QUESTION 18 In most laboratory applications, for plate counts to be considered v
ID: 200100 • Letter: Q
Question
QUESTION 18 In most laboratory applications, for plate counts to be considered valid, they must have between 30 and 300 colony forming units on them. To achieve this, scientists must dilute the sample prior to plating it. If a culture of bacteria is experiencing exponential growth has 2,014 cells per mL, and an instantaneous growth rate constant of 0.5 hours-1, after 48 hours, what is the total dilution that needs to be performed to yield 286 colony forming units on an agar plate? Assume each colony forming unit came from a single cell. Report your answer in exponential form to two decimal place .A dilution of 0.0001 would be reported as 1.00e-4 QUESTION 19 A culture of bacteria contains 108 cells per mL. In order to inoculate a flask with 1,000 mL of media so the initial culture will have 7,777 bacteria per mL, how many mL of culture should be transfered? .Assume the volume of culture added to the flask is inconsequential Under this assumption, the volume of media remains the same o Report your answer to two decimal places in scientific notatiorn e.g. 0.00125 mL would be reported as 1.25e-3Explanation / Answer
Number of bacteria/ml= Number of Colony forming units/volume plated x total dilution
2014/ml = 286/x = 1.4e-1
108x X= 7777 x 1000 =
X= 7.7e-2