Notesale: Turn your study into money

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Unit 3- Assignment 4- P7 and M3
Results:
Concentration Area of non
growth (cm) Test 1
0
1/100
1/200
1/400
1/600
1/800
1/1000
1

0
4
...
3
3
...
1
2
...
7
5

Area of non
growth (cm) Test
2
0
4
...
1
3
...
3
2
...
6
5

Surface cleaner is used for this experiment, not Dettol
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3
3
...
4
3
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7
1
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6
4
3
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3
2
1
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4 apart
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I chose to carry out standard deviation with my results rather than chi squared because, standard
deviation in easier to carry out and easier to explain
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Unit 3- Assignment 4- P8 and P9
As displayed in the bar chart, as the concentration of surface cleaner was decreased, the average of
area of non-growth decreased
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This therefore confirmed the hypothesis that: "The more concentrated the disinfectant was, the
more bacteria it would have killed
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" Due to the hypothesis being proven, it was accepted
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Although, the negative correlation was not a straight line
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Unit 3- Assignment 4- M4
I have compared my results for my investigation with another set of results I have researched
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), the other person has formatted them in
percentages (like 20%, 40%, etc
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Other investigation: http://filestore
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org
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PDF

By comparing my graph with theirs, I can see that as you increase the concentration of the
disinfectant, the area of which the bacteria has grown also increases
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Also, both of our results
supported our hypothesis' along with the case study
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If you decrease the concentration of disinfectant, the
area of non-growth decreases
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Also, their plotted points are lined up by a
curved line (therefore missing points), but mine are joint together in one line (going through all the
points)
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This is because, as I was too cautious about the water being at a temperature that was too hot,
therefore having a bigger chance for an accident to occur (for example, someone getting scolded by
the hot water), it means that it was not at a high enough temperature for the agar to remain molten
once taken out of the bath
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This can lead to inaccuracy as it may not kill most of the bacteria
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There is also a chance that you may use the same pipette for a different solution, for
example, using the pipette you used for one solution with another
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Finally, when putting a drop of solution into the petri dish, it is likely that you may put too
much or too little, which could cause for the results to be inaccurate
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There are a lot of errors than can occur in this experiment which could cause the results
to be inaccurate, invalid and even cause the bacteria not to grow to a reasonable size
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When carrying out the microbiology investigation, you must ensure accuracy to reduce the errors
that may cause the results to be inaccurate
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This is to kill all
the microbes and get rid of the moisture that may change the outcome of the results
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This is so that you will not mix your results up with anyone else's
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The lid and base of an agar plate should be taped together with two to four strips of masking tape as
a protection from accidental opening during the incubation
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The agar plates have to be incubated with the base of the petri dish, if not, the condensation on the
lid will drip onto the culture of bacteria
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The base of the plate has to be covered and do not let the agar touch the lid of the plate
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To make this possible, it must be poured as soon it is
taken out of the water bath
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To
prevent the agar from drying, they must be sealed in plastic bags
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The glass spreaders must be sterilised by the roaring flame of the Bunsen burner before and after it
is used
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Make sure all the ethanol has burnt off in the flame
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This will allow the bacteria
to grow evenly on the surface
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This will also cause the outcome to be reliable and of course
valid
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An improvement was made to my originally intended method, was to increase the temperature of
the water bath, so that the agar will remain at a liquid stage when pouring it into the petri dish
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This will also allow
the bacteria to grow and spread evenly and the results to be fair, reliable and valid
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Another improvement that could be made to my method could be, to leave the petri dishes in the
cupboard for a longer period of time - perhaps another day or two
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This means that there is a greater chance for
bacteria to grow
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This will cause the results to be more
fair, reliable and valid
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Finally I would have also sterilised the surface of the petri dish more thoroughly to absolutely ensure
that the whole surface has been covered
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This would be useful for this method as it
would decrease the percentage error and ensure accuracy
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These improvement could improve my overall investigation as by doing so, there is a greater chance
of bacteria to grow which is what went wrong in my investigation
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