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Transcript
PLANT UNIT Chapters 23 - 26 “Plant”? # Cells? Multicellular Cell Type? Eukaryotic Metabolism? Structure? Photosynthetic autrotrophs made of cellulose and chlorophyll a and b in chloroplasts Cells walls Land plants evolved from? green algae Four main groups of land plants: Bryophytes Pteridophytes (ferns) (mosses) Gymnosperms (conifers) Angiosperms (Flowering plants) Seed/Flowers ~130 mya “Vascular” ~400 mya “Nonvascular” “Seedless” ~550 mya Seed/Cone ~360 mya VASCULAR SEED PLANTS Vascular = food and water transport tissue Seed = embryo packaged along with a food supply within a protective coat Non-Seed = Spores Angiosperms (flowers) Gymnosperms (cones) Seeds Angiosperms 250,000 known species by far the most diverse and widespread group of land plants Division Anthophyta Importance? Primary Producers 2 main classes: Monocots and Dicots Monocots lilies, orchids, yuccas, grasses, and grains (65,000 species) Dicots includes roses, peas, sunflowers, oaks, and maples (165,000 species) PLANT STRUCTURE Basic Morphology Stem Leaves 3 Organs? Roots Roots? Anchor Absorb minerals and water Store food Fibrous root systems Monocots (grasses) Anchors / + Surface Area Taproot system Dicots Anchor / Store Food Root hairs Most absorption of water and minerals Increase the surface area enormously Shoots Stems and Leaves Nodes = the points at which leaves are attached Internodes = the stem segments between nodes Terminal bud (apex) = Growth of a young shoot is concentrated Axillary bud At the angle formed by each leaf and the stem potential to form a vegetative branch Modified shoots Stolons “runners” grow on the surface (asexual dominance) Tubers/ Bulbs for food storage Rhizomes are horizontal stems that grow underground Leaves? main photosynthetic organs Blade Petiole = joins the leaf to a stem node monocots ? dicot Leaves have become adapted by evolution for other functions tendrils to cling to supports modified for water storage spines for defense brightly colored for attracting pollinators Leaf is used to identify and classify plants simple leaves have a single, undivided blade compound leaves have several leaflets attached to the petiole Pinnate Compound Simple Palmate Compound Whorled Shape? Elliptic Cordate Margin? Serrate “toothed” Entire 6 3 4 5 1 7 8 9 10 2 Three tissue types: Each organ of a plant -Dermal -Vascular -Ground tissue Each is continuous throughout the plant body 1. Dermal tissue (epidermis) covers and protects “Cuticle” waxy coating Upper Epidermis Lower Epidermis 2. Vascular tissue transport of materials Phloem (alive) Xylem (dead) Longitudinal Section “Vascular Bundle” Cross Section 3. Ground tissue Tissue that is neither dermal tissue nor vascular tissue Function = include photosynthesis, storage, and support Divided into pith, internal to vascular tissue, and cortex, external to the vascular tissue Cortex Pith PLANT GROWTH AND DEVELOPMENT The Seed -Embryo -Seed Coat -Storage Material (Endosperm or Cotyledons) Starch (oils and protein) (Dicot) Shoot tip Young leaves Young shoot Root Nutrients GERMINATION AND DEVELOPMENT Dormant (upon reaching maturity) until specific environmental cues are encountered: -Water -Temperature -Light -Seed coat damage (fire/ digestive tracts) Water PLANT GROWTH Meristems = embryonic tissues in the growth region 2 types of Growth: 1. Primary 2. Secondary Primary growth = growth in length Apical meristems = located at the tips of roots and in the buds of shoots “Young” growth Down – roots Up - stems “Primary Root Growth” Cap = protects the meristem as the root pushes through the abrasive soil secretes a lubricating slime Primary Shoot Growth Apical meristem at the terminal bud Secondary growth = progressive thickening/girth of roots and shoots Lateral meristems = cylinders of dividing cells extending along the length of roots and shoots “Woody” parts of plants “Older” growth Periods of growth and dormancy Annual Age and Rianfall REPRODUCTION Four Organs: Nonreproductive: Sepals Petals Reproductive: Stamen (male) Carpel/Pistil (female) Complete Flower = contains all 4 organs “Perfect” Male and Female flower Incomplete Flower = lacks one or more organs “Imperfect” Male or Female flowers “Pollination” Wind Animals: Bees Butterflies Moths Beetles Flies Hummingbirds Bats “Radial” Symmetry “Bilateral” Symmetry Ultraviolet Suck the nectar Pollen sticks to its body Avoid self-fertilization “Genetic Variability” Fertilization Eggs Mature Ovary Swells Fruit Develops Seed Encased In Fruit Ripens “Ethylene” Seeds Dispersed PRIMARY STRUCTURE OF ROOTS Dermal Tissue Epidermis Root Hairs Ground Tissue Cortex Endodermis Vascular Tissue Xylem/Phloem Pith PRIMARY STRUCTURE OF STEMS Dermal Tissue Epidermis Cuticle Ground Tissue Cortex (chloroplast) Pith Vascular Tissue Xylem/ Phloem Cortex Xylem Phloem Pith Epidermis STRUCTURE OF THE LEAF Dermal Tissue Epidermis Cuticle Ground Tissue Palisade Mesophyll (chloroplast) Spongy Mesophyll (gas exchange) Vascular Tissue Vein Xylem/ Phloem Stomata/ Guard Cells Guard Cells Stoma Root Leaf Cortex Xylem Phloem Pith Stem Epidermis 1 2 5 3 4 8 7 6 SECONDARY STRUCTURE OF STEMS AND ROOTS The stems and roots, but not the leaves, of most dicots increase in girth by secondary growth The vascular cambium acts as a meristem for the production of secondary xylem and secondary phloem Inside = cells differentiate into secondary xylem Outside = secondary phloem Vascular Cambium Over the years, secondary xylem accumulates and increases the girth of stem/root In addition, new secondary phloem is added yearly to the outside As a result, tissues “grow” in both directions (girth) Bark refers to all tissues external to the vascular cambium, including secondary phloem, cork cambium, and cork Primary tissues (epidermis/ cortex) are “sloughed off” Periderm = replace the shed epidermis (protective covering) Cork Cambium (meristematic) Cork cells (suberin) Periderm Each year new layers of secondary xylem are produced (vascular cambium) Xylem tissue (wood) is dead at maturity Sapwood = active xylem Heartwood = older xylem (support) Heartwood Sapwood Vascular Cambium Growth – vascular cambium active (new cells) Dormancy Growth Annual ringsSecondary xylem tissue Age and Rianfall TRANSPORT OF WATER Moves toward the center of the root by one of 2 pathways: Water/ dissolved minerals enter roots through root hairs by osmosis Apoplast = Pathway of water moving through cell walls from cell to cell w/o entering the cells “Nonliving” portion Symplast = Cytoplasm from one cell to another through plasmodesmata “Living” portion Endodermis Stele (vascular bundle) Xylem Symplast pathway (casparian strip/suberin blocks) Tracheids Vessel Elements Three mechanisms are involved in the movement of water/ dissolved minerals: 1. Osmosis 2. Capillary Action 3. Cohesion-Tension Theory Life Cycles • Annual = complete their life cycle in a single year or less (wildflowers, cereals and legumes) • Biennial = life spans two years. – Often, there is an intervening cold period between the vegetative growth season and the flowering season. • Perennials =live many years (trees, shrubs, and some grasses) Drupe