2. Leaf Disk Photosynthesis Lab

2. “Leaf Disk Photosynthesis” Lab

1). Scientific Question: What factors affect the rate of photosynthesis in living leaves?

2.) Hypothesis:______

______.

3.) Materials:

Syringes -2, beakers 150 ml -2, water - 100 ml, baking soda and water - 100 ml, spinach leaf disks – 20, and a timer.

4.) Procedures:

1. Using a pencil, label 1 beaker water and the other beaker baking soda with water.
2. Fill the beaker labeled water with 100 ml of water using the provided graduated cylinder and large container labeled as water.
3. Fill the beaker labeled baking soda with water with 100 ml using the provided graduated cylinder and large container labeled as baking soda and water.
4. To keep everything in both conditions the same (leaf disks in water and leaf disks in water with baking soda), the remaining steps will need to be performed at the same time. One person in the group will need to work with the leaf disks and water and a different person will need to work with the leaf disks and baking soda and water.
5. Remove the plunger from the syringe
6. Place 10 leaf disks in to the syringe barrel and tap them to the bottom.
7. Insert the plunger into the syringe to the 1 cc mark
8. Insert the syringe tip into the solution in the beaker.
9. Extract the plunger to the 5 cc mark.
10. Turn the syringe so the tip is up.
11. Swirl the leaf disks to remove air bubbles from the disks.
12. Push the plunger to remove the air from the syringe. The syringe should now be at the 4 cc mark.
13. Cover the syringe tip with your finger/thumb.
14. Pull the plunger back to the 10 cc mark and swirl the leaf disks for 10 seconds.
15. Slowly push the plunger back into the barrel to release the vacuum.
16. Check to make sure all the disks in each syringe sink.
17. Repeat in both syringes if any disks do not sink.
18. After all disks sink, pour the leaf disks and solution into the corresponding beaker.
19. Set both beakers under one of the light sources provided.
20. Each minute record on the chart the number of disks floating and then gently swirl each beaker two seconds.
21. Repeat until all leaf disks are floating.

5.) Results:

6. Data Analysis questions:

1. Explain the process that caused the leaves to rise.

______

1. Which solution worked best? Why?

______

1. What was the purpose of using the beaker with water only?

______

7.) Conclusion:

C ______

E ______

R ______