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Introduction

Is the bacteria Escherichia coli (e coli) adversely affected (killed) by King white cleaning products. Higher level biology 14/04/2010 Contents page Page Content 1 Title page 2 Contents page 3 1.1.1- Focus question, 1.1.2- Hypothesis, 1.1.3- Theory 4 1.2.1- Variables , 1.2.2- Control experiment 5 1.3.1- Martials and apparatus, 1.3.2- Safety aspects 6 1.3.2- Safety aspects (cont) 7 1.3.3- Method, 1.3.4- Experimental setup 8 2.1.1- Changes to experimental design 2.1.2- Qualitative data , 2.1.3- Raw data table 9 2.2.1- Overview, 2.2.2- Calculations, 2.2.3- Experimental setup 10 2.3.1- Processed data table, 2.3.2- Process data graph 11 3.1.0- Conclusion 12 3.1.0- Conclusion (cont) 13 3.2.0- Limitations of experimental design 14 3.3.0-Impovements to experimental design 15 Bibliography 1.1.0 Experimental design 1.1.1 Focus question- Is the bacteria Escherichia coli (e coli) adversely affected (killed) by King white cleaning products. 1.1.2 Hypothesis - King White toilet cleaner will most adversely affect (kill) the bacteria Escherichia coli (e coli) to the highest degree when compared to a range of toilet cleaning products. 1.1.3 Theory- Escherichia coli (E coli) are bacteria which causes severe stomach cramps and diarrhoea. It is the leading cause of b****y stools and in older people/younger children certain strains of e coli can be fatal (Family doctor, pg 1, 2008). E coli are common bacteria in humans and some mammals. It is vital in the body as it produces vitamin K as a by-product and is generally a harmless pathogen providing that it remains within the large intestine. However its bi-product becomes negatory when e coli move into other diameters of the body such as the stomach. The bacteria are most commonly transmitted by consuming tainted meat, contaminated water, and raw milk and between cattle workers. However the bacteria may also be transmitted by unhygienic bathroom practise (Pinkster E, pg 1, 2007). E coli is found in human waste which is passed through bathroom toilets, hence some of these e coli bacteria may contaminate bathroom surfaces. ...read more.

Middle

These zones where circular but many where not perfectly circular. Some had diameters that where larger than others. The measurement of diameter was taken from the largest point for all samples. Some zones of inhibitions crossed with other and some even hit the edges of agar plate, like the other samples the largest complete diameter of these particular samples was found. 2.1.3- Raw data table (table 3) - The diameter in millimetres of the zone of inhibition in a e coli growth colony after 24 hours when tested with different cleaning products. Sample Diluted water (mm+0.1) Bleach (mm+0.1) Harpic toilet cleaner (mm+0.1) Home brand toilet cleaner (mm+0.1) Duck toilet cleaner (mm+0.1) King white toilet cleaner (mm+0.1) 1 0 34 15 8 7 20 2 0 33 19 16 10 29 3 0 30 12 11 11 26 4 0 27 17 13 9 34 5 0 25 19 15 13 33 2.2.0 Processing raw data 2.2.1- Overview- Each different cleaning product showed results that were fairly similar. Hence the independent values can be averaged (including the calculation of standard deviation). This average will represent the average diameter of the zone of inhibition for a given substance. These averages with respective standard deviations will be placed into a bar graph so that the effectiveness of different products can be visually compared. 2.2.2- Calculations used (table 4) Statistical Analysis Formulae Sample Calculation Mean X=Mean value X=Sum of all values n= Number of values Mean of bleach diameter (mm+0.1) X=(34+33+30+27+25)+0.1/5+0.1 =29.8mm +0.1 Standard Deviation X -X)2= Variance squared N= Number of values is system /4 (mm) =3.83mm standard deviation 2.2.3- Experimental setup (figure 2)- inserted a bit later 2.3.0 Presenting raw data 2.3.1- Processed data table (table 5) - The average diameter (mm2) of the zone of inhibition of e coli growth colonies after 24 hours for difference different cleaning products. Diluted water Bleach Harpic toilet cleaner Home brand toilet cleaner Duck toilet cleaner King white toilet cleaner Avenge diameter (mm+0.1) ...read more.

Conclusion

Systematic Use better research methods to find how the specific chemical make-ups of different solutions would affect bacteria, or view dead bacteria under a microscope to examine physiological changes. Some samples had higher viscosity then others Systematic Allocate a static volume for each solution and use the volume for each sample. Some samples diffused more than others Systematic Physically spread solutions (dense and thin) over the same surface diameter to reduce the impact of diffusion. Unequal spreading of e coli over agar plates Systematic Use the continuous line cross section grid method to ensure the bacterial colonies are equal in size/density, and have been drawn from the same source. Movement of agar plates Systematic The movements of agar plates should be kept to an absolute minimum. This can be achieved through improved experimental practice. For instance the agar plate should be open, e coli colonies prepared, and then all samples placed within the same time period. Using this method the agar plate only needs to be opened once. Shape of the zone of inhibition Random The number of substances on each agar plate should be reduced or the size of the agar plates should be increased. This will help to ensure the a more accurate circle is produced (does not collide with agar plate edges, ect) Decontamination mechanism was shared amongst others Systematic The decontamination mechanism (methylated sprits) was shared with another experimenter using different solutions. For the purpose of decreasing the opportunity for cross contamination individual decontamination mechanisms should be employed. It may also be responsible to use separate decontamination vessels for individual substances. Timing of recording results Random The recording of results should be taken as per the experimental design. If this time cannot be reach by the experimenter then another or partner experimenter should be requested to record results. Movement in the diameter of the experiments Random Distractions and the movement of other experimenters increase the chance of cross contamination and other random errors. Future experiments should be performed away from other experimenters and a solitary environment. ...read more.

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