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Intro to Lab #9 / Chpt. 36 Plant Structure and Transport pg. 744 - 753 PowerPoint Presentation
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Intro to Lab #9 / Chpt. 36 Plant Structure and Transport pg. 744 - 753

Intro to Lab #9 / Chpt. 36 Plant Structure and Transport pg. 744 - 753

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Intro to Lab #9 / Chpt. 36 Plant Structure and Transport pg. 744 - 753

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  1. Intro to Lab #9 / Chpt. 36 Plant Structure and Transport pg. 744 - 753

  2. Transport in Plants Did you know, an average size maple tree looses 200 L of water perhour during the summer via. transpiration. What would happen if this water were not replaced by the roots???

  3. Question ? • How do plants move materials from one organ to the other ?

  4. TRANSPIRATION TRANSPIRATION - when a plant looses water vapor from the inside of the leaf, to the outside environment -via. stomata

  5. COHESION - TENSIONTHEORY - water is pulled up from roots to leaves via. higher  in the leaf to a lower in the air 

  6. Water & mineral absorption to Xylem: • Water absorption from soil - osmosis - aquaporins

  7. ROOT HAIRS = increase surface area for the absorption of water & minerals

  8. Water & mineral absorption to Xylem:  Mineral absorption • active transport • proton pumps • active transport of H+ proton pumps

  9. Water & mineral absorption to Xylem: • Proton pumps • active transport of H+ ions out of cell • chemiosmosis • H+ gradient • creates membranepotential • difference in charge • drives cation uptake • creates gradient • cotransport of othersolutes against theirgradient proton pumps

  10. Transport in Plants uptake and loss by individual cells: The survival of plant cells depends on the ability to balance the uptake & loss of H2O

  11. Remember this? *Presence of the cell wall adds physical pressure, this affects movement into the cell negatively!

  12. Remember this? *Solute concentration also affects movement:

  13. Transport in Plants How can we predict the direction of osmosis when a plant cell is surrounded by a solution???

  14. Transport in Plants WATER  POTENTIAL

  15. Remember this? Water moves from the solution of higherwaterpotential, to a solution of lowerwaterpotential.  For plants, it is not just enough to know if the extracellular solution is hypotonic or hypertonic.

  16. Remember this? *Measured in MEGAPASCALS  • Has two components: • Pressure potential: yr • Solute potential: yp • y = yr + yp

  17. Remember this? You have to know these two numbers first, when determining water potential. You must know water potential in order to know which direction water will move! Pressure potential: yrSolute potential: yp y = yr + yp 

  18. Remember this?

  19. Remember this? any solution will have a negative w.p.  adding solutes, lowers w.p.

  20. Transport in Plants *Solute concentration affects movement

  21. Transport in Plants *External pressure on a solution counters its tendency to take up water due to the presence of solutes

  22. Transport in Plants    = + P S

  23. Transport in Plants  the force that moves water across the membranes of plant cells =

  24. COHESION - TENSIONTHEORY - water is “pulled” b/c of it’s cohesiveproperty

  25. Evolutionary advantage of ROOT HAIRS: add surface area - thus increasing amount of H20/mineral solution coming into the plant!!

  26. Mycorrhizae increase absorption • Symbiotic relationship between fungi & plant • symbiotic fungi greatly increases surface area for absorption of water & minerals • increases volume of soil reached to plant • increases transport to host plant

  27. Mycorrhizae

  28. COHESION - TENSIONTHEORY - Because higher water potential outside

  29. COHESION - TENSIONTHEORY - minerals absorbed from soil into root~ creates “rootpressure” that pushes H2O/soil solution into xylem

  30. COHESION - TENSIONTHEORY - • uptake of soil solution by root hairs to apoplasticroute-through the cell walls

  31. Transport routes in plant cells

  32. COHESION - TENSIONTHEORY - • uptake of minerals & water by root hairs to symplasticroute - through plasmodesmata 

  33. Transport routes in plant cells

  34. Controlling the route of water in root • Endodermis • cell layer surrounding vascular cylinder of root • lined with impermeable Casparian strip • forces fluid through selective cell membrane • filtered & forced into xylem cells

  35. Controlling the route of water in root • some soil solution from apoplast route, diffuses into the symplastic route -through the plasma membrane 

  36. COHESION - TENSIONTHEORY - Water then travels thru the root where the Casparian strip forces H2O into the xylem REMEMBER: the casparian strip blocks water from entering via. The apoplastic route

  37. COHESION - TENSIONTHEORY - • only minerals in the symplastic route can detour around the Casparian Strip AND PASS INTO THE VASCULAR XYLEM!! 

  38. Root anatomy eudicot monocot

  39. COHESION - TENSIONTHEORY - •  XYLEM vessels transport water and minerals upward into the shoot system (stem and veins) 

  40. COHESION - TENSIONTHEORY - problem… this can only take the water “so far”

  41. COHESION - TENSIONTHEORY - At the leaf of the plant, water loss due to evaporation is taking place.

  42. Evaporating H2O decreases the water potential of the leaf.