* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Lecture #13 Date ______
Ornamental bulbous plant wikipedia , lookup
Magnesium in biology wikipedia , lookup
Gartons Agricultural Plant Breeders wikipedia , lookup
Plant stress measurement wikipedia , lookup
Plant use of endophytic fungi in defense wikipedia , lookup
History of botany wikipedia , lookup
Venus flytrap wikipedia , lookup
Plant defense against herbivory wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Plant breeding wikipedia , lookup
Plant nutrition wikipedia , lookup
Plant secondary metabolism wikipedia , lookup
Plant physiology wikipedia , lookup
Plant ecology wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Plant reproduction wikipedia , lookup
Flowering plant wikipedia , lookup
Plant morphology wikipedia , lookup
Sustainable landscaping wikipedia , lookup
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 Obtaining Resources Organs Vascular tissue in plants Apical meristem Support Lignin Maintaining Moisture Cuticle Stomata 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 II. PLANT CLASSIFICATION II. PLANT CLASSIFICATION, cont Bryophytes • Non-vascular • Mosses, liverworts, and hornworts • Flagellated (water) sperm • No vascular tissue • No lignin (short stature) • Haploid gametophyte is the dominant generation II. PLANT CLASSIFICATION, cont Bryophyte Life Cycle II. PLANT CLASSIFICATION, cont Pterophytes • 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 II. PLANT CLASSIFICATION, cont Fern Life Cycle II. PLANT CLASSIFICATION, cont Seed Plants II. PLANT CLASSIFICATION, cont Seed Plants • Gymnosperms & Angiosperms • Reduced Gametophyte • Seed – – – – • Heterosporous – Megaspore → female gametophyte → egg – Microspore → male gametophyte → sperm • Pollen II. PLANT CLASSIFICATION, cont Seed Plants II. PLANT CLASSIFICATION, cont Seed Plants Seed Germination II. PLANT CLASSIFICATION, cont Gymnosperms • 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 II. PLANT CLASSIFICATION, cont Angiosperms • • • • 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) II. PLANT CLASSIFICATION, cont Angiosperms Monocot vs. Dicot II. PLANT CLASSIFICATION, cont Angiosperms 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 • Fruit • Pollination II. PLANT CLASSIFICATION, cont Angiosperm Adaptations 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 foodstoring tissue called endosperm A CLOSER LOOK AT PLANT STRUCTURE & GROWTH III. PLANT STRUCTURE, cont Three Tissue Types • Dermal – Outer protective covering – Made up of a single layer of cells called the epidermis in nonwoody 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 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 III. PLANT STRUCTURE, cont A Closer Look at Roots III. PLANT STRUCTURE, cont A 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 III. PLANT STRUCTURE, cont A 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 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 IV. PLANT GROWTH, cont Primary 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 • • IV. PLANT GROWTH, cont Secondary 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 IV. PLANT GROWTH, cont Secondary 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 Plant Nutrition 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 V. WATER TRANSPORT, cont Uptake 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. V. WATER TRANSPORT, cont Uptake of Water & Minerals A Closer Look V. WATER TRANSPORT, cont Transport 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 V. WATER TRANSPORT, cont Control 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 VI. NUTRIENT TRANSPORT Essential 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 VI. NUTRIENT TRANSPORT, cont Phloem Cells 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 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 Control Systems in Plants 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 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 IX. PLANT HORMONES, cont Auxin • 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 IX. PLANT HORMONES, cont Cytokinins • • • • • 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 IX. PLANT HORMONES, cont Gibberellins • • • • • 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 IX. PLANT HORMONES, cont Abscisic Acid • ABA • Inhibits growth; maintains seed dormancy; causes stomata to close during dry conditions • Found in leaves, stems, roots, unripe fruit IX. PLANT HORMONES, cont Ethylene • 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 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 X. PLANT RESPONSES, cont Photoperiodism • 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