Standard Plate Count Worksheet
This worksheet assesses understanding of the Standard Plate Count method, including its principles, procedure, calculations, and applications in microbiology.
Includes
Standards
Topics
Standard Plate Count
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Read each question carefully and answer to the best of your ability. Show all calculations where applicable.
1. What is the primary purpose of performing a Standard Plate Count?
To identify specific types of bacteria.
To determine the total viable bacterial population in a sample.
To measure the metabolic activity of microorganisms.
To sterilize laboratory equipment.
2. Which of the following is crucial for obtaining accurate results in a Standard Plate Count?
Using a sterile technique during dilutions and plating.
Incubating plates at very high temperatures.
Using only tap water for dilutions.
Counting colonies immediately after plating.
3. The acceptable range for colony counting on a plate is typically between and colonies.
4. Serial dilutions are performed to the concentration of microorganisms in a sample, making it easier to count individual colonies.
5. CFU stands for , which represents the number of viable bacterial cells in a sample.
6. Describe the process of performing a pour plate technique in the Standard Plate Count method.
7. A student performs a Standard Plate Count on a water sample. They dilute the sample by a factor of 10^-4. They then plate 0.1 mL of this diluted sample onto an agar plate. After incubation, they count 75 colonies. Calculate the original concentration of bacteria in the water sample (CFU/mL). Show your work.
8. All microorganisms present in a sample will grow and form colonies on the agar plate in a Standard Plate Count.
True
False
9. Aseptic technique is not necessary when handling environmental samples for Standard Plate Count.
True
False
10. Observe the petri dish below. If this plate was inoculated with 1 mL of a 10^-3 dilution of a bacterial sample, what is the approximate CFU/mL of the original sample? (Assume each dot represents a colony).
