BIO101 Labkitreport L05 Photosynthesis PDF

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Plant Pigments and Photosynthesis PRE-LAB QUESTIONS 1. What is the color of the following plant pigments? Which wavelengths do they absorb?

Pigment Chlorophyll A Chlorophyll B Carotene Xanthophyll Anthocyanin

Color green green Red,yellow, orange yellow red

Wavelengths (colors) absorbed 430mn(blue) and 662nm(red) 453nm & 642nm 460nm & 550nm 453nm & 642nm Between 500 & 600nm

2. Explain how the wavelengths absorbed and reflected determine the color of a pigment.

The set of wavelengths that a pigment doesn't absorb are reflected, and the reflected light is what we see as color.

3. Take a look at the overall reaction for photosynthesis and suggest two ways that the rate of photosynthesis could be measured (Hint: Consider how the substrates and products will change throughout the course of the reaction.)

6 CO2 + 6 H2O + Light Energy → C6H12O6 + 6O2

by the production of oxygen(counting bubbles) or the uptake of carbon dioxide (measuring pH of surroundings)

4. Many deciduous trees have leaves that turn yellow in the fall. What is happening in the leaves at the cellular and molecular level that is responsible for this color change?

As weather gets colder in the fall plants stop making chlorophyll and instead breaks chlorophyll down into smaller molecules causing the yellow color of the leaves.

5. Chloroplasts are the organelles in plant cells that convert solar energy to chemical energy (sugars) that can be used by the cell. Mitochondria are organelles in all eukaryotic cells that convert sugars to ATP Both organelles are have double membranes and contain their own set of DNA. What is the likely explanation for this?

Plant Pigments and Photosynthesis Because of endosymbiosis. Symbiosis is a relationship in which organisms from two separate species live in a close, dependent relationship. Endosymbiosis is a specific type of symbiosis where one organism lives inside the other.

Plant Pigments and Photosynthesis EXPERIMENT 1: PAPER CHROMATOGRAPHY Data Tables Table 1: Chromatography Data Solvent

Distance from Original Line to Solvent Front

Number of Bands

Rf Values for Each Band

Water

0

1

0

Acetone

6cm

1

6

Mineral Oil

0

1

0

Acetic Acid

0

1

0

Post-Lab Questions Chromatography 1. Which colors did you observe in the chromatography papers?

Greens and yellows and on the paper with acetone, a tiny spot of pink.

6. Which plant pigments do you believe each color corresponds to?

7. Which of the four solvents resulted in the best separation? What chemical characteristics of the pigments and/or solvents made this an ideal solvent?

Acetone, the acetone moved the pigment band up the chromatography paper significantly. The others did not move at all so I feel that my experiment may have not come out correctly.

8. How did the Rf values differ between pigments and solvents? What chemical characteristics of the pigments and/or solvents influenced the Rf values?

Significantly. The only one of the bands that moved in my experiment at all was the acetone so it is hard to tell.

Plant Pigments and Photosynthesis Reflection (Discuss what you have learned by doing this experiment. How have your ideas changed? Do you have any new questions? What connections did you make between the lab and lecture?): I learned about how pigment color in plants happens and how the pigment can move on chromatography paper in the presents of acetone. I feel these experiments would be better conducted in a lab with an instructor as well as in a classes that have a lecture for a better learning experience and value as well as a more likelihood that these experiments will be conducted correctly and exact without a lot of flaws.

Microscopy 1. What color are the chloroplasts?

Green.

2. How does this compare with the colors you observed during your paper chromatography experiment?

The colors are very similar in both the chromatography paper and the microscope slide.

Reflection (Discuss what you have learned by doing this experiment. How have your ideas changed? Do you have any new questions? What connections did you make between the lab and lecture?): It is interesting to see what the color of spinach looks like under a microscope.

Plant Pigments and Photosynthesis EXPERIMENT 2: MEASURING THE RATE OF PHOTOSYNTHESIS WITH FLOATING LEAF DISCS Data Tables Purpose (What question is this experiment designed to answer?): use plant leaf disks to view the net photosynthetic rate of plants

Hypothesis (Based on what you’ve learned in the pre-lab materials, write and If/Then statement regarding the outcome of this experiment.): When a normal, air-based environment is infiltrated with a new solution, the density of the leaf disks increases. As a result, they sink to the bottom of the solution. However, as photosynthesis proceeds, oxygen is produced. This decreases the density, allowing the leaf disks to rise

Table 2: Measuring Photosynthetic Rate Time (minutes)

Part A

1

4

2

4

3

3

4

3

5

3

6

2

7

2

8

2

9

2

Part B

Part C

Part D

Plant Pigments and Photosynthesis 10

2

11

2

12

1

13

1

14

1

15

0

Claim (What are the results of your experiment?): only a total of 4 leaf discs floated to the top in the baking soda mixture and none moved in the soapy water.

Evidence (What data did you collect that supports your claim? Explain the meaning behind the data and the calculations.): timing the leaf discs rising to the top of the solution in both mixtures.

Post-Lab Questions 1. Present your results in a graph. Include a brief statement describing why you selected the graphing method you did. Be sure to clearly indicate the x and y axes, the units used, and the graph title(s).

9. Write a detailed conclusion based on your results. How does light and sodium bicarbonate impact the rate of photosynthesis in spinach leaf discs?

10. Identify the controls used in this experiment. Which control is positive, and which control is negative? I used plain water for a negative control and the other two mixtures for positive controls.

11. Did you receive the results you would expect? Why or why not? No. because I thought that at some point all of the leaves would float to the top.

Plant Pigments and Photosynthesis 12. Why did the leaves rise? Will the lead discs float faster or slower if the rate of photosynthesis is decreased? I don’t know because the leaves did not rise correctly.

13. What was the purpose of the soap? I don’t know because it didn’t work. I even tried with a bit more soap. Nothing happened.

14. What do you believe would happen if the leaf disks were boiled prior to this experiment? Why? I believe they would not rise because they would become denatured.

15. If you were to improve this experiment, what would you do differently? Include at least two suggestions for improvement. I would try to figure out which solutions and amounts of these solution would allow for the discs to rise. I used the spinach leaves. Was this correct? (it was listed to use them) or should I have used actual tree leaves from outside. Maybe the spinach is too dense??

16. How would you design an experiment to test the following hypothesis: “The optimal temperature for photosynthesis in spinach leaves is 20 oC”? the same experiment as above but heating the mixture that would work to this temperature.

Reflection (Discuss what you have learned by doing this experiment. How have your ideas changed? Do you have any new questions? What connections did you make between the lab and lecture?): It is hard to say what I learned because my experiment, I believe, was unsuccessful unless the point was for them not to float. A bit confused about the whole thing.

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