9. Microscopes

Gram Stain

Multiple Choice
In the Gram stain procedure, which dye is used as the counterstain?
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Multiple Choice
Which of the following correctly lists the order of reagents used in the Gram stain procedure?
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Multiple Choice
In the Gram stain, why must fresh (young) bacterial cells be used to obtain reliable results?
Multiple Choice
In a standard Gram stain, what color do Gram-negative bacteria typically appear after the safranin counterstain is applied?
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Multiple Choice
Which of the following would you include when performing a Gram stain?
Multiple Choice
Which of the following correctly lists the steps of the Gram stain procedure in the proper order?
Multiple Choice
A scientists has a sample with two different species of bacteria. The first species is Staphylococcus aureus, a gram-positive bacterium. The second species is Escherichia coli, a gram-negative bacterium. The scientist gram-stains his sample of bacteria. What colors will the two species of bacteria be after staining?
Multiple Choice
Which of the following statements is false?
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Multiple Choice
After performing a Gram stain, why do Gram-positive bacteria appear purple under the microscope?
Multiple Choice
The Gram-staining procedure is best described as which of the following?
Multiple Choice
In a completed Gram stain procedure, what is the final color of Gram-negative bacteria when observed under a microscope?
Multiple Choice
Which dye stains gram-negative bacteria pink during the Gram stain procedure?
Textbook Question
Which of the following pairs is mismatched?
a. Capsule—negative stain
b. Cell arrangement—simple stain
c. Cell size—negative stain
d. Gram stain—bacterial identification
e. None of the above
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Multiple Choice
1. Why is it important to use fresh bacterial cells when performing a Gram stain?
Textbook Question
Explain why Gram-positive mycoplasmas appear pink in a Gram-stained smear.