This year, I have accomplished many things, from experiments to research and data analysis. Beginning of the year, I was worried that I wouldn't be able to collect proper data or my experiments would not turn out the way I expected them to. However, through thorough research and with the help of my mentor, I was able to successfully get all the materials I needed and carry out the experiments in a safe environment. My results were also accurate enough to lead to a logical scientific conclusion which helped me wrap up my Signature project well.
Overall, I think the presentation went smoothly. I think I did speak faster than I have practiced but other than that, I am satisfied with my presentation. I received a few questions which were all questions that I have also been wondering and wanting to dig deeper into. When I received those questions, I did my best to use my knowledge from prior research to answer them. On the other hand, those questions prompted me to interpret my results in a another way and strive further. I have enjoyed being a part of Emma's Signature Group. In the future, I anticipate using what I've learned from my experience to perform more accurate experiments regarding a similar topic or even continue this project.
1 Comment
In hopes of finding an explanation for the unexpected increase in the average heartbeat of the "Daphnia Magna" after incubation in dilution factor 4 for the original Tide experiment, I learned some factors that could have contributed to the increase.
Many experiments have been conducted to test the effect of temperature on the crustacean's heart rate. Many of the findings suggest that increasing the temperature in which the crustaceans are in would increase their heart rates. Since "Daphnia" are cold-blooded animals, they do not thermoregulate. Thus, as temperature increases, the metabolism of the crustacean increases as well. This means that the heart rate will speed up in order to provide oxygen to the cells as the metabolism increases. This type of natural response could have occurred in the "Daphnia" when it has been put under the microscope lamp. By the time I was conducting my experiment for dilution factor 4, the lamp would have been turned on for nearly an hour or even more. The intense heating on the minuscule crustacean could have caused their heart to beat faster despite the prior incubation in a diluted solution of detergent. Source: http://www.nuffieldfoundation.org/practical-biology/investigating-factors-affecting-heart-rate-daphnia After collecting all my data, I have organised them into a Google spreadsheet for convenient comparison and analysis. This is the data for the original Tide detergent. The row goes from top to bottom in order of dilution factor 1 to dilution factor 5. Each of the Pre and Post numbers represent an average of the 8 data that I collected. For example, the 252.125 beats/min in the top row is an average of the 8 "Daphnia Magna's" heartbeats before incubation into dilution factor 1 whereas the 114 beats/min in the top row is an average of the 8 "Daphnia Magna's" heartbeats after incubation into dilution factor 1. The difference value adjacent to the Post column represents the difference between the average Pre and Post heartbeats which correspond to dilution factor 1. The left graph represents the original Tide data. To the right of the graph is the data table for the graph. I also calculated each of the slopes for the line segments for accurate comparison. This is the data for the Purclean Tide detergent. Surprisingly, the difference between the Pre and Post heartbeats for dilution factor 1 in the Purclean experiment is greater than that of the original Tide experiment. This was a particularly interesting observation since 2 of the 8 crustaceans in the original Tide experiment died after incubation in dilution factor 1. However, the original Tide shows a smaller difference than the Purclean Tide, which means the crustaceans in the Purclean Tide experiment on average had a bigger drop in heartbeat after incubation in dilution factor 1 than did those in the original Tide experiment. However, all of the other differences in the Purclean data table, except for the difference for dilution factor 4, are greater than those in the original Tide data table. As a result, these unexpected results disproved Purclean's purpose of an "eco-friendly" detergent. The graph above represents the Purclean Tide data while the data table on the right corresponds to the graph as well as shows the slopes of the four line segments. As the data shows, the first three slopes which represent the slopes of the lines between dilution factor 1 and 2, 2 and 3, and 3 and 4, respectively, are more negative, or steeper, than the first three slopes in the original Tide data table. This means there was a greater drop in average difference for the Purclean than for the original Tide. However, the last slope of the original Tide graph is steeper or more negative than that of the Purclean. This could be accounted for by the greater toxicity of the original Tide detergent despite the fact that the slope is representative of the two most diluted solutions.
After analyzing my data, I found what I have to research and learn more about in order to fully comprehend my results and make a valid conclusion. For example, I would want to investigate more into why the third slope in the original Tide graph is positive when the next slope is negative. Theoretically, since the next slope represents incubation in a more diluted solution, the preceding slope should be more negative, or at the very least, negative. I have completed the first half of my experiment for the Purclean tide and have collected four sets of data. As the four sets of data show, the general pattern remains similar as the data from the previous experiment using the original Tide showed: the difference between pre and post heartbeats, on average, decreased as the dilution factor increased. An interesting thing to note was the increase in heartbeat for dilution factor 5 in sets 2 and 3. This kind of odd pattern also appeared in one of the eight sets of data from the previous experiment. I am planning to do some more research on some possible reasons behind the increase in heartbeat.
It is difficult to point out a definite difference between this experiment and the previous experiment which each used different detergents. However, none of the "Daphnia" from the four sets died after incubation in the dilution factor 1, whereas one of them did die in the previous experiment. This difference supports Tide's claim that their Purclean Tide is more environmentally friendly than their original Tide. However, more analysis must be done in order to prove that their claim is entirely correct by comparing how wide the gap between the pre and post heartbeat is for the same dilution factor in both experiments. I explored more about the Purclean detergent than I used for my second experiment. Below is a table that lists the ingredients that were used to manufacture and their purposes in making the environmentally friendly detergent still effective as a detergent. As much as it was accounted for the 65% USDA BioPreferred certification, the surfactants used are built from plant based raw materials and contain some petroleum based components. The formula mentioned in some "purpose" sections contains small amounts of sodium formate, sorbitol, and phenoxyethanol. These ingredients act as enzyme stabilizers to ensure the best cleaning performance possible. Formula also contains a small amount of silicone polymer for manufacturing.
On the second day of the experiment, I collected the next four sets of data as represented by the picture below. Overall, the pattern fits with my hypothesis that as the dilution factor increases, the heartbeat will slow down at a slower rate. In other words, the difference between the pre and post heartbeat will decrease as the dilution factor increases. As you can see in Set 6, the post heartbeat of the "Daphnia" that was incubated in dilution factor 1 died. Unlike the one in Set 3 in which the "Daphnia" died while I was counting its heartbeat, this one's heart did not beat as soon as I put it under the microscope, meaning it died in the solution during the 5-minutes incubation time.
I think my second four sets of data is "better" than my first four in the sense that they fit more well with the expected pattern. In the first four sets, there were many more outliers than the second four. For example, the "Daphnia" incubated in dilution factor 5 of Set 2 experienced an increase in the heartbeat after the incubation. Although it was incubated in the most diluted solution, an increase is definitely an outlier. One reason that could account for the unexpected result could be the "Daphnia" became anxious when I pipetted it on to the lens and slightly "poked" it with the paper towel when I was soaking up the surrounding water so that it would not move as much when I am counting its heartbeat. I tried my best to not touch the "Daphnia", but my mistake could have caused its heartbeat to beat faster. This week, I am following the same procedure except testing the Tide Purclean. This detergent is the first 65% USDA certified bio-based laundry detergent that, according to Tide, has the same cleaning power as the original Tide does. It is made with 100% renewable wind power electricity and is free of dyes, chlorine, and phosphates. I look forward to comparing my results of the original Tide and the Tide Purclean to see whether the Tide Purclean actually does have a less harmful effect on the "Daphnia magna". Before I left for long weekend, I completed my experiment with the original Tide detergent. Following the procedure mentioned in my previous post, I ran the experiment over two days, each day collecting four sets of data. This is the original Tide that I used for my experiment. This is a tank containing a new batch of "Daphnia magna" that my mentor ordered for me. This is a picture of my workspace. The beaker right beside the microscope contains a few "Daphnia Magna" that I incubated in serial diluted factors. I used highly precise pipets to exactly measure the amount of water and detergent that will go in the first test tube. Then, using a different pipet, I transferred 0.2 mL of the first solution into the next and so on. The picture above are five test tubes that hold the serial dilution. As the colors indicate, the serial dilution goes in order from left to right, with the right solution being the most diluted. This is a close-up version of the above picture. If you look closely, you will see a "Daphnia" in each of the tubes, swimming in the relatively less toxic solutions. Here are the results that I recorded on the first day. The tables each include the dilution factor (1 being the least diluted and 5 being the most diluted), heartbeats per minute before the incubation (Pre), and the heartbeats per minute after the incubation (Post). The numbers next to the table are the minutes at which I was supposed to take the "Daphnia" out. It made it easier for me to note them next to the dilution factor so that I would not confuse myself.
One interesting thing to note is the "Daphnia" that I incubated in the first dilution factor in Set 3 died while I was counting its post-heartbeats per minute. Perhaps, I took it out right when it was on the verge of dying, which is why its heart stopped beating while I was counting. Nonetheless, this kind of incident was not unexpected since the first dilution factor is the most toxic, and therefore, is expected to greatly slow down the crustaceans' heartbeats, if not, kill them. The other results indicate a slightly unexpected pattern. For instance in Set 4, the heartbeat of the "Daphnia" in dilution factor 2 slowed down by a far greater extent than that of the "Daphnia" in dilution factor 1. However, the results of dilution factors 3, 4, and 5 show the expected pattern of results: the heartbeat slowed down less and less as the dilution factor increased. In my next post, I hope to gain a more accurate overall picture of the effect that the original Tide has on "Daphnia" by combining my next four sets of data with these. Today, I met with my mentor to discuss my plans for my main experiment, which will take place in February. For the experiment, I will be comparing the effect of two detergents, one original and one claimed to be green, that have same purposes, such as washing clothes or dishes, on the "Daphnia magna" by measuring its heart beat. I think it would be interesting to see if there is any difference between the effect of the original detergent versus the "green" detergent when the "Daphnia magna" is put into the same concentration of each of the detergents. Through this experiment, I could potentially prove or disprove the "green" label on the detergent.
To create the solutions in which the daphnia would be put into, I would prepare several test tubes and label them to represent the different dilution factors. I would fill each test tube with more water, which I will decide the exact amount later, than the detergent. Then, I would take out 1/10 of the mixture from the first test tube and transfer it to the second test tube. I would repeat this process until all of the solutions in the test tubes are diluted from the previous solution. For the incubation process which will follow after, I would measure the heart beats of "Daphnia magna" before putting them into the test tubes. Then, I would put a "Daphnia" into the first test tube. After 5 minutes, I would take it out and count its heart beat again. I would do the same to all of the other test tubes, incubating "Daphnia" into each of them for 5 minutes and measuring their heart beats after every incubation. I still have to do some research to decide on which two detergents I want to use. I also have to decide whether I want to do the experiment for the two detergents separately with two different patches of "Daphnia" or order one patch and complete the experiment within two days of its arrival since Carolina Biological recommends experiments on it to be done in that time frame. I am looking forward to collecting all of my results in February and getting most of my work done before I start analyzing them. Sean S. Madden is 42 years old and grew up on the coast of Massachusetts about half way between Boston and Cape Cod. He went to college at the University of Vermont in Burlington, VT where he received a B.S. in Wildlife Biology. Later Ihe went back to school for a Master’s degree in Biodiversity, Conservation and Policy at the University at Albany. He is married to a pediatrician named Jeena and has two children, Jake and Rosie. He has been a biologist working for the New York State Department of Environmental Conservation (DEC) for ten years. He works on what is called a natural resource damage assessment (NRDA) for the Hudson River for which he functions as one of the representatives for DEC working with Trustee partners, US Fish and Wildlife Service and NOAA, to determine how PCBs have injured the natural resources of the Hudson River. He mainly helps coordinate field studies, write reports, and plan ways to restore the river to compensate the public for injuries to natural resources.
A couple of years after college, he took an AmeriCorps position with a non-profit called Riverkeeper, which is one of the major Hudson River advocacy groups. He developed public outreach and education programs about how PCBs had negatively affected commercial and recreational fisheries on the Hudson. He fell in love with the area and the river, and after his year with Riverkeeper was over, he took a job with Clearwater, another of the major Hudson River non-profit groups. He worked on a 100-ft traditionally-rigged Hudson River sloop, which was built in the 1960s to get people reconnected with the Hudson. For three years he sailed, and taught, and sang aboard the boat and got to experience the Hudson up close and personal. He was working for Clearwater when the Record of Decision for the dredging of the PCBs in the upper Hudson River was issued, which represented an enormous victory. Sean believes the most important environmental problems today are climate change and unsustainable consumption of resources. He explained that "those two problems are intertwined and certainly human population size is part of the problem." However, he has great hope because the world has made some tremendous changes for the better over the past 60 years of the modern environmental movement. Due to the packed Revels schedule, I did not have time to meet with my mentor this week. However, in our last meeting, we discussed about what research and preparation are needed to be done for the next experiment. During winter break, I am planning to do the research and gain as much knowledge on the pH of natural lakes and rivers as well as the impact of a slight change in pH on the aquatic organisms. This will help me determine how much I should alter my pH by in order to observe a noticeable change in the "Daphnia Magna's" heartbeat. I believe the hardest part of this experiment is going to be figuring out how much to change the pH by in order to barely bring out a change. Lowering or highering the pH significantly will bring out an obvious result. However, finding the pH level that just barely affects their heartbeats will be a significant finding. Due to the difficulty and need of trial and error, I imagine that this experiment could take a little longer than the previous one. I hope to discuss my results in my next post which I will post next semester.
|
AuthorHello! My name is Alice Kim, and I am a senior at Emma Willard. I am interested in learning about environmental issues. ArchivesCategories |