1) The number of single colonies on a correctly-prepared agar plate can be used to estimate the concentration of viable cells in a broth culture because:(Multiple Choiceï¼
A. The plate was inoculated with a known volume of culture.
B. Each colony contains only viable cells.
C. Each colony arises from a single viable cell.
A and B
A and C
2) A student needs to determine the concentration of viable cells in a broth culture of E.coli. What should they do? (Multiple Choiceï¼
Measure the optical density (OD) of the culture using a spectrophotometer.
Use a sterile spreader to spread a known volume of the culture across an agar plate.
Use a sterile loop to streak a small volume of the culture across an agar plate.
Perform serial dilutions of the culture, and then use a sterile spreader to spread a known volume of the dilutions across agar plates.
Perform serial dilutions of the culture, and then use a sterile loop to streak a small volume of the dilutions across agar plates.
If a bacterial broth culture has a concentration of 7.5x1011 cells/mL, what dilution is required to give a concentration of 3x104 cells/mL? (Multiple Choiceï¼
4.4*10-17 dilution
2.25*1016 dilution
4*1014 dilution
4*10-8 dilution
2.5*107 dilution
1) The number of single colonies on a correctly-prepared agar plate can be used to estimate the concentration of viable cells in a broth culture because:(Multiple Choiceï¼
A. The plate was inoculated with a known volume of culture.
B. Each colony contains only viable cells.
C. Each colony arises from a single viable cell.
A and B
A and C
2) A student needs to determine the concentration of viable cells in a broth culture of E.coli. What should they do? (Multiple Choiceï¼
Measure the optical density (OD) of the culture using a spectrophotometer.
Use a sterile spreader to spread a known volume of the culture across an agar plate.
Use a sterile loop to streak a small volume of the culture across an agar plate.
Perform serial dilutions of the culture, and then use a sterile spreader to spread a known volume of the dilutions across agar plates.
Perform serial dilutions of the culture, and then use a sterile loop to streak a small volume of the dilutions across agar plates.
If a bacterial broth culture has a concentration of 7.5x1011 cells/mL, what dilution is required to give a concentration of 3x104 cells/mL? (Multiple Choiceï¼
4.4*10-17 dilution
2.25*1016 dilution
4*1014 dilution
4*10-8 dilution
2.5*107 dilution