12/1/2017 0 Comments Trials, Results, and ConclusionsThe conduction of trials went as smoothly as hoped. In order to determine the effect of chlorinated and non chlorinated water on bacteria growth, a two-sample t test was conducted to compare the mean value of bacteria colonies in both chlorinated and non chlorinated water. The same process was done as used in pretrials as no errors were encountered in the experimental process. The table on the left shows the number of bacteria colonies that grew in the Petri dishes from chlorinated water for all 30 trials. The table on the left shows the number of bacteria colonies that grew in the Petri dishes from non chlorinated water for all 30 trials. Shown above are the box plots representing the data. The blue box plot on the top represents the number of bacteria colonies for chlorinated water. The orange box plot on the bottom represents the number of bacteria colonies for non chlorinated water. On average, chlorinated water contained about 198 bacteria colonies (you cannot have 0.5 of a bacteria colony); non chlorinated water contained about 256 bacteria colonies. There were two outliers for non chlorinated water; therefore, two two-sample t tests will be done, one with the outliers and one without. Above shows the null and alternative hypothesis. The null hypothesis, Ho, states that the mean of the bacteria colonies in chlorinated water, c, will be the same as the mean of the bacteria colonies in non chlorinated, n. The alternative hypothesis, Ha, states that the mean of bacteria colonies in chlorinated water will not be less than the mean of the bacteria colonies in non chlorinated water. The chart and graph above shows the results of the two-sample t test with the outliers included. The t-value is -2.7719 meaning the number of standard deviations away from the mean. The t-value can be used to find the p-value, either by hand using table C in The Practice of Statistics, or in this case, the p-value can be automatically found using the TI-NSpire computer software. Based on the results of the two sample t-test, the null hypothesis is rejected because the p-value of 0.003759 is less than the alpha level, , 0.05. There is evidence to believe that the number of bacteria colonies in chlorinated water is less than the number of bacteria colonies in non chlorinated water. There is only a 0.3759% chance that chlorinated water contained less bacteria than non chlorinated water by chance alone. The chart and graph above show the results of the two-sample t test without the outliers included. The t-value is -2.3015,1 meaning the number of standard deviations away from the mean. The t-value can be used to find the p-value, either by hand using table C in The Practice of Statistics, or in this case, the p-value can be automatically found using the TI-NSpire computer software. Based on the results of the two sample t-test, the null hypothesis is rejected because the p-value of 0.012568 is less than the alpha level, , 0.05. There is evidence to believe that the number of bacteria colonies in chlorinated water is less than the number of bacteria colonies in non chlorinated water. There is only a 1.2568% chance that chlorinated water contained less bacteria than non chlorinated water by chance alone. Overall, it can be concluded that chlorinated water contains fewer bacteria colonies than non chlorinated water. We believe this is do to the presence of chlorine in the chlorinated water. Having chlorine in the water allows for more bacteria to be killed; therefore, making the water cleaner. Without the presence of chlorine in the non chlorinated water, the bacteria had more of an opportunity to reproduce, allowing for more bacteria colonies to grow. If this project were to be done again, multiple improvements would be made. a few errors were encountered after reviewing the experiment; incubation time and the straining method of the bacteria. The incubation time for each Petri dish was different from trial to trail due to the variance in the daily class schedules. Biology was not during the same time everyday, so the incubation time was not consistent. The time varied from about 1-2 hours each trial, depending on when biology was scheduled. The straining method used also posed a problem. When straining the bacteria, Kara had to hold down the sterilized coffee filters in the funnel so that they did not fall through the funnel. This allowed for the transfer of the bacteria from her hands to the coffee filter. In order to correct this, if we were to run this experiment again, whoever has to hold the coffee filters in place would wear sterilized gloves. The video below shows the straining method used for the experiment. If anyone wishes to do research on this topic, we would encourage them to go for it. Although it seems fairly simple, it reveals interesting things that you would have never thought to think about. We would suggest being careful about cross contamination when working with the bacteria in water because you don't want outside factors getting into your water, increasing or decreasing the actual amount of bacteria within the water. In order to further this research, we could test different amounts of chlorine within the water. We already know that chlorinated water contains fewer bacteria than non chlorinated, so testing different amounts of chlorine in the water. We would be able to see which amount kills off the most amount of bacteria, while still being safe for humans to consume.
0 Comments
10/4/2017 34 Comments Pre-TrialsTo begin the research process, we began by conducting pre-trials. The purpose of running pre-trials was to determine what did and did not work in our experiment. We wanted to run through our entire experimental design and see if any changes needed to be made in order to properly carry out the experiment. The first thing we did when starting pre-trials was make the agar needed in the Petri Dishes in order to grow the bacteria within the water. The water bottles were then washed with soap and hot water and then labeled 1-12. We then had to create a sterile straining method to strain the bacteria out of the water. In order to do this, coffee filters were cut to the size of the Petri Dishes and then placed in boiling water for one minute. After being boiled, they were placed in plastic bags to attempt to keep them in a sterile environment. All of the beakers were also washed with soap and hot water and the funnel was boiled to attempt to sterilize it. After everything was prepared and all of our materials were cleaned, it was time to begin the experimental process. Water bottles 1-6 were filled with 250 mL of tap water and water bottles 7-12 were filled with 250 mL of distilled water. Kendall then proceeded to drink out of each of the water bottles, trying her best to drink the same amount of water every time. The only bottles not drank out of were bottles 6 and 12, which were used as a control. The water bottles were then left on the counter over night. The next day, the water was poured through the sterile coffee filters using the funnel. After all of the water was strained through the coffee filters, the coffee filters were then placed on top of the agar previously created for approximately 15 seconds to transfer the bacteria from the coffee filters to the Petri Dishes. Once all of the bacteria was transferred, the Petri Dishes were placed in an incubator over night. Once the Petri Dishes were removed from the incubator, the number of colonies formed was counted. This was done by taking a marker and marking on the Petri Dishes the colonies as you count them. Overall, the experiment worked as it was expected to. We ran into no errors during the experimental process. No changes will be made to the experimental design for when we conduct our actual trials. The picture above shows all of the materials used in the experiment. The only things not pictured are the tap water, the scale, and the incubator. The picture above shows what the agar should look like once it is ready to be poured into the Petri Dishes. It is important to know that the foam created when the agar is done rises extremely quickly and that you should pay close attention to your agar. If the flask is not taken off of the hot plate immediately after it starts foaming, the foam will rise up and out of the flask, creating a large mess and ruining that batch of agar. The picture above shows the two standards for the experiment. The top Petri Dish contains the bacteria grown in the tap water and the bottom Petri Dish contains the bacteria grown in the distilled water. The pictures above show how the bacteria colonies within the Petri Dish were counted. The picture on the left shows a Petri Dish that has not yet been counted. The picture on the right shows the same Petri Dish after the number of bacteria colonies were counted. The dots on the Petri Dish represent each bacteria colony accounted for.
9/28/2017 42 Comments Beginning of ResearchIt has been a controversial topic on whether or not bottled water is cleaner than tap water. Some view bottled water as the only source that they can get their water from because it has been chlorinated, while others believe that tap water is better because it still contains all of the natural vitamins and minerals. The purpose of this research was to determine whether or not bottled water is in fact cleaner than tap water based on bacteria content after been drunk out of.
Internet research has stated that certain bacteria within water can be hazardous to one's health. This bacteria can lead to anything from an increase in the bad bacteria in your mouth causing gum infections, to stomach ulcers. The preservation of water in bottles ensures the life of the bacteria within the water, allowing for growth. When finding sources to gain background knowledge on the growth of bacteria in water and its effects on the human body, MEL.org was most often used. MEL.org contained scientific experiments similar to our research and scientific articles explaining how bacteria grows in water. In order to perform this research, a few things will be needed, the number one thing being reusable water bottles. We will need to buy 12 reusable water bottles, at least 80 petri dishes, coffee filters, distilled water, and dish soap (to clean everything between uses). We will also need to create the agar that the bacteria will grow in, get access to an incubator, hotplate, a few different beakers, and a pair of tongs. To gain more knowledge on the growth of bacteria in water, we will attempt to contact a water treatment facility and ask them questions about how the different water treatments affect the bacteria in the water. |
|