Plant Structure and Function

Is It a Stem, Leaf, Root, Flower, Fruit or Seed? Fruit/Vegetable Part of Plant Broccoli Cabbage Carrot Celery Stalk Corn Kernel Garlic Onion Potato Tomato Zucchini

Plant Body ShootShoot system = leaves + stem + reproductive structures RootRoot system MeristemMeristem = cells that divide for life of plant, can give rise to all plant structures

Three Types of Plant Tissues Vascular TissueVascular Tissue –Transport –Support Ground TissueGround Tissue –Synthesis of Sugars –Storage –Support Dermal TissueDermal Tissue –Protection

Functions of Some Types of Plant Cells Metabolic functions: photosynthesis, aerobic respiration, food storageMetabolic functions: photosynthesis, aerobic respiration, food storage –Parenchyma cells Starch-storing vesicles Primary cell wall (thin) Pit

Functions of Some Types of Plant Cells Water-conducting cellsWater-conducting cells –In Xylem –Tracheids –Vessel Elements Pits Tracheids Vessel element Openings in end wall

Transpiration: Force that Pulls Water through Xylem Transpiration Outside air Stoma Air space within leaf Mesophyll cells Xylem sap Flow of water 1 Cohesion and adhesion in the xylem Xylem cells Cohesion by hydrogen bonding 2 Root hair Soil particle Water Water uptake from soil 3 Adhesion Cell wall 4 Water molecule Water evaporates from leaf surface Water column rises by cohesion and adhesion Additional water enters through roots

Functions of Some Types of Plant Cells Food-conducting cellsFood-conducting cells –In Phloem –Sieve Tube Members –Companion Cells Sieve Plate Sieve Tube Member Companion Cell

Pressure Flow: Sugar Transport Mechanism in Phloem Sugar sink High sugar concentration Sugar Water Sugar Water XylemPhloem Sieve plate Source cell High water pressure Low water pressure Low sugar concentration Sink cell Sugar source High water pressure at the source: Sugar enters by active transport, water follows Low water pressure at the “sink”: Sugar exits, water follows

Division of Meristem Cells Causes Plant Growth Apical MeristemApical Meristem –tips of root and shoot –increase in height Lateral MeristemLateral Meristem –cylinders within plant body –increase in width

Plant Body Functions Exposes surface to sunlight Major site of photosynthesis Conserves water Provides for gas exchangeBlade Petiole Leaf = blade + petiole Stoma = opening in the leaf for gas exchange, water evaporation

Guard Cells Change Stoma Size to Control Transpiration Stoma opening Stoma closing StomaGuard cells Vacuole H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O K+K+ Potassium (K + ) enters vacuoles, water follows by osmosis, increased turgidity separates cells Potassium (K + ) exits vacuoles, water follows by osmosis, stoma closes as guard cells lose turgidity

Structures of the Leaf Photosynthesis Conserves water Transports water and sugar to stem and roots

Plant Body Stem: series of nodes and internodes Functions Holds leaves up to light Transports substances through vascular tissue Xylem conducts water and minerals Phloem transports sugar

Lateral Meristem Causes the Stem to Grow in Width

Wood and Bark are Products of Lateral Meristem

Plant Body Root Functions Anchors plant in soil Takes up water and minerals from soil Stores food Taproot Root hairs increase surface area

Routes of Water and Minerals from Soil to Vascular Tissue Extracellular route, via cell walls; stopped by Casparian strip Intracellular route, via cell interiors, through plasmodesmata Root hair Plasmodesmata Epidermis Endodermis Cortex Xylem Plasma membranes of root cells control water and mineral uptake

Applying Your Knowledge A.Where is the primary site of photosynthesis in a plant? B.Which one is responsible for an increase in plant height? C.Which one transports materials throughout the plant? 1.Apical Meristem 2.Vascular Tissue 3.Stem 4.Leaf 5.Lateral Meristem