Laboratory Techniques in Microbiology
Biology ⇒ Microorganisms and Microbiology
Laboratory Techniques in Microbiology starts at 9 and continues till grade 12.
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See sample questions for grade 11
A student is preparing a Gram stain and forgets to add the decolorizer. What will be the likely result?
A student observes that after Gram staining, some bacteria appear pink while others appear purple. What does this indicate about the bacteria?
Describe the main difference between selective and differential media.
Describe the main purpose of using a streak plate method in microbiology.
Describe the purpose of using a control plate in a microbiology experiment.
Describe the purpose of using a negative stain in microbiology.
Explain the importance of using controls in microbiological experiments.
Explain why it is important to incubate agar plates upside down.
Explain why it is important to label petri dishes on the bottom rather than the lid.
Explain why oil immersion is used with the 100x objective lens in light microscopy.
Name one selective medium and explain its purpose in microbiology.
What is the function of the condenser in a compound light microscope?
What is the function of the inoculating loop in microbiology?
What is the main advantage of using an agar slant over an agar plate for storing bacterial cultures?
A laboratory technician is using a spectrophotometer to measure the growth of a bacterial culture. Explain how the optical density (OD) reading relates to the number of bacteria present and discuss one limitation of this method.
A microbiologist needs to determine whether a bacterial culture is motile. Describe a laboratory technique that can be used to assess bacterial motility and explain the principle behind it.
A student is given an unknown bacterial sample and asked to determine if it produces endospores. Describe the staining technique that should be used and the expected results if endospores are present.
Explain the principle of the serial dilution and plating technique for estimating the concentration of bacteria in a liquid sample. Why is it important to use serial dilutions rather than plating the undiluted sample directly?
A researcher is testing the effectiveness of a new disinfectant on a bacterial culture. After treating the culture, they perform a viable plate count and observe a reduction from 1.2 × 106 CFU/mL to 3.0 × 103 CFU/mL. Calculate the log10 reduction achieved by the disinfectant.
A student is using a hemocytometer to count yeast cells in a suspension. If the student counts an average of 120 cells per large square, and the dilution factor is 1:10, what is the concentration of cells per mL in the original sample? (Each large square has a volume of 0.1 mm3.)
