Photosynthesis Lab
Purpose
What is the effect of intensity and wavelength of light on photosynthesis?
Materials
Procedure
Part I
1. Cover 3 to 5 leaves of the green plant with black paper
2. Cover 3 to 5 leaves of the green plant with cellophane
3. Leave some leaves uncovered to use as controls
4. Leave the coleus plant's leaves uncovered
Part II
1. Cut off some controlled leaves, black covered leaves, and cellophane covered leaves.
2. Separate green and red parts of the coleus plant.
3. Roll up the leaves and place in test tubes.
4. Extract chlorophyll using alcohol and a hot water bath.
5. Rinse leaves with water, and place in petri dishes.
6. Cover each leaf with iodine.
7. After 1 minute, remove the leaves and place on a paper towel.
8. Record the color of the leaves.
Data
What is the effect of intensity and wavelength of light on photosynthesis?
Materials
- Scissors
- Petri dishes
- black paper
- colored cellophane paper
- tape
- alcohol
- test tubes
- iodine
- green plant
- coleus plant
Procedure
Part I
1. Cover 3 to 5 leaves of the green plant with black paper
2. Cover 3 to 5 leaves of the green plant with cellophane
3. Leave some leaves uncovered to use as controls
4. Leave the coleus plant's leaves uncovered
Part II
1. Cut off some controlled leaves, black covered leaves, and cellophane covered leaves.
2. Separate green and red parts of the coleus plant.
3. Roll up the leaves and place in test tubes.
4. Extract chlorophyll using alcohol and a hot water bath.
5. Rinse leaves with water, and place in petri dishes.
6. Cover each leaf with iodine.
7. After 1 minute, remove the leaves and place on a paper towel.
8. Record the color of the leaves.
Data
Conclusion
From our observations we learned that the most photosynthesis happens when the leaves are left uncovered. We also found that the red and green parts of the coleus plants had about the same amount of photosynthesis occurring. We may have run into a lot of experimental error. First of all some of the plants were not as close to the window, therefore not all the plants received the same amount of light. In order to fix this problem we could have rotated the plants every so often. Another mistake we made was not covering the leaves all the way. Although we tried our best to completely cover the leaves, some parts were still showing, or sometimes the paper even slipped off the leaves. We also might have experienced a stronger result in the difference between the red and green leaves if we had been more thorough in separating them.
Reflection
This lab was very quick, but was also quite interesting. I found it very cool that we were able to extract the chlorophyll. While doing the lab I was very interested in whether the green or red part of the coleus plant would have a more positive result. I had never even thought about how the color of the plant could effect photosynthesis. Our group worked very well together. We all helped place the different leaves in separate test tubes. We all helped to separate the red and green parts of the coleus plant. Most importantly we analyzed the results all together. We also did a good job with cleaning all of the petri dishes and leaving our area spotless! One major thing I would change next time would be to get a plant with more red in it so that it would be easier to compare the green and red parts. The plant we were using had a very small amount of red in it, so it made it difficult to separate the parts.