General Biology Lab
General Biology Lab BIOL 1121
Popular in Course
Popular in Biology
verified elite notetaker
This 22 page Class Notes was uploaded by Floy Quitzon III on Wednesday September 23, 2015. The Class Notes belongs to BIOL 1121 at Middle Tennessee State University taught by George Benz in Fall. Since its upload, it has received 6 views. For similar materials see /class/213217/biol-1121-middle-tennessee-state-university in Biology at Middle Tennessee State University.
Reviews for General Biology Lab
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/23/15
Like all organisms planTs sense and inTer39acT wiTh Their envir onmenT For39 example The gr owTh paTTer ns of planTs ar e ofTen guided by envir onmenTal cues such as lighT gr39aviTy and TacTile sTimuli OfTen These andor oTher cues iniTiaTe some dir ecTional response on The par T of The planT a posiTive r esponse ie Towar d someThing or a negaTive r esponse away from someThing Such dir ecTional responses are called Tr opisms For example a planT ThaT is posiTively phoToTr opic moves Towar d or or ienTs iTself To face lighT while one ThaT is negaTively phoToTr opic moves away from lighT Tr opisms allow planTs To Take advanTage of posiTive facTor39s and downplay negaTive facTor s AlThough planT responses can be observed on a macroscopic scale The mechanisms faciliTaTing These responses occur aT The cellular level Thus undersTanding planT Tropisms requires biologisTs To quotconnecTquot an environmenTal sTimulus wiTh The cellular percepTion of ThaT sTimulus by The planT which in Turn produces a quotsignalquot ThaT ulTimaTely induces a response by The planT Fyure 2 Of course lighT plays a criTical role in The lives of planTs and H can for example iniTiaTe seed germinaTion flowering and dormancy in addiTion To oTher Things In responding To lighT planTs exhibiT phoTomothoqenesis and phoToTropism PhoTomorphogenesis is lighTTriggered developmenT and iT can include such Things as seed germinaTion and flowering PhoToTropism is a direcTional response To lighT ie The planT bends Toward posiTively phoToTropic or away negaTively phoToTropic from The lighT The firsT sTep in a phoToTropic or phoTomorphogenic response is for The planT To perceive The sTimulus ie lighT PhoTorecepTors help planTs To quotperceivequot differenT wavelengThs of lighT wiTh blue and red wavelengThs being mosT common In This lecTure we will discuss The mechanisms via which planTs perceive red lighT See your fexfbook for Informa on on how pam s perceve bue 39g1 7 PlanTs use lighT recepTor compounds called phyTochromes in The process of perceiving red lighT of various wavelengThs A phyTochrome is a pigmenTconTaining proTein several Types have been found ThaT can exisT in Two inTerconverTible forms gure 3 For example Pr absorbs red lighT 660 nm wavelengTh P1r absorbs farred lighT 730 nm wavelengTh When Pr absorbs a phoTon of red lighT iT changes inTo P1r Fyure 3 When P1r absorbs a phoTon of farred lighT iT changes inTo Pr gure 3 Only P1r is biologically acTive regarding The inducTion of some planT responses Fyure 4 meaning ThaT iTs presence and noT The presence of Pr iniTiaTes specific biological responses NOTE ThaT H is acTually The proTein componenT of The phyTochrome ThaT iniTiaTes a signal TransducTion leading To a parTicular Tropism PhyTochromes are involved in many planT phoTomorphogenesis responses For example Seed germinaTion in many planTs is inhibiTed by far red lighT ThaT converTs The biologically acTive P1r To The biologically inacTive Pr and sTimulaTed by red lighT ThaT converTs Pr To The biologically acTive compound Pfr The ger minaTion of seeds on a for esT floor39 under a canopy of green leaves will be inhibiTed because chlor ophyll in The leaves absor bs r ed lighT beTTer39 Than iT does far39 r ed lighT The far r ed lighT passing Through The leaves will produce Pr fr om pr and Thus an inhibiTor y response will occur because no P1r exisTs again H is P1r ThaT is biologically acTive GerminaTion will be more likely To happen in The spring pr ior To The leaves for ming because aT ThaT Time r ed lighT will reach The for esT floor and conver T Pr To pr Thus The young planT will grow and wiThouT leaves above iT will more easily obTain sunlighT Gr aviTr opism is a response of a planT To The gr aviTaTional field of The ear Th ShooTs ar39e Typically neanively qr aviTr opic and hence They grow upwar ds RooTs ar e Typically posiTively qr aviTr opic and hence They grow downwar ds Following is an ouTline of The 4 sTeps ThaT lead To a gr aviTr opic response 1 Gr39aviTy The sTimulus is perceived by The cell 2 Signals form in The cell ThaT has per ceived gr39aviTy 3 The signals are Tr anslaTed inTr39a and inTercellular ly 4 Differ enTial cell elongaTion occur s beTween cells in The quotupquot and quotdownquot sides of The planT r ooTs or shooTs To affecT planT Tr opism planT movemenT Some of The sTeps in perceiving graviTy are sTill being sTudied and debaTed However amyloplasTs plasTids conTaining sTarch Fyure 5 may play a role in ThaT They may sink Toward The cyToskeleTon on one side The down side of a planT and in doing so They may somehow allow The planT hormone auxin To accumulaTe There The hormones auxin and eThyene will cause differenTial cell elongaTion ThaT in Turn will resulT for example in The upper sides of rooTs orienTed horizonTally growing fasTer Than The boTTom sides and hence rooT is posiTively graviTropic and grows downwards Fyure 6 ThigmoTropsim is a growTh response of a planT or a planT parT caused by conTacT wiTh an objecT or The wind For example when a planT Tendril Fyure 7 makes conTacT wiTh an objecT specialized epidermal cells perceive The objecT and They promoTe uneven growTh which causes The Tendril To curl abouT The objecT The hormones auxin and eThyene appear To be involved in Tendril movemenTs OTher Types of planT Tropisms ElecTroTropism response To elecTriciTy ChemoTropism response To chemicals TraumoTropism response To wounding ThermoTropism response To TemperaTure AeroTropism response To oxygen SkoToTropism response To darkness GeomagneToTropism response To magneTic fields HydroTropism responses To waTer noT all scienTisTs consider This a True Tropism Unlike Tropisms which are growThbased movemenTs in planTs some Touchinduced planT movemenTs are noT based on growTh responses InsTead They resulT from reversible changes in Turgor pressure of specialized cells A sTaTe of Tugorquot in a living cell is posiTively relaTed To The pressure wiThin The cell resulTing from diffusion of waTer osmosis inTo or ouT of The cell Changes in Turgor can resulT in planT movemenT Tugor movemenT JusT as changes in air pressure in a long rubber balloon can cause changes in The balloon39s posiTion For example many planTs including represenTaTives of The legume family Fabacae exhibiT leaf movemenTs in response To Touch or oTher sTimuli gure 8 These movemenTs are caused by changes in Turgor pressure in mulTicellular swellings locaTed aT The base of each leaf or leafleT ThaT are known as pulvini pl pulvinus sing For example when The leaves of The sensiTive planT Mmosa padca are sTimulaTed as for example by wind heaT or Touch an elecTrical signal is TranslaTed inTo a chemical signal gure 8 This chemical signal resulTs in poTassium ions and waTer migraTing from The cells in one half of each pulvinus To The inTercellular spaces in The oTher half of The pulvinus The resulTanT loss of Turgor in one side of The pulvini causes leavesleafleTs To foldmove This reacTion happens rapidly However as Time passes waTer will passively diffuse back inTo The low Turgor pressure cells and The leavesleafleTs will reTurn To Their normal posiTion Some planTs will use similar mechanisms To help Them follow The paTh of The sun wiTh Their leaf surfaces or allow Their leaves To droop a biT aT nighT To reduce TranspiraTion or open or close flowers aT various Times of day or nighT Circadian clocks or endogenous biorhyThms wiTh a period of abouT 24 hours exisT in planTs and many oTher organisms These rhyThms all share 4 characTerisTics gure 9 1 They musT conTinue To operaTe in The absence of exTernal inpuTs ie They are endogenous 2 They musT have a periodiciTy of abouT 24 hours 3 They can be reseT in various ways 4 They can compensaTe for noT be Thrown off by changes in TemperaTure The sensiTive planT menTioned above has a sTrong circadian clock IT opens iTs leaves and leafleTs during The day and closes Them aT nighT probably To conTrol iTs TranspiraTion raTe SomeTimes modifying The direcTion of growTh or alTering Turgor pressure is noT enough To proTecT The planT from harsh condiTions gure 10 The abiliTy To cease growTh and become dormanT provides a survival advanTage for some planTs by allowing Them To waiT ouT condiTions ThaT are unfavorable for growTh and survival EnvironmenTal sTimuli boTh iniTiaTe and end dormanT phases in The life of a planT and These phasealTering sTimuli can vary among planT species FacTors such as lighT TemperaTure and waTer availabiliTy can play large roles in The iniTiaTion and cessaTion of planT dormancy In TemperaTe areas winTer is associaTed wiTh planT dormancy During winTer freezing TemperaTures and The general unavailabiliTy of waTer make iT difficulT To impossible for many planTs To grow Globally seasonal periods of droughT play a large role in planT dormancy cycles Of course The seed provides an excellenT mechanism for a seed planT To remain dormanT and some seeds can remain dormanT for exTremely long periods of Time For example legumes planTs such as peas and beans have Tough seeds ThaT are impermeable To waTer and oxygen Such seeds ofTen can remain viable for decades buT They can germinaTe when Their seed coaTs have cracked and waTer is available In facT some seeds ThaT were Thousands of years old have been germinaTed In some insTances TemperaTure changes rapidly such ThaT planTs don39T have opporTuniTy To enTer dormancy Therefore iT should noT surprise us ThaT some planTs have mechanisms To proTecT Themselves from rapid lifeThreaTening environmenTal changes For example in freezing weaTher The formaTion of ice crysTals wiThin cells can cause cell deaTh Some planTs living in freezing environmenTs produce anTifreeze proTeins To decrease The TemperaTure aT which Their Tissues freeze High TemperaTures can also be problemaTic as They can denaTure proTeins Some planTs can produce heaT shock proTeins under said condiTions These special proTeins acT To sTabilize oTher proTeins under high TemperaTure condiTions For an overvew of seecfed sensory sysfems m pan 7 s see Fyure I I and for more defaIs regardHg any of 1056 sysfems read on furfher m your fexfbook Plan hormones are involved in plan responses o he envir39onmen as well as in r egulaing iner nal developmen Plan hormones of course are chemical subsances ha are produced by he plan They are ofen produced in very small quaniies in one par of he plan before being r39anspor39ed o where hey are needed elsewhere in he plan ofen bu no always via he phloem in vascular plans Hor mones can simulae cer39ain responses or physical processes or hey may inhibi hem How a par icular hor mone acs in a par icular insance is deer mined by he specific hor39mone involved as well as he specific issue ha r eceives he hor monal quotmessagequot There are 7 major caegor39ies of plan hor mones gures 12 1 13 auxins gibber ellins cyokinins abscisic acid ehylene br assinoser39oids and sysemin See gure 12 1 13 for summary mformafon on each of 1656 pam hormone ca fegoresfypes Auxin from he Greek word auxem o incr easequot Auxin was he fir s plan hor39mone o be discovered mor e han a cenur y ago Auxins pr omoTe sTem elongaTion and gr owTh The for maTion of advenTiTious r39ooTs The inhibiTion of leaf abscission or fr uiT abscission The pr omoTion of cell division The inducemenT of eThylene pr oducTion anoTher39 planT hormone and The pr omoTion of laTer39al bud dormancy Auxins also play an impor TanT role in The phoToTr opic responses of planTs And fur Ther yeT auxins play an impor TanT role in The r egulaTion of The gr owTh response To gr aviTy in The r ooT Tips of planTs Auxins are also involved in a gr eaT many oTher planT maTTer39spr39ocesses see your Tebeook for more deTails One form of auxin is known as IAA indoleaceTic acid indoleaceTic acid IAA r esembles and is probably synThesized from The amino acid Tr ypTophan Auxin is produced in sTem apical mer isTems regions of planT elongaTion as well as in some oTher immaTur e par39Ts of planTs eg in young leaves Auxins ar39e Tr39anspor39Ted via par enchyma cells in ground and vascular39 Tissues from The sTem apical mer isTems To The r ooT Tips before being Tr anspor Ted back upward and ouTwar ds Thr oughouT The planT body Fyure 14 How auxins work in planT sTems When lighT hiTs The Tip of a planT auxins are produced r efer To gure 15 The auxin produced on The lighTed planT side migr aTes To The dar ker planT side such ThaT The darker side has a gr eaTer concenTr aTion of auxin The auxin causes The cells on The dark side To elongaTe Fyure 15 and Thus The shooT bends Towar d The lighT Impor Tanle here in order for planT cells To elongaTe Their39 cell walls musT lack exTensive secondar y cell wall for maTion ie They musT be r elaTively young cells Cells wiTh Thick and inflexible secondar y cell walls are Too r igid To elongaTe Auxin aids in pr oducinq flexible cell walls and This is how auxin faciliTaTes cell elongaTion The presence of auxin causes r esponse cells To acTively Tr anspor T hydrogen ions from The cyToplasm inTo The cell wall space Fyure 16 This decreases The pHin The cell wall space and This decrease in pHacTivaTes enzymes ThaT can break bonds beTween cell wall fiber s As more and more cell wall fibers have Their inTer connecTing bonds broken The cell wall becomes more and more flexible This mechanism allows for a rapid response To an envir onmenTal signalsTimulus Auxins also moder aTe gr owTh in r ooTs Fyure 17 13 However in rooTs graviTy raTher Than lighT probably provides The sTimulus for The asymmeTric disTribuTion of auxin ThaT promoTes cell elongaTion on one side of The rooT AnoTher difference beTween auxin39s acTion in sTems vs rooTs is The facT ThaT in rooTs high concenTraTions of auxin inhibiT growTh while lower concenTraTions sTimulaTe growTh FyLre 17 This is because high concenTraTions of auxin promoTe The producTion of eThylene anoTher planT hormone ThaT inhibiTs The growTh of rooT cells SynTheTic auxins such as NAA naphThalene aceTic acid and IBA indolebuTyric acid have many uses in agriculTure and horTiculTure For example synTheTic auxins are used To prevenT or posTpone fruiT drop in apples before The fruiT is ripe hold berries on holly promoTe flowering and fruiTing in pineapples induce rooT formaTion in cuTTings and more SynTheTic auxins are also used To conTrol weeds For example The synTheTic auxin known as 2 4D kills eudicoT weeds when applied To lawns by causing The cessaTion of all axial growTh AnoTher synTheTic auxin ThaT was used as a broadspecTrum herbicide To kill weeds and seedlings in woody planTs is 24 5 T 24 5T became noTorious during The VieTnam War as a componenT of The Jungle defolianT known as agenT orange AgenT orange was banned in 1979 for mosT uses in The US because when iT is manufacTured H is unavoidably conTaminaTed wiTh a compound known as dioxin Dioxin even in doses as small as a few parTs per million is known To cause liver and lung disease leukemia miscarriages birTh defecTs and even deaTh in laboraTory animals CyTokinins are a class of planT hormones ThaT TogeTher wiTh auxin sTimulaTe planT cell division and differenTiaTion ThaT deTermines The physical form of The planT CyTokinins appear To be a derivaTive of The purine base adenine MosT cyTokinins are produced in The rooT apical merisTem and are TransporTed ThroughouT The planT via The phloem Developing fruiT is also a siTe of cyTokinin synThesis CyTokinins promoTe The growTh of laTeral buds inTo branches while The presence of auxin inhibiTs such growTh gure 18 Thus when one pinches off The apical merisTem of a shooT ie The siTe of auxin producTion The quotpowerquot of cyTokinins Takes over and The laTeral buds JusT below will form branches gure 18 Regarding rooTs cyTokinins inhibiT The formaTion of laTeral rooTs while auxins promoTe laTeral rooT formaTion 15 CyTokinins appear To funcTion by promoTing The synThesis or acTivaTion of proTeins ThaT are specifically required for miTosis IT39s inTeresTing and imporTanT ThaT some planT paThogens such as The bacTeria Agrobacferum spp can inTroduce genes inTo a planT ThaT will increase The raTe of cyTokinin and auxin producTion This causes massive cell division and The formaTion of a Tumor called a crown gall Fyure 19 Various raTios of cyTokininsauxins in The planT can deTermine if shooTs rooTs or undifferenTiaTed planT Tissues will be formed Fyure 20 Gibberellins comprise a large class planT hormones wiTh over 100 known forms While gibberellins funcTion endogenously ie inTernally as hormones They also funcTion as pheromones ie exogenoust or exTernally in ferns In ferns gibberellinlike compounds released from one gameTophyTe can Trigger The developmenT of male reproducTive sTrucTures on a neighboring gameTophyTe Gibberellins are synThesized in The apical porTion of sTems and rooTs They acT by promoTing sTem elongaTion as well as by sTimulaTing enzyme producTion in germinaTing seeds gures 21 1 22 Of course enzymes are needed by The developing embryo for The uTilizaTion of food resources gures 21 cf 22 In some cases gibberellins hasTen seed germinaTion apparenle by subsTiTuTing for The effecT of cold or lighT requiremenTs Gibberellins are used commercially To exTend The inTernode beTween grape flowers such ThaT The fruiT has more room To grow This resulTs in larger grapes The elongaTion effecT caused by gibberellins is enhanced if auxin is also presenT The hormone abscisic acid appears To be synThesized mainly in maTure green leaves fruiTs and rooT caps Abscisic acid levels become greale elevaTed when a planT is subjecT To sTress especially during droughT Abscisic acid suppresses The growTh of buds and H promoTes leaf senescence Thus iT seems ThaT abscisic acid can counTeracT some of The elongaTion effecTs of gibberellins as well as The senescence reTarding effecT of auxin Abscisic acid also plays a role in seed dormancy ie as an anTagonisT To gibberellins during germinaTion And abscisic acid also affecTs The closing of sTomaTa by influencing The movemenT of poTassium ions ouT of guard cells EThylene HzCCHZ is a simple gaseous hydrocarbon ThaT is a naTurally occurring planT hormone EThylene can reTard laTeral bud growTh suppress sTem and rooT elongaTion hasTen The ripening of fruiT Fyure 23 and cause leaf Fyure 24 flower and fruiT abscission EThylene gas is widely used To commercially ripen TomaToes lemons and oranges Transgenic TomaToes ie TomaToes inTo which special genes have been inserTed have been produced so ThaT eThylene producTion is halTed These fruiTs can be shipped green unripe when They are harder and less easily bruised LaTer They can be ripened arTificially by exposing Them To eThylene gas InTeresTingly carbon dioxide noT considered a planT hormone has an effecT opposiTe To ThaT of eThylene on fruiT ie iT keeps fruiT from ripening And Thus some fruiTs such as apples are sTored and shipped in a C02 aTmosphere To delay ripening and increase sTore shelf life BrassinosTeroids show some similariTies To animal sTeroid hormones and iT is plausible ThaT Their evoluTionary origin predaTed The planTanimal spliT in evoluTion AssociaTed wiTh pollen immaTure seeds shooTs and leaves brassinosTeroids promoTe a broad specTrum of physiological effecTs including elongaTion cell division bending of sTems vascular Tissue developmenT delayed senescence membrane polarizaTion and reproducTive developmenT Many of The funcTions of brassinosTeroids overlap wiTh Those of auxins and gibberellins EnvironmenTal signals can Trigger brassinosTeroid acTions Like oTher organisms planTs can be aTTacked by a varieTy of viruses bacTeria fungi animals and even oTher planTs Therefore iT shouldn39T surprise us ThaT planTs use a varieTy of mechanisms To defend Themselves For example The Thick cuTicle and cell walls of planTs cerTainly provide proTecTion as do bark Thorns and some Trichomes And as we have already discussed axillary buds provide a second chancequot for conTinued growTh for many planTs ThaT have losT Their apical shooT Tips apical merisTems BuT in addiTion planTs can use a varieTy of compounds as Toxins To proTecT Themselves and in doing so various sensory and communicaTion mechanisms may come inTo play As a group planTs can poison Their enemies in number of ways For example over 3000 planT species produce cyanide conTaining compounds called cyanogenic glycosides These compounds break down inTo cyanide when They are ingesTed by animals Exposure To cyanide causes deaTh in animals because cyanide sTops elecTron TransporT and Thus iT blocks cellular respiraTion Many planT Toxins ThaT kill or oTherwise negaTively affecT herbivores are generally made by planTs as secondary meTaboliTes Secondary meTaboliTes are producTs of meTabolism ThaT are noT essenTial for The normal growTh developmenT or reproducTion of The organism ThaT produces Them For example alkaloids such as caffeine nicoTine morphine and cocaine are used by planTs To eiTher oversTimulaTe or sedaTe enemies such ThaT The survival of Those enemies is reduced or The negaTive acTions of The enemy againsT The planT are lessened Tannins anoTher Type of planT secondary meTaboliTe bind To proTeins and inacTivaTe Them So for example Tannins can block animal enzymes from digesTing planTs such ThaT an animal ThaT eaTs a loT of planT maTerial is sickened Various oils produced by planTs such as pepperminT and sage planTs help To repel aTTacks by herbivorous insecTs PlanTs generally use Two sTraTegies To keep Themselves from being harmed by The Toxins They produce 20 One sTraTegy is To sequesTer The Toxin in a membranebound sTrucTure so ThaT iT can39T harm The planT A second sTraTegy is for The planT To produce a compound ThaT is nonToxic unless iT is meTabolized ofTen by microorganisms in The guT of an herbivore Cyanogenic glycosides menTioned above are examples of This second sTraTegy and in This case The planT produces a sugarbound cyanide compound ThaT doesn39T affecT eecTron TransporT If however an animal ingesTs The sugarbound compound The compound is enzymaTically broken down such ThaT cyanide is released Some chemical Toxins are used by panTs To proTecT Themselves from oTher panTs For example a process known as allelopaThy occurs when a chemical signal secreTed by The rooTs of one planT block germinaTion of nearby seeds or inhibiT The growTh of a nearby planT Humans have used secondary planT meTaboliTes for boTh good and evil for aT leasT The lasT 2000 years For example The Greek philosopher SocraTes 470399 BC died he was execuTed afTer he drank a hemlock exTracT conTaining an alkaloid ThaT paralyzes moTor nerve endings Some secondary planT meTaboliTes can mimic sTrong human hormones when ingesTed For example soy and some oTher panTs conTains phyToesTrogens ie compounds so similar To human esTrogen ThaT They can bind To human esTrogen recepTors We are noT yeT sure whaT all of The ramificaTions of This are ie is This good bad or neiTher regarding human healTh 20 21 Taxol is anoTher secondary planT meTaboliTe ThaT is used by humans Taxol is used To fighT breasT cancer Quinine is a secondary planT meTaboliTe found in The bark of The cinchona Tree Quinine has been used since The 160039s To fighT malaria a disease caused by several species of parasiTic proTisTs ThaT are TransmiTTed by cerTain species of mosquiToes Wound responses have advanTages over sTaTic defense mechanisms such as The producTion of alkaloids The advanTage lies in The facT ThaT wound responses conserve energy ie defense compounds are only produced when They are needed An example of such a wound response would be The producTion of proTeinase inhibiTors When a leaf for example is chewed by an herbivore proTeinase inhibiTors are rapidly produced ThaT will bind To The digesTive enzymes in The guT of The aTTacker When The herbivore ingesTs a large amounT of These inhibiTors iT geTs sick As a resulT herbivores use TasTe To avoid planT Tissues wiTh high concenTraTions of These proTecTive molecules The process ThaT resulTs in The producTion of The proTeinase inhibiTors is as follows Fyure 25 1 The wounded leaves produce an 18amino acid pepTide hormone called sysTemin 2 sysTemin moves beTween The cell walls of The wounded cell area inTo The phloem and iT Then circulaTes ThroughouT The planT body 3 cells wiTh a sysTemin recepTor bind The sysTemin and This leads To The producTion of 39asmonic acid and 21 22 4 Jasmonic acid signals gene expression which in Turn leads To The producTion of The proTeinase inhibiTor AlThough some wound responses may be independenT of The specific idenTiTy of The aTTacker oTher planT responses are iniTiaTed by a specific paThogen ThaT has a specific gene allele ThaT produces a specific recognizable proTein The presence of The specific allele faciliTaTes The aTTacker39s desTrucTion by The planT via a mechanism known as The qeneforqene model of planT response Via This mechanism wounding by a specific paThogen causes a planT resisTance gene To produce a compound R see gure 26ThaT inTeracTs wiTh a paThogen avirulence gene producT avr see FyLre 26 This inTeracTion leads To The Triggering of The hypersensiTive response HR which in Turn leads To rapid cell deaTh around The source of The invasionproblem m also To a longerTerm resisTance The resulT is ThaT This process seals off The wounded area of The planT and Thus prevenTs furTher invasion In The case of virulenT disease causing invaders There is no R gene producT recogniTion and hence no HR response as in The case of The bacTerium in gure 26 In such a case however There may be oTher changes ThaT aT leasT parTially block The movemenT of The paThogen or pesT furTher inTo The planT ie oTher wound responses In some insTances planTs and animals Typically insecTs have coevolved such ThaT They live in a symbioTic relaTionship in which The animal proTecTs The planT 22
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'