Dilution problems I Please note: for all dilution problems, use only the followi

Question

Dilution problems I Please note: for all dilution problems, use only the following diluent volumes: 0.9 mL 9 mL 9.9 mL Answer the following on separate paper: Problems: 1. You have a broth that contains 5.6 x 10 CFU/mL. How many colonies would you expect to count on a plate if you spread out the volume listed below. Please answer using whole number, not exponent. a. 1.0 mL? 5.x 1o30 colonies b. 0.5 mL? 5,600/a: a,8oo colonie s 2. Draw two ways of making the following dilutions. Indicate all transfer volumes and diluent volumes. a. 10 dilution b. 10 dilution 3. Using only 9.0 mL and 9.9 mL tubes of diluents, draw two ways of obtaining a 101 dilution. Indicate all transfer volumes and diluent volumes.

Explanation / Answer

1)

a. 5 .6*103 CFU/ml i.e. 5.6*103 bactera in 1 ml (assuming that one bacteria forms one colony.)=5600

b. Hence, 0.5ml would have half of the above number = 2800

2)

a. 1)Add 1ul culture to 9999ul broth

2)add 0.5ul culture to 4999.5 ul broth

b. 1)add 1ul culture to 99999999ul broth

2) add 0.5ul to 499999999.5ul broth

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