Standard Plate Count Worksheet
A Grade 11 science worksheet covering the principles and procedures of the Standard Plate Count method, including serial dilutions and colony counting.
Includes
Standards
Standard Plate Count Worksheet
Name:
Date:
Score:
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 (SPC)?
To identify specific types of bacteria in a sample.
To determine the total number of viable microorganisms in a sample.
To sterilize a bacterial culture.
To isolate bacterial DNA.
2. Why is serial dilution a crucial step in the Standard Plate Count method?
To increase the growth rate of bacteria.
To obtain a countable number of colonies on an agar plate.
To make bacteria more resistant to antibiotics.
To ensure aseptic technique.
3. In a Standard Plate Count, a is typically used to spread the diluted sample evenly over the agar surface.
4. The units for reporting the results of an SPC are per milliliter (CFU/mL).
5. Colonies that are too numerous to count (TNTC) typically exceed colonies per plate.
6. Describe the ideal range of colony counts on a plate for accurate Standard Plate Count results. Explain why counts outside this range are considered unreliable.
7. A student performs a serial dilution and plates 0.1 mL from a 10^-5 dilution onto an agar plate. After incubation, they count 75 colonies. Calculate the original concentration of bacteria in CFU/mL.
8. The Standard Plate Count method counts both viable and non-viable microorganisms.
True
False
9. Aseptic technique is critical throughout the Standard Plate Count procedure to prevent contamination.
True
False
Match the term on the left with its definition on the right.
10. Diluent
a. A visible mass of microorganisms growing on an agar surface.
11. Colony Forming Unit (CFU)
b. The liquid used to dilute a sample.
12. Colony
c. A single viable microbial cell that can multiply to form a colony.