Week 7: Chapter 24/25 & Lecture Notes
Week 7: Chapter 24/25 & Lecture Notes BIOL 1306/1106
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This 16 page Class Notes was uploaded by Hayley Lecker on Friday October 9, 2015. The Class Notes belongs to BIOL 1306/1106 at University of Texas at El Paso taught by Anthony Darrouzet-Nardi in Fall 2015. Since its upload, it has received 73 views. For similar materials see Organismal Biology in Biology at University of Texas at El Paso.
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Date Created: 10/09/15
Biology Week 7 Important Information Professor s Email aidarrouzetnardiutepedu or anthonvdnutepedu All vocabulary will be defined at the end of the notes Chapter 24 241 The Plant Body is Organized and Constructed in a Distinctive Way The vegetative organs of flowering plants are roots which form a root system and stems and leaveswhich together with flowers are sexual organs form a shoot system Example below r Terminal bud f Axillary bud ai Phytomer Node The shoot system consists of stems so and leaves in l a which photosynthesis takes place The root system anchors the plant and provides water and nutrients for the Roots shoot system PRINCIPLES OF LIFE 29 Figure 241 o 2014 Sinauer Associates Inc Plant development is influenced by three unique properties of plants compared with animals meristems the presence of cell walls and the totipotency of most plant cells During embryogenesis the apicalbasal axis and the radial axis of the plant body are established as the shoot apical meristem and the root apical meristem Epidermis dermal Shoot Ground Vascular Root Apical basal Radial pattern axis Y Apical basal pattern PRINCIPLES OF LIFE 2 Figure 244 nH inquot Aumuin In The three tissue systems arranged concentrically extend throughout the plant body the dermal tissue system group tissue system and vascular tissue system The ground tissue system carries out photosynthesis stores photosynthetic products and helps support the plant The dermal tissue system is the outer covering of the plant Shoot apical meristem The vascular tissue system conducts water and solutes throughout the plant Dermal Root Seedling apical meristem PRINCIPLES OF LIFE 22 Figure 246 39222 2014 Sinauer Associates Inc The vascular tissue system includes xylem which conducts water and mineral ions absorbed by the roots to the shoot and phloem which conducts the products of photosynthesis throughout the plant body 242 Apical Meristems Build the Primary Plant Body Primary growth is characterized by the lengthening of roots and shoots and by the proliferation of new roots and shoots through branching Some plants also undergo secondary growth by which they increase in thickness LLLi39 quot39TiL 39GI1 lwr39nzluzl 4le A I 31 rlt l T 39 I c metenmnnl budcontans ii in ashootaplmlmerlstem 39 A39mlluIg hurl m 7 quot1741 I In woody plants the vascular cambium and cork cambium quot 1 thicken the stem and root I Lateral meristems quotwk imwln LIFE 9e Figure 3410 Apical meristems generate primary growth and lateral meristems generate secondary growth Apical meristems at the tips of shoots and roots give rise to three primary meristems protoderm ground meristem and procambium which in turn produce the three tissue systems of the plant body The root apical meristem gives rise to the root cap and the three primary meristems The cells in the root tip are arranged in three zones that grade into one another the zone of cell division the zone of cell elongation and zone of cell maturation Bl Lpidem39u Dew apart lateral 3900 I Corex Erufiodermls Stale lCi Zorn GI 1039 n I ll4ll39 illI l1 Primary meristems Zurzn ml 1031 congaAil pf 39llldellll 239 39i 7 I139mnl menstan I PIC111ml39m 1m New daughter cells are produced in the root apical meristem Most daughter cells dll ereuuale Into the Dflm f tissues of tho root CIHIIISL39IOHC Url39lf i Some daughtcr cons become part of the root cap which is Constantly being erodeo away PRINCIPLES OF LIFE Ze Figure 248 H 2014 Smauer ASSOUleS Inc The vascular tissue of roots is contained within the stele It is arranged differently in eudicot and m OhOCOt FOOtS The root system of eudicots typical consists of a taproot and lateral roots Monocots typically have a fibrous root system made up of adventitious roots A Taproot system B Fibrous root system Leaves bulb Adventitious roots PRII V CIPLES 2F LIFE 22 Figure 2410 In stems the vascular tissue is divided into vascular bundles each containing both xylem and phloem Eudicot leaves have two zones of photosynthetic mesophyll cells that are supplied by veins with water and minerals The organs of the primary plant body may be modified to perform specialized functions Tendril modified leaf Shoots Runner horizontal stem PRINCIPLES OF LIFE 29 Figure 2413 Part 3 2014 Sinauer Associates lnc 243 Many Eudicot Stems and Roots Undergo Secondary Growth Two lateral meristems the vascular cambium and cork cambium are responsible for secondary growth The vascular cambium produces secondary xylem this is wood and secondary phloem inner bark The cork cambium produces a protective tissue called cork Secondary Vascular xylem cam bium Cork one year s growth Bark cambium Cork Pith Spring Summer Secondary wood wood phloem PRINCIPLES OF LIFE 2e Figure 2415 2014 Sinauer Associates lnc 244 Domestication Has Altered Plant Form Although the plant body plan is simple it can be changed dramatically by minor genetic difference as evidenced by the natural diversity of wild plants Crop domestication involves artificial selection of certain desirable traits found in wild populations As a result of artificial selection over many generations the body forms of crop plants by very different from those of their wild relatives Chapter 25 251 Plants Acquire Mineral Nutrients from the Soil Plants are photosynthetic autotrophs that require water and certain mineral nutrients to survive The obtain most of these mineral nutrients as ions from the soil solution The essential elements for plants include six macronutrients and several micronutrients Plants that lack a particular nutrient show characteristic deficiency symptoms The essential elements were discovered by growing plants hydroponically in solutions that lacked individual elements Soils supply plants with mechanical support water and dissolved ions air and the services of other organisms Protons take the place of mineral nutrient cations bound to clay particles in soil in a process called ion exchange Farms may use shifting agriculture or fertilizer to make up for nutrient deficiencies in soil Element e eieney Leeyee e ltght eotor errd to yethw hogeh at ot39 t that growth drttee ty Ml II Leeyee e dart greerr or grey mtth tehee Lorrg terrrr reeotte to poor root 39tor39rrretiort New deyetog errd quotm gllll errd dry Lorrg term growth errd as poor root torrrr tioh Leeyee yetlow errd deyetog bt Wt t hot teat greerr Erode do hot deyetog Leeyee tarowh mtth dart yetlow errd Ettltl tip 5 Lead yetlow errd become dart WWW rteer ot39 t E heeorrte torrr mm tarowh the errd mm heeorrre ty troh Leeyee dry out errd orthttty greeh v Leeyee deyetog e ererree errd growth llulerrgerreee l1 Hm HIPS Growth rate ot39 t or Stops Eaquot me m Leeyee dart hrowh errd t39e t ott39 other trace 252 Soil Organisms Contribute to Plant Nutrition Signaling molecules called strigoactones induce the hyphae of arbuscular mycorrhizal fungi to invade root cortical cells and form arbusculars which serve as sits of nutrient exchange between fungus and plant See Part A below Root hair Cortical cells Root hairs release Ej Ham room prom chemical signals strigolactories that Stimulate that antact rhizobia rapid growth of fungal hyphae 3 toward the root 39 2 Fihizobia proliferate and cause a root hair to curl and infection an 39nfection thread tofonn j oohFungal Signal Fungal signal stimulates plant to produce a pre jmetwim apparatus PPA J Stimulated by Nod factors r secreted by bacteria root cells begin to divide J 3 Fungal hypha enters the PPA and is gu ded to the root codex through the apoplast The infection thread grows into the cortex of the root I Fungts grows along eff J the root length The infection thread releases 1 bacterial cells which become bacteroids in the root cells Hyphae induce formation of new PPA structu39es inside cortical cells The nodule forms as plant cells continue to divide and become infected with bacteria 0 l Hyphae enter PPAs and branch to form arbuscules where nutrients are exchanged Bacteroids PRINCIPLES OF LIFE Figure 255 2012 Sinauer Associates Inc Legumes signal nitrogenfixing bacteria rhizobia to form bacteroids within nodules that form on their roots See Part B above In Nitrogen fixation nitrogen gas N2 is reduced to ammonia in a reaction catalyzed by nitrogenase A reducing agent transfers three The final products two molecules successive pairs of hydrogen atoms to N2 Of ammonia are released freeing The enzyme n39TrOgenase b39nds X the nitrogenase to bind another N2 a molecule of nitrogen gas A molecule f Substrate 2 2 5 2 it Nitrogen gas N y 2 we a Product Ammonia NHB Nitrogenase 4 Enzyme Enzyme binds Nitrogenase substrate PRINCIPLES OF LIFE Figure 256 2012 Sinauer Associates lnc Reduction Reduction Reduction Carnivorous plants supplement their nutrient supplies by trapping and digesting arthropods Parasitic plants obtain minerals water or products of photosynthesis from other plants 253 Water and Solutes Are Transported in the Xylem by TranspirationCohesionTension Water moves through biological membranes by osmosis always moving toward regions with more negative water potential The water potential of a cell of solution is the sum of its solute potential and its pressure potential A 5 Q 3 l l In this tube the solute In this tube a piston is potentials on the two used to increase the sides of the The water potentials The right side of the pressure potential of of the two sides are potential but has of the cell balances its a positive pressure solute potential so the potentiaL 39 N cell s water potential is zero There is no net has a lower solute potential than the surrounding water The cell has a pressure potential of zero membrane differ but ya tube has a lower water the right side equal 80 there is no the pressure potentials 5 potential so there is a 35 net movement of are the same 39 0 net mOVemem 0f 39oo39 water i quot water to the right l r O o r 0 ll O I v I l U I iquot 0quot S I t 39i i gun I Solution L g f O U Ion T lquot 0 wp 10 MPa i l mp 0 MPa r i 1 0 MP Pure water e w 1 0 MP8 Pure water y We a q 0 MPa Membrane 3 l 0 MPa w e 0 MPa qr 10 MPa B quotTquota e ltT 2 The cell has a g 394 i E I The inside of the cell N l negative solute y The pressure potential water potential than the water outside so there is net movement The cell has a lower movement of water of water Into the cell Flaccid cell i 2 IA 5 Turgid 08 k 1 WP 0 Mp3 x wp 10 MP8 Pure water W3 10 MPa Pure water IVS 10 MP8 ZOMPa lI 10MPa WOMP3 wOMPa PRINCIPLES OF LIFE Figure 258 2012 Sinauer Associates Inc The physical structure of many plants is maintained by the positive pressure potential of their cells turgor pressure If the pressure potential drops the plant wilts Water moves into root cells by osmosis through aquaporins Mineral ions move into root cells through ion channels by facilitated diffusion and by secondary active transport A proton pump generates The difference in A transport protein couples the differences in H concentration electric charge causes diffusion of HJr to the transport and electric charge across the cations such as K to against an electrochemical membrane enter the cell gradient of anions such as Cl into the cell Outside w v g of cell w w a plasma w o Transport protein membrane k t a l rated Doug1 Potassium channel Inside of cell PRINCIPLES OF LIFE Figure 2510 2012 Sinauer Associates Inc Water and ions may pass from the soil into the root by way of the apoplast or the symplast but they must pass through the symplast to cross the endodermis and enter the xylem The casparian strip in the endodermis blocks further movement of water and ions through the apoplast Root z The Casparian strip prevents water and ions in the apoplast from passing between the endodermal cells into the stele 1 Root cross To bypass the Casparian 5 section strip water must cross a plasma membrane and enter the symplast 7 Root hair Cell wall Plasmodesmata Casparian strip Water and ions cross a plasma membrane to enter the symplast Endodermis Pericycle Xylem Phloem J W Stele Water and ions travel into and through cell walls and intercelluiar spaces in the apoplast Root hair PRINCIPLES OF LIFE Figure 251 1 2012 Sinauer Associates Inc Water is transported in the xylem by the transpirationcohesiontension mechanism Evaporation from the leaf produces tension in the mesophyll which pulls a column of waterheld together by cohesion up through the xylem from the root 3 Tension pulls water from the veins into the apoplast surrounding the mesophyll cells 4 whioh in turn pulls water in the veins of the leaves upward and outward 5 whioh in turn pulls the water column in the xylem of the shoot and root upward water molecules forms a continuous water column from the roots to the leaves 7 Water enters the root and moves into the xylem by osmosis PRINCIPLES OF LIFE Figure 2512 2012 Sinauer Associates Inc Stomata allow a balance between water retention and C02 uptake Their opening and closing is regulated by guard cells In the light guard cells actively pump protons out thus facilitating the entry of K and Cl Higher internal K and Cl concentrations give guard cells a more negative water potential causing them to take up water The resulting increase in turgor pressure stretches the cells and opens the stoma I l Stoma 10 pm Cellulose microfibrils In the absence of light Kquot and Cl diffuse passively out of the guard cells and water follows by osmosis The guard cells shrink and the stoma closes PRINCIPLES OF LIFE Figure 251 3 2012 Sinauer Associates Inc 254 Solutes Are Transported in the Phloem by Pressure Flow 1 Source cells actively load sucrose into companion cells from which it enters sieve tube elements reducing their solute potential Sieve tube companion cell complex Source cell 2 Water is taken up from the xylem by osmosis raising the pressure Sieve potential in the sieve tube tube element A y 3 The resulting pressure I Sink cell difference drives the gt phloem sap along the sieve tube to sink cells 4 Sucrose is and water moves back unloaded into into the xylem by osmosis sink cells PRINCIPLES or LIFE Figure 2514 2012 Sinauer Associates Inc Translocation is the movement of the products of photosynthesis as well as some other small molecules through sieve tubes in the phloem The solutes move from sources to sinks Translocation is explained by the pressure flow model the difference in solute potential between sources and sinks creates a difference in pressure potential that pushes phloem sap along the sieve tubes Lecture Notes A quick table for monocots vs eudicots Monocots Embryos Stems Leaf venation Root system Flowers Pollen J Qa PRINCIPLES OF LIFE 23 Figure 242 2014 Sinauer Associates Inc One cotyledon Vascular tissue scattered Veins usually parallel Fibrous no main root Floral organs usually in multiples of three Pollen grain with single furrow or pore Eudicots n 0E Two cotyledons Vascular tissue arranged in concentric circles Veins form a network Taproot main root usually present Floral organs usually in multiples of four or five Pollen grain with three furrows or pores Tissue An organized group of cells that have features in common and that work together as a structural and functional unit Root system Anchoes plant in place Shoot System The aerial portion of a plant body consisting of stems leaves and flowers Meristem The tissue in most plants containing undifferentitated cells meristematic cells found in zones of plant where growth can take place Meristematic cells give rise to various organs of the plant and keep the plant growing Organ An anatomical features that consists of several types of tissue that together carry out a particular function Roots The organ responsible for anchoring the plant in the soil and absorbing water and minerals and producing certain hormones Dermal Tissue Forms plant epidermis usually one cell layer Some epidermal cells differentiate o Stomata pores for gas exchange 0 Trichomes leaf hairs protect from herbivores and damaging solar radiation 0 Root hairs increase root surface area Totipotent Capable of developing into complete organisms or differentiating into any of its cells or tissues Indeterminate growth Growth processes that do not terminate when the adult stage is reached or a predetermined structures has formed Instead growth is open ended and lifelong Hormone Signaling molecules that regulate and control physiology growth or behavior Secondary metabolites Organic compounds that are not directly involved in the normal growth development or reproduction of an organism Often they contribute to a quotsecondaryquot function such as defense against herbivory Taproot Largest most central and most dominant root from which other roots sprout laterally Organ A compound that has a distinctive color due to selective color absorption
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