Class Note for ECOL 182R with Professor Huxman at UA
Class Note for ECOL 182R with Professor Huxman at UA
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Date Created: 02/06/15
Posted on web 22807 at 530 pm Plant Diversity Ecol 182 382007 quotO Summary from last time We talked about Nontracheophytes 39 39 39 Z 0 common Club mosses W a ancestor g E 9 Horsetalls g b g Tracheids 0 branching Whisk ferns 1 8 H independent K3 7 3 m klt n sporophyte f d r Iquot l m g quotS Multi agellate n E sperm complex 7 lt 8 leaves k a g Comfers E o m 0 m 9 Seeds R 3 H a a m 839 o Gnetophytes Flowers carpels triploid endosperm Angiosperms LIFE THE SCIENCE OF BIOLOGY Savant Edition Figure 2WThe Evolulinn o1 Tnday39s Flams 2qu Smauer Assocmes me am w H Freeman 5 Co The Seed Plants Microspores and megaspores sunadsouuu g Conifers common ancestor Gnetophytes 0 Flowers g Angiosperms Seed plants are the most derived tracheophytes Gymnosperms such as pines and cycads four phyla Angiosperms owering plants one phyla 0 Big evolutionary innovations Evolution of a seed Reduction in gametophyte generation 0 The haploid gametophyte is attached to and nutritionally dependent on the diploid sporophyte Terminal bud Thjs Bud scale yearS Vascular growth ll i Gamblum Primary growth Prlmary xylem Cork I Perlderm Secondary Prlmary Cork cambium xylem Cortex Primary Last year s Phloem growth J r r 1 Secondary IIlquotquot39Hl4 phloem Secondary growth Vascular Scars left by bud Cambium Growth scales from from two previous year Years ago Lateral bud Leaf scar LIFE THE SCIENCE DFBoLoBY Seventh Edition Figure 3514 A Waody Twig a 2mm Smauer Asswaias inc and w H Freeman amp Co Gymnosperms Naked Seeds 0 Gymnosperms except Gnetophyta have only tracheids and simple phloem Tracheids are simple xylem that conduct water throughout the plant body Tracheids undergo apoptosis and operate as empty cells cell walls remain Phloem are alive and transport carbohydrates and other materials throughout the plant Tracheids Sieve cell LIFE THE SCIENCE OF BIOLOGY Sevenlh Edition Figure 3510 Eu Tracheids Pores of sieve plate 39 Sieve plate a Sieve tube element The Angiosperms Flowering Plants Phylum Angiospermae 257000 species Angi0sperm means enclosed seed The angiosperms are the most derived form of the tracheophytes The Angiosperms Flowering Plants A number of synapomorphies or shared derived traits characterize the angiosperrns They have They produce Their ovules and seeds are They have They produce Their xylem contains Their phloem contains The Angiosperms Flowering Plants Double fertilization two male gametes participate in fertilization events Within the megagametophyte Endosperm nucleus Microspores a DIPLOID HAI LOID Mega Antipodal gimteto C6115 Pollen grain P y e Surviving megaspore f nude LIFE THE SCIENCE OF BIOLOGY Seven Edition Figure 3011 The Life Cycle of an Angiospeml a 2004 Smauer Assnmales me and w H Freeman 1 Cu The Angiosperms Flowering Plants Petal All the parts of a ower are modified leaves Stamens lament bearing anthers containing pollen producing microsporangia Pistil one or more carpels with a swollen base ovary containing megasporangia Style is the apical stalk of the pistil terminal surface receiving pollen is called the stigma Stigma 4 Anther Style quot Ovary I Ovule Filament Receptacle The Angiosperms Flowering Plants Specialized leaves petals and sepals are important for attracting pollinators Many angiosperms are animalpollinated increasing the likelihood of outcrossing in exchange for nectar or pollen Coevolution has resulted in some highly speci c interactions but most plantpollinator systems are not highly speci c Evolutionarily ancient angiosperms have a large and variable number of oral structures petals sepals carpels and stamens Evolutionary trend Within the group reduction in number of oral organs differentiation of petals and sepals changes in symmetry and fusion of parts Figure 308 In orescences Umbels Disk owers Ray owers a Daucus carom l7 Echimzcea purpztrea Compound umbel g C Permisetum setaceum LIFE THE SCIENCE OF BIOLOGY Seven Editian Figuve ma Inllomcences 2304 Smauer Assumes Inc and w H Freeman 5 Co The Angiosperms Flowering Plants Perfect owers have both microsporangia and megasporangia Imperfect owers have either but not both Monoecious species produce both types of imperfect owers on the same plant In dioecious species a plant produces either megasporangiate or microsporangiate owers but not both Developing embryos consists of an embryonic axis and one or two cotyledons seed leaves which metabolize endosperm and may become photosynthetic Monocots Eudicots Arrangement of primary vascular Cotyledons bundles in stem Veins in leaves Flower parts LIFE THE SEIENEE DF BIDLDGY Seventh Edilicn gure 351 Mnnacols velsu Eudicots 2cm Smauer Assnmmea me am w H Freeman 5 Co Internode Leaf 39 Petiole Blade LIFE THESEIENL E 0F BIOLOGY Salan Edition gure 352 Vegetative Organs Ind System 2004 Sinausv Associates Inc and w H Freeman 5 Co Organs of the Angiosperms Two main types of root system taproot and brous root Many eudicots have a taproot system a single large deep growing primary root with smaller lateral roots Monocots and some eudicots have a brous root system composed of numerous thin roots roughly equal in diameter A brous root system holds soil in place very effectively Some plants have adventitious roots which arise from points along the stem Where roots would not usually occur Figure 353 Root Systems LIFE THE SCIENCE or BIDLOGV SalEn Ediriun Figure 15 Ram Sysxems 2004 Smauer Assacrzues me and w H Freeman 5 Ca Angiosperm vascular systems Xylem in angiosperms consists of vessel elements in addition to tracheids Vessel elements also conduct water and are formed from dead cells Vessel elements are generally larger in diameter than tracheids and are laid down endtoend to form hollow tubes Sieve tube elements Phloem in Angiosperms are stacked similar to xylem Have adjacent companion cells that retain all organelles Companion cells may regulate the performance of the sieve tube members through their effects on active transport of solutes Figure 359 Plant Cell Types Part 3 e j7 Tracheids Vessel elements 50 pm Why is a greater diameter a big deal for the evolution of plants L1 Xylem b Phloem Vessel elements Tracheids Sieve cell Sieve tube element Companion cell LIFE THE SCIENCE OF BIOLOGY Savenlh Edi an Figum 31m Evolution of me Cnnducling Calls MVascLIIM Sysxems 2004 Smauer Assacrates me and w H Freeman E Co Pores of sieve plate Sieve plate Sieve tube element Companion cell Sieve tube element Angiosperms Flowering Plants Monocots a single embryonic co ledon rasses cattails Carpels riploid g endosperm seeds Amborella hhes orchids and palms in fruit Gymnospermlike I Eudicots two cotyledons and ancestor include the majority of familiar seed plants Vessel elements Water lilies Star anise Additional clades water lilies star anise and the magnoliid Magnoliids complex exams any 39 Big question in plant evolution oty e on What is the basal angiosperm Pollen with th e s EUdimtS grooves LIFE THE SCIENCE OF BIOLOGYV Sewnm Edlflnn Figure 30 Evalulinnm Relationships among 12 Anglosprmls 5 EC Enauenlssx mas ln and W H Franzquot 5 C0 Uptake and Movement of Water and Solutes Transport of Water and Minerals in the Xylem Transpiration and the Stomata Translocation of Substances in the Phloem General problem in plant function 0 Need for H20 for photosynthesis Solute transport temperature control internal pressure for growth 0 Plants obtain water and minerals from the soil Via the roots in turn roots extract carbohydrates and other important materials from the leaves H O and 0 Water enters the plant through di solved OSl l lOSiS minerals but the uptake of minerals requires transport proteins LIFE THE SCIENCE OF BIOLOGY Sevenquot Edilian Figum Uptake amp Movement of Water amp Solutes in Plants Osmosis is the diffusion of water through a membrane primary means of water transport in plants Osmotic potential or solute potential determines the direction of water movement across a membrane Potential refers to the potential energy contained in the system measured Dissolved solutes have the effect of lowering the concentration of water changing the potential energy Greater solute concentration results in a more negative solute potential and a greater the tendency of water to diffuse to the solution Uptake amp Movement of Water amp Solutes in Plants Water potential is the tendency of a solution to take up water from pure water LP Water potential of a system is the sum of the negative solute potential VS and the usually positive pressure potential wp wwswp Solute potential pressure potential and water potential are measured in megapascals Mpa Hypertonic Isotonic Hypotonic Inside Outside of cell of cell Animal cell Plant cell LIFE THE SCIENCE OF BIaLoGY Seventh Edition Figure 55 Osmosis Mndilies the shapes of calls a 2004 Smauar Assomales lnc and w H Freeman 14 Cu m ml Membrane LIFE THE SCIENCE OF BIOLOGY Seven Edmun Figure 362 Walzr Polenlial Selma Poleniial and Pussule Futunlial 2004 Shaw Assmmes W and w H Freeman amp Cm Root hair Epidermis O o w s FDquot Plasmodesmata x Plasma Casparian membrane strip Endodermis Pericycle N 93 Tracheary 5 elements LIFE THE SCIENCE DF BIOLOGY Sevanin Ediliorl Figure 36 lt9 2004 Shaw Assncmes w 4 Apapxasl Ind Sympllsl m and W H Freeman E Co Plasmodesmata Endodermis Pericycle LIFE THE SCIENCE OF BIOLOGY Seventh Editian gure 35 s CupKiln Strip a 2mm smauer Assumes Inc and w H Freeman 5 Co Transport of Water and Minerals in the Xylem The adhesioncohesion tension theory of water movement The concentration of water vapor is higher inside the leaf than outside so water diffuses out of the leaf through the stomata this is transpiration This creates a tension in the mesophyll that draws water from the xylem of the nearest vein into the apoplast surrounding the mesophyll cells The removal of water from the veins in turn establishes tension on the entire volume of water in the xylem so the column is drawn up from the roots Leaf Stoma LIFE THE SCIENCE OFBIULOGY Seventh Edilian Figur 368 The Transpimian Cohesiun Tension Machniam ZDOASmauer Assnmmes me am w H Freeman amp on Transport of Water and Minerals in the Xylem Hydrogen bonding results in cohesion sticking of molecules to one another The narrower the tube the greater the tension the water column can stand Maintenance of the water column also occurs through adhesion of water molecules to the walls of the tube Transport of Water and Minerals in the Xylem The key elements in water transport in xylem Transpiration Tension Cohesion The transpiration cohesion tension mechanism does not require energy At each step water moves passively toward a region with a more negative water potential Transport of Water and Minerals in the Xylem Mineral ions in the xylem sap rise passively with the solution Transpiration also contributes to the plant s temperature regulation cooling plants in hot environments Transport of Water and Minerals in the Xylem The key elements in water transport in xylem Transpiration Tension Adhesion Cohesion The adhesion cohesion tension mechanism does not require energy At each step water moves passively toward a region with a more negative water potential Mineral ions in the xylem sap rise passively with the solution Transpiration also contributes to the plant s temperature regulation cooling plants in hot environments RESEARCH METHOD Sap Pressure gauge Gas pressure Pressure release valve LIFE THE SCIENCE OF Emmav Seventh Edition Figure 369 A Pressure Bamh 2004 Smauer Assncmes me and w H Freeman amp Cc Water potential MPa 1 2 3 4 5 6 Time days Why is there a disconnect temporally between leaf root and soil Short and longterm responses to water limitation When water is Withheld the pressure potential of the cells declines hours to days and rates of cell expansion are reduced longterm Rates ofplzotosyntlzesz39s declines stomata cl0se short New leaves are smaller with smaller cells long Pr0f0una change in patterns of allocation long Regulation of Transpiration by Stomata Leaf and stem epidermis has a waxy cuticle that is impermeable to water but also to C02 Stomata or pores in the epidermis allow CO2 to enter by diffusion Guard cells control the opening and closing of the stomata Most plants open their stomata only when the light is intense enough to maintain photosynthesis Stomata also close if too much water is being lost a Stomatal aperture is regulated by controlling K concentrations in the guard cells Blue light activates a proton pump to actively pump protons out of the guard cells The proton gradient drives accumulation of K inside the cells Increasing K concentration makes the water potential of guard cells more negative and water enters by osmosis The guard cells respond by changing their shape and allowing a gap to form between them Abscisic acid a stress hormone can invoke this stomatal closure in addition to blue light Changes in guardcell photosynthesis can also invoke this stomatal response b Guard cells LIFE THE SCIEN
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