1. VII. Plant Transport A.Transport into the roots 1. Most minerals (solutes) and some water are actively transported into root hairs (ATP)

2. 2. These minerals are transported cell to cell toward the stele through plasmodesmata 3. Most water, on the other hand, is carried between cells, through the cell walls 4. Therefore the endodermis and Casparian strip control the entry of water and solutes into the vascular cylinder (stele) *Because of root organization all water and solutes must pass through a plasma membrane at some point, making selection of solutes possible

6. B. Transport of water (xylem sap)(2ft./min.) 1. Transpiration - evaporation from leaves a. 99% of absorbed water is lost through evaporation (95% from stomata) b. Why? i. cooling of plant ii. CO 2 uptake iii. adequate mineral supply to leaf

9. 2. Root pressure a. Water potential is higher in soil than in root due to mineral uptake (mineral are trapped in stele by endodermis) b. Therefore water diffuses into stele c. Therefore water is forced up xylem in stele

10. 3.Transpiration-cohesion-tension mechanism

12. C. Transport of food (translocation) - phloem sap (1m./hr.) - primarily sucrose 1.Source Sink - leaves - fruit - roots - shoot tip 2. Pressure-flow mechanism a. Sucrose is actively loaded into companion cell (cotransport with proton (H + ) pump) (ATP) b.Sucrose immediately diffuses into sieve tube member through plasmodesmata c.Water diffuses into hypertonic sieve tube mem. d.Resulting pressure causes flow of sucrose solution through sieve tube (bulk flow) e.At sink sucrose is actively transported out and water follows osmotically

13. Companion cell Sieve tube member

15. VIII. Stomata - most common on undersurface of leaves A. Guard cell structure 1.Inner cell wall thicker 2. Unlike epidermal cells they have chloroplasts 3.Radial microfibrils in cell walls, thus they can only elongate

16. B. Factors affecting opening and closing of stomata 1.Light and dark 2. CO 2 concentration in leaf 3.Circadian rhythm of plant itself C. Steps in the process of stomatal opening are the following: 1.Blue-light receptors in guard cell membrane stimulate proton pump to pump out H +, 2.which makes the cytosol negatively charged, 3. which causes K + to diffuse in, [K + ] 4.which causes water to diffuse in osmotically, [H2O] 5.which causes an increase in guard cell turgor, 6. which causes guard cell elongation, 7.which causes stomatal opening.