Photosynthesis Lab
AP Lab #5 Plant Pigments/Photosynthesis
I. Identifying the Effects of Different Variables of Light and Carbon Dioxide on the Rate of
Photosynthesis and Observing the Separation of Pigments Through Chromatography
II. Introduction
Plants have a variety of pigments, all of which absorb a different color of light. The three main pigments are chlorophyll a, chlorophyll b and carotenoids. Chlorophyll a is the primary plant pigment that absorbs red and blue light, which ultimately appears green to the human eye because green light is reflected instead of being absorbed. Chlorophyll b and carotenoids both function to capture light energy and transfer it to the reaction center located in chlorophyll a. Part
A of this lab involves the experimentation of chromatography to separate spinach pigments. …show more content…
There are three factors that affect the functionality of chromatography which are the pigments’ attraction the paper, solubility, and size of the pigments. The factor that allows the solvent to move up the chromatography paper is its attraction to the paper. However, the pigments will move up the chromatography paper at different rates because they are not equally soluble to the solvent. Photosynthesis has two main stages, the lightindependent reaction and the lightdependent reaction. Light independent reactions occur only in the light and produce ATP and NADPH which are then used by the lightdependent reactions to fuel its process. Part B of this lab involves differing variables of light and carbon dioxide and the effects they have on the rate of photosynthesis. In this experiment, the rate of photosynthesis will be measured through the floating of leaf disks in solution.
III. Hypothesis, Materials, and Method
Part A:
Hypothesis: The plant will produce varying bands of yellow and green pigments along the chromatography paper.
Part B:
Hypothesis: The more light or carbon dioxide there is, the faster the rate of photosynthesis.
IV. Variables
Part A:
Independent Variable: Colors of the bands
Dependent Variable: Plant pigment
Part B:
Independent Variable: Sodium bicarbonate solution
Dependent Variable: Time each disk took to float
Control: Water/Soap solution without carbon dioxide
V. Data and Observations.
Part A: Plant Pigments and Chromatography
Observations: The plant produced five visible bands of color: dark green, light green, green, light yellow and dark yellow. All of the bands were the same distance apart except for band 4 and the solvent front which were both 2mm apart.
Data:
Band #
Distance(mm)
Band Color
1
0.5mm
dark brown
2
1.5mm
light green
3
2.5mm
green
4
4.5mm
light yellow
Solvent Front
6.5mm
dark yellow
Part B: Photosynthesis
Observations: The closer the light source or the more light available to be absorbed by the plant, the higher the rate of photosynthesis. Plants must have carbon dioxide to perform photosynthesis.
Red light seems to be more effective than regular ambient light.
Data:
Control w/o CO2
CO2 light 30cm away
Min
# of leaf disks floating Min
# of leaf disks floating 5
0
1
0
10
0
2
0
15
0
3
0
20
0
4
1
25
0
5
3
30
0
6
6
7
8
8
8
9
9
10
10
Every Group
Control
w/o CO2
Min
Groups 11,10,9
CO2
Groups 8,7,6 Groups 5,4,3
CO2
ambient
light 30
light
cm
Groups 2,1
CO2 light
CO2 Red
50 cm
light
# leaf Min
# leaf Min
# leaf Min
# leaf Min
# leaf
disk
disk
disk
disk
disk
floati
floati
floati
floati
floati
ng
ng
ng
ng
ng
1
0
1
0.00
1
0.33
1
0.00
1
0.00
2
0
2
0.00
2
0.33
2
0.00
2
0.00
3
0
3
0.00
3
1.67
3
0.00
3
0.00
4
0
4
0.33
4
2.33
4
0.00
4
0.00
5
0
5
0.33
5
3.67
5
0.00
5
0.00
6
0
6
0.67
6
5.33
6
2.33
6
0.50
7
0
7
0.67
7
7.33
7
3.00
7
1.50
8
0
8
1.00
8
8.00
8
3.67
8
1.50
9
0
9
1.33
9
9.67
9
4.67
9
2.00
10
0
10
1.67
10
10.00 10
5.00
10
3.00
11
0
11
2.00
11
10.00 11
6.33
11
4.50
12
0
12
2.00
12
10.00 12
6.67
12
4.50
13
0
13
2.33
13
10.00 13
7.00
13
5.50
14
0
14
3.33
14
10.00 14
7.33
14
6.00
15
0
15
3.33
15
10.00 15
7.67
15
7.50
16
0
16
3.33
16
10.00 16
7.67
16
8.00
17
0
17
4.00
17
10.00 17
8.00
17
8.50
18
0
18
4.33
18
10.00 18
8.00
18
9.00
19
0
19
4.67
19
10.00 19
8.67
19
9.00
20
0
20
5.00
20
10.00 20
8.67
20
9.00
21
0
21
5.00
21
10.00 21
8.67
21
9.00
22
0
22
5.00
22
10.00 22
8.67
22
9.00
23
0
23
5.00
23
10.00 23
8.67
23
9.50
24
0
24
5.33
24
10.00 24
8.67
24
9.50
25
0
25
5.67
25
10.00 25
8.67
25
9.50
AVERAGE
CO2 ambient light CO2 light 30 cm
CO2 light 50
CO2 Red light 30
cm
cm
5 Disks Floating 19 min 40 sec
5 min 7.33 sec
11 min 11.67
12 min 1.50 sec
sec
10 Disks
Incomplete data
9 min 24.33 sec
21 min 59 sec
22 min 46 sec
floating
VI. Analysis and Questions
Part A:
1. Calculate the Rf(Reference front) values for each of the four pigments
4.5 / 6.5 = 0.691
= Rf for carotene
2.5 / 6.5 = 0.385
= Rf for xanthrophyll
1.5 / 6.5 = 0.230
= Rf for chlorophyll a
0.5 / 6.5 = 0.077
= Rf for chlorophyll b
2. What factors are involved in the separation of the pigments?
A: The pigment’s solubility to the paper in solution, the size of the pigment particles, and the attraction to the paper.
3. If you repeated this activity using a different solvent, would you expect to get the same
Rf values for the pigments? Explain your answer.
A: No, the Rf values would be different because the pigments dissolve differently in other types of solvents.
4. Which is the main photosynthetic pigment? What are the functions of the other three pigments? A: Chlorophyll a is the main photosynthetic pigment. The other three pigments collect wavelengths and transfer energy from the harvesting of wavelengths to chlorophyll a.
Part B:
2. Explain the process of carbon fixation
A: Carbon fixation is when carbon dioxide is attached to another sugar by an enzyme.
3. Explain the process the causes the leaf disks to rise.
A: The process that caused the leaves to rise was photosynthesis. The production of oxygen that occupied the gaseous space in the leaf caused the leaf to rise to the surface of the solution.
4. Which trial worked best? Explain.
A: The trial with carbon dioxide and a light source 30cm away worked best. This is because the light source for this variable was the closest to the plant out of all the trials, which means that the plant is receiving the most light in order to perform photosynthesis at a more optimal rate.
5. What was the purpose of using the water/soap solution for one of the trials?
A: The soap causes the membrane in plant cells to open and allow free exchange of oxygen and carbon dioxide. This solution served as the control for this experiment.
6. What is the effect of darkness on photosynthesis?
A: Darkness significantly slows the rate of photosynthesis. Without light, photosynthesis cannot occur as photosynthesis requires light as a reactant for the process to occur.
7. If we were to boil the leaf disks, what kind of results would you expect? Explain.
A: Photosynthesis would not occur since the molecules would be denatured, disallowing the functionality of the molecules to react with one another. There would also be no space for gases to move in and out, forcing the leaf disks to stay at the bottom of the
solution.
8. How does light intensity affect the rate of photosynthesis?
A: The more exposure of light there is, the higher the rate of photosynthesis.
9. How does light intensity and the rate of photosynthesis relate to the position of the sun, both during the day and during the year?
A: Enough light is given for photosynthesis during the day. Each season, the sun is at a different position from Earth, making certain seasons more optimal for plant growth. Spring is when photosynthesis occurs best because it is when the sun’s rays are best shined on Earth. During the summer, the rays of the sun fall more vertically onto Earth, making it hotter than the winter where the sun is not vertically above us, rather it is more tilted horizontally.
10. Design an experiment using the same setup to investigate a different variable in the rate of photosynthesis.
A: I would test the effects of varying concentrations of carbon dioxide on Photosynthesis. Our group was actually able to test this and we found that higher concentrations of carbon dioxide do increase the rate of photosynthesis. However there is an optimal amount of carbon dioxide for photosynthesis and once that amount is surpassed, photosynthesis will begin to slow down and eventually come to a halt.
VII. Discussion
We followed all of the directions correctly in part A of this lab, however we failed to do so in part B. In part B of this lab, we did not stay the full time to record our control data for the solution without carbon dioxide in ambient light. We only stayed thirtyminutes, when we should’ve been patient and stayed longer even if it required us to miss lunch. We will definitely learn from this experience and be more responsible for future labs.
For part A of this lab, we hypothesized that the plant pigment will produce variations of yellow and green color bands because we thought that to our human eye, generally only those two wavelengths will be reflected by a plant dependent on Photosynthesis. For the most part, we were correct except for one band which was dark brown. We could understand why the first band was brown because on the color wavelength chart, brown is just to the right of yellow.
For part B of this lab, our hypothesis was correct. However, we discovered that there is a maximum amount of carbon dioxide that a plant can absorb. Once that maximum is passed, there will be a surplus of reactants, and photosynthesis may take longer to occur or even come to a stop. We discovered this by experimenting with two extra variables, one solution with a mass amount of sodium bicarbonate and another solution where light is 20 centimeters away. We found that the solution with a mass amount of sodium bicarbonate in ambient light took significantly longer to raise the leaf disks than the solution with a regular amount of sodium bicarbonate in ambient light, while the solution with light 20 centimeters away actually got all ten disks to rise to the surface before the solution that was 30 centimeters away did.
VIII. References
AP Lab #5: Photosynthesis/Plant Pigments Lab Manual, Print.
Reece, Campbell. Biology, 7th Edition, pgs. 181199 AP. San Francisco: Pearson Education,
2005.
Print.
Andersen, Paul. "Plant Pigments and Photosynthesis." YouTube. YouTube, 14 Mar. 2012. Web.
29
Nov. 2013
I. Identifying the Effects of Different Variables of Light and Carbon Dioxide on the Rate of
Photosynthesis and Observing the Separation of Pigments Through Chromatography
II. Introduction
Plants have a variety of pigments, all of which absorb a different color of light. The three main pigments are chlorophyll a, chlorophyll b and carotenoids. Chlorophyll a is the primary plant pigment that absorbs red and blue light, which ultimately appears green to the human eye because green light is reflected instead of being absorbed. Chlorophyll b and carotenoids both function to capture light energy and transfer it to the reaction center located in chlorophyll a. Part
A of this lab involves the experimentation of chromatography to separate spinach pigments. …show more content…
There are three factors that affect the functionality of chromatography which are the pigments’ attraction the paper, solubility, and size of the pigments. The factor that allows the solvent to move up the chromatography paper is its attraction to the paper. However, the pigments will move up the chromatography paper at different rates because they are not equally soluble to the solvent. Photosynthesis has two main stages, the lightindependent reaction and the lightdependent reaction. Light independent reactions occur only in the light and produce ATP and NADPH which are then used by the lightdependent reactions to fuel its process. Part B of this lab involves differing variables of light and carbon dioxide and the effects they have on the rate of photosynthesis. In this experiment, the rate of photosynthesis will be measured through the floating of leaf disks in solution.
III. Hypothesis, Materials, and Method
Part A:
Hypothesis: The plant will produce varying bands of yellow and green pigments along the chromatography paper.
Part B:
Hypothesis: The more light or carbon dioxide there is, the faster the rate of photosynthesis.
IV. Variables
Part A:
Independent Variable: Colors of the bands
Dependent Variable: Plant pigment
Part B:
Independent Variable: Sodium bicarbonate solution
Dependent Variable: Time each disk took to float
Control: Water/Soap solution without carbon dioxide
V. Data and Observations.
Part A: Plant Pigments and Chromatography
Observations: The plant produced five visible bands of color: dark green, light green, green, light yellow and dark yellow. All of the bands were the same distance apart except for band 4 and the solvent front which were both 2mm apart.
Data:
Band #
Distance(mm)
Band Color
1
0.5mm
dark brown
2
1.5mm
light green
3
2.5mm
green
4
4.5mm
light yellow
Solvent Front
6.5mm
dark yellow
Part B: Photosynthesis
Observations: The closer the light source or the more light available to be absorbed by the plant, the higher the rate of photosynthesis. Plants must have carbon dioxide to perform photosynthesis.
Red light seems to be more effective than regular ambient light.
Data:
Control w/o CO2
CO2 light 30cm away
Min
# of leaf disks floating Min
# of leaf disks floating 5
0
1
0
10
0
2
0
15
0
3
0
20
0
4
1
25
0
5
3
30
0
6
6
7
8
8
8
9
9
10
10
Every Group
Control
w/o CO2
Min
Groups 11,10,9
CO2
Groups 8,7,6 Groups 5,4,3
CO2
ambient
light 30
light
cm
Groups 2,1
CO2 light
CO2 Red
50 cm
light
# leaf Min
# leaf Min
# leaf Min
# leaf Min
# leaf
disk
disk
disk
disk
disk
floati
floati
floati
floati
floati
ng
ng
ng
ng
ng
1
0
1
0.00
1
0.33
1
0.00
1
0.00
2
0
2
0.00
2
0.33
2
0.00
2
0.00
3
0
3
0.00
3
1.67
3
0.00
3
0.00
4
0
4
0.33
4
2.33
4
0.00
4
0.00
5
0
5
0.33
5
3.67
5
0.00
5
0.00
6
0
6
0.67
6
5.33
6
2.33
6
0.50
7
0
7
0.67
7
7.33
7
3.00
7
1.50
8
0
8
1.00
8
8.00
8
3.67
8
1.50
9
0
9
1.33
9
9.67
9
4.67
9
2.00
10
0
10
1.67
10
10.00 10
5.00
10
3.00
11
0
11
2.00
11
10.00 11
6.33
11
4.50
12
0
12
2.00
12
10.00 12
6.67
12
4.50
13
0
13
2.33
13
10.00 13
7.00
13
5.50
14
0
14
3.33
14
10.00 14
7.33
14
6.00
15
0
15
3.33
15
10.00 15
7.67
15
7.50
16
0
16
3.33
16
10.00 16
7.67
16
8.00
17
0
17
4.00
17
10.00 17
8.00
17
8.50
18
0
18
4.33
18
10.00 18
8.00
18
9.00
19
0
19
4.67
19
10.00 19
8.67
19
9.00
20
0
20
5.00
20
10.00 20
8.67
20
9.00
21
0
21
5.00
21
10.00 21
8.67
21
9.00
22
0
22
5.00
22
10.00 22
8.67
22
9.00
23
0
23
5.00
23
10.00 23
8.67
23
9.50
24
0
24
5.33
24
10.00 24
8.67
24
9.50
25
0
25
5.67
25
10.00 25
8.67
25
9.50
AVERAGE
CO2 ambient light CO2 light 30 cm
CO2 light 50
CO2 Red light 30
cm
cm
5 Disks Floating 19 min 40 sec
5 min 7.33 sec
11 min 11.67
12 min 1.50 sec
sec
10 Disks
Incomplete data
9 min 24.33 sec
21 min 59 sec
22 min 46 sec
floating
VI. Analysis and Questions
Part A:
1. Calculate the Rf(Reference front) values for each of the four pigments
4.5 / 6.5 = 0.691
= Rf for carotene
2.5 / 6.5 = 0.385
= Rf for xanthrophyll
1.5 / 6.5 = 0.230
= Rf for chlorophyll a
0.5 / 6.5 = 0.077
= Rf for chlorophyll b
2. What factors are involved in the separation of the pigments?
A: The pigment’s solubility to the paper in solution, the size of the pigment particles, and the attraction to the paper.
3. If you repeated this activity using a different solvent, would you expect to get the same
Rf values for the pigments? Explain your answer.
A: No, the Rf values would be different because the pigments dissolve differently in other types of solvents.
4. Which is the main photosynthetic pigment? What are the functions of the other three pigments? A: Chlorophyll a is the main photosynthetic pigment. The other three pigments collect wavelengths and transfer energy from the harvesting of wavelengths to chlorophyll a.
Part B:
2. Explain the process of carbon fixation
A: Carbon fixation is when carbon dioxide is attached to another sugar by an enzyme.
3. Explain the process the causes the leaf disks to rise.
A: The process that caused the leaves to rise was photosynthesis. The production of oxygen that occupied the gaseous space in the leaf caused the leaf to rise to the surface of the solution.
4. Which trial worked best? Explain.
A: The trial with carbon dioxide and a light source 30cm away worked best. This is because the light source for this variable was the closest to the plant out of all the trials, which means that the plant is receiving the most light in order to perform photosynthesis at a more optimal rate.
5. What was the purpose of using the water/soap solution for one of the trials?
A: The soap causes the membrane in plant cells to open and allow free exchange of oxygen and carbon dioxide. This solution served as the control for this experiment.
6. What is the effect of darkness on photosynthesis?
A: Darkness significantly slows the rate of photosynthesis. Without light, photosynthesis cannot occur as photosynthesis requires light as a reactant for the process to occur.
7. If we were to boil the leaf disks, what kind of results would you expect? Explain.
A: Photosynthesis would not occur since the molecules would be denatured, disallowing the functionality of the molecules to react with one another. There would also be no space for gases to move in and out, forcing the leaf disks to stay at the bottom of the
solution.
8. How does light intensity affect the rate of photosynthesis?
A: The more exposure of light there is, the higher the rate of photosynthesis.
9. How does light intensity and the rate of photosynthesis relate to the position of the sun, both during the day and during the year?
A: Enough light is given for photosynthesis during the day. Each season, the sun is at a different position from Earth, making certain seasons more optimal for plant growth. Spring is when photosynthesis occurs best because it is when the sun’s rays are best shined on Earth. During the summer, the rays of the sun fall more vertically onto Earth, making it hotter than the winter where the sun is not vertically above us, rather it is more tilted horizontally.
10. Design an experiment using the same setup to investigate a different variable in the rate of photosynthesis.
A: I would test the effects of varying concentrations of carbon dioxide on Photosynthesis. Our group was actually able to test this and we found that higher concentrations of carbon dioxide do increase the rate of photosynthesis. However there is an optimal amount of carbon dioxide for photosynthesis and once that amount is surpassed, photosynthesis will begin to slow down and eventually come to a halt.
VII. Discussion
We followed all of the directions correctly in part A of this lab, however we failed to do so in part B. In part B of this lab, we did not stay the full time to record our control data for the solution without carbon dioxide in ambient light. We only stayed thirtyminutes, when we should’ve been patient and stayed longer even if it required us to miss lunch. We will definitely learn from this experience and be more responsible for future labs.
For part A of this lab, we hypothesized that the plant pigment will produce variations of yellow and green color bands because we thought that to our human eye, generally only those two wavelengths will be reflected by a plant dependent on Photosynthesis. For the most part, we were correct except for one band which was dark brown. We could understand why the first band was brown because on the color wavelength chart, brown is just to the right of yellow.
For part B of this lab, our hypothesis was correct. However, we discovered that there is a maximum amount of carbon dioxide that a plant can absorb. Once that maximum is passed, there will be a surplus of reactants, and photosynthesis may take longer to occur or even come to a stop. We discovered this by experimenting with two extra variables, one solution with a mass amount of sodium bicarbonate and another solution where light is 20 centimeters away. We found that the solution with a mass amount of sodium bicarbonate in ambient light took significantly longer to raise the leaf disks than the solution with a regular amount of sodium bicarbonate in ambient light, while the solution with light 20 centimeters away actually got all ten disks to rise to the surface before the solution that was 30 centimeters away did.
VIII. References
AP Lab #5: Photosynthesis/Plant Pigments Lab Manual, Print.
Reece, Campbell. Biology, 7th Edition, pgs. 181199 AP. San Francisco: Pearson Education,
2005.
Print.
Andersen, Paul. "Plant Pigments and Photosynthesis." YouTube. YouTube, 14 Mar. 2012. Web.
29
Nov. 2013