plant physiology Test 2

  1. In sink tissue, solute potential and water potential does what?
    • Solute potential decreases
    • Water potential increases
  2. Cross walls in translocation pathway allows for what?
    Allows water to move from xylem and phloem
  3. Pressure difference is maintained by?
    Photosyntheic processes and movement of water
  4. During the day, photosynthetic materials are?
    Moved from chloroplasts to cytosol
  5. At night, compounds along with glucose and starch are formed into?
  6. Both 1st and 2nd steps of phloem loading occurs is what cell?
  7. Sieve loading, sugar concentrations are what?
    More concentrated in sieve ellements than in mesophyll cells
  8. Symplastic pathway?
    Initial short distance pathway. From one cell to another via plasmodesmata
  9. Apoplast loading?
    Sugars enter apoplast (cell wall and extracellular spaces) prior to ploem loading.
  10. Pathway of phloem loading (name the cells)
    Bundle sheath>Intermediary cell>sieve element
  11. Sucrose is converted into raffinose where? What is combined with sucrose to make raffinose?
    Intermediary cell. Galactose is combined with sucrose
  12. Why is sucrose converted into raffinose in the intermediary cell?
    Raffinose is too large to go backwards
  13. Sucrose is synthesized where?
    Mesophyll. Combined with glucose and fructose.
  14. 3 steps to phloem unloading
    Sieve element unloading>Short distance transport>Storage and metabolism
  15. Phloem unloading can occur in what pathways?
    Symplastic and apoplastic
  16. Symplastic unloading
    • In young dicot is all symplastic
    • Solutes move through plasmodesmata
  17. Apoplastic unloading
    Unloading sieve elements and companion cells occurs in apoplast
  18. When leaf in 25% expanded/?
    Source sink occurs
  19. When leaf is 50% expanded
    Source sink is complete
  20. An immature leaf gets its photosynthate from?
    Mature leaf cells
  21. Photosynthesis rate
    Total amount of fixed carbons per u/t
  22. Allocation
    Regulation of distributed carbon to different pathways
  23. Partitioning
    Differential distribution of photosynthate throughout the entire plant
  24. Sink strength=
    Sink size x sink activity
  25. Sink activity?
    Uptake rate of photosynthate u/t
  26. Functions of ploem
    • Long distance transport of sugars
    • Transport signaling molecules (physical and chemical)
  27. Physical signals can include?
    • Turgor pressure
    • Ploem loading and/or unloading
  28. Chemical signals can include?
    • Plant proteins and hormones
    • mRNA and RNA
  29. When sieve element is damaged?
    The pressure causes contents to surge towards damaged site
  30. Damage to sieve elements can be caused by?
    • Insects
    • Winds, storm, temp.
    • Pollution can cause a change in light wavelength
  31. Protective mechanisms of the phloem
    • P-proteins-short term sollution. Seals damage by plugging sieve plate pores
    • Callose-long term sollution. Made in sieve plate elements and plugs off sieve plate damage
Card Set
plant physiology Test 2
Plant Physiology Test 2