Aim: I want to investigate how the concentration of Dettol affects the growth of bacteria.
Hypothesis: As we increased the concentration of Dettol that we added to the paper filter's, then it will have a greater effect on the bacterial growth.
Equipment: Agar Plate - cotton bud - Permanent marker - Dettol - water - Filter paper - Hole Punch - Bacteria (Yoghurt) - Beaker - Plastic Pipette - Spotting tile - Tweezers
Method:
1. Get the equipment that is listed above.
2. Next punch (x4) holes of your filtered paper with your hole puncher and then place them to the side until you have gotten the Dettol solution ready.
3. Once you have finished step 1 and 2 you would then get your agar plate and draw with your permanent marker even lines to divide them into fours (like the picture shown on your right)
4. Once you have drawn on your agar plate you would then go in with your yogurt solution.
Swab just enough yogurt to cover your cotton buds tip and place a thin and even coat around the top part of your agar plate.
(Where your permanent marker is)
5. After you have put your thin coat of yogurt you will then get your spotting tile, Bunsen burner, tweezers, your Dettol solution and also the filtered paper that you put aside in the first step.
6. place 10 drops of Dettol solution with your plastic pipette in one of the little individual spotted tiles that are allocated. Once you have done this - grab 9 drops from the previous spotting tile and place it in the tile next one-two it. Once you have done this get one drop of water and add it to the 2nd spotting tile that has 9 drops of the Dettol.
Grab 9 drops of the 2nd and place it in the third, then do the same with the 4th.
If you have done this correctly you should have mimicked dilating the Dettol solution.
7. Place the 4 filtered papers into each spotting tile that has the solution.
8. Well you wait for your solution to soak in you will then bring out your bunsen burner, tweezers, the alcohol (To sterilize the tweezers.) Once you have finished getting these 3 items you then will turn on your bunsen burner and make sure it is on the blue flame (as it is the hottest) and dab your tweezers in the alcohol to sterilize them.
Hold your tweezers carefully in the flame until you can see that the tweezers turn black.
9. Grab the first filtered paper that is in the first spotting tile and place it in section A on your agar plate in the middle. Do this for the all the filtered papers that are in the solution and then get ready for the second to last step!
10. Once you have placed the filtered papers on the agar plate put the lid on, grab your tape and tape it around the rounded edge so that it is sealed shut.
11. Get your vivid once again and put your name on the cornered edge (we place the name on the cornered edge so that we can see the results more clearly.
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Solution:
Our experiment with the yogurt, unfortunately, did not work but luckily enough we did have two girls who were kind enough to let us finish our experiment by using their solution.
Below is a variation of how the bacteria died. and the reason that there are different measurements is that when you go back to step 6 when you are applying the Detol solution to the filtered paper on A it is more enhanced the B - D
A: On average - 13ml
B: 5ml
C: 4ml
D: 0ml
Planning Sheet Student name: Oceana Olsen
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2. FAIR TEST
Which variable will be changed? (This is the independent variable)
We are changing the concentration of Detol
How will the independent variable be changed?
We will be putting different amounts of Detol into the water to die loot
Give a suitable range of values for this variable
Values - 10 drops of detol (100% of concentrated Detol)
- 10% - 1% - 0.1% | |
3. FAIR TEST
Which variable will have to be measured or observed in order to get some data or information from the investigation? (This is the dependent variable)
We are measuring the growth of bacteria within our experiment of the agar plate
How will the dependent variable be measured or observed?
We will measure the clear zone around the filtered paper that had our Detol solution on it. By doing this we will be measuring how much of the bacteria that got killed off.
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Other variables
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Describe how this variable will be controlled or kept the same.
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| Amount of bacteria |
We can control the number of bacteria by the amount of peppercorn solution we use
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| Amount of water |
By controlling how much our water you put in the detol you control how strong it works
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Not cleaning the tweezers
| By not cleaning tweezers there may already be bacteria on the tweezers resulting in different results. |
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Recorded data:
1
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2
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3
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Average
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A
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0
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1.5
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1.3
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14
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B
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0
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0.5
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0.5
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05
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C
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0
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0.3
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0.1
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04
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D
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0
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0.1
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0.2
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03
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Interpretation of data:
This data showed…
Our group's experiment didn’t work however from what we saw from the other people in our class, was that not only did their experiment work but that we could tell that this has happened because as they increased the amount of concentration of Dettol the more Bacteria they killed off.
Conclusion: I conclude…
I conclude that this data showed as we increased the concentration of Dettol we killed off more bacteria that was grown on our agar plate
From the graph, you can see above there is an increasing trend. The reason for the increase is because the more Dettol solution you use the more bacteria you kill off.
Discussion and Evaluation of the Method and Data.
Dettol, also known as para-chloro-meta-xylenol. It is an antiseptic and disinfectant used for skin disinfection and cleaning surgical instruments. The active ingredient that works on bacteria in Dettol is Chloroxylenol, this is the product that kills off bacteria the most inside Dettol
The structure of bacteria like the diagram on the right is a makeup of the cell walls, membrane, cytoplasm, nuclear material, capsule, flagella, pili, and spore.1. Capsule - Protects the bacteria, (it acts like a coat)
2. Cell wall - The cell wall keeps the structure of the cell
3. Cell membrane - Controls what enters the cell
4. DNA - Is the genetic code
5. Ribosomes - Is where the proteins are made
6. Plasmid - Is DNA that codes for non-essentials of DNA processes
7. Flagellum- Is the tail that is used to move
8. Pili - Transfers the genetic information.
If you are wondering how bacteria can reproduce, - is because it can go through the process of binary fission. This is where the bacteria (which is a single cell) divides into two which is the Identical daughters. Binary fission starts when the DNA of the bacteria divides into two causing the bacteria to reproduce.
As you can see in the drawing on your right this is a more broken down version of what binary fission is.
1 - parent cell is the original that will build the cell wall.
2 - DNA replicated is the bacterial genome that replicates and will still remain attached to the membrane. But also at the same time, the plasmids present the replicate in replicated.
3 - Cell Grows. The cross wall forms completely around and divides the DNA
5 - cell divides Once the parent cell has gone through this process it divides
6 - Cell separates The parent cell is completely separated causing it to be a duplicate.
The question you need to answer is Explain the conclusion and also the evaluation
As you can see in the drawing on your right this is a more broken down version of what binary fission is.
1 - parent cell is the original that will build the cell wall.
2 - DNA replicated is the bacterial genome that replicates and will still remain attached to the membrane. But also at the same time, the plasmids present the replicate in replicated.
3 - Cell Grows. The cross wall forms completely around and divides the DNA
5 - cell divides Once the parent cell has gone through this process it divides
6 - Cell separates The parent cell is completely separated causing it to be a duplicate.
The question you need to answer is Explain the conclusion and also the evaluation
In Conclusion, the experiment was reliable because we not only did 1 or two trials but we also used another reference from our class. However, our first time we trialed the experiment it was unsuccessful as we did not sellotape the lid and the bass of the agar plate together properly which caused our bacteria when it formed to dry out in the incubator.
We did not have enough time to fix our experiment, but we fixed it by using the other people on our tables results. There were no anomalies that we found in the results which were good because that means they did the experiment properly and also its good so that we no in future reference if we would use that experiment again.
In future reference to fix the problem of our bacteria drying up, we would get another pair from our class to check if we sellotaped the sides properly or not. This way we could have two sets of eyes that could see where we made a mistake.
A question I would like to ask is - if the bacteria got dried up because of the air that was seeping in from the outside, in real life is that why we can not see the bacteria because the air we breath is making it not visible?
We did not have enough time to fix our experiment, but we fixed it by using the other people on our tables results. There were no anomalies that we found in the results which were good because that means they did the experiment properly and also its good so that we no in future reference if we would use that experiment again.
In future reference to fix the problem of our bacteria drying up, we would get another pair from our class to check if we sellotaped the sides properly or not. This way we could have two sets of eyes that could see where we made a mistake.
A question I would like to ask is - if the bacteria got dried up because of the air that was seeping in from the outside, in real life is that why we can not see the bacteria because the air we breath is making it not visible?
