Show your work please! I will give good ratings! Thanks in advance! 2. Suppose y
ID: 269002 • Letter: S
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Show your work please! I will give good ratings! Thanks in advance!
2. Suppose you were instructed to add 0.2ml of a culture (tube A) to 9.8ml of diluent, but instead added 2 ml of sample. a) What was the intended dilution and the actual dilution in the tube (Tube B)? [2 points] b) Transfer 1ml of the culture from tube B into a tube continuing 20ml of diluent (tube C) Mix well. Transfer 3 ml of the culture from Tube C into a tube containing 5 ml of diluent (tube D). Mix well. - Is it a dilution series or serial dilution? [1 point] b) Calculate the CDF at each step. [2 points] d) You plate 0.5 ml from Tube D and obtain 36 colonies. What is the concentration of the original culture? 12 points]Explanation / Answer
In this case final volume will considered first
Final volume= 2+9.8=11.8
Final dilution at this step 2/11.8= 0.169
Now take the 1ml and transfer into tube that contain 20 ml
Final volume 20 +1= 21 ml
Dilution at this step= 1/ 21= 0.047
Now in third step 3 ml is added in to 5 ml
Final volume 5 + 3= 8 ml
Final dilution at this step=3/8= 0.375
Now calculate the cumulative dilution factor
= (1/11.8)* (1/21)* (3/8)
= 1/ 11.8*7*8
=1/660.8
According to CFU/ml= (No of colonies * inverse of dilution factor)/ volume plated
= 36 * 660.8/ 0.5
= 47577.6 Cfu/ml
= 4.75* 104 cfu/ml
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