Question

1. You have a bacterial cell culture with a concentration of 1x109 cells/ml. You need to dilute the cells to a concentration of 1x103. What is the correct ratio for this dilution?

2. You add 0.1 ml of a yeast culture to a test tube that contains 9.9 ml of buffer solution. What is the dilution factor of this mixture?

3. In a 1000 µl total dilution volume, the volume of cell culture used is 800 µl. What is the volume of diluent?

4. The following dilution factors are equivalent to each other: 1/10, 1:10, 10^-1.

True or False

5. What is the dilution factor, or ratio, of a dilution that has a total volume of 1000 µl and used 100 µl of cell culture?

6. You need to create a 3:5 dilution with a total volume of 1000 µl. What volume of cell culture and diluent should you use to achieve the correct dilution?

7. A bacterial cell culture with a concentration of 1x10⁸ cells/ml. This is equivalent to 1,000,000 cells/ml.

True or False

8. The following dilution factors are equivalent to each other: 1/1,000,000, 1:1,000,000, 10^-6. True or False

9. You have diluted a bacterial cell culture to a concentration of 115 cells/ml. This is equivalent to 1.15x10¹.True or False

10. You add 1 ml of a yeast cell culture to a test tube that contains 9 ml of buffer solution. What is the dilution factor of this mixture?

11. Your lab partner needs to make a 1/50 dilution of yeast cells but only has 3 µl of yeast cell culture available. What volume of sterile water should they use to dilute to cells?

12. You have a yeast culture that has a concentration of 963,000 cells/ml. If you diluted this culture in a 1:10,000 ratio, what would be your final cell concentration?

13. Your lab partner is diluting a bacterial cell culture in a 3/5 ratio and needs a total volume of 50 ml. They should use 30 ml cells and 20 ml diluent (water). True or False

14. You have diluted a bacterial cell culture to a concentration of 100 cells/ml. This is equivalent to 1x10². T or F

15. A fellow lab mate is diluting a yeast cell culture. They need a total volume of 5 ml and their desired dilution factor is 1/10. What volume of cell culture should they use?

16. Your lab partner is making a 1:25 dilution of a bacterial cell culture using 5 µl of cells. What volume of diluent (water) should they use?

17. Which type of dilution refers to a series of dilution steps?

Answer 1

1) dilution= final concentratio/ concnetration of stock

final concentration = 10^3 cells/mL

stock concentrtation= 10^9 cells/mL

dilution= 10^3/10^9

= 1/10^6

so dilution is 10^-6

2) dilution= aliqout volume/final volume

Final volume=9.9+0.1=10 mL

aliqout volume= 0.1 mL

dilution= 0.1/10

= 1/100

dilution= 10^-2

so dilution factor= 1/dilution

= 100

3) final volume= 1000 uL

aliqout volume= 800 uL

final volume= aliqout volume+ diluent volume

diluent volume= final volume-aliqout volume

= 1000-800

= 200 uL