Presentation on theme: "Copyright Notice! This PowerPoint slide set is copyrighted by Ross Koning and is thereby preserved for all to use from plantphys.info for as long as that."— Presentation transcript:
1Copyright Notice!This PowerPoint slide set is copyrighted by Ross Koning and is thereby preserved for all to use from plantphys.info for as long as that website is available. Images lacking photo credits are mine and, as long as you are engaged in non-profit educational missions, you have my permission to use my images and slides in your teaching. However, please notice that some of the images in these slides have an associated URL photo credit to provide you with the location of their original source within internet cyberspace. Those images may have separate copyright protection. If you are seeking permission for use of those images, you need to consult the original sources for such permission; they are NOT mine to give you permission.
2Biology: What is Life? life study of Properties of Life Cellular Structure: the unit of life, one or manyMetabolism: photosynthesis, respiration, fermentation, digestion, gas exchange, secretion, excretion, circulation--processing materials and energyGrowth: cell enlargement, cell numberMovement: intracellular, movement, locomotionReproduction: avoid extinction at deathBehavior: short term response to stimuliEvolution: long term adaptation
4Cyclosis in Physarum polycephalum, a slime mold This organism consists of one very large cytoplasm (plasmodium) with many nuclei and food vacuoles in the cytosol (coenocytic).Slime molds can weigh up toward kilogram range and move their blob-like mass around exclusively by cyclosis.Here you can see, in a thin region of cytoplasm, that it moves along pathways that are river-like in appearance.Transport is NOT always unidirectional.The correct taxonomic affiliation is unclear.It has been treated as Fungus and Protist.Further study is needed to resolve its position.What is the ATP source?
5Cyclosis: cytoplasmic streaming…intracellular circulation Elodea canadensisChloroplasts and other organelles have surface proteins with myosin-like activity.Microfilaments of actin are found just under cell membrane.ATP and Calcium allow myosin to slide along actin filaments, resulting in circulation of organelles within the cell.What is the source of ATP?Can you be more specific?If light intensity were reduced, what would be the prediction based on your hypothesis?
6Figure 36-3 Page 793Apical budThe shoot organ system is photoautotrophic, taking in CO2 and releasing O2 in daylight.Axillary budNodeCO2 in and O2 outInternodeNodeShoot systemLeavesBranchO2 in and CO2 outDiffusion is sufficient to exchange gases. But solutes need to be circulated in the large plant body as diffusion is too slow!!StemLateral rootsThe root organ system is chemoheterotrophic, taking in O2 and releasing CO2 in the darkness of the soil environment.Root systemO2 in and CO2 outTaproot
7Carbohydrate etc. Transpiration Translocation Water and Minerals Figure 36-3 Page 793Apical budThe shoot system produces carbohydrates (etc.) by photosynthesis. These solutes are transported to the roots in the phloem tissue:TranslocationAxillary budNodeCarbohydrate etc.InternodeNodeShoot systemLeavesBranchStemTranspirationTranslocationThe root system removes water and minerals from the soil environment. These solutes are transported to the shoot in the xylem tissue:TranspirationLateral rootsRoot systemWater and MineralsTaproot
8Carbohydrate etc. Transpiration Translocation Water and Minerals Figure 36-3 Page 793Apical budAxillary budNodeCarbohydrate etc.InternodeBecause these pathways involve solutes in water passing in the adjacent tissues of a narrow vascular bundle, this is a circulation system!Transpiration and TranslocationThe water is moving up the xylem, and down the phloem, making a full circuit!NodeShoot systemLeavesBranchStemTranspirationTranslocationLateral rootsRoot systemWater and MineralsTaproot
9Plants occur in two major groups (and some minor ones) Figure Page 802Plants occur in two major groups (and some minor ones)They differ, in part, in their circulation systems:Cross section of a eudicot stemCross section of a monocot stemEpidermisCortexGround tissuePithVascular bundlesDicots initially have one ring of vascular bundlesMonocots rapidly develop multiple, concentric, rings of vascular bundles
30Mendocino Tree (Coastal Redwood) Sequoia sempervirens Ukiah, California112 m tall (367.5 feet)!This tree is more than ten times taller than is “theoretically possible” based solely upon the length of the column of uncavitated water.How could this be achieved?
31Transpiration in a tall tree has at least 3 critical components: Evaporation: pulling up water from aboveCapillarity: climbing up of water within xylemRoot Pressure: pushing up water from below
33Transpiration: root pressure (osmotic “push”) The veins (coarse and fine) show that no cell in a leaf is far from xylem and phloem (i.e.water and food!).The xylem of the veins leaks at the leaf margin in a modified stoma called the hydathode.These droplets are xylem sap.Root pressure accounts for maybe a half-meter of “push” up a tree trunk.
34Capillarity: maximum height of unbroken water column glass tubevacuum createdThe small diameter of vessels and tracheids and the surface tension of water provide capillary (“climb”).Cohesion of water, caused by hydrogen bonds, helps avoid cavitation.A tree taller than 10.4 m would need some adaptations to avoid “cavitation”gravity pulls water down10.4matmospheric pressure keeps water in tubewater
36Conifer stem anatomy: bordered pits as “check-valve” for flow secondary wallprimary wallmiddle lamellapit aperturepit membraneThese pit features allow conifers to be very tall and still avoid cavitation in their xylem cells.As pressures change between adjacent cells, the torus movement blocks catastrophic flow that would result in cavitation.pit bordertoruspit chamberP lowP high
37Transpiration: evaporation (“pull”) Transpiration can lift the mercury above its normal cavitation height!vacuumwatermercuryWater evaporating from a porous clay cap also lifts the mercury!76 cmmercury
41Transpiration Carbohydrate etc. Transpiration Translocation Apical budAxillary budNodeEvaporation:Water evaporates from mesophyll into atmosphere.Water molecules are pulled up the xylem by virtue of cohesion.Carbohydrate etc.InternodeNodeShoot systemLeavesBranchCapillarity:Water climbs in the xylem cell walls by adhesion.Water molecules follow by cohesion.StemTranspirationTranslocationLateral rootsRoot Pressure:Water moves into the root because of solutes from phloem.Pressure pushes the water up the stem.Root systemWater and MineralsTaprootFigure 36-3 Page 793
42Translocation Carbohydrate etc. Transpiration Translocation Apical budAxillary budNodeLeaf = SourcePhotosynthesis produces solutes.Solutes loaded into phloem by active transport.Water follows by osmosis, increasing pressure.Carbohydrate etc.InternodeNodeShoot systemLeavesBranchStemTranspirationTranslocationRoot (etc.) = SinksSolutes removed from phloem by active transport.Water follows by osmosis, reducing pressure.Lateral rootsRoot systemPressure = Bulk FlowThe pressure gradient forces phloem sap away from leaves to all sinks (bidirectionally).Water and MineralsTaprootFigure 36-3 Page 793