AP Biology Photosynthesis Lab

AP Biology
Photosynthesis Lab
Bethany Boyer
Due 11/12/14

Lab Write-Up Questions
First Experiment
1) The independent variable in this experiment was the presence of CO2 (carbon dioxide). The dependent variable was the speed at which the leaf disks started to float.
2) In the leaf tissue, the bicarbonate and light are combining to carry out photosynthesis. This will cause oxygen to collect in the leaf tissue, causing it to rise.
3) If we were to boil the leaf disks, the reaction would most likely be sped up while the temperature is rising, but would slow down or stop when it gets too hot. When the water is boiling, the proteins used to carry out photosynthesis are denatured.
Second Experiment
4) We selected to test the effect of different concentrations of bicarbonate (baking soda) in the leaf disk solutions.
5) Our results showed us that the higher the concentration of bicarbonate, the faster the reaction occurred.
6) Compared to our control, our experimental variable had more bicarbonate solution.

First Experiment Data Tables
Individual Results: With CO2 present
Time (minutes)
Number of floating disks
0:00
0
1:00
0
2:00
0
3:00
0
4:00
0
5:00
0
6:00
0
7:00
1
8:00
7
9:00
10

Individual Results: Without CO2 present
Time (minutes)
Number of floating disks
0:00
0
1:00
0
2:00
0
3:00
0
4:00
0
5:00
0
6:00
0
7:00
0
8:00
0
9:00
0

Second Experiment Data Tables
2g of bicarbonate (baking soda)

3g of bicarbonate
Time (minutes)
Number of floating disks
1-13
0
14
3
15
3
16
3
17
5
18
6
19
7
20
9

4g of bicarbonate
Time (minutes)
Number of floating disks
1
0
2
2
3
4
4
4
5
6
6
6
7
8
8
10

5g of bicarbonate
Time (minutes)
Number of floating disks
1
0
2
0
3
3
4
3
5
6
6
6
7
10

First Experiment Data Tables
Class Data: With CO2 present
Trial
ET50 – Pure Water
ET50 – 0.2% bicarbonate
1
900
1050
2
1080
810
3
0
470
4
0
684
5
0
1080
6
0
540
7
0
420
8
0
420
9
0
240
10
0
360
11
0
480
12
0
540
MEAN
990
591
SD
127
265
SE
90
171