Evaluation

·       Limitations:

At the beginning, we were going to use a different method which consisted on creating a solid culture, and then open delicately two circular openings in the culture for the deposit of the filter papers steeped in the tobacco solution that we had previously made, and then we could observe the future effect over the bacteria growth in this culture. The main problem that limited this method was that our tobacco solution did not really affect that much the bacteria growth. We believe that the possible cause of this error was that the filter papers were not steeped enough in the tobacco solution, or maybe were the different filter paper sizes, because we cut them with scissors, which is not an effective way to do it. This error could obviously affect to the effect on bacteria growth.

The problem could also be related with the making of cultures in solid states, and the posterior measure of the bacteria growth with a ruler, which is not a very precise and effective process, and this will obviously affect the results. These limitations required a change on the main method of our experiment, as regard as the cultures and the measure of the bacteria growth affected by the tobacco solutions. We specially changed the measure method, in which we changed the ruler and used the spectometer, to obtain a data more coherent and effective.   Secondly, we made another tobacco solution following the same method, to obtain the more results for the comparison with the other results, and to determine the possible errors caused by the measure of the weighing scales.

But the main limitation was caused by the solution, which has spent too much time out of the refrigerator and began to develop a new ecosystem provided with fungi and moss.  So, we could not perform the experiment again because we lacked time and the process was very long.

·       STRONG POINTS:

One of the strong points of our experiment was the second method that we used to find the amount of bacteria by the absorbance of light of the solution with the spectometer. The results were much more accurate and consistent than with the ruler, and it is a very reliable method. We also used a magnetic stirrer for the better mixing and dissolving of the tobacco solution, and to obtain a most homogeneous solution before making the culture for the bacteria.

·       WEAK POINTS:

There were a number of weak points that in some cases could have minimally altered the results of the experiment. One of the weak points was the filtration process of the tobacco solution because when we filtered some of the solid substance was lost, so solution was not entirely representative, as it didn’t contain all the substances of the cigarette. The solution was made only of a part of the composition of the cigarette.

Another weak point could be the first method, in which we use the ruler as the measure method for the measure of the bacteria growth. This is not an effective method and the results could be altered. Another last point could be the filter paper that absorbed too much substance and sometimes, we saw some solid substance in the solution. Finally, the last weak point could be that when these solid substances were fixed on the wall of the beaker, we cleaned the walls of the beaker with water, which made the amount of water increase and be inexact.

·       IMPROVEMENTS:

The first improvement that we could have done, would be do more repetitions of the experiment to get more results in a more accurate method, to compare the new results with the old ones and find the possible errors of the scales and measure, which would be minimized. We could also use another filter paper, in more professional way, or maybe avoid the problem related with the solid substances on the wall of the beaker.