2 Learning Targets 23.1What are the principal organs and tissues of vascular plants?How is meristematic tissue different from other plant tissues?What specialized cells make up vascular tissue?
3 Specialized Tissues in Plants Three main organs of plants:ROOTS: underground organs that absorb water and mineralsAlso anchor the plant and hold it uprightSTEMS: supporting structures that connect roots and leavesCarry water and nutrientsHolds leaves up to lightLEAVES: carry out photosynthesisCapture light, flat so cover more surface areaCuticle and adjustable pores protect leaves from water loss
4 Tissue SystemsWithin the roots, stems and leaves are FOUR specialized tissue systems:DERMAL TISSUE: forms the skin of a plant (is the outermost layer of cells)VASCULAR TISSUE: like the plant’s bloodstream (transports water and nutrients throughout the plant)GROUND TISSUE: cells between the dermal and vascular tissuesMERISTEMATIC TISSUE: found only in the tips of shoots and roots
5 Three tissues of plants LeafStemRootThree tissues of plantsDermal tissueVascular tissueGround tissue
6 Dermal Tissue Outer covering of a plant Consists of: Epidermis: outermost layerCuticle: thick, waxy layer that protects against water loss and injury (covers epidermis)On under side of leaves, contains guard cells which regulate water loss and gas exchange
8 Vascular Tissue Transport system: “bloodstream” Consists of xylem and phloemXylem: water-conducting tissueTransports water to leavesPhloem: food-conducting tissueTakes sugar to the roots
9 Ground Tissue Tissue that lies between dermal and vascular tissue Consists of parenchyma, collenchyma and sclerenchyma
10 Ground Tissue Parenchyma: Collenchyma Thin cell walls and large vacuolesIn leaves, these cells are packed with chloroplasts and are the site of photosynthesisCollenchymaCells with strong, flexible walls that help to support larger plantsThis is what makes up the stringy part of celery
11 Ground Tissue Sclerenchyma Cells that have an extremely thick, ridged, cell wall that makes ground tissue tough and strong.
12 Meristematic TissueNew growth is produced in cells that make up meristematic tissueIt is the ONLY plant tissue that produces new cells by mitosis!!Best place to see this at the tip of a shoot/root where apical meristem is located
14 Learning Targets 23.2 What are the two main types of roots? What are the main tissues in a mature root?What are the different functions of roots?
15 Roots Functions: TWO MAIN TYPES OF ROOTS: Absorb water and nutrients Anchor plantTWO MAIN TYPES OF ROOTS:Taproots: found mainly in dicotsEX: carrot, dandelions, beets, radishes, oak treeFibrous Roots: found mainly in monocotsEX: grass
17 Root StructureEpidermis of root is covered with tiny projections called root hairsIncrease surface area of root to absorb more waterRoots grow in length as their apical meristem produces new cells near the root tipThe fragile new cells are covered by a tough root cap that protects the root as it forces its way through soil
19 Learning Targets 23.3 What are the three main functions of stems? How do monocot and dicot stems differ?How do primary growth and secondary growth occur in stems?
20 StemsFUNCTIONS:Produce Leaves, branches and flowersHold leaves up in the sunlightTransport substances between roots and leavesComposed of dermal, vascular and ground tissue (like the rest of the plant)
21 Stem Parts Nodes: where leaves are attached Internodes: regions between the nodesBuds: contain undeveloped tissue that can produce new stems and leaves
23 Monocot v. Dicot StemsMoncots: vascular bundles are scattered throughout the stem
24 Monocot v. Dicot StemsDicots: vascular bundles are arranged in a cylinder
25 Primary GrowthFor a plant’s entire life, new cells are produced at the tips of roots and shootsThis is called primary growthThey increase in lengthIt takes place in all seed plants
26 Secondary GrowthThe pattern of growth in which stems increase in width is called secondary growthIn conifers and dicots, secondary growth takes place in lateral meristematic tissue called the vascular cambium and cork cabium
27 WOOD WOOD is actually layers of XYLEM Heartwood: older xylem in center of wood, that no longer conducts waterDarkens with age as it accumulates impuritiesSapwood: surrounds heartwood, active in transport
28 WOOD Growth Rings Indicate age of tree and environmental conditions Thick rings indicate the growing season experienced adequate moistureThin rings indicate there was less water (draught)
29 WoodBarkCorkContains old, nonfunctioning xylem that helps support the treeContains active xylem that transports water and mineralsProduces new xylem and phloem, which increase the width of the stemTransports sugars produced by photosynthesisProduces protective layer of corkContains old, nonfunctioning phloem that protects the treeXylem: HeartwoodCork CambiumPhloemVascular CambiumXylem: Sapwood
30 Learning Targets 23.4How does the structure of a leaf enable it to carry out photosynthesis?How does gas exchange take place in a leaf?
31 Leaves Main organs of photosynthesis Makes food for plants (glucose: C6H12O2)Structure is optimized for absorbing light and carrying out photosynthesisBlades: thin, flattened to increase surface area to absorb sunlightAttached to stem by petioleEpidermis: outer layerCuticle: waxy, protective layerProtects tissues and limits water loss
34 Leaf Structure/Function PhotosynthesisMost of photosynthesis carried out in MESOPHYLL layerPacked with chloroplastsPalisade Mesophyll: column-shaped cells just under epidermisAbsorb most of light coming into leaf
38 Leaf Structure/Function STOMATA: pores in underside of leaf that let carbon dioxide and oxygen diffuse in and out of the leafEach stoma consists of two GUARD CELLSGuard Cells: cells in the epidermis that control the opening and closing of the stomata by responding to water pressure changes
40 Leaf Structure/Function Gas ExchangeLeaves take in CO2 and give off O2 during photosynthesisPlant leaves allow gas exchange by opening their stomataIf kept open all the time, there would be large amounts of water loss due to transpirationPlants keep stomata open just enough to allow photosynthesis to take place, not long enough to lose too much water
41 Leaf Structure/Function Guard cells regulate opening/closing of the stomataIf water pressure is high, they open the stomataIf water pressure is low, they close the stoma
44 Learning Targets 23.5 How is water transported throughout a plant? How are the products of photosynthesis transported throughout the plan?
45 Water TransportCombo of root pressure, capillary action and transpiration provides force to move water through the xylemRoot Pressure: pressure created by water entering the tissues of a root that pushes water upward in a plant stemCapillary Action: tendency of water to rise in a THIN tubeWater is attracted to the walls of the tube and to other water molecules
46 Water Transport Transpiration: loss of water through plant leaves When water is lost through transpiration the leaf “pulls” water upward from the rootsMoves water from HIGH to LOW pressure
47 Water Movement Evaporation of water molecules out of leaves. Pull of water molecules upward from the roots.