1. Pre-Lab #9: Floating Leaf Disks and Photosynthesis
AP BIOLOGY
Ms. Day

2. How is photosynthesis divided?
Light reactions vs Dark reactions / Calvin Cycle/ Dark cycle

3. -Creates ATP and NADPH for Calvin Cycle
Light Dependent Reactions
-Creates ATP and NADPH for Calvin Cycle
**water splits and O2 is released!
sunlight
photolysis
THYLAKOID COMPARTMENT
second electron transport system
H2O
NADP+
NADPH e–
ATP
ATP SYNTHASE
PHOTOSYSTEM I
PHOTOSYSTEM II
ADP + Pi
first electron transport system
STROMA
DPIP!

4. Calvin Cycle - Take place in the stroma of chloroplast.
- Uses ATP & NADPH to convert CO2 to sugar

5. Recall…Fill in the letters of the leaf anatomyB E C D

6. Leaf Anatomy

7. In this experiment…
You will determine the rate of photosynthesis using the production of oxygen gas in the light reactions.
BUT…
Remember…Plants need carbon dioxide (CO2) for photosynthesis. Why?

8. In this experiment…
Little disks of spinach leaves (leaf disks) will be used
Each disk has many chloroplasts

9. In this experiment…
Air spaces in spongy mesophyll of leaf disks are filled with a sodium bicarbonate solution
Solution causes disks to sink in a solution
The leaf disks are then exposed to light and the cells undergo photosynthesis.

10. Why use sodium bicarbonate solution?
Sodium biocarbonate solution
a baking soda solution that you will make
Carbon dioxide (for Calvin cycle) is provided by a baking soda solution.

11. What happens in air spaces during photosynthesis?
oxygen is released into air spaces which changes disks buoyancy causing the disks to rise

12. What happens in air spaces during photosynthesis?

13. When is oxygen made in Photosynthesis?
Photolysis
water splits during light reactions (PS II)
Replenishes electrons to P680 chl a

14. Hypotheses
If leaf discs are placed in _(intensity)_ type of light then they will produce ____?____ and they will__(float/sink) ____ because _____________.
If leaf discs are placed in the dark then they will not produce ________and they will_________ because ___________ .

15. Procedure
Making the carbon dioxide source for photosynthesis (baking soda solution)
Mix 1/8 t () of baking soda and mix it in 300 ml of tap water in one of the beakers provided.
USE 0.62 grams

16. Procedure You need to add soap to baking soda solution
Soap = breaks the hydrophobic barrier of the cuticle so the solution can enter the disk

17. Procedure Making leaf disks  don’t let them dry out!
Avoid the veins….WHY? NO chloroplasts

18. Create a vacuum with your thumb
Add small about of solution
Create a vacuum with your thumb

19. You need to get the disks to sink before exposing them to light

21. Please watch the following videos:
6:45 min
4:22 min