You are Here: Home

Serial Dilutions Watch

1. 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...?
2. Anybody?
3. (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
4. (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?
5. (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.
6. OLOLOL "SERIAL" DILUTIONS is that where you put too much milk on your cornflakes?!?!?!1

LOLOLOsalowelqel
7. (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?

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: December 6, 2010
Today on TSR

Degrees to get rich!

... and the ones that won't

Women equal with Men?

Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.