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    Q2. A serial dilution is performed in which 1cm3 of a solution containing 8.83 x 10^7 cells is diluted to 10cm3 (to give solution A), then 1cm3 of solution A is diluted to 10cm3 (to give solution B).

    Q2.1. What is the overall dilution factor (between the original and final solution)?

    1 in 10
    1 in 100
    1 in 1000
    1 in 10000
    1 in 100000

    I know that the dilution factor is final solution/original solution.

    for 1 in 10 would it be 10/1 = 10
    and then for 1 in 100 would it be 100/1 = 100

    and so on...?
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    (Original post by I Have No Imagination)
    Q2. A serial dilution is performed in which 1cm3 of a solution containing 8.83 x 107 cells is diluted to 10cm3 (to give solution A), then 1cm3 of solution A is diluted to 10cm3 (to give solution B).

    Q2.1. What is the overall dilution factor (between the original and final solution)?

    1 in 10
    1 in 100
    1 in 1000
    1 in 10000
    1 in 100000

    I know that the dilution factor is final solution/original solution.

    for 1 in 10 would it be 10/1 = 10
    and then for 1 in 100 would it be 100/1 = 100

    and so on...?
    Yes, 1 to 10 dilution followed be another 1 to 10 is the same as one 1 to 100 dilution
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    (Original post by charco)
    Yes, 1 to 10 dilution followed be another 1 to 10 is the same as one 1 to 100 dilution

    Thank you. In relation to the same question how would I work out the concentration of cells per cm3 of solution A?
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    (Original post by I Have No Imagination)
    Thank you. In relation to the same question how would I work out the concentration of cells per cm3 of solution A?
    If you think about it 1/10 of your solution A is your original solution so theoretically you would have 1/10 of your original concentration which is basically number of cells per cm3.
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    OLOLOL "SERIAL" DILUTIONS is that where you put too much milk on your cornflakes?!?!?!1


    LOLOLOsalowelqel
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    (Original post by Calian)
    If you think about it 1/10 of your solution A is your original solution so theoretically you would have 1/10 of your original concentration which is basically number of cells per cm3.
    Thanks a lot. I completely understand that now.

    I have a few more questions that I'm finding rather difficult.

    Q3. Three pour and spread dilutions were prepared and 3 plates were set up for each dilution. The resulting counts are shown in Table 1 below.


    Table 1. Colony counts per plate of malt extract agar for a viable count of Saccharomyces cerevisiae using the pour plate technique incorporating an inoculum of 1cm3 per plate:

    10^-4 10^-5 10^-6
    <30 45 >300
    <30 48 >300
    <30 39 >300

    Q3.1. Calculate the mean number of colonies per plate obtained from the 10-5
    dilution.

    I've got this as 44?


    Q3.2. Calculate the mean number of colony forming units (cfu) per cm3 of the original culture.

    No idea how to do this?
 
 
 
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