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Absorption and Transport

Absorption and Transport. Chapter 11. H 2 O vapor. product of photosynthesis (sucrose). H 2 O vapor. H 2 O vapor. H 2 O. mineral ions. H 2 O. Fig. 11-1, p. 164. Hydrogen bonds in water. slight negative charge at this end. but the whole molecule has no net charge (+ and – balance

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Absorption and Transport

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  1. Absorption and Transport Chapter 11

  2. H2O vapor product of photosynthesis (sucrose) H2O vapor H2O vapor H2O mineral ions H2O Fig. 11-1, p. 164

  3. Hydrogen bonds in water slight negative charge at this end but the whole molecule has no net charge (+ and – balance each other) slight positive charge at this end Fig. 2-6, p. 18

  4. (1) Diffusion water vapor molecules Fig. 11-2a, p. 165

  5. (2) Osmosis starch solution Differentially permeable membrane (water goes through, but not starch) water net flow Fig. 11-2b, p. 165

  6. (3) Hydrostatic pressure • Involves osmosis and the cell wall. Fig. 11-2b, p. 165

  7. Polysaccharides: • Cellulose (cellular structure) • - monomer is glucose • - connected in a straight chain • - cellulose molecules bind with each other via hydrogen bonds, resulting in cellulose microfibers • Starch (energy storage) • - monomer is glucose • - connected in a helix Fig. 2-10, p. 22

  8. PROTOPLAST SOLUTION (3) Hydrostatic pressure in cells Concentration 0.3 molar Concentration 0.3 molar (Isotonic) Pressure 0 megapascals Concentration 0.27 molar Concentration 0 molar (Hypotonic) Pressure 0.66 megapascals Turgor pressure is one type of hydrostatic pressure. Turgor pressure is the result of a combination of osmosis and cell wall rigidity. Concentration 0.5 molar Concentration 0.5 molar (Hypertonic) Pressure 0 megapascals Fig. 3-7 (a-c), p. 36

  9. Plasmolyzed cells Fig. 3-7 (d), p. 36

  10. (4) Capillary forces force pulling water along side of tube air-water interface force pulling the air-water interface straight capillary tube water molecules connected by hydrogen bonds tension in water column water Fig. 11-2c, p. 165

  11. (5) Gravity • Gravity • Takes force to move water upward • Significant factor in tall trees

  12. Transpiration

  13. water-filled leaf cells substomatal cavity (intercellular space) cuticle is relatively impermeable to H2O water-filled xylem in vein cell wall permeated with H2O air not saturated Fig. 11-5, p. 168

  14. thick boundary layer; gentle gradient; slow diffusion thin boundary layer; steep gradient; fast diffusion Boundary layer: an unstirred layer of air close to the leaf Bulk air: air outside of the boundary layer Wind stirs up the air close to the leaf and makes the boundary layer thinner. Plants transpire much faster on a windy day than on a still one. Fig. 11-3, p. 167

  15. Cross section of a yucca leaf spongy parenchyma cuticle stomatal crypts sunken stomata fibers sunken stomata Fig. 11-4, p. 167

  16. Flow of Water Into Leaves

  17. Capillary forces can convert Water loss into a tension within a tracheid. Before evaporation, there is little tension. After evaporation, there is high tension. A. B. Capillary forces pulling water into the tracheid Tension in the water pulling the tracheid wall inward. Dots: water molecules Short lines: forces of cohesion and adhesion Fig. 11-6, p. 168 Pits

  18. Tracheary elements compared Vessel members Tracheids one vessel member pits in wall perforation plate Vessel members join end to end, but they digest out the end walls forming a tube called a vessel. Tracheids join end to end and along their sides and are connected by bordered pits. Fig. 4-11, p. 58

  19. H2O vapor product of photosynthesis (sucrose) H2O vapor H2O vapor H2O mineral ions H2O Fig. 11-1, p. 164

  20. Symplastic and apoplastic flow through roots root hair plasmodesma xylem symplastic flow apoplastic flow cell wall symplast of endodermis Casparian strip of endodermis cytoplasm cortex stele epidermis Fig. 11-7, p. 169

  21. Control of Water Flow • Environmental factors affecting rate of transpiration • Temperature • Relative humidity of bulk air • Wind speed

  22. Control of Water Flow • Transpiration • Slow at night • Increases after sun comes up • Peaks middle of day • Decreases to night level over afternoon • Rate of transpiration directly related to intensity of light on leaves

  23. LIGHT Events leading to the opening of a stoma: The production of malate and the influx of K+ and Cl- powered by the electrical and pH gradients produced by the proton pump increase the concentration of osmotically active solutes in the guard cells. As a result, water flows into the cells by osmosis. starch malic acid malate– plasma membrane ATP H+ proton pump ADP + Pi  H+ K+ + CI K+ H+ CI Fig. 11-8a, p. 170

  24. cells connected cellulose microfibrils (radial micellation) reinforced inner wall How radial micellation and reinforcement of guard cell walls force an expanding cell to bow outward. With increased pressure, cell gets longer. Because the outer wall can expand more readily, cell bows outward. Fig. 11-9a, p. 170

  25. Fig. 11-9b, p. 170

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