Leaf disc Lab
Devon Stork
11-29-09
DCPA1:
Raw Data:
DCPA2:
Processed Data:
Minuites
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
White
light
0
1
3
4
5
6
6
6
7
7
8
8
8
8
8
8
Under light
Green
light
0
1
4
5
6
6
7
8
8
8
8
8
8
8
8
8
Minuites
0
1
2
3
4
5
6
7
8
9
White
light
10
9
9
9
9
9
9
9
9
9
Without light
Green
Purple
light
light
10
10
10
9
10
9
10
9
10
9
10
9
10
8
10
8
10
9*
9
10*
Purple
light
0
1
1
2
2
2
2
3
3
3
3
3
3
4
4
4
Orange light
0
3
4
4
2*
5
5
5
5
5
5
5
5
5
5
5
Orange light
10
10
10
9
9
9
9
9
9
9
*means unreliable data because of errors in measurement
DCPA3:
Leaf discs floating
12
10
8
6
4
2
0
0
2
4
8
10
12
Time vs. Leaves floating, Exposed to light
6
Minuites
14
White light
Purple light
Green light
Orange light
Linear (Purple light)
Linear (Orange light)
Linear (White light)
Linear (Green light)
16
Leaf discs floating
12
10
8
6
4
2
0
0
2
6
8
Time vs. Leaves floating, deprived of light
4
Minuites
10
Green light
Purple light
Orange light
White light
Linear (Green light)
Linear (White light)
Linear (Purple light)
Linear (Orange light)
This lab was fraught with error. All of the Trials started with several leaf discs floating,
ranging from 2-6. This made the following data less reliable, as there was less room for
more data, and the maximum number of leaf discs was reached quickly, meaning that
differences between the colors of the lights were more difficult to determine. A limitation
resulting in error was the fact that it was sometimes difficult to determine whither or not a
disk was floating or not, and this resulted in three errors with our lab.
CAE1:
Conclusion:
It was possible to determine which light source gave the most energy, even if the analysis
was incorrect. The greater the slope in the graph where the discs were exposed to light,
the more photosynthesis was occurring with that wavelength of light. From the slopes of
the best fit lines of the graph it should be concluded that white light creates the largest
amount of photosynthesis, which is correct. However, then the data then suggests that
green light gives the next most energy, which is obviously wrong. Then the purple light
has a greater slope then the orange light, which again makes sense, as the purple
wavelengths are shorter, and thus have more energy. The reference to the data here is in
the slopes of the graphs.
This lab had many limitations and weaknesses. Above is mentioned some of the
errors, one of which occurred from a limitation, as it was very difficult to count the
number of leaf disks in the dark. A related limitation was that the leaf disks were exposed
to the light from the overhead fluorescents for a while before the experiment began,
resulting in the large amount of leaf disks floating at the beginning of the experiment.
Also, while the experiment was underway, the green light beaker, the one with very
incorrect results, was partially exposed to the light emanating from the hallway. This is a
weakness. Lastly, the limitation of time existed. There wasn’t enough time to allow the
leaf disks to sink again, so this section of the lab was inconclusive.
Improvements in the lab would have been fairly simple. Many of the limitations
and weaknesses were related to light, and this would have been easily fixed by
conducting this experiment without full-spectrum light, using an ultraviolet possibly.
Secondly, more time could have been allotted to complete this lab.