MICRO 260 lab 8 -Questions and Correct Answers (Expert verified) / Latest Update 2024/2025/100% Pass

MICRO 260 lab 8 -Questions and Co rrect Answers (Expert verified ) / Latest Update 2024/2025/ 100% Pass from the results, about how many organisms/ml can be in a clear broth without showing any sign of turbidity? - ✔✔MANY what are two so urces of error in this procedure? - ✔✔There are many potential sources of error. Examples include: incorrect measuring of the sample or diluent; insufficient mixing; not switching pipettes between each step of the serial dilution; contamination because of poor sterile technique; or inadequate mixing of sample and molten agar in the Petri dish. if you serially dilute a sample with three 1:10 dilutions, what is the dilution of the last tube? - ✔✔10-3 if you add 1.0ml to 99ml of water, what is the dilution of the sample? - ✔✔10-2 if you had a solution containing 6000 organisms/ml, how could you dilute and plate a sample so that you had a countable plate? - ✔✔A common answer to this question is as follo ws: 1. Add 1.0ml of the original broth culture to 9.0ml water (to obtain a 10 -1dilution). The 10 -1 dilution will have 600 cells/ml. 2. Add 1.0ml of the 10 -1 dilution to 9.0ml water (to obtain a 10 -2 dilution). The 10 -2 dilution will have 60 cells/ml. 3. Ad d 1.0ml of the 10 -2 dilution to an empty Petri dish. Then add molten agar and mix. 4. After incubation takes place, you would expect 60 colonies to grow (since each cell leads to an individual colony). This is a perfect number for a 'countable plate' (i.e. a plate that has between 30 and 300 colonies). serial dilution - ✔✔preparing a dilutin in steps instead of one dilution turbidity - ✔✔cloudiness viable (bacteria) - ✔✔capable of growing and dividing