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Chapter 29 Plant Diversity

Algae also. Chapter 29 Plant Diversity. What are the characteristics of plants? Photosynthetic autotrophs Cellulose in cell walls Starch as storage polysaccharide PROBLEM – light, CO 2 & O 2 are above ground - water & minerals are below ground

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Chapter 29 Plant Diversity

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  1. Algae also Chapter 29 Plant Diversity • What are the characteristics of plants? • Photosynthetic autotrophs • Cellulose in cell walls • Starch as storage polysaccharide • PROBLEM – light, CO2 & O2 are above ground • - water & minerals are below ground • SOLUTION – evolution of specialized structures • What adaptations do plants have for survival on land? • Stomata – pores used for gas exchange • Roots – absorb water & minerals from underground • Apical meristems – tips of shoots & roots where growth occurs • Cuticle – waxy covering to prevent water loss thru leaves • Jacketed gametangia – gamete producing organ with protective jacket of cells to prevent dehydration • Sporopollenin – polymer that formed around exposed zygotes & forms walls of plant spores preventing dehydration • Lignin – structural polymer that provides strength for woody tissues of vascular plants

  2. Chapter 29: Plant Diversity • What are the characteristics of plants? • What adaptations do plants have for survival on land? • 3. What were the adaptations/highlights of plant evolution? • Plants likely evolved from Charophytes (green algae) • similar peroxisome enzymes • similar %age of cellulose found in plants & charophytes • nuclear & chloroplast genes have similar DNA • Movement to land led to Bryophytes (mosses & worts) • Tougher spores (sporopollenin) • Jacketed gametangia • Vascular tissue (ferns) • Cells joined to transport water & nutrients • Lacked seeds • Development of seeds (Gymnosperms, e.g. pine tree) • More protection of embryo • Embryo w/ food • Development of flowers (Angiosperms, e.g. oak tree) • Complex reproductive structure

  3. Land plants Vascular plants Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Mosses Liverworts Hornworts Angiosperms Gymnosperms Charophyceans Pterophytes (ferns, horsetails, whisk ferns) Lycophytes (club mosses, spike mosses, quillworts) Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Figure 29.7 Highlights of plant evolution

  4. Haploid multicellular organism (gametophyte) Mitosis Mitosis n n n n n Spores Gametes MEIOSIS FERTILIZATION 2n 2n Zygote Mitosis Diploid multicellular organism (sporophyte) Alternation of generations: a generalized scheme Chapter 29 Plant Diversity • What are the characteristics of plants? • What adaptations do plants have for survival on land? • 3. What were the adaptations/highlights of plant evolution? • 4. Describe alternation of generations • Alternates between sexual • & asexual reproduction • Gametophyte (n) make gametes • by mitosis • Sporophyte (2n) makes spores • by meiosis

  5. Raindrop Key Male gametophyte Haploid (n) Sperm Diploid (2n) “Bud” Antheridia Protonemata “Bud” Egg Spores Gametophore Arch-egonia Femalegametophyte Peristome Rhizoid Sporangium Seta FERTILIZATION MEIOSIS Capsule(sporangium) (within archegonium) Zygote Calyptra Maturesporophytes Mature sporophytes Embryo Foot Archegonium Youngsporophytes Femalegametophytes Capsule with peristome (LM) Figure 29.8 The life cycle of a Polytrichum moss

  6. LIVERWORTS (PHYLUM HEPATOPHYTA) Gametophore of female gametophyte Plagiochila deltoidea, a “leafy” liverwort Foot Seta Sporangium Marchantia polymorpha, a “thalloid” liverwort Marchantia sporophyte (LM) 500 µm MOSSES (PHYLUM BRYOPHYTA) HORNWORTS (PHYLUM ANTHOCEROPHYTA) An Anthoceros hornwort species Polytrichum commune, hairy-cap moss Sporophyte Sporophyte Gametophyte Gametophyte Figure 29.9 Bryophyte Diversity

  7. Figure 29.12 The life cycle of a fern 1 Although this illustration shows an egg and sperm from the same gametophyte, a variety of mechanisms promote cross-fertilization between gametophytes. 3 The fern spore develops into a small, photosynthetic gametophyte. 2 Sporangia release spores. Most fern species produce a single type of spore that gives rise to a bisexual gametophyte. Key Haploid (n) Diploid (2n) Antheridium Young gametophyte Spore MEIOSIS Sporangium Sperm Archegonium Egg New sporophyte Mature sporophyte Zygote Sporangium FERTILIZATION Sorus On the underside of the sporophyte‘s reproductive leaves are spots called sori. Each sorus is a cluster of sporangia. 6 Fern sperm use flagella to swim from the antheridia to eggs in the archegonia. 4 Gametophyte A zygote develops into a new sporophyte, and the young plant grows out from an archegonium of its parent, the gametophyte. 5 Fiddlehead

  8. LYCOPHYTES (PHYLUM LYCOPHYTA) Strobili (clusters of sporophylls) Isoetes gunnii, a quillwort Selaginella apoda, a spike moss Diphasiastrum tristachyum, a club moss PTEROPHYTES (PHYLUM PTEROPHYTA) Psilotum nudum, a whisk fern Equisetum arvense, field horsetail Athyrium filix-femina, lady fern Vegetative stem Strobilus on fertile stem FERNS HORSETAILS WHISK FERNS AND RELATIVES Figure 29.14 Seedless Vascular Plant Diversity

  9. Chapter 30: The Evolution of Seed Plants • What are the 3 most important reproductive adaptations? • Reduction of the gametophyte • Advent of the seed – replaced spore • Evolution of pollen – male gametophyte • Air dispersal instead of sperm swimming

  10. Sporophyte (2n) Sporophyte (2n) Gametophyte (n) Gametophyte (n) (a) Sporophyte dependent on gametophyte (mosses and other bryophytes). (b) Large sporophyte and small, independent gametophyte (ferns and other seedless vascular plants). Microscopic female gametophytes (n) in ovulate cones (dependent) Microscopic female gametophytes (n) inside these parts of flowers (dependent) Microscopic male gametophytes (n) inside these parts of flowers (dependent) Microscopic male gametophytes (n) in pollen cones (dependent) Sporophyte (2n), the flowering plant (independent) Sporophyte (2n) (independent) (c) Reduced gametophyte dependent on sporophyte (seed plants: gymnosperms and angiosperms). Figure 30.2 Gametophyte/sporophyte relationships

  11. Chapter 30: The Evolution of Seed Plants • What are the 3 most important reproductive adaptations? • Reduction of the gametophyte • Advent of the seed – replaced spore as • Evolution of pollen – male gametophyte • How does an ovule become a seed? • Fertilization • Growth of the embryo

  12. Female gametophyte (n) Seed coat (derived from integument) Integument Egg nucleus (n) Spore wall Food supply (female gametophyte tissue) (n) Megasporangium (2n) Male gametophyte (within germinating pollen grain) (n) Discharged sperm nucleus (n) Embryo (2n) (new sporophyte) Megaspore (n) Pollen grain (n) Micropyle (a) (b) Unfertilized ovule. In this sectional view through the ovule of a pine (a gymnosperm), a fleshy megasporangium is surrounded by a protective layer of tissue called an integument. (Angiosperms have two integuments.) Fertilized ovule. A megaspore develops into a multicellular female gametophyte. The micropyle, the only opening through the integument, allows entry of a pollen grain. The pollen grain contains a male gametophyte, which develops a pollen tube that discharges sperm. (c) Gymnosperm seed. Fertilization initiates the transformation of the ovule into a seed, which consists of a sporophyte embryo, a food supply, and a protective seed coat derived from the integument. Figure 30.3 From ovule to seed

  13. Chapter 30: The Evolution of Seed Plants • What are the 3 most important reproductive adaptations? • How does an ovule become a seed? • What’s the difference between a megaspore & a microspore? • Megasporangia  megaspores  female gametophytes (eggs) • Microsporangia  microspores  male gametophytes (sperm) • What are gymnosperms? • “naked seed” plants • Pines, spruce, fir, sequoia, yews, junipers, ginkgo • Most lumber & paper products • The gymnosperm life cycle…

  14. Key Haploid (n) Ovule Diploid (2n) Megasporocyte (2n) Ovulate cone Integument Longitudinal section of ovulate cone Micropyle Pollen cone Megasporangium Microsporocytes (2n) Mature sporophyte (2n) Germinating pollen grain Pollen grains (n) (containing male gametophytes) MEIOSIS MEIOSIS Surviving megaspore (n) Longitudinal section of pollen cone Sporophyll Microsporangium Seedling Germinating pollen grain Archegonium Egg (n) Integument Female gametophyte Seeds on surface of ovulate scale Germinating pollen grain (n) Food reserves (gametophyte tissue) (n) Seed coat (derived from parent sporophyte) (2n) Discharged sperm nucleus (n) Pollen tube Embryo (new sporophyte) (2n) FERTILIZATION Egg nucleus (n) Figure 30.6 The life cycle of a pine

  15. Chapter 30: The Evolution of Seed Plants • What are the 3 most important reproductive adaptations? • How does an ovule become a seed? • What’s the difference between a megaspore & a microspore? • What are gymnosperms? • “naked seed” plants • Pines, spruce, fir, sequoia, yews, junipers, ginkgo • Most lumber & paper products • The gymnosperm life cycle… • What are angiosperms? • - Flowering plants • What is a flower? • - Reproductive structure of an angiosperm

  16. Carpel Stigma Anther Style Stamen Ovary Filament Petal Sepal Receptacle Ovule Figure 30.7 The structure of an idealized flower Female structures Male structures

  17. Chapter 30: The Evolution of Seed Plants • What are the 3 most important reproductive adaptations? • How does an ovule become a seed? • What’s the difference between a megaspore & a microspore? • What are gymnosperms? • What are angiosperms? • What is a flower? • Reproductive structure of an angiosperm • What is a fruit? • Mature ovary • Helps seed dispersal

  18. (b) Ruby grapefruit, a fleshy fruit with a hard outer layer and soft inner layer of pericarp (a) Tomato, a fleshy fruit with soft outer and inner layers of pericarp (c) Nectarine, a fleshy fruit with a soft outer layer and hard inner layer (pit) of pericarp (d) Milkweed, a dry fruit that splits open at maturity (e) Walnut, a dry fruit that remains closed at maturity Figure 30.8 Some variations in fruit structure

  19. (a) Wings enable maple fruits to be easily carried by the wind. (b) Seeds within berries and other edible fruits are often dispersed in animal feces. (c) The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals. Figure 30.9 Fruit adaptations that enhance seed dispersal

  20. Chapter 30: The Evolution of Seed Plants • What are the 3 most important reproductive adaptations? • How does an ovule become a seed? • What’s the difference between a megaspore & a microspore? • What are gymnosperms? • What are angiosperms? • What is a flower? • What is a fruit? • The angiosperm life cycle….

  21. Key Haploid (n) Diploid (2n) Anther Microsporangium Microsporocytes (2n) Mature flower on sporophyte plant (2n) MEIOSIS Microspore (n) Generative cell Ovule with megasporangium (2n) Tube cell Male gametophyte (in pollen grain) Ovary Pollen grains MEIOSIS Germinating seed Stigma Pollen tube Megasporangium (n) Embryo (2n) Sperm Endosperm (food supply) (3n) Pollen tube Surviving megaspore (n) Seed Seed coat (2n) Style Antipodal cells Polar nuclei Synergids Egg (n) Female gametophyte (embryo sac) Pollen tube Zygote (2n) Egg nucleus (n) Nucleus of developing endosperm (3n) Sperm (n) FERTILIZATION Discharged sperm nuclei (n) Figure 30.10 The life cycle of an angiosperm Double fertilization

  22. Chapter 30: The Evolution of Seed Plants • What are the 3 most important reproductive adaptations? • How does an ovule become a seed? • What’s the difference between a megaspore & a microspore? • What are gymnosperms? • What are angiosperms? • What is a flower? • What is a fruit? • The angiosperm life cycle…. • Why is double fertilization important? • Synchronizes food development with embryo development • Prevents angiosperms from wasting nutrients on unfertilized ovules • What are the 2 general types of angiosperms? • Monocots • Eudicots

  23. MONOCOTS EUDICOTS Monocot Characteristics Eudicot Characteristics California poppy (Eschscholzia californica) Orchid (Lemboglossum rossii) Embryos One cotyledon Two cotyledons Leaf venation Pyrenean oak (Quercus pyrenaica) Veins usually parallel Veins usually netlike Pygmy date palm (Phoenix roebelenii) Stems Vascular tissue usually arranged in ring Lily (Lilium “Enchant- ment”) Vascular tissue scattered Root Dog rose (Rosa canina), a wild rose Root system Usually fibrous (no main root) Taproot (main root) usually present Barley (Hordeum vulgare), a grass Pea (Lathyrus nervosus, Lord Anson’s blue pea), a legume Pollen Pollen grain with three openings Pollen grain with one opening Flowers Anther Zucchini (Cucurbita Pepo), female (left) and male flowers Floral organs usually in multiples of three Floral organs usually in multiples of four or five Stigma Filament Ovary

  24. Table 29.1 Ten Phyla of Extant Plants

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