151 Plant Structure and Function Cvs.pptx - Plant Structure...

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1Plant Structure & FunctionBIO 151
2desiccation, excessive water loss, is aconstant challenge for land plants
3Sister group ofgreen algaeLiverwortsMossesHornwortsLycophytesFerns andhorsetailsGymnospermsAngiospermsVascular plantsBryophytesGreen algaeLandplantsPhylogeny of Plants
ReproductiveorgansLeafStemRootsShootAnatomy of a Vascular PlantEvidence ofadaptation to aterrestrialenvironment
The LeafCuticleUpperepidermis________cellsLowerepidermisCuticleGuard cellStomaVeinH2OCO2Mesophyll cells near the uppersurface of the leaf have acolumnar arrangement thatmaximizes light interception.Mesophyll cells near the uppersurface of the leaf have acolumnar arrangement thatmaximizes light interception.Mesophyll cells close to the stomata havea honeycomb-like arrangement to allowCO2to spread easily throughout the leaf.Mesophyll cells close to the stomata havea honeycomb-like arrangement to allowCO2to spread easily throughout the leaf.
StomataSmall openings in the surface of the leaf that allow forgas exchange (e.g. H2O, CO2); flanked byguard cells
The LeafCuticleUpperepidermis_______cellsLowerepidermisCuticleGuard cellStomaVeinH2O~400ppm~20,000ppmCO2~200 ppm~40,000 ppmCO2gradientWater vapor gradientThe concentration difference driving the diffusion ofCO2into the leaf is typically 100 times smaller thanthe concentration difference driving the diffusion ofwater vapor out of the leaf.The concentration difference driving the diffusion ofCO2into the leaf is typically 100 times smaller thanthe concentration difference driving the diffusion ofwater vapor out of the leaf.Action of guard cells is important to control theamount of gas exchange that can occur; admitcarbon dioxide, but control water lossAction of guard cells is important to control theamount of gas exchange that can occur; admitcarbon dioxide, but control water loss
Stomata and Guard CellsSolutesH2OSolutesH2OGuardcellRadiallyorientedcellulosemicrofibrilsGuard cellsshrink.Guard cellsswell.Open, high-volumestateClosed, low-volumestate (default)Uptake of solutes by guard cells causeswater to be drawn in by osmosis. As theguard cells swell, they bow apart, openingthe stoma.Uptake of solutes by guard cells causeswater to be drawn in by osmosis. As theguard cells swell, they bow apart, openingthe stoma.Release of solutescauses water to flowout of the guard cells,closing the stoma.Release of solutescauses water to flowout of the guard cells,closing the stoma.
Slightly inflated balloonTied endAddturgorpressure(air)“Stoma”“balloon analogy” of guard cell action
Open stoma:turgidguard cellsK+Cl

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Term
Fall
Professor
Robert Kues
Tags
Biology, Plants, Photosynthesis, Phylogeny, phloem, phloem transport, Xylem

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