Domestos Trial Essay

In this extension experiment there were a few errors that occurred in some of the trials. This is to be expected as perfect sterile techniques are unable to be achieved in the conditions provided. This is also why it was chosen to do three trials of each antiseptic so when errors do occur they can be easily recognised as anomalies. In the Domestos trials the main error was in the second plate where no results could be found for any of the four sections. As can be seen in the photo a small amount of culture did grow around part of the edge of the dish. This means that the error was not due to no Bacillus Subtilis being added to the pour plate. The error could possibly have been not swirling the plate after the agar was poured which would mean …show more content…
In trial 1 and 2 in section D a result occurred but in trial 3 no result occurred. In section D sterile water was used to dip the paper disk in, therefore there should not have been any result as sterile water has no antiseptic properties. This error could have occurred from some form of contamination in the water that was used, but if this were the reason it would be expected that all three trials results would have been affected. The error could have occurred from contamination from the forceps as the same pair was used for each trial. Although the forceps were flamed in the Bunsen burner in between sections and trials to try to eliminate contamination there is a high possibility that not all of the antiseptic was removed. In future experiments multiple forceps will be used to try to eliminate contamination. In trial three another error occurred where all three of the antiseptic dilutions paper discs exclusion zones joined together. This is due to the antiseptic solution on the disks “running” as there is too much antiseptic on the disk when it was placed on the agar. This error is easily fixed by gently shaking any excess solution of the