Question 1

Which of the following best describes the correct way to write the scientific name for the bacterium that causes anthrax?

Accepted Answer

Bacillus anthracis

Question 2

A microbiologist observes a bacterium that appears as a chain of rod-shaped cells under the microscope. Which term best describes this arrangement?

Accepted Answer

Streptobacillus

Question 3

Which of the following statements about Gram staining is correct?

Accepted Answer

Gram-positive bacteria retain the crystal violet-iodine complex due to a thick peptidoglycan layer.

Question 4

Which dye would you use for a negative stain to visualize bacterial capsules, and what is the expected result?

Accepted Answer

Nigrosin; background is stained, capsules appear clear

Question 5

A laboratory technician performs a Gram stain but forgets to add the decolorizer (ethanol). What will be the appearance of both Gram-positive and Gram-negative cells under the microscope?

Accepted Answer

Both will appear purple

Question 6

Which of the following best explains why basic dyes are used for positive staining of bacterial cells?

Accepted Answer

Bacterial cells are negatively charged and attract the positively charged basic dyes

Question 7

Which of the following is a correct example of binomial nomenclature for a microorganism?

Accepted Answer

Staphylococcus aureus

Question 8

During the acid-fast staining procedure, which component allows the primary dye to penetrate the waxy cell wall of Mycobacterium species?

Accepted Answer

Steaming (heating)

Question 9

Which of the following best describes the main structural difference between Gram-positive and Gram-negative bacterial cell walls?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer; Gram-negative have an outer membrane and thin peptidoglycan

Question 10

A patient sample is stained using the Ziehl-Neelsen acid-fast stain. The cells retain the red color after acid-alcohol decolorization. What does this indicate?

Accepted Answer

The cells are acid-fast, likely Mycobacterium species

Question 11

Which of the following is the correct order of steps in the Gram staining procedure?

Accepted Answer

Crystal violet, iodine, ethanol, safranin

Question 12

Which of the following best describes the purpose of using a counterstain (such as safranin) in the Gram stain procedure?

Accepted Answer

To stain Gram-negative cells pink after decolorization

Question 13

Which of the following arrangements describes a group of four spherical bacterial cells?

Accepted Answer

Tetrad

Question 14

A microbiologist is trying to visualize flagella on a bacterial cell. Which staining technique should be used?

Accepted Answer

Flagella stain with a mordant such as silver

Question 15

Which of the following best explains why Gram staining should be performed on cultures less than 24 hours old?

Accepted Answer

Older cultures may give false Gram-negative results due to cell wall degradation

Question 16

Which of the following is the correct plural form for the word 'bacterium'?

Accepted Answer

Bacteria

Question 17

Which of the following best describes the outcome of a simple stain using methylene blue?

Accepted Answer

Cells are stained uniformly blue

Question 18

Which of the following is a real-world application of the endospore stain?

Accepted Answer

Detecting Bacillus and Clostridium species in contaminated food

Question 19

Which of the following best describes the effect of using an acidic dye in a negative staining procedure?

Accepted Answer

The background is stained and the cell remains clear

Question 20

Which of the following is the correct sequence of taxonomic ranks from broadest to most specific?

Accepted Answer

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Cell Structure, Scientific Nomenclature, and Staining Techniques in Microbiology Ch.4

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