phototake 18-20 Figure 18.6C Whisk fern (Psilotum)
  21. 21. 18.6 Ferns have large leaves called megaphylls Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ferns  11,00 species  Megaphylls spores on fertile frond called fronds  Leaves first Cinnamon fern, Osmunda cinamomea appear as frond (undivided) fiddleheads frond (divided)  2 generations separate and axis independent leaflet Hart’s tongue fern Maidenhair fern, Campyloneurum scolopendrium Adiantum pedatum (cinnamon fern): © James Randklev/Getty Images; (harts tongue): © Walter H. Hodge/Peter Arnold/Photolibrary; (maidenhair): © Jeff Foott/Getty Images 18-21 Figure 18.6D Diversity of fern fronds
  22. 22. Figure 18.6E Fern life cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 The sporophyte: Sori The sporophyte is dominant in ferns. Sporophyte frond 6 Young sporophyte: Dryopterus The sporophyte embryo develops leaflet inside an archegonium. sporangium As the distinctive first leaf appears Sorus above the 2 The sporangia: gametophyte, and young sporophyte In this fern, the as the roots fiddlehead roots on gametophyte sporangia are develop below it, located within sori the young sporophyte (sing., sorus) on Mitosis becomes visible. the underside of the leaflets. zygote Sporangium diploid (2n) FERTILIZATION MEIOSIS haploid (n) 3 The spores: 5 Fertilization: Within a Fertilization takes sporangium, place when egg meiosis occurs Spores moisture is and spores are present, because produced. When a sperm the flagellated Archegonium sporangium opens, sperm must swim Mitosis the spores are in a film of water released. from the antheridia germinating to eggs within spore archegonia. 4 The gametophyte: Antheridium A spore germinates into a heart-shaped gametophyte, which typically bears archegonia Gametophyte at the notch and antheridia at the tip between the rhizoids. (Top right): © Matt Meadows/Peter Arnold/Photolibrary 18-22
  23. 23. Gymnosperms & Angiosperms Gymnosperms and angiosperms are seed plants Seed contains a sporophyte generation, along with stored food, within a protective seed coat Ability of seeds to survive harsh conditions until the environment is again favorable for growth largely accounts for the dominance of seed plants today 18-23
  24. 24. 18.7 Most gymnosperms bear cones on which the seeds are “naked” Diversity of Gymnosperms  Four groups of living gymnosperms: cycads, ginkgoes, gnetophytes, and conifers  All have ovules and develop seeds that are exposed on the surface of cone scales or analogous structures Conifers  Consist of about 575 species of trees  Many are evergreens such as pines, spruces, firs, cedars and hemlocks  Economic Value of Conifers  Wood of conifers is used extensively in construction 18-24
  25. 25. Figure 18.7A Gymnosperm diversity 18-25
  26. 26. Figure 18.7A Gymnosperm diversity (Cont.) 18-26
  27. 27. Figure 18.7A Gymnosperm diversity (Cont.) 18-27
  28. 28. Figure 18.7B Pine life cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 The pollen cones: Typically, the pollen The sporophyte cones are quite small 5 embryo:After and develop near the fertilization, the tips of lower ovule matures and branches. becomes the seed composed of the Sporophyte embryo, reserve The seed cones: food, and a seed The seed cones are seed wing coat. Finally, in the larger than the pollen fall of the second Seed cones cones and are located season, the seed Pollen cones near the tips of higher cone, by Ovule branches. now woody and Pollen sac hard, opens to sporophyte release winged embryo seeds. When a seed germinates, seed coat seed cone scale 2 Megaspores: the sporophyte stored food pollen cone scale Megaspore mother cell Seed in ovule undergoes Mitosis meiosis to produce megaspores.One megaspore will become the zygote microspore megaspore egg-producing 4 Fertilization: mother cell mother cell Once a pollen grain reaches a seed cone, diploid (2n) it becomes a mature FERTILIZATION MEIOSIS MEIOSIS Microspores: haploid (n) male gametophyte. Microspore mother A pollen tube digests Pollen grain cells undergo meiosis its way slowly Microspores to produce toward a female Mature female gametophyte microspores. Each Mitosis gametophyte and egg Megaspores microspore becomes a discharges pollen grain. nonflagellated sperm. Pollination The fertilized ovule wall Ovule egg is a zygote. Mitosis Mature male gametophyte pollen grain pollen tube sperm 200 µm 3 The pollen grain: The pollen grain has two wings and is carried by the wind to the seed cone during pollination (Bottom right): © Phototake 18-28
  29. 29. HOW LIFE CHANGES 18A Carboniferous Forests Became the Coal We Use Today Our industrial society runs on fossil fuels, such as coal During Carboniferous period (>300 MYA) a great swamp forest encompassed what is now northern Europe, the Ukraine, and the Appalachian Mountains in the United States.  Enormous amount of biomass  Remains became covered by sediment that changed to sedimentary rock  With pressure, the organic material became coal 18-29
  30. 30. Figure 18A Swamp forest of the Carboniferous period Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fossil seed fern (fossil fern): © Sinclair Stammers/SPL/Photo Researchers, Inc. 18-30
  31. 31. Figure 18A Swamp forest of the Carboniferous period (Cont.) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fossil seed fern club mosses horsetail seed fern early gymnosperm fern 18-31 (fossil fern): © Sinclair Stammers/SPL/Photo Researchers, Inc
  32. 32. Angiosperms: Flowering Plants Angiosperms are flowering plants  Evolved some 200 MYA  240,000 known species  Ovules always enclosed within sporophyte tissue Angiosperm Diversity  Monocots – One cotyledon  Eudicots – Two cotyledons  Cotyledons – seed leaves with nutrients that nourish the embryo 18-32
  33. 33. Figure 18.8A Generalized flower Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anther stigma pollen tube filament style stamens ovary ovule carpel receptacle petals (corolla) sepals (calyx) 18-33
  34. 34. Figure 18.8B Flowering plant life cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stamen Carpel 1 The stamen: The carpel: anther stigma An anther at the top of each The ovary at the base of a filament style stamen has four pollen sacs. carpel contains one or more ovules. The contents of an ovary ovule change during the ovule flowering plant life cycle.6 The sporophyte embryo: The embryo within a seed is the immature sporophyte. When a seed germinates, Mitosis stigma growth and differentiation receptacle produce the mature Sporophyte fruit style sporophyte of a flowering Anther (mature ovary) plant. seed (mature ovule) Carpel ovule5 The seed: The ovule now develops into ovary the seed, which contains an seed coat pollen embryo and food enclosed sporophyte embryo sac by a protective seed coat. The wall of the ovary and endosperm (3n) microspore sometimes adjacent parts mother cell megaspore develop into a fruit that Seed mother cell surrounds the seed(s). diploid (2n) FERTILIZATION MEIOSIS MEIOSIS haploid (n) Pollen grain (mature male gametophyte)4 Double fertilization: Mi On reaching the ovule, the ovule wall Pollination tos pollen tube discharges the pollen Microspores Megaspores is sperm. One of the two sperm polar nuclei tube migrates to and fertilizes the sperm sperm egg, forming a zygote; the egg other unites with the two polar nuclei polar nuclei, producing a 3n pollen tube degenerating Mi (triploid) endosperm nucleus. egg tos The endosperm nucleus megaspores Double Fertilization is divides to form endosperm, food for the developing plant. Ovule Embryo sac 2 Microspores: (mature female gametophyte) Microspore mother cells undergo meiosis to produce microspores. Each microspore becomes a pollen grain. 3 The mature male gametophyte: The mature female gametophyte: Megaspores: A p[ollen grain that lands on the carpel of the same type The ovule now contains the mature female Megaspore mother cell inside ovule undergoes meiosis to of plant germinates and produces a pollen tube, gametophyte (embryo sac), which typically consists of produce megaspores. One megaspore will become the which delivers two nonflagellated sperm to the female eight haploid nuclei embedded in a mass of cytoplasm. egg-producing female gametophyte. gametophyte. A fully germinated pollen grain is the The cytoplasm differentiates into cells, one of which is mature male gametophyte. an egg and another of which contains two polar nuclei. 18-34
  35. 35. HOW BIOLOGY IMPACTS OUR LIVES 18B Flowering plants provide many services Humans derive most of their sustenance from three flowering plants  Wheat  First cultivated in the Middle East about 8000 B.C.  Thought to be one of the earliest cultivated plants  Corn  Maize first cultivated in Central America about 7,000 years ago  Rice  Originated several thousand years ago in southeastern Asia, where it grew in swamps About 50% of all pharmaceuticals come from plants 18-35
  36. 36. Figure 18B.1 Species of grains important to humans Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. grain head grain head ear Wheat plants,Triticum Corn plants, Zea Rice plants, Oryza (wheat): © Creatas Images RF; (corn plants, rice plant): © Corbis RF; (ear of corn): © Dorling Kindersley/Getty RF; (rice grains): © Dex Image/Getty RF; © Corbis RF 18-36
  37. 37. Figure 18B.2 Uses of plants 18-37
  38. 38. Fungi differ from plants & animals Structurally diverse group of eukaryotes Strict Heterotrophs  Unlike animals, fungi release digestive enzymes into the external environment and digest their food outside the body Most are saprotrophs – decomposers Body of most fungi made of a mass of filaments (hypha) called a mycelium Cell walls contain chitin 18-38
  39. 39. Figure 18.9A Fungal myceliaCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. and hyphae nuclei septum cell wall nonseptate septate hypha hypha a. Fungal mycelia on a corn tortilla b. Cell structure of hyphae (a): © Gary R. Robinson/Visuals Unlimited 18-39
  40. 40. 18.10 Fungi have mutualistic relationships with algae and plants In a mutualistic relationship, two different species live together and help each other out  Mycorrhizal fungi form mutualistic relationships (mycorrhizae) with the roots of most plants  Lichen – a mutualistic association between a fungus and a green algae 18-40
  41. 41. Figure 18.10 Lichen structure and examples Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.algal reproductive unit fungalcell hyphae sac fungi reproductive cupsCrustose lichenFoliose lichen, Xanthoparmelia Fruticose lichen, Cladonia (foliose): © Kerry T. Givens; (fruticose): © Stephen Sharnoff/Visuals Unlimited 18-41
  42. 42. 18.11 Land fungiCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. occur in 4 3 zygospore FERTILIZATION 2n n MEIOSIS three main Sexual reproduction 5 groups sporangium  Zygospore Fungi  Mainly saprotrophs, 1 but some are Asexual reproduction parasites – 2 germinating spores + mycelium Figure 18.11A Black bread mold, (top left): © Runk/Schoenberger/Grant Heilman Photography Rhizopus stolonifer 18-42
  43. 43. 18.11 Land fungi occur in three main groups Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Sac Fungi ascocarp  Nearly 75% of all described fungal ascocarp species Cup fungi  Ex: Yeast – 1 celled nuclear fusion zygote Morel fungi. (2n) meiosis mature ascospores ascus dikaryotic hyphae + mating type (n) – mating type (n) spore spore male organ female organ Ascocarp of the cup fungus Sarcoscypha (cup fungi): © Felix Labhardt/Getty RF; (morel): © Robert Marien/Corbis RF18-43Figure 18.11B Sexual reproduction in sac fungi
  44. 44. Figure 18.11C Asexual reproductive structures in sac fungi Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. budding conidia yeast cella. b. a: © David Philips/Visuals Unlimited; b: © David Philips/Visuals Unlimited; 18-44
  45. 45. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 18.11 Land fungi nuclei in basidium occur in three main groups  Club Fungi fusion meiosis spores  Name comes from the reproductive structure, the basidium gill of mushroom  The basidia are located within a basidiocarp basidiocarp  When you eat a mushroom, you are eating a basidiocarp - + Sexual reproduction 18-45Figure 18.11D Sexual reproduction in club fungi
  46. 46. Figure 18.11D Sexual Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. reproduction in club fungi involves a basidiocarp of which three types are shown (Cont.) Mushroom Shelf fungi Gaint puffball(mushroom): © Biophoto Assoc./Photo Researchers, Inc.; (shelf fungi): © Inga Spence; (puffball): © L. West/Photo Researchers, Inc 18-46
  47. 47. HOW BIOLOGY IMPACTS OUR LIVES 18.15 Land Fungi Have Economic and Medical Importance Economic Importance  Help produce medicines and many foods  Mold Penicillium was original source of penicillin  Excellent low-calorie meat substitute containing lots of vitamins  Fungal pathogens are a major concern for farmers Medical Importance  Certain mushrooms are poisonous  Mycoses are diseases caused by fungi  3 levels of infection  Cutaneous-skin  Subcutaneous-affects a deeper level 18-47  Systemic-spread through body via blood
  48. 48. Figure 18C.1 Plant fungal disease 18-48
  49. 49. Figure 18C.2 Human fungal diseases Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. back of throat tonguea. Ringworm b.Athlete’s foot c. Thrush © John Hadfield/SPL/Photo Researchers, Inc.; © CMSP/Getty Images; Courtesy of the Centers for Diseare Control and Prevention 18-49
  50. 50. Connecting the Concepts: Chapter 18 Plants  Trend towards gametophyte dependence on a sporophyte with large leaves and vascular tissue  Angiosperms are the most widely dispersed of the land plants Fungi  Adapted to the land environment because they produce windblown spores. 18-50

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