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Plant transport notes


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Plant transport notes

  1. 1. AP BIOLOGY NAME_____________________ PLANTS FORM & FUNCTION ACTIVITY #3 DATE__________HOUR______ TRANSPORT IN PLANTS OVERVIEW OF TRANSPORT IN PLANTS 4. Leaves take in CO2 via stomata Use CO2 and H2O to 3. Water loss make food via via transpiration photosynthesis pulls water in Release O2 xylem upward2. Xylem transportswater & minerals up toleaves 5. Phloem transports sugar to other plant parts 1. Roots absorb 6. Roots take in oxygen water & minerals needed for cellular respiration & release carbon dioxide Plant Form & Function Activity #3 page 1
  2. 2. Proton (H+)PROTON PUMPS AnionInside Cell Outside cell ATP High proton conc. ATP + Pi Cations driven into Cation cell by membrane (K+) potential Anion Transport Cotransport Couple transport of anion with diffusion of H+ down conc. gradientPlant Form & Function Activity #3 page 2
  3. 3. LATERAL TRANSPORT ROUTES IN PLANTS Transmembrane transport Across cell membrane, through cell wall, across cell membrane, through cell, across cell membrane, etc. Symplast From cell to cell via plasmodesmata Apolast Transport through cell wall matrix Substance never enters cellLATERAL TRANSPORT IN ROOTS Symplast Apoplast Materials cannot enter stele until they pass through living cell; Casparian strip prevents apoplastic transport into stelePlant Form & Function Activity #3 page 3
  4. 4. Xylem WATER TRANSPORT IN STEMTransport of WaterAdhesion of water tocell wall keeps column ofwater from fallingCohesion between watermolecules forms columnof water Types of Cells Tracheids Vessel Element • Dead at functional maturity • Wider, shorter cells • Long, think cells with with thinner cell walls tapered ends • Ends of cells • Water moves from cell to perforated to allow cell through pits water to flow freely • Secondary cell walls between cells thickened with lignin; • Dead at functional provide support maturity Plant Form & Function Activity #3 page 4
  5. 5. TRANSPIRATION = Evaporation of water from leaf• Water exits leaf via stomata• Water potential in air spaces decreases• Water pulled from mesophyll cells• Water potential inside mesophyll cells decreases• Water pulled from top of xylem• Water potential at top of xylem decreases• Water pulled up xylem from rootsPlant Form & Function Activity #3 page 5
  6. 6. GUARD CELLS Control of stomata Stomata open (day) • Guard cells accumulate K+ • Water potential inside guard cells becomes more negative • Water enters guard cells • Guard cells swellStoma • Stoma opens TriggersGuard cells 1. light triggers blue-light receptor 2. Depletion of CO2 in air spaces 3. Internal clock Stomata close (night) • Guard cells lose K+ • Water potential inside guard cells becomes less negative • Water exits • Guard cells become flaccid • Stoma closes Plant Form & Function Activity #3 page 6
  7. 7. PHLOEM LOADING Symplast Apoplast • Requires active transport into companion cells & sieve- tube members • Proton pumps usedPlant Form & Function Activity #3 page 7
  8. 8. Source cellBULK TRANSPORT IN PHLOEM • Sucrose entersPhloem sap flows from high sieve-tube memberhydrostatic pressure to low • Water potential(from source to sink) becomes more negative • Water enters sieve-tube memberSink Cell• Removes sucrose• Water potential in sieve-tube member becomes less negative• Water enters sieve-tube memberPlant Form & Function Activity #3 page 8