4What is plant physiology? What is plant anatomy?ANATOMY: study of the structure of organisms… looking at cells, tissues(Morphology: Study of form)What is plant physiology?PHYSIOLOGY: study of the function of cells, tissues, organs of living things;and the physics/chemistry of these functions…
5“Structure correlates to function” Always keep in mind that in plant anatomy, morphology & physiology…“Structure correlates to function”
6How can water move fromthe groundall the wayto the topof a 100 mtall redwoodtree?
7Plant Anatomy: Cells Plant cells are basic building blocks Can specialize in form and functionBy working together, forming tissues, they can support each other and surviveLevels of organizationatoms > molecules > cells > tissues > organs > whole plant > pop.
8Plant Tissues TypesAll plant organs (roots, stems, leaves) are composed of the same tissue types.There are three types of tissue:1. Dermal – outermost layer2. Vascular – conducting tissue, transport3. Ground – bulk of inner layers
91. Dermal tissue Epidermis is the outermost layer of cells Like the “skin” of animalsIn stems and leaves, epidermis has cuticle, a waxy layer that prevents water loss.Some have trichomes, hairs.Root epidermis has root hairs, for water and nutrient absorption
102. Vascular tissueTransports water and organic materials (sugars) throughout the plantXylem – transports water anddissolved ions from the rootto the stem and leaves.Phloem – carries dissolved sugarsfrom leaves to rest of the plant
11Xylem Transports water and dissolved minerals Tracheids: long, thin tube like structures without perforations at the endsVessel elements: short, wide tubes perforated at the ends (together form a pipe, called vessel).Both cells have pits (thin sections) on the wallsTracheidsVessel elements
12Xylem cells Xylem cells are dead! They are hollow cells and consist only of cell wall
13Phloem Cells that transport organic materials (sugars) Phloem cells are ALIVE! (unlike xylem)However, they lack nucleus and organelles
14Phloem: transports sugars Phloem composed of cells called sieve tube members (STM)Companion cells join sieve tube members, are related, and help to load materials into STMEnd walls of STM have large pores calledsieve platesCompanion cellsSieve tube memberSieve plates
153. Ground tissue Makes up the bulk of plant organs. Functions: Metabolism, storage and support.Root Stem Leaf
16Plant OrgansOrgans: tissues that act together to serve a specific functionRootsStemsLeavesDermalVascularGroundDermalVascularGroundDermalVascularGround
17Functions of plant organs: ROOTS: Anchorage, water/nutrient absorption from soil, storage, water/nutrient transportSTEMS: Support, water/nutrient transportLEAVES: Photosynthesis (food production)
18ROOTS ROOTS “the hidden half” Functions of roots: Ancorage Absorption of water & dissolved mineralsStorage (surplus sugars, starch)Conduction water/nutrients
20Root Epidermis Outermost, single layer of cells that: Protects (from diseases)Absorbs water and nutrientsROOT HAIRS: tubular extensionsof epidermal cells.Increase surface area of root,for better water/nutrientabsorption
21Root Hairs: water and mineral absorption increase surfacearea for betterabsorption
22Root CortexStores starch, sugars and other substances
23You’re not a yam, you’re a sweetpotato! Root Ground tissueIn roots, ground tissue (a.k.a. cortex) provides support, andoften stores sugars and starch(for example: yams, sweet potato, etc.)You’re not a yam, you’re a sweetpotato!Hey!I yam what I yam, man!cortex
24Root Cortex: Endodermis Endodermis: the innermost layer of the cortex
25Root cortex: Casparian strip The Casparian strip is a water-impermeable strip of waxy material found in the endodermis (innermost layer of the cortex).The Casparian strip helps to control the uptake of minerals into the xylem: they have to go through the cytoplasm of the cell!
26STEMS Above-ground organs (usually) Support leaves and fruits Conduct water and sugarsthroughout plant (xylem and phloem)
27Stem anatomy Dermal, ground and vascular tissues… epidermis cortex pithVascularbundles
30Tissues of stems Epidermis (Dermal tissue type) Provides protection Has cuticle (wax) prevents water lossTrichomes (hairs) for protection, to release scents, oils, etc.
31Stem Vascular tissueVascular bundles – composed of both xylem and phloemXylemConducts waterSupportPhloemConducts foodVascularcambium
32Vascular cambium Occurs in woody stems Vascular cambium located in the middle of the vascular bundle, between xylem and phloem
33Vascular tissue: Trees Vascular tissue is located on the outer layers of the tree.barkwoodphloemVascular cambiumxylem
34Girdling: cutting around a tree Damages the phloem and xylem, eventually killing the tree!
35Vascular tissue forms rings in trees Annual rings: xylem formed by the vascular cambium during one growing seasonOne ring = one year
36History of the tree: annual rings Dendrochronology : tree time-keeping1917 & 1945: TreeSurvives two WorldWars1776: Declarationof US independence1969: Manlands on Moon1492: Columbus lands inthe Americas1620: Pilgrims landin Plymouth, Mass.1861: Start ofCivil War1489: Tree is plantedby Native American1971: Birth Yearof the IDIOTwho cut downthis tree!!!
38LEAVES: ‘Photosynthetic factories’ of the plant… Function: Photosynthesis – foodproduction for the whole plantBlade: Flat expanded areaPetiole: stalk that connectsleaf blade to stem, andtransports materialsBLADE
39Leaf Anatomy Leaf anatomy is correlated to photosynthesis: Carbon dioxide + Water sugars + oxygendermalgroundvasculardermal
40Leaf epidermis Is transparent – so that sun light can go through. Waxy cuticle protects against drying outLower epidermis: stomata with guard cells – for gas exchange (CO2, H2O in; O2 out)
42Leaf vascular tissue VEINS vascular tissue of leaves. Veins are composed of xylem (water transport) phloem (food transport)and bundle sheaths,cells surrounding thexylem/phloem forstrength & support
43Leaf Mesophyll Middle of the leaf (meso-phyll) Composed of photosynthetic ground cells:Palisade parenchyma(long columns below epidermis;have lots chloroplasts forphotosynthesis)Spongy parenchyma(spherical cells)with air spaces around,(for gas exchange)
44Plant water transport How can water move from the ground all the way to the topof a 100 mtall redwoodtree?
45Water transport in plants: The same way we drink sodafrom a straw!Water’s greatcohesive forces (moleculessticking to each other)and adhesive forces(attaching to walls of xylem cells)
46Transpiration-cohesion Theory for water transport in the xylem Evaporation of water in the leaves (through stomates) generates the ‘sucking force’ that pulls adjacent water molecules up the leaf surface
47Water transport (cont.) Like a long chain, water molecules pull each other up the column.The column goes from roots leaves.What’s amazing is that thewater moves up by using the sun’sevaporative energy…Plants control transpiration by opening/closing stomata
48Sugar translocation1. Sugars made in leaf mesophyll cells (source) diffuse to phloem cells in the vascular bundles.2. Companion cells load dissolved sugars into the phloem STM using energy (ATP).3. Water moves into cells with high sugar concentration.4. Osmotic water flow generates a high hydraulic pressure that moves dissolved sugars through the phloem to the rest of the plant (sink).
49Pressure flow in phloem Sugars made in the leaves are loaded into companion cells and into phloem STM.Water (from xylem) moves in by osmosis, creating pressure flow down the phloem.
50Plant Hormones Chemical compounds produced by plants Effective at very low concentrationsFive major hormone groups are:AuxinsGibberellinsCytokininsAbscisic AcidEthylene
511. AUXINS Promote cell growth Involved in gravitropism and phototropismControl fruit development