1. Plants Form and Function

2. Parts of a Leaf

3. What do these parts do?  Cuticle (waxy layer) and Upper Epidermis  Prevent Water Loss  Palisade Mesophyll  Cells contain lots of chloroplasts: absorption of light for photosynthesis  Vascular Bundles  Transport water to the leaf (xylem) and starch away (phloem)

4. What leaf parts do, con’t  Spongy Mesophyll  Loosely packed, surfaces for gas exchange  Lower Epidermis and Guard Cells  Guard cells open and close, controlling water loss by transpiration and allowing for gas exchange

5. The Xylem Xylem Phloem

6. The Xylem  Mainly carry water and dissolved minerals from roots to leaves  Woody plants- they provide support for the plant

7. The Phloem  Transports organic nutrients throughout the plant.  Carries starches away from plant.

8. Root Picture of Xylem and Phloem Xylem Phloem

9. Transpiration  Transpiration is the loss of water from leaves and stems of plants  This loss of water causes a “pull” on the rest of the water in the plant, causing water from the roots of the plant to continue moving upward.  This is caused by the cohesion between water molecules

10. Transpiration Pull  Upward movement through xylem generates a transpiration pull  Cohesion between water molecules allows water to by ‘sucked up’

11. Transpiration flow is controlled by the rate of water loss through the stomata

12. Closed Stoma  CO 2 uptake is LOW  Water loss is LOW

13. Stomata closing caused by:  Water shortage: forced closure to prevent dehydration  Darkness

14. Open Stoma  CO 2 uptake is high  Water loss is high

15. Stomata opening caused by:  Sunlight/high photosynthesis  Reduced CO 2 concentration

16. What affects rate of transpiration?  Wind  Increases the rate of transpiration because humid air near the stomata is carried away  Temperature  Increasing Temperature causes greater transpiration because more water evaporates  Light  Speeds up transpiration by warming the leaf and opening stomata  Humidity  Decreasing humidity increases transpiration because of the greater difference in water concentration

17. Photosynthesis  Generates a chemical storage of energy in the form of carbohydrates.  Converts light energy to chemical energy  Photosynthetic organisms are examples of autotrophs.

18. Photosynthesis Equation