Total Hours Spent on
Group 4 Project:
Name
|
Total Hours
|
Tasks
|
Colton
|
12
|
Attended meeting at school;
attended first summer meeting; brainstorming; independent research; attended
second summer meeting; group research; developing design basics; completing
chemistry procedures in experiment; attended post-experiment meeting;
calculations; final edits
|
Katie
|
14
|
Attended meeting at school;
attended first summer meeting; brainstorming; independent research; attended
second summer meeting; group research; developing design basics; finalizing
details and editing of design; completing biology procedures in experiment;
attended post-experiment meeting; assembling multimedia presentation;
formatting weaknesses and improvements section; final edits
|
Rebecca
|
12
|
Attended meeting at school;
attended first summer meeting; brainstorming; independent research; attended
second summer meeting; group research; developing design basics; completing
chemistry procedures in experiment; attended post-experiment meeting;
calculations; final edits
|
Kelsey
|
12
|
Attended first summer meeting;
brainstorming; independent research; attended second summer meeting; group
research; developing variables; springboard for final details of design;
completing biology procedures in experiment; attended post-experiment
meeting; processing data; writing conclusions and abstract; final edits
|
Abstract:
Because of the strong
association between photosynthesis and chlorophyll, the green pigment that
absorbs the light energy necessary for this process, it could be assumed that a
higher transmittance of green light, due to a higher presence of green pigment,
would result in a higher rate of photosynthesis. This experiment was designed
to test the correlation between the transmittance of green pigments in the
leaves of plants and their rate of photosynthesis. The hypothesis was that
leaves exhibiting lower transmittance of green pigments will also have lower
rates of photosynthesis. During the experiment, each plant’s carbon
dioxide intake was monitored with a CO2 monitor in order to
calculate the rate of photosynthesis. At the same time, pigment was extracted
from the leaves of the same species of plants and run through a colorimeter;
these results were used in calculations to determine the green light transmittance
of each plant. The plant with the lowest green light transmittance of 35%, Salvia
farinacea, had the second lowest rate of photosynthesis at -2.2 ppm/min. Crossandra
infundibuliformis had the second highest rate of photosynthesis at
-0.5 ppm/min and the highest green light transmittance of 90.1%. The
hypothesis of a lower transmittance leading to a lower rate of photosynthesis
could not be supported by the results, as they were inconsistent. Overall,
there was a slight increase in the rate of photosynthesis as the level of
transmittance increased, but the results were so scattered, they could neither
support nor refute the hypothesis.
Link to Multimedia Presentation (note: the presentation must be downloaded once the link is clicked):
If you used different colored plants (not green), would the results regarding the photosynthesis change?
ReplyDeleteWhat does your hypothesis tell us about the correlation between transmittanence and the photosynthesis rate of plants and their chlorophyll?
In the same conditions as the experiment we performed, I do not
Deletebelieve there there would be a change in results regarding
photosynthesis. other colored leaves, such as the red leaves of the Japanese maples, perform photosynthesis just as efficiently as green leaves when exposed to a lot of light. However in dimmer lights, the colored leaves are less efficient than green leaves. Since each plant was given the same exposure to light using the lamp, I don't not think there would be a change. Here is a link for more information on photosynthesis in different colored leaves:
http://baynature.org/articles/photosynthesis-in-leaves-that-arent-green/
We hypothesized that the correlation between transmittance and the photosynthesis rate would be positive. After researching the topic, we thought that a lower green light transmittance would result in a lower rate of photosynthesis. Since our results are inconclusive, we are neither able to support nor refute our hypothesis.
How did you go about using the results from the colorimeter in calculations to determine the green light transmittance?
ReplyDeleteWhat are the underlying assumptions in having data that neither support nor refute the hypothesis?
Since the data we collected neither supports nor refutes our
Deletehypothesis, we assume that there is no correlation between the
concentration of a pigment of a plant and its rate of photosynthesis. With further testing and different plants it might be possible to find a correlation, but just from this experiment we have to assume that there is none.
The colorimeter gave us results in terms of absorption of light. We used Beer's Law to convert from absorption to transmittance as absorption and transmittance are related through a logarithm.
DeleteHow did you go about choosing the plants for this experiment?
ReplyDeleteWhat is an alternate way to extract pigment from the leaves besides using the acetone hexane solution?
This comment has been removed by the author.
DeleteWe went to Pike's and from the selection of plants available, we chose plants that preferred similar environmental conditions (part sun, etc.) and that, to the naked eye, appeared to have different leaf colors. We wanted to make sure that the pigmentation in the leaves was different even without testing plants in the colorimeter beforehand so that the plants would not all have the same/nearly the same transmittance.
DeleteAlternate methods of extracting pigments include boiling the leaves in water and mashing the leaves with ethyl or isopropyl alcohol, or repeating our method while using a solution of petroleum ether and acetone.
DeleteHow do you know that your use of the lamp was an accurate way for the plant to perform photosynthesis?
ReplyDeleteHow would you explain, or try to explain, why the results were inconsistent? Or what you could have done to make them consistent?
The purpose of the lamp in the experiment was to simulate the light of the sun and to have a way to control the light intensity for each plant. By placing the lamp the same distance from each plant, there was a controlled light intensity, reducing the amount of error in the experiment.
DeleteI would say that the results were largely inconsistent mostly due to errors such as having to change from using the cuvettes to a test tube, human error, delays between and during trials, and having to change equipment. It may also be that the results were inconsistent because there may be no relation between our two variables. One way to possibly make our results consistent would be to have our experiment more consistent with less errors.
DeleteWhat is the same and what is different from your experiment and the plants in their natural environments that could have affected photosynthesis?
ReplyDeleteHow did you go about controlling the amount of leaves on each plant that conducted photosynthesis?
All five of the plants we used are native to warm, somewhat tropical environments. Similarities between our tank and this climate include light intensity (strong) and level of watering before the experiment (regular and high). However, there were several differences between our tank and this climate that may have inhibited photosynthesis. The temperature in the lab was much colder than the tropics. The lab was also likely less humid than the tropics. In the tank, the plants had no competition with other plants for light and other resources whereas they would experience this in a natural environment. Finally, plants were confined to a tank in this experiment but are not similarly confined in a natural environment.
DeleteTo control the general size of each plant, we massed the plants before testing them in the photosynthesis tank and removed leaves from those plants who had much greater masses than the other. This technique was not without error as we could not get all of the plants to reach exactly the same mass or have exactly the same surface area of leaves, and each plant had leaves of different sizes.
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ReplyDeleteWhat was the basis for choosing the three plants? How do you know that other experimental factors didn't influence the rate of photosynthesis?
ReplyDeleteWe went to Pike's and from the selection of plants available, we chose plants that preferred similar environmental conditions (part sun, etc.) and that, to the naked eye, appeared to have different leaf colors. We wanted to make sure that the pigmentation in the leaves was different even without testing plants in the colorimeter beforehand so that the plants would not all have the same/nearly the same transmittance.
DeleteThere were certainly some experimental factors that influenced the rate of photosynthesis, such as time spent in photosynthesis, size/area of the plant and its leaves, carbon dioxide concentration, temperature, and light intensity. We attempted to control these variables by setting up the photosynthesis tank in the same way for each trial and massing the plants to be tested, but there were some human errors in this process.
Gabriel E. Hernandez (Student-Teacher with Amos)
ReplyDeleteLet us assume for a moment that the plant leaves were all of equal size (bad assumption, but just play along). If all other things were equal, you seem to be suggesting then that one plant my still undergo photosynthesis more so than another. My guess would be that some plants may have more chlorophyll than another. My question to this group is, why might a plant need to have so much chlorophyll? What environments are these plants found in? Could environment have played an influence as to the biological fitness of these different plants?
A plant needs chlorophyll to absorb the light energy necessary for the process of photosynthesis to occur. The levels of chlorophyll in plants may depend on the availability of sunlight. A plant that has less opportunity to absorb sunlight might need less chlorophyll to survive because it has adapted to operate with less need for photosynthesis. A plant in a sunny climate might have more chlorophyll because there is a greater opportunity to conduct photosynthesis.
DeleteAll five of the plants we used are native to warm, somewhat tropical environments (including Brazil, parts of Africa, Mexico, and India/Sri Lanka). Because of this, they probably all contain higher levels of chlorophyll because of the availability of sunlight. However, the experimental environment differed from the plants' natural environment (see Brie's question), so this could have inhibited the plants' photosynthesis.