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UNIT IX – KINGDOM PLANTAE

UNIT IX – KINGDOM PLANTAE. Big Campbell – Ch 29, 30, 35 – 39 Baby Campbell – Ch 17, 31 – 33. KINGDOM PLANTAE. All All All All All have cell walls composed of Most contain. I. EVOLUTION OF PLANTS. Evolved from green algae known as charophytes Land Adaptations

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UNIT IX – KINGDOM PLANTAE

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  1. UNIT IX – KINGDOM PLANTAE Big Campbell – Ch 29, 30, 35 – 39 Baby Campbell – Ch 17, 31 – 33

  2. KINGDOM PLANTAE • All • All • All • All • All have cell walls composed of • Most contain

  3. I. EVOLUTION OF PLANTS • Evolved from green algae known as charophytes • Land Adaptations • Obtaining Resources • Organs • Vascular tissue in plants • Apical meristem • Support • Lignin • Maintaining Moisture • Cuticle • Stomata

  4. I. EVOLUTION OF PLANTS, cont • Reproduction • Alternation of Generations • Walled spores produced in sporangia • Production of gametes within multicellular structures called gametangia • Developing embryo protected, nourished by female parent plant

  5. II. PLANT CLASSIFICATION

  6. II. PLANT CLASSIFICATION, contBryophytes • Non-vascular • Mosses, liverworts, and hornworts • Flagellated (water) sperm • No vascular tissue • No lignin (short stature) • Haploid gametophyte is the dominant generation

  7. II. PLANT CLASSIFICATION, contBryophyte Life Cycle

  8. II. PLANT CLASSIFICATION, contPterophytes • Seedless vascular plants • Ferns, club ‘moss’, horsetails • Contain vascular tissue • Xylem • Phloem • True roots and leaves • Roots have lignified vascular tissue • Dominant stage = • Bisexual gametophyte • Flagellated sperm • Carboniferous period plants

  9. II. PLANT CLASSIFICATION, contFern Life Cycle

  10. II. PLANT CLASSIFICATION, contSeed Plants

  11. II. PLANT CLASSIFICATION, contSeed Plants • Gymnosperms & Angiosperms • Reduced Gametophyte • Seed • Heterosporous • Megaspore → female gametophyte → egg • Microspore → male gametophyte → sperm • Pollen

  12. II. PLANT CLASSIFICATION, contSeed Plants

  13. II. PLANT CLASSIFICATION, contSeed Plants Seed Germination

  14. II. PLANT CLASSIFICATION, contGymnosperms • Vascular Plants with seeds • “Naked seed” • Seed is not protected by a fruit • Cone-bearing plants • Ginkgo, cycads, and conifers • “Evergreens” • Most have needles • Reproduction occurs in the cone

  15. II. PLANT CLASSIFICATION, contAngiosperms • Vascular plant with seeds, fruit • “Flowering plants” • Most successful of all plants • Flower - Reproductive system of angiosperms • Fruit – Protects, disperses seed • Angiosperms divided into 2 groups: • Monocots - 1 embryonic seed leaf (lilies, palms, grasses, grain crops) • Dicots - 2 embryonic seed leaves (roses, peas, sunflowers, oaks, maples)

  16. II. PLANT CLASSIFICATION, contAngiosperms Monocot vs. Dicot

  17. II. PLANT CLASSIFICATION, contAngiosperms Flower Structure • Sepals • Encloses, protects flower • Petals • Attracts pollinators • Stamen • Male reproductive organ • Anther, filament • Pollen produced by anther • Pollen is male gametophyte • Carpel (Pistil) • Female reproductive organ • Stigma, style, ovary, ovule • Ovule is female gametophyte • Fertilization occurs in ovule

  18. Fruit Pollination Pollen grain lands on “sticky stigma” Pollen tube formed Extends through style to ovary Mitosis occurs in pollen grain to form 2 sperm Double Fertilization One sperm fertilizes egg contained in ovule; forms zygote Nucleus of second sperm fuses with diploid cell in embryo sac Triploid cell develops into food-storing tissue called endosperm II. PLANT CLASSIFICATION, contAngiosperm Adaptations

  19. A CLOSER LOOK AT PLANT STRUCTURE & GROWTH

  20. III. PLANT STRUCTURE, cont Three Tissue Types • Dermal • Outer protective covering • Made up of a single layer of cells called the epidermis in non-woody plants • Root hairs • Cuticle • Woody plants have a tissue layer called periderm • Vascular • Xylem • Transports water, minerals • Two types of “cells” • Vessel Elements • Tracheids • Phloem • Transports nutrients • Composed of • Sieve Tube Members • Companion Cells

  21. III. PLANT STRUCTURE Ground Remaining plant tissue Location of photosynthesis, hormone production, carbohydrate storage, etc Made up of three cell types Parenchyma Most abundant cell type Living cells with thin, flexible primary cell walls Perform most of the metabolic functions Contain large central vacuole Capable of cell division, differentiation Collenchyma Uneven, thickened primary cell walls; lack secondary cell walls Living cells that provide flexible support Sclerenchyma Provide structural support Contain secondary cell walls, strengthened with lignin Dead at maturity Two types Fibers Sclereids

  22. III. PLANT STRUCTURE, contA Closer Look at Roots

  23. III. PLANT STRUCTURE, contA Closer Look at Stems • Vascular bundles (xylem and phloem) • Surrounded by ground tissue (xylem faces pith and phloem faces cortex) • Mostly parenchyma; some collenchyma, sclerenchyma for support

  24. III. PLANT STRUCTURE, contA Closer Look at Leaves • Epidermis • Cuticle • Stomata & Guard Cells • Mesophyll • Ground tissue between upper & lower epidermis • Parenchyma cells • Made up of 2 regions • Palisade • Spongy

  25. IV. PLANT GROWTH • Indeterminate Growth • Growth carried out through increased cell numbers and increased cell size • Meristem • Embryonic tissue capable of unlimited growth; growing part of plant • Two types • Apical Meristem • Found at tips • Known as primary growth • Lateral Meristem • Cylinders of cells that extend the length of the plant • Increases girth of plant • Known as secondary growth

  26. IV. PLANT GROWTH, contPrimary Growth The Root System • Provides plant with water, minerals; anchors plant • Root Cap • Protects the apical meristem; cells constantly replaced by meristem • Zone of Cellular Division • Apical meristem • Zone of Cellular Elongation • Made up of cells increasing in length • Zone of Cellular Maturation • Differentiation of cells to make up three tissue types • Root Hairs

  27. IV. PLANT GROWTH, contSecondary Growth • Increases girth of plant • Carried out by two cylinders of cells that run the length of root, stem known as lateral meristems • Vascular Cambium – Found only in woody gymnosperms, angiosperms. Occurs between 1˚ xylem & phloem. Inside vascular cambium → secondary xylem; outside → secondary phloem. • Secondary xylem makes up the wood of a tree. Cells contain large amounts of lignin. Layering of 2˚ xylem = growth rings. • Secondary phloem transports sugar; part of bark

  28. IV. PLANT GROWTH, contSecondary Growth, cont • Cork Cambium • Typically produces new cells to the outside • Produces cork cells; replace epidermis as it is sloughed off. • Forms from parenchyma cells. • Important component of bark, although bark technically consists of all cells outside vascular cambium • Heartwood • Sapwood

  29. Plant Nutrition

  30. V. WATER TRANSPORT • Water Transport • Osmosis • Hyper, Hypo, Iso • Water moves from high to low water potential • Ψ = Ψs + Ψp • Solute potential of pure water = 0 • Solute present; solute potential is negative • Pressure potential increased by cell wall • Plasmolysis • Cell in hypertonic environment • Cell membrane pulls away • Turgor pressure • Cell in hypotonic environment • Influx of water

  31. V. WATER TRANSPORT, contUptake of Water & Minerals • Root hairs greatly increase surface area, absorptive capacity • Water and solutes enter through epidermis and cortex of root • Movement into xylem can happen in 2 ways: • Symplastic – Water & solutes cross cell wall, cell membrane into epidermal cell. Plasmodesmata allow solution to move from cell to cell without crossing cell membranes all the way to xylem • Apoplastic – Solution does not move into epidermal cells; stays in extracellular spaces. Crosses no cell membranes until it reaches Casparian strip – a continuous waxy barrier that forces solution through selectively permeable cell membrane of endodermal cell, then enters xylem.

  32. V. WATER TRANSPORT, contUptake of Water & Minerals A Closer Look

  33. V. WATER TRANSPORT, contTransport of Xylem Sap From Roots to Shoots • Transpiration • Loss of water vapor from leaves pulls water from roots (transpirational pull) • Cohesion and adhesion of water • Root pressure • At night, low transpiration, roots cells continue to pump minerals into xylem • Generates pressure, pushing sap upwards; guttation • Not as great a force as transpiration

  34. V. WATER TRANSPORT, contControl of Transpiration • Photosynthesis-Transpiration compromise…. • Guard cells control the size of the stomata • Xerophytes - Plants adapted to arid environments; have thick cuticle, small spines for leaves • CAM, C4 plants

  35. VI. NUTRIENT TRANSPORTEssential Nutrients Required by Plants • Macro • Carbon • Oxygen • Hydrogen • Nitrogen • Phosphorus • Sulfur • Potassium, calcium, magnesium • Micro • cofactors of enzymes • chlorine, iron, boron, manganese, zinc, copper, molybdenum, nickel

  36. VI. NUTRIENT TRANSPORT, cont Phloem Cells

  37. VI. NUTRIENT TRANSPORT, cont Transport of Phloem Sap • Sugar Source – Plant organ that produces sugar; leaves • Sugar Sink – Organ that consumes or stores sugar; growing roots, stems, fruit • Translocation – Process of sugar transport • Sugar is actively transported into phloem tube • Raises solute concentration; lowers ψ • Water moves into phloem tube; increases pressure at the source end • Forces sap to move toward area of lower pressure • Pressure gradient by movement of sugar out of phloem tube at sink end • Xylem moves water from sink to source

  38. VII. PLANT RELATIONSHIPS • Mutualism • Rhizobium bacteria • Nitrogen fixation • Found in roots of legume (bean) plants • Mycorrhizae fungi • Increase plant root surface area • Parasitism • Mistletoe • Epiphytes • Live attached to plant but nutritionally self-supportive • Orchids • Carnivorous • Venus Flytrap • Pitcher Plants • Insects provide needed minerals

  39. Control Systems in Plants

  40. VIII. TROPISM • Movement toward or away from a stimulus • Phototropism • Adaptive response first tested by Darwin • Went identified chemical responsible • Auxin Acts by stimulating growth • Gravitropism • Thigmatropism

  41. IX. PLANT HORMONES • Chemical signals that coordinate activities of an organism • Produced in one part of the body and then transported to other parts of the body • Bind to specific receptor; triggers a signal transduction pathway • Low concentrations; have a profound effect • Five major types of plant hormones • Auxins • Cytokinins • Giberellins • Abscisic Acid • Ethylene

  42. IX. PLANT HORMONES, contAuxin • IAA (indoleacetic acid) • Found in seed embryo, meristems of apical buds and young leaves • Stimulates elongation of cells • Functions include stem elongation, root growth, differentiation, branching, fruit development; apical dominance; tropisms • Produced by developing seeds

  43. IX. PLANT HORMONES, contCytokinins • Promote cell division, cytokinesis • Found in roots, actively growing tissues • Stimulate root growth and differentiation, germination • Slow down aging of flowers, leaves • Work with auxins to control apical dominance; that is, the ability of the terminal bud to suppress the growth of axillary buds

  44. IX. PLANT HORMONES, contGibberellins • Isolated by Japanese farmers; originally thought it was due to a fungus • Acts as growth regulator • Stimulate cell division and elongation in stems and leaves • Enhance effects of auxins • Found in roots and young leaves

  45. IX. PLANT HORMONES, contAbscisic Acid • ABA • Inhibits growth; maintains seed dormancy; causes stomata to close during dry conditions • Found in leaves, stems, roots, unripe fruit

  46. IX. PLANT HORMONES, contEthylene • Gaseous hormone • Stimulates fruit ripening • Breaks down cell walls, “softens” fruit • Triggers breakdown of starch to glucose • Separates leaf from stem; autumn leaf drop • Stimulates formation of an abscission layer • Works in opposition to auxins

  47. X. PLANT RESPONSES • Critical night length controls flowering • Short-day Plant • Light period shorter than a critical length to flower • Flower in late summer, fall, winter • Poinsettias, chrysanthemums • Long-day Plant • Light period longer than a critical period to flower • Flower in late spring, early summer • Spinach, iris, radish, lettuce • Day-neutral Plant • Unaffected by photoperiod • Tomatoes, rice (is nice!), dandelions

  48. X. PLANT RESPONSES, contPhotoperiodism • Internal plant clock • Based on relative lengths of day and night, especially night • Allows plants to respond to seasonal changes • Phytochromes • Plant pigment that measures length of darkness in a photoperiod • Absorbs red light; therefore, appear bluish in color • Two forms • Pr – “red-absorbing”, 660 nm • Pfr - “far-red absorbing”, 730 nm

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