1. Plant Structure & Transport Systems Chapter 28 & 29

2. I. Plant Structures  A. Roots : anchor, absorb minerals and water, store carbs  1. Root hairs: individual cells: absorption  2. Tap roots: Main vertical root: anchor  3. Lateral roots: Branch to sides: absorb  4. fibrous roots: mat of shallow roots

4.  B. Shoots: leaves and stems  1. Stems & Branches: transport & elevation  a. veins in stem transport  i. xylem cell : water up  ii. phloem cells : sugars down  b. Elevation advantage..  i. light  ii. pollen dispersal

5.  2. Leaves: photosynthesis/Gas exchange  a. mesophyll cells do Photosynthesis  i. fill interior of leaf  ii. Chloroplasts  b. stoma  i. opening  ii. Allow gas  in/out of  air spaces  inside leaf

6. II. Gas Exchange  A. Guard Cells: open and close stomata  1.Open stomata let CO 2 in but..  also let water out by transpiration  2. Transpiration in leaf  i. water evaporates from mesophyll cells into air space (High ψ to low ψ)  ii. Water vapor moves from air space through stomata into air  (High ψ to low ψ)

8. C. Stomata number & location  Drier climate : fewer stomata  Aquatic plants : many stoma always open  Most stomata on bottom of leaf  Stomata open & close in response to stimuli

9. D. Guard Cells Open  Blue light stimulus received by photoreceptors on guard cells  Signal transduction causes active transport of K + into guard cell  water flows into cell  Increasing turgor pressure  Bending guard cells apart= response

10. E. Guard Cells Close Stoma  ABA hormone = signal molecule produced by plant cells lacking water  ABA binds guard cell receptors  Signal transduction opens Ca+ and K+ channels reducing solute conc in cell  H2O leaves cell. Low turgor pressure due  to shrinking vacuole makes cell flaccid  Stoma closes

11. III. Water Transport  A. Into Root  1. hydrophilic cell walls of root tips/root hairs  2. water & minerals flow into cortex extracellular spaces  3. cortex & epidermal  cells selectively absorb  minerals (high SA)  4. Active transport increases mineral conc.

12. Apoplast –extracellular Symplast-cytoplasm

13. B. Into Vascular cylinder  1. Endodermis cells regulate what enters  vascular cylinder  2. Casparian strip of wax (suberin) forms tight junctions around endodermal cells  3. only what crosses endodermal cell membranes can enter Xylem  4. active transport moves ions increasing osmotic pressure as H 2 O follows

15.  4. Root pressure pushes xylem sap (water/minerals) up root by bulk flow  (fluid movement by pressure)

17. C. Up Stem & to veins in leaves (p588)  1. Cohesion-tension hypothesis  a. Pulls sap up stem & into leaf veins  b. Water evaporates from cell wall of mesophyll cells into air spaces  c. Lost water creates tension on water in the rest of the leaf (negative pressure)  d. tension and negative pressure potential result in low water potential  e. cohesion pulls water toward air space  f. adhesion keeps them from falling

18. Transpiration https://www.youtube.com/watch?v=xGCnuXxbZGk https://www.youtube.com/watch?v=xGCnuXxbZGk

25.  Translocation