A culture shows a growth of 1,200 colonies after incubation. If the dilution fac
Practice Questions
Q1
A culture shows a growth of 1,200 colonies after incubation. If the dilution factor was 1:100, what was the original concentration of bacteria in the sample?
120,000 CFU/mL
12,000 CFU/mL
1,200 CFU/mL
120 CFU/mL
Questions & Step-by-Step Solutions
A culture shows a growth of 1,200 colonies after incubation. If the dilution factor was 1:100, what was the original concentration of bacteria in the sample?
Step 1: Understand that the number of colonies (1,200) represents the number of bacteria that grew from a diluted sample.
Step 2: Recognize that the dilution factor (1:100) means that the original sample was diluted 100 times.
Step 3: To find the original concentration of bacteria, you need to multiply the number of colonies by the dilution factor.
Step 5: The result (120,000) represents the original concentration of bacteria in the sample, measured in CFU/mL (colony-forming units per milliliter).
Dilution Factor – Understanding how dilution affects the concentration of bacteria in a sample.
Colony Forming Units (CFU) – Interpreting the number of colonies as a measure of viable bacterial cells.
Basic Arithmetic in Biology – Applying multiplication to calculate original concentrations from diluted samples.
