MldLerm 2 Muluple Cholce:30 Cuesuons = 100 pL Coverlng chapLers :19, 20, 21, 22, 23,24, 23, 26, 27, 28, 29. 30 Creen scanLronWhen Louched, Lhe leaves of Lhe sensluve planL (!"#$%& ()*"+&, qulckly fold, and only slowly unfold 2 ChapLer 28 llowerlng lanL 8ehavlor 3 ChapLer 28 llowerlng lanLs: 8ehavlor Cverv|ew of |ant 8ehav|ora| kesponses |ant kesponses to L|ght |ant kesponses to Grav|ty and 1ouch |ant kesponses to Auack ChapLer CuLllne: 1lme-lapse phoLography shows LhaL mosL planLs are constant|y |n monon 8endlng, Lwlsung, or roLaung - known as nutanonCLher examp|es of p|ant behav|or: ShooLs grow Loward llghL and agalnsL gravlLy 8ooLs grow Loward waLer and Loward gravlLy Seeds germlnaLe when Lhey deLecL llghL and molsLure llowers, frulL, and seeds grow only aL Lhe rlghL seasonlanLs respond Lo auack by mlcrobes or anlmals Cverv|ew of |ant8ehav|ora| kesponses 8esponses Lo lnLernal and exLernal sumull Interna| snmu|| Chemlcal slgnals - hormones, phyLohormones or planL growLh subsLances Cen lnLeracL wlLh each oLher and exLernal slgnals Lo malnLaln homeosLasls and progress Lhrough llfe sLages Lnv|ronmenta| snmu|| LlghL, aLmospherlc gases (CC2 and waLer vapor), LemperaLure, Louch, wlnd, gravlLy, waLer, rocks, and soll sumull Perblvores, paLhogens, organlc chemlcals from nelghborlng planLs, and beneclal or harmful soll organlsms AgrlculLural chemlcals lncludlng hormones 3 WhaL lanLs 1alk AbouL 6 CopyrlghL 1he McCraw-Plll Companles, lnc. ermlsslon requlred for reproducuon or dlsplay. 8|o|og|ca| snmu||hys|ca| snmu|| Lnv|ronmenta|: L|ght Atmospher|c gases |nc|ud|ng CC2 num|d|ty 1emperature 1ouch, w|nd Grav|ty So|| water kocks and Cther barr|ers So|| m|nera|s Interna|: c|rcad|an rhythms hormones Lnv|ronmenta|: nerb|vores Agr|cu|tura| hormone app||canons athogens Crgan|c chem|ca|s em|ued by other p|ants So|| m|croorgan|sms SLrucLural barrlers (cuucles, epldermal Lrlchomes, and ouLer bark) help Lo reduce lnfecuon and herblvore auack nerb|vore auack Wlde varleLy of chemlcal defenses Make planLs LasLe bad Some chemlcals auracL enemles of Lhelr auackers or cause nelghbor planLs Lo produce defenslve compounds 7 |ant kesponses to Auack L||c|tors are molecules produced by bacLerlal and fungal paLhogens LhaL promoLe lnfecuon lanLs have several defense sLraLegles |asma membrane receptors LhaL blnd mlcroblal molecules, such as llpopolysaccharldes or chlunLncoded by k genes (res|stance genes) M|crokNAs ln Lhe cyLosol desLroy Lhe nuclelc acldsof lnvadlng vlruses keceptors |n the cytoso| recognlze ln[ecLed ellcLors, Lrlggerlng Lhe producuon of chemlcal defenses or programmed cell deaLh aLhogen auack nypersens|nve response (nk) Cccurs when a planL recognlzes a paLhogen by chemlcal means and responds ln such a way LhaL Lhe dlsease sympLoms are llmlLed Several componenLs lncludlng lncreased producuon of hydrogen perox|de N|tr|c ox|de also produced SynLhesls of hydrolyuc enzymes, defenslve secondary meLabollLes, Lhe hormone sallcyllc acld, and Lough llgnln ln cell walls of nearby ussues 9 lanL responses keceptor mo|ecu|es locaLed ln planL cells sense varlous klnds of sumull and lead Lo approprlaLe responses ex: hototrop|sm - lnvolves boLh a cellular percepuon of llghL and a growLh response of sLem ussue Lo an lnLernal chemlcal slgnal (auxln) 10 System|c acqu|red res|stance (SAk) Locallzed hypersensluve response can resulL ln Lhe producuon of alarm slgnals LhaL Lravel Lo nonlnfecLed reglons of a planL and lnduce wldespread reslsLance Lo dlverse paLhogens Iasmon|c ac|d May produce defenslve enzymes or tann|ns (Loxlc Lo mlcroorganlsms) 11 12 CopyrlghL 1he McCraw-Plll Companles, lnc. ermlsslon requlred for reproducuon or dlsplay. Methy| sa||cy|ate S|tes of pathogen auack Defens|ve responses Defens|ve responses System|n Iasmon|c ac|d Defens|ve responses System|n Iasmon|c ac|d Defens|ve responses Sa||cy||c ac|d Sa||cy||c ac|d lanL slgnal Lransducuon rocess ln whlch a cell percelves a slgnal, swlLchlng on an lnLercellular paLhway LhaL leads Lo cellular response 1hree sLages 1.keceptor acnvanon 2.1ransducnon of the s|gna| vla second messengers 3.Ce||u|ar response vla eecLor molecules 13 8ased on Lhe presence of llghL recepLors wlLhln cells hoLorecepLors respond Lo llghL absorpuon by swlLchlng on slgnal Lransducuon 8esulLs lnSun Lracklng hoLoLroplsm llowerlngSeed germlnauon 14 |ant kesponses to L|ght A planL llghL-swlLch" 8ed- and far-red-llghL recepLor lllps back and forLh beLween 2 conformauons lays a crlucal role ln photoper|od|sm andplanL responses Lo shad|ng 13 hyLochrome hoLoperlodlsm hyLochromes play a crlucal rolelnuences Lhe umlng of dormancy and owerlng llowerlng planLs can be classled as |ong-day, short-day, or day-neutra| accordlng Lo Lhe way Lhelr owerlng responds Lo nlghL lengLh |ants measure n|ght |ength - -$. day lengLh 16 Shadlng responses Also medlaLed by phyLochrome8esponses lncludeLxLenslon of leaves from shady poruons of a dense Lree canopy lnLo Lhe llghL CrowLh LhaL allows planLs Lo avold belng shaded by nelghborlng planLs Cccur by Lhe elongauon of branch lnLernodes Leaves deLecL shade as an lncreased proporuon of far-red llghL Lo red llghL 17 |ant kesponses toGrav|ty and 1ouch Why do planL sLems grow up and rooLs grow down? 8esponses Lo gravlLy and Louch Grav|trop|sm CrowLh ln response Lo Lhe force of gravlLy ShooLs are sald Lo be negauvely gravlLroplc MosL rooLs are posluvely gravlLroplc 19 koots encounter rocks as Lhey grow down 1ouch response Lemporarlly supersedesLhe response Lo gravlLy 8ooLs grow horlzonLally unul Lhey geL aroundLhe barrler, Lhen downward growLh ln response Lo gravlLy resumes 20 CravlLy and Louch response are relaLed 21 Chapter 29 llowerlng lanLs: nuLrluon and 1ransporL |ant Nutr|nona| kequ|rements 1he ko|e of So|| |n |ant Nutr|non 1ransport at the Ce||u|ar Leve| Long D|stance 1ransport |n |ants ChapLer CuLllne: Nutr|ent - subsLance meLabollzed by or lncorporaLed lnLo an organlsm Dehc|ency symptoms develop ln planLs LhaL recelve Loo llule of a nuLrlenL ScarclLy of nuLrlenLs selecLs for adaptanons LhaL help ln acqulrlng nuLrlenLs 22 |ant Nutr|nona| kequ|rements 23 C2 L|ght Carbon d|ox|de (CC2) gas Cxygen (C2) gas Water (n2C) D|sso|ved m|nera| |ons (k+,NC3-,Ca2+,and so on) L|m|nng factors - lacLors LhaL can llmlL growLh WaLer LlghL Carbon dloxlde CLher mlneral nuLrlenLsllg. 29.13CopyrlghL McCraw-Plll Lducauon. ermlsslon requlred for reproducuon or dlsplay. A turgid cell is one in which the plasma membrane presses tightly against the cell wall. (a) Turgid cell in a hypotonic solution Vacuole Solute Cell wall Plasma membrane Water A plasmolyzed cell is one in which so much cell water has been lost by osmosis that the plasma membrane contorts away from the wall. (b) Plasmolyzed cell in a hypertonic solution A flaccid cell is one in which the plasma membrane does not press tightly against the cell wall. Plasma membrane Plasma membrane (c) Flaccid cell in an isotonic solution llg. 29.23 Thickened inner walls Radially oriented cellulose microfibrils Guard cells attached at their ends Pore opens as guard cells increase in length and volume, and bend. (b) The roles of radial orientation of cellulose microfibrils and thickened inner walls in opening or closing guard cells (a) Stomatal guard cells 8.5 m a: Andrew Syred/SL/Sclence Source CopyrlghL McCraw-Plll Lducauon. ermlsslon requlred for reproducuon or dlsplay. 1ransporL of waLer and soluLes ln planLs 1.Across Lhe cell membrane Csmosls, dluslon, membrane LransporL 2.ShorL dlsLances (ussue level) Membrane LransporL and oLher mechanlsms 3.Long dlsLances (xylem, phloem) ressure drlven, bulk ow Campbell 8lology llgs ass|ve transport S|mp|e D|us|on Iac|||tated d|us|on Acnve transport A1n2C1urg|d (norma|)n2Cn2CI|acc|dn2C|asmo|yzedCSMCSIS uluslon of waLer uown concenLrauon gradlenL vla passlve LransporL-no energy requlred Across a selecuvely permeable membrane ASSIVL VS. AC1IVL 1kANSCk1 of other mo|ecu|es [summarlzed on nexL sllde] MovemenL Across Membranes 1. Slmple dluslon (asslve LransporL) ulrecL movemenL across membrane uown concenLrauon gradlenL usually small, hydrophoblc (CC2, C2, hydrocarbons) 2. laclllLaLed dluslon (asslve LransporL) 1ransporL proLelns requlred uown concenLrauon gradlenL used for hydrophlllc molecules (polar, lons, eLc) 3. Acuve LransporL 1ransporL proLelns requlred AgalnsL concenLrauon gradlenL-requlres A1 used for any molecule agalnsL lLs conc. gradlenLFig. 29.14 Also see 29.24how stomata open/close CopyrlghL McCraw-Plll Lducauon. ermlsslon requlred for reproducuon or dlsplay. Epidermal root hairs Root tip Soil particle Proton pump NH4+ Root hair K+ H2O PO42 H+ H+ 1ransporL aL Lhe cell membrane Cauon exchange 1)ass|ve: s|mp|e or fac|||tated d|us|on 2)Acnve:requ|res A1 e|ther d|rect|y or |nd|rect|y Fig. 29.12 CopyrlghL McCraw-Plll Lducauon. ermlsslon requlred for reproducuon or dlsplay. Shoot system O2 Organic compounds Xylem (simplified) CO2 Atmosphere Phloem (simplified) Soil Water Minerals (e.g., PO42; NH4+) O2 Root system Long-dlsLance Lravel 8u|k owmass movement of ||qu|d due to pressure, grav|ty or both. App||es to movement |n xy|em and ph|oem. n2C Fig. 29.20, 29.21 CopyrlghL McCraw-Plll Lducauon. ermlsslon requlred for reproducuon or dlsplay. Air Cuticle Mesophyll Upper epidermis Lower epidermis Cuticle Xylem Dry air H2O CO2 O2 CO2 H2OO2 Stomate Stream of water Xylem cells Cohesion by hydrogen bonding Cell wall (b) Cohesion in xylem causes water to form a continuous stream. (a) Transpiration occurs when leaf water is exposed to drier air. Air Meniscus (c) When water evaporates, the surface tension increases in the intercellular spaces of cells, pulling on the water stream in xylem. Water stream in xylem Vessel cell wall Evaporation of water Mesophyll cells Water film Long-dlsLance Lravel: xylem Cohes|on-tens|on theory 1ransp|ranon:causes tens|on (neganve pressure) n-bond|ng:cohes|on, adhes|on, moves co|umns of water Water moves from reg|ons of h|gher water potenna| to reg|ons of |ower water potenna|. Water potenna| grad|ent n2C AdapLauons for survlval Llmlung facLor WaLer Leaf, cell, fungl LlghL Leaf, cell, seed, fungl CC2 Leaf, L carboxylase Cuticle Stomata Mesophyll I|g. 29.21 (Ch|orophy|| and caroteno|ds) Fig. 29.24 CopyrlghL McCraw-Plll Lducauon. ermlsslon requlred for reproducuon or dlsplay. Pore K+ K+ H+ H+ + Closed stomate Open stomate Blue light stimulates H+ -ATPase proton pumps, providing the membrane potential needed for guard cells to import K+ and sugar. As a result, water enters by osmosis via aquaporin channels. The water-swollen guard cells separate, opening the pore. ChloroplastBlue light H+ Proton pump sugar H2O H2O H+ + sugar Aquaporin A stomate in the process of opening ATP ADP+Pi Closed stomate Open stomate (b) The process of stomate closing (a) The process of stomate opening H2O K+ K+ H2OCl! Ca2+ Ca2+ ABA receptor ABA A stomate in the process of closing At night or under conditions of water stress that stimulate ABA production, K+ and other solutes exit guard cells. This causes water to leave, deflating guard cells and closing the pore.