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Osmosis and Water Potential

Osmosis and Water Potential. Ch 7 - Principles of Transport/Osmosis and Effects on Cells Ch 36 Osmosis-Water Potential in plants. Problem:. Permeable to simple sugars but not dissacharides . Can we answer Q 6 a-e on page 141?. Environment: 0.01 M sucrose 0.01 M glucose 0.01 M fructose.

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Osmosis and Water Potential

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  1. Osmosis and Water Potential Ch 7 - Principles of Transport/Osmosis and Effects on Cells Ch 36 Osmosis-Water Potential in plants

  2. Problem: Permeable to simple sugars but not dissacharides. Can we answer Q 6 a-e on page 141? Environment: 0.01 M sucrose 0.01 M glucose 0.01 M fructose “Cell”: 0.03 M sucrose 0.02 M glucose

  3. “Tonicity” drives direction of water movement • Hypertonic • Hypotonic • Isotonic

  4. Effects on Cells • Plant cells--What adaptations do plant cell have to deal with water balance? • Vocab: turgid, flaccid, plasmolysis • Animal cells • Vocab: lysis

  5. Freshwater adaptations that prevent cell lysis • Freshwater Fish…drink a little, but pee a lot • Protista…contractile vacuole (eg. Paramecium)

  6. Ch 36 - Adaptations for Resource Acquisition • Private Life of Plants excerpt:Perfect Pumps

  7. What drives the movement of water? • What is this a picture of? (hint: a major plant organ) • What adaptations do plants have to control the route water takes?

  8. Cell wall Apoplastic route Cytosol Symplastic route Transmembrane route Key Plasmodesma Apoplast Plasma membrane Symplast Three routes of transport • Apoplastic - external to cell membrane, through walls and spaces • Symplastic - through cytoplasm and plasmodesmata • Transmembrane - passage across cell membranes and walls

  9. Investigating Solute Movement • Water follows ions…but how do ions become concentrated. • Active Transport • We will also discuss this in relation to the human kidney • Ch. 8 147-151 • Ch. 44 936-953

  10. Source vs. Sink

  11. Comparing Xylem and Phloem

  12. Role of Xylem and Phloem

  13. Water Potential • Tendency of water moves from areas of higher water potential to lower water potential. • Water potential= pressure potential plus solute potential

  14. Model of Water Potential

  15. Turgor Pressure • Plant cell walls exert pressure on the cells • Turgid = Healthy state

  16. Water potential in a Hypertonic Solution • Why is the cell losing water? • What is the end result--what happens to the water potential inside/outside the cell?

  17. Water potential in a hypotonic solution? • What happens to the cell over time? • Where is the water potential greater to begin? • Which direction does the water move?

  18. Now let’s go back and see why water moves up the tree?

  19. Loss of water drives movement • Loss of water from stomata • Cohesion-tension hypothesis • Movement by Bulk Flow • Online - Transpiration Case Study

  20. Regulation of Transpiration • Where would we find guard cells ? • Can you explain picture B using the concept of water potential?

  21. Review the Concept of Water Potential Background research: • Osmosis Lab Bench • Case Study 36: How are Water and Solute Potentials Calculated

  22. Lab: • As a class, we are going to compare water potential of different plant parts: • Roots, Stems, Tubers, Leaves, Fruit • Each group will develop a standard curve to estimate the water potential of their assigned plant part. • You will be able to make a 1 M sucrose solution, and then you will use serial dilutions to make known sucrose standards.

  23. How to use sucrose concentration to solve for water potential?

  24. What will you use for concentration? • What will your indepedent and dependent variables be? • What can you use your standard curve to solve for?

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