1. AIM: SWBAT explain how stomata open and close Please Do Now: 1) Define transpiration 2) What excites the electrons (and starts them along the electron transport chain) during the light dependent reactions?

2. Agenda Do Now Photosynthesis review questions Guard Cell notes Video

3. Practice Questions In the overall equation for photosynthesis, six molecules of carbon dioxide result in six molecules of a.glucose. b.water. c.oxygen. d.ATP.

4. Practice Questions In the overall equation for photosynthesis, six molecules of carbon dioxide result in six molecules of a.glucose. b.water. c.oxygen. d.ATP.

5. a.thylakoids. b.chloroplasts. c.plant cells. d.all of the above The stroma is the space that surrounds

6. a.thylakoids. b.chloroplasts. c.plant cells. d.all of the above The stroma is the space that surrounds

7. If carbon dioxide is removed from a plant’s environment, what would you expect to happen to the plant’s production of high-energy sugars? a.More sugars will be produced. b.Fewer sugars will be produced. c.The same number of sugars will be produced but without carbon dioxide. d.Carbon dioxide does not affect the production of high-energy sugars in plants.

8. If carbon dioxide is removed from a plant’s environment, what would you expect to happen to the plant’s production of high-energy sugars? a.More sugars will be produced. b.Fewer sugars will be produced. c.The same number of sugars will be produced but without carbon dioxide. d.Carbon dioxide does not affect the production of high-energy sugars in plants.

9. What is the role of RuBP in the light independent reactions? A. It reduces the 6-carbon molecule and forms 2 G3Ps B. It provides the chemical energy for the regeneration step C. It is what carbon dioxide is fixed on to in the first step of the Calvin cycle D. It is one of the enzymes in the regeneration step

10. What is the role of RuBP in the light independent reactions? A. It reduces the 6-carbon molecule and forms 2 G3Ps B. It provides the chemical energy for the regeneration step C. It is what carbon dioxide is fixed on to in the first step of the Calvin cycle D. It is one of the enzymes in the regeneration step

11. It takes 3 molecules of ATP every turn of the Calvin cycle. How many molecules of ATP does it take to fix enough carbon for a 6 carbon molecule like glucose? A. 9 B. 18 C. 27 D. 54

12. It takes 3 molecules of ATP every turn of the Calvin cycle. How many molecules of ATP does it take to fix enough carbon for a 6 carbon molecule like glucose? A. 9 B. 18 C. 27 D. 54

13. Remember Plants lose water via transpiration This is bad because plants need water for a lot of things It mostly happens via stomata, little tiny holes in the leaf Leaves need stomata to let CO2 in and oxygen out during photosynthesis Water escapes whenever they are open

14. How do plants minimize their water loss through the stomata? The stomata in plants are surrounded by guard cells There are always 2, and they are capable of opening and closing the stomata It is like opening and closing a door: when closed there is no CO2 coming in, but no water escaping

15. How do guard cells open and close the stomata? The guard cells are crescent shaped with thick inner walls and thin outer walls They are basically like balloons that inflate and deflate to open/close the stomata

16. How do guard cells inflate/deflate? When the plants want the stomata to be open, they inflate the guard cells by pumping potassium ions (K+) into the cells Osmosis then draws water into the cells and inflates them to their full crescent shape

17. Regulation of the guard cells 17 Guard cells flaccid Stoma closed K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K + ions have the same concentration in guard cells and epidermal cells (the surrounding cells) Light activates K + pumps which actively transport K + from the epidermal cells into the guard cells

18. Regulation of guard cells 18 K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ Increased concentration of K + in guard cells Lowers the concentration of water in the guard cells Water moves in by osmosis, down osmotic gradient H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O

19. 19 Stoma open Guard cells turgid K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ Increased concentration of K + in guard cells Lowers the  in the guard cells Water moves in by osmosis, down  gradient H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O

20. Summary (fill in the blank on your own) Guard cells are important for maintaining the balance between ____________________ and _________________________

21. Summary (fill in the blank on your own) Guard cells are important for maintaining the balance between gas exchange and water loss