1. Plant Nutrition and Transport AP Chapter 30

2. Key Concepts: Many structures and functions of plants are adaptive responses Root systems spread through soil and obtain nutrients The cuticle and stomata help consume water Stomata usually open during the day and close at night

3. Key Concepts: In vascular plants, the flow of water and solutes connects all cells of the plant Transpiration pulls the columns of water molecules Translocation allows sucrose and other organic compounds to be distributed throughout the plant

4. Carnivorous Plants Capture animals to supplement their nutrient (N 2 ) intake Venus flytrap lures insects with sugary bait; closes on victim Cobra lily lures insects down a one- way passage A fruit fly trapped in a Venus Flytrap. Credit: © Dr. Richard Kessel & Dr. Randy Kardon/Tissues & Organs/ Visuals Unlimited

5. Plant Nutritional Requirements Nearly all plants are photoautotrophs Require carbon dioxide, water, minerals Many aspects of plant structure are responses to low concentrations of these vital resources in the environment Indian Pipe grows only four to ten inches tall. It has flowers that droop and tiny, scale-like leaves. This plant is parasitic taking nutrients from both trees and fungi.flowers leaves

6. Soil and Its Nutrients Soil consists of: Minerals Humus – decomposing organic material holds water Water Oxygen Three soil-particle sizes: Sand – largest Silt – medium sized Clay – finest particles Loam Soils with equal amounts of sand, silt and clay Topsoil Most essential layer

7. Nutrients Essential for Plant Growth Macronutrients – amount required > 0.5% plant’s dry weight Carbon Hydrogen Oxygen Nitrogen Potassium Calcium Magnesium Phosphorus Sulfur Micronutrients – needed in trace amounts Chlorine Iron Boron Manganese Zinc Copper Molybdenum

8. Leaching and Erosion Leaching Removal of nutrients from soil as water flows through it Most pronounced in sandy soils Clays hold onto nutrients best Erosion Movement of soil under the force of wind, running water, and ice

9. Absorption of Water and Mineral Ions Into Roots Vascular cylinder Central column Endodermis Around column Casparian strip Throughout cell walls Exodermis Layer of cells just inside roots

10. Water and Solute Movement Into a Root Vascular Cylinder Casparian strip Prevents water and solutes from passing between cells into vascular cylinder Water & solutes must pass through cells Transport proteins control flow

11. Specialized Absorption Structures Root hairs – extension of epidermis Root nodules Mutualism Contain nitrogen fixing bacteria Bacteria convert N 2 into forms plant can use Mycorrhizae Symbiotic (mutualism) Root and fungus Remember Ch. 24!

12. A Theory of Water Transport Through Plants Transpiration Evaporation from leaves, stems and other plant parts Creates negative tensions in xylem diameter of trunk decreases during maximum transpiration Cohesion-tension theory Tensions extend downward from leaves to roots Hydrogen-bonded H 2 O causes water in xylem to be pulled upwards as continuous columns (cohesion)

13. A Theory of Water Transport Through Plants Water evaporates from leaves through stomata This creates a tension in water column in xylem Replacement water is drawn in through roots

14. Root pressure Glass tube Water Cut stem Water The leaves pull (transpiration) The roots push (root pressure) Is capillarity enough?

15. Water Potential The tendency of water molecules to move along gradients of concentration and pressure Water potential is relative to something else With stomata open, large water potential (tendency to evaporate) Will support 300 meter water column Cohesion pulls more water up

16. Water Potential – osmosis and wilting

17. Conservation of Water in Stems and Leaves Cuticle Consists of waxes in cutin Translucent – allows light to pass (not H 2 0) Stomata – openings in cuticle Guard cells define opening Allow gases in and out Turgor pressure in guard cells: High - Stoma opens Low - Closes stoma K+ also play a role

19. CAM Plants Most plants are C3 or C4 plants Stomata open during day and photosynthesis proceeds CAM plants are better at water conservation Stomata open at night and carbon dioxide is fixed Next day, stomata remain closed while carbon dioxide is used

20. Distribution of Organic Compounds Through the Plant Phloem Transport organic compounds Conducting tubes are sieve tubes Sieve tubes Living cells side by side and end to end in vascular tissue Companion cells Lie next to sieve tubes Help load organic compounds into sieve tubes and supply energy to start process

21. Sieve-Tube Members

22. Sugar Transport Sugar moves only in sieve tubes of phloem Woody stems have sieve tubes only in the inner bark Girdling a tree (removing strip of bark around a tree) will kill it

23. Transportable Organic Compounds Carbohydrates are stored as starches Starches, proteins, and fats are too large or insoluble for transport Cells break them down to smaller molecules for transport Sucrose is main carbohydrate transported

24. Maple Syrup Production On the average, it takes 40 gallons of maple sap to make 1 gallon of pure maple syrup. One tap hole is placed in each maple trees, which gives 10 gallons of sap in an average year. So, 4 maple trees, 40 to 200 years old, are needed to make one gallon of pure maple syrup.

25. Pressure-Flow Hypothesis The aphid’s contribution to pressure- flow!

26. Translocation and Pressure Flow Transport of sucrose through phloem High pressure system Pressure flow theory Internal positive pressure high at source end Solute-rich solution is pushed towards the “sink”

27. SOURCE WATER SINK bulk flow sieve tube of the phloem Active transport moves solutes into sieve tubes Water moves in, increasing turgor pressure Pressure pushes solutes by bulk flow between source and sink Pressure and solute concentrations decrease between source and sink Solutes unloaded into sink cells, lowering their water potential; water follows Stepped Art

28. Interdependent Processes ATP formation by roots absorption of minerals and water by roots respiration of sucrose by roots transport of sucrose to roots transport of minerals and water to leaves photosynthesis

29. In Conclusion A vascular plant depends on the distribution of water, ions, and organic compounds to all of its cells Root systems take up water and nutrients Specialized structures and symbiotic relationships with other organisms help the uptake of nutrients

30. In Conclusion Distribution of water and ions occurs through xylem Plants lose water through transpiration Cohesion-tension theory states that negative pressures extend from the leaves to the roots as transpiration occurs, causing tension A cuticle protects the plant parts

31. In Conclusion Water loss and uptake occurs in the stomata Opening and closing of stomata is controlled by guard cells which balance water conservation with CO 2 uptake CAM plants open stomata and fix carbon dioxide by the C 4 pathway at night

32. In Conclusion Plants distribute organic compounds through sieve tubes The pressure flow theory states that translocation is driven by differences in solute concentration and pressure between source and sink regions