2 Types of Plant Cells Parenchyma Thin flexible cell walls.2 main functions – storage and food production.Large vacuole stores water, starch and oils.Can contain many chloroplasts.
3 Types of Plant Cells Collenchyma Typically long cells.Unevenly thickened cell walls.Thin parts can stretch and grow.Provide support for surrounding tissue.ie. – tough strands in celery.
4 Types of Plant Cells Sclerenchyma Thick and rigid.Used for supportTwo types: fibers and stone cells.Fibers – long thin strands, support, strength, vascular tissue.Stone cells – circular cellsGritty texture of pearsFruit pits
5 Plant Tissues Dermal or Epidermis Flattened parenchyma cells cover and protect plant like skinProduce a waxy cuticle – prevents water loss.
6 Plant Tissues Dermal or Epidermis Contain stomata: openings that control gas exchange.Guard cells control opening and closing.
7 Plant Tissues Dermal or Epidermis Root hairs: extensions of cell that help absorb water and minerals.
8 Plant Tissues Dermal or Epidermis Trichomes: hair like – give fuzzy textureReduce evaporation.Some protect by secreting toxic substances.
9 Plant Tissues Vascular Tissues Transport food minerals and water through the plant.Two types:Xylem – Moves water and minerals from roots to rest of plant.Phloem – Transport sugars and organic compounds from leaves to rest of plant.
10 Plant Tissues Xylem Two types Tracheids: In conifers. Tubular, tapered ends, dead at maturity.Cell walls have pits for water flow across cells.Vessel elements: In Anthopytes.Wider and shorter.Openings in end walls for water flow through cells.
12 Plant Tissue Phloem Transport sugars and organic compounds. Living, tubular cells.Phloem cells are called sieve tube members.Have cytoplasm but no nucleus or ribosomes.Companion cells – next to each sieve tube member. Help manage transport.
13 Plant Tissues Ground Tissue All other tissuesMostly parenchymaFunctions: photosynthesis, storage, support.In stems and roots: have large vacuoles to store starch and water.
14 Plant Tissues Meristematic Tissues Region of actively dividing cells.Small, round, with large nuclei.Apical meristems:At tips of roots and stems.Increase length.Lateral meristems:Cylinders of dividing cells in roots and stems.Increase diameter.Vascular cambium: produce xylem and phloem.Cork cambium: produces tough covering for root and stems.
16 Roots Anchor, absorb water and minerals from soil. Some used for food storage (carrots)Two typesTaproots: central fleshy with small branch roots. (carrots, beets)Fibrous roots: numerous branches from central point.
17 Root Variations Adventitious roots: Aerial roots: Prop roots above ground to support tall plants.Aerial roots:Cling to objects to provide support.
18 Root Structure Epidermis: outer layer. Root hair: extension of single epidermal cell.Absorbs water, oxygen and minerals.
19 Root Structure Cortex: next layer. Transports water and ions into vascular core.Made of parenchyma cellssometimes used for storage
20 Root StructureEndodermis: forms waterproof seal around vascular tissue.All water and minerals must pass through endodermis cells.
21 Root Structure Pericycle: just within endodermis. Gives rise to lateral roots (offshoots of older roots).
22 Root Structure Xylem and phloem: center of root. Transport of water, minerals and organic materials through plant.
25 Root Growth Apical meristem Vascular cambium Root cap Lengthens root Increase diameterFound between xylem and phloemRoot capLayer of cells at root tip.Protection
26 Stems Transport, support and storage. Some are Underground Corm: short, thick, surrounded by leaf scales. (gladiolus)Tuber: swollen underground stem with buds that sprout new plants. (potato)Rhizomes: (iris)
27 Stem: Internal Structure Vascular tissue arranged in bundles.Dicot Monocot
28 Woody Stems Secondary Growth: thickness from vascular cambium. Xylem: wood – causes growth rings.Bark: old phloem and cork cambium.
29 Stems – Material Transport Xylem: transports water from roots to leaves.Phloem: transports sugars, minerals, and hormones.Source: photosynthetic tissue – mostly leaves.Sink: storage area (cortex of roots)Translocation: movement from source to sink.
30 Leaf Variation Simple: blade no divided Compound: divided into leafletsAlternate: only one leaf from a single point on stemOpposite: leaves in pairs along stemWhorled: three or more leaves occurring at same place on stem
31 Leaf Structure Vascular tissue in veins. Epidermis: outer layer of cells.Two layers of Mesophyll.Palisade mesophyll:Most photosynthesis.Spongy mesophyll:Loosely packed with irregular shaped cells.Air spaces for gas exchange: O2, CO2, H2O.Gases move in and out of stomata.
35 Leaf ModificationsCactus spines: leaves that reduce water loss and protect plant.Bulb: short stem covered by large fleshy leaves, modified for food storage.Pitcher plant: modified to trap insects.Aloe vera: adapted to store water.
39 Plant HormonesChemicals produced in one part of an organism and transported to another to cause a change in growth or development.
40 Auxins: Hormone Promote cell elongation. (IAA) Indoleacetic acid. Produced in apical meristem.Increases cell division and promotes cell elongation.Weakens connections between cellulose fibers in the cell wall allowing cells to stretch.
41 AuxinAuxins produced in apical meristem inhibits growth of side branches.Remove stem tip – branches form
42 Gibberellins: Hormone Growth hormone.Stimulates cell elongation.Also increases rate of seed germination and bud development.
43 Cytokinins: Hormone Stimulate cell division or cytokinesis. Stimulate production of proteins needed for mitosis.Produced in meristem of roots and travel up xylem to rest of plant.
44 Ethylene: HormoneA gas that speeds ripening of fruits.
45 Tropism Response to an external stimulus from a particular direction. Positive tropism: plant grows toward stimulus.Negative tropism: plant grows away from stimulus.
46 Types of Tropism Phototropism: growth toward light. More auxin on side of stem away from light.Cell elongation on one side – dark side.Gravitropism: direction of plant growth in response to gravity.Stems up and roots down.Thigmotropism: response to touch.Tendrils of vine coil around objects.
47 Nastic ResponsesResponse movement that is not dependent on direction of stimulus.Mimosa Venus Flytrap