(5) Transport in Plants

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(5) Transport in Plants
2010-04-26 23:52:02
transport plants

bio 102 exam
Show Answers:

  1. diffusion
    • when something moves in or out(down its concentation gradient)
    • moves high to low
  2. facilitated diffusion
    uses transport proteins
  3. carrier protein
    has a receptor site and changes conformation
  4. channels
    for ions, gated
  5. primary active transport
    uses ATP directly, in plants involves proton pump (found in plasma membrane of cells)
  6. electrochemical gradient
    generated by pumping protons out
  7. electro
    negative outside and positive inside
  8. chemical
    substances want to diffuse down their chemical gradient (cells want to come back in)
  9. membrane potential
    a source of potential energy that allows cells to do work, caused by the electrochemical gradient
  10. secondary active transport
    uses ATP indirectly, needs cotransport proteins
  11. cotransport proteins
    couple the downhill movement with the uphill movement of something else
  12. chemiosmosis
    creation of a transmembrane proton graient which genrats a membrane potential which is a source of potential energy that the cell can use to do work
  13. osmosis
    diffusion of water across a semi permeable membrane
  14. aquaporins
    channel proteins specific to water
  15. water moves from ___tonic to ___tonic
    hypotonic to hypertonic
  16. turgor pressure
    created when water comes into a plant cell and the plasma membrane presses on the cell wall
  17. causes osmosis to stop
    turgor pressure
  18. osmotic pressure
    the pressure of water coming in
  19. water potential
    form of potential energy
  20. water is measured in ____
  21. solutes always ____ water potential
  22. negative pressure
    any pressure less than 1 atm (TENSION)
  23. ex. of negative pressure
    sucking a straw lowers water potential
  24. positive pressure
    any pressure greater that 1atm
  25. ex. of positive pressure
    injecting a syringe raises water potential
  26. 3 routes of tissue transport
    • transmembrane
    • symplastic
    • apoplastic
  27. transmembrane route
    • slowest, most complex, very unlikely and selective
    • crosses the plasma membrane over and over
    • needs carrier/transport proteins
  28. symplastic route
    • crosses the plasma membrane once
    • selective
    • fast because of plasmodesmata
  29. apoplastic route
    • never crosses a membrane
    • oozes along pores of the cell wall
    • fast and nonselective
  30. casparian strip
    • region of wax on epidermis that blocks the apoplastic route, therfore forcing the symplastic route, which forces selectivity
    • (lateral transport in roots)
  31. transpiration
    evaporation of water from leaves of a plant
  32. 2 ways xylem sap ascends
    • pushing
    • pulling
  33. pushing
    weak force caused by root pressure where solutes are actively transported from soil into xylem
  34. explain pushing
    water potential of stele is less that cortex and soil, so the water moves in and raises water potential, which pushes xylem sap up, then guttation occurs
  35. guttation
    xylem sap fills up the spongy mesophyll and it comes out the stoma, ex. of root pressure
  36. pulling
    • transpiration cohesion tension mechanism
    • solar powered so no ATP needed
  37. explain pulling
    • 1. transpiration occurs, providing energy to pull xylem sap and cool down leaves
    • 2. cohesion happens
    • 3. transpiration creates tension, which causes water to move from regions of high water potential to those with low water potential
    • 4. evaporating water increases the meniscus which stretches H bonds
  38. cohesion
    water molecules stick together because of H bonds
  39. tension
    a negative pressure that lowers water potential
  40. meniscus
    curved region where air and water interface, forms at junction of cells and air space of spongy mesophyll