A) The predictions that my lab table gave were approximately what we received as results. In tube 1 (the milk), the milk never transformed into yogurt, because there was no addition of a probiotic. Tube 1 was acting as a control, a basis for what the milk was to look and smell like, and also to give the lab researcher an idea of the texture. Some of the physical properties of tube 1 include: a semi-liquid texture, a smell of slightly sour milk, a white color, and a pH of 7. In tube 2, the milk and the addition of the yogurt (the probiotic), transformed the milk and yogurt into yogurt. Tube 2 was a variable, because the results of the milk added to the yogurt could have either changed or remained the same. The purpose of a variable is to measure the transformation and possible change that a certain experiment could cause. The properties of tube 2 include: a semi-solid texture, a smell of yogurt, a white color with a transparent film at the top, and a pH of 4. Tube 3 was composed of milk, yogurt, and ampicillin. This tube was also a variable in this experiment, as we were trying to figure out if yogurt could be produced with the addition of an antibiotic. The end result was no, because the ampicillin killed the bacteria in yogurt which did not allow the transformation from milk to yogurt to occur. The physical properties of tube 3 include: a semi-liquid texture, a smell of sour milk, a white color and a pH of 7. In our final test tube, tube 4, we tried using a different type of bacteria to make yogurt. This was also a variable, because E.Coli is another type of bacteria, and our lab group was attempting to find if any type of bacteria could create yogurt. E.Coli did not produce yogurt, some of the physical properties of tube 4 are: a semi-liquid texture, an unattractive smell (bad smell), a white color and a pH of 7. The yogurt up in the front of the classroom is worthy of mentioning, as it acted a control for tube 2. The yogurt had a pH of 4, and a yogurt smell, a white color, and a semi-solid texture. Our table succeeded in creating yogurt.
B) Possible Sources of error include:
- Accidentally adding ampicillin to tube 2, which causes all the bacteria to die. Which means no yogurt is produced.
- We used the same yellow rod to add yogurt to all 4 of our tubes, and we add ampicillin to tube(s) 1, 2, or 4 on accident.
-The vortex could have shaken the tubes so violently that the ampicillin stuck to the roof of the tube and we created yogurt in tube 3.
-The hot water bath was so hot that the DNA strands in the bacteria's nucleoids denatured, thus making the process of yogurt making impossible.
- The hot water bath was not hot enough to pasteurize the yogurt, so bad bacteria survived and spoiled the milk or yogurt
- The vortex did not move enough to thoroughly mix in the contents of tube 2, tube 3, or tube 4 so either yogurt was not produced, ampicillin did not come into contact with the yogurt and yogurt was produced, or the E.Coli was just pooled at the bottom
- We dropped all of our tubes on the ground and bad bacteria entered all of the tubes and spoiled the various results
Excellent - A+
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