Mint and Garlic

Why do they put mint in toothpaste? Would Garlic be better?

Aim

To investigate the different antibacterial properties of mint and garlic to determine which ones are the most appropriate and will work best in toothpaste.

Hypothesis

I predict that the mint will be most affective as an antibacterial defence as it is already commonly used in toothpaste and must therefore be better when fighting microorganisms. It also is used in ‘Bonjela’ and contains menthol, which can act as a local anaesthetic property.

Null Hypothesis

There will be no significant difference between mint and garlic on their effect in inhibiting bacterial growth.

Method

Firstly spread E-coli onto agar plates, being careful not to touch it or leave it exposed to the air for a long time. To spread the E-coli use a wire loop, and spread evenly. After using the loop, burn it under a Bunsen burner until glows red in order to kill bacteria. To guarantee safety use aseptic technique. After this has been prepared, weigh out 3g of garlic plant material and 3g or mint plant material, putting them in separate mortars and using a pestle to crush them. Next, add the crushed plant to 10cm3 of ethanol, measured using a pipette, in order for any existing bacteria to be killed. When doing so, be careful not to let ethanol become in contact to a naked flame, as ethanol is highly flammable. The next step is to pipette 0.1cm3 of the extract on to paper discs which are put in to separate petri dishes, allowing them to dry for approximately ten minutes after doing so. The three petri dishes should then be marked into mint, garlic and control groups using a marker pen, allowing each one to be clearly identified. Lastly, seal the petri dishes securely in a cross formation in four places using clear tape. You do this and not the whole way around to prevent anaerobic respiration in which the bacteria growing become more toxic. Lastly, incubate for 24 hours at a temperature of 25oC

Ensuring Safety- Aseptic Technique

Aseptic technique ensures that cross contamination of microorganisms or spores does not occur and also protects people from being contaminated.

Aseptic technique should be used when transferring bacteria using the wire loops. The loop should be held vertically into the hottest part of a Bunsen flame until it glows red. After using the loop the same procedure should be carried out again. This ensures sterilisation.

This technique should also be used when sterilising bottle necks. When opening and closing the bottle, the neck should be passed through a flame for 2-3 ...

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Ensuring Safety- Aseptic Technique

Aseptic technique ensures that cross contamination of microorganisms or spores does not occur and also protects people from being contaminated.

This technique should also be used when sterilising bottle necks. When opening and closing the bottle, the neck should be passed through a flame for 2-3 seconds. However, it has to be taken into consideration that ethanol is flammable.

General Safety procedures include:

-Covering cuts with plasters so that bacteria can not infect them

-Disinfect work surfaces

-Light a Bunsen burner on the work surface so that there is an updraft to attract bacteria away from the bench.

-Disinfect contaminated items between use

-Wash your hands with warm water and antibacterial soap before and after practical work.

Equipment involved

Agar plate with seeded bacteria
Garlic Cloves
Mint Leaves
Pestle and mortar
10cm3 ethanol
Pipette
Filter discs
Petri dish
Forceps
Clear tape
Marker pen
Incubator at 25oC
Goggles

Variables

Independent Variables: Plant materials; to identify which one is the better material when fighting bacteria, concluding which is more appropriate to put in toothpaste.

Dependant Variables: Diameter of zone of inhibition of bacterial growth in the petri dishes. The less growth; the better the plant material is at fighting bacteria.

Controlled Variables: Temperature; the higher or the lower the temperature will affect bacteria growth. A set temperature needs to be devised (by incubating the petri dishes) that is the optimum temperature for bacteria growth.

The volume of plant material on the paper discs; the greater the volume of plant material then the better it will be at fighting bacteria, giving an unfair advantage.

Uncontrollable Variables: Whether the different samples are from different yields of plant; affecting their strength and quality.

Results

(Diameter in mm)

[Graph attached on Graph paper]

Conclusion

The trend and patterns of my results show that the garlic is the better bacterial defence. These results are significant because they show that although there are antibacterial properties in each, the garlic is better at fighting off bacteria. It also questions the motives of using mint in toothpaste and whether it is solely for bacteria fighting purposes or other contributing influences. The results proved my hypothesis to be wrong, as the mint was not the better defence. This is because garlic has strong anti bacterial properties, a chemical contained in it called allicin, that inhibit the growth of disease causing bacteria such as e-coli and Staphylococcus aureus. Garlic also supplements the stimulation of the immune system, by increasing the number of white blood cells and natural killer cells.

Evaluation

An anomalous result identified when testing garlic was the result displaying 11mm. This is an outlier as it irregular, and is not in trend with the other results from this experiment. This is most likely a random error as there is no other results that show a fault with equipment that may determine it as a systematic error. This result will be treated as an outlier, and when an average is taken will make less of an impact on the accuracy of the data. The data is very accurate as it is precise, and the data is within a small range, of which the error bars show. The fact that such a clear pattern is shown in the graph, allows me to feel confident in my results. I also feel confident in my results as it was repeated six times with averages taken. Certain limitations included the amount of times the experiment could be completed. If there was more apparatus, then different controls could have been tested to see if there was an even better antibacterial defence. Different controlled temperatures could have also been carried out to identify whether the garlic responds better at different degrees.

Daphnia experiment

Aim

To investigate whether caffeine will have an affect on the heart rate of Daphnia

Hypothesis

I predict that the concentration of caffeine will have an affect on the Daphnia’s heart rate, as caffeine the caffeine will increase the heart rate which in turn will increase blood pressure.

Null Hypothesis

There will be no significant difference between the concentration of caffeine and the heart rate of the Daphnia.

Method

Firstly pipette 10ml of water containing the daphnia onto a slide, with cotton wool either side, stopping the daphnia moving around too much. Secondly, pipette the first concentration of caffeine to the water until a solution is formed. Then placing the sling under a microscope with a light shining on it time a ten second period in which the heart beat can be counted. Using a piece of paper and a pencil draw a dot each time you see the heart beat.

Equipment

-Microscope

-Daphnia

-Cotton wool

-Water

-Pipette

-Caffeine

-Timer

-Light

Ethical issues

-Is it right to kill living creatures in the name of research?

-Should we be allowed to use Daphnia only to show results that we already know with no other real benefit other than to learn a technique rather than gain information?

-Do smaller insects have as much value as larger animals?

-Should testing creatures only be allowed for medical and medicinal purposes?

Variables

Independent Variables: concentration of caffeine; to identify whether caffeine affects heart rate

Dependant Variables: The heart rate of the Daphnia. The faster the heart rate; the bigger the affect of the caffeine on the daphnia.

Controlled Variables: Temperature; the higher the temperature the faster the hear rate of the Daphnia

The volume of caffeine; to see if different volumes affect the heart rate.

Uncontrollable Variables: The state of the Daphnia. Whether they are
pregnant, their age, their sex and their physical condition will have an affect on
the results.

Results

[Graph attached on Graph paper]

Conclusion

The trend and patterns of my continuous results show that with an increase of caffeine concentration, there is an increase in Daphnia heart rate. These results are significant because they show that caffeine directly affects the heart rate. This could be because caffeine stimulates the production of adrenaline, which in turn increases blood pressure as this constricts arteries, and the heart has to pump harder to move blood around the body. Caffeine also increases the level of cyclic Adenosine MonoPhosphate in the heart cells which diffuses through the cell and acts as a "secondary messenger," activating protein kinase and increasing heart rate. The results proved my hypothesis right as it was affected greatly due to a stimulated SA node.

Evaluation

Although there are no anomalous results identified in the averages of the results, in the actual results themselves it shows that there are quite a few. These outliers are quite regular, and are not in trend with the other results from this experiment. This is most likely a systematic error, as the uncontrollable variable would have a very large effect on the results. However due to there being a strong trend shown in the graph, I have a large amount of confidence in my data as it is also very accurate and precise. I also feel confident in my results as it was repeated three times with averages taken. Certain limitations included the amount of times the experiment could be completed. If there were more daphnia, then a better average could be achieved as the experiment could be carried out more than three times.