$$CFU\/mL = \frac{\text{Number of colonies}}{\text{Dilution factor} \times \text{Volume plated (mL)}}$$

Question 1

Which of the following best describes the primary difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus surrounded by a nuclear envelope, while prokaryotic cells lack a true nucleus.

Question 2

During a Gram stain procedure, what is the primary reason Gram-positive bacteria retain the crystal violet stain?

Accepted Answer

They have a thick peptidoglycan layer that traps the crystal violet-iodine complex.

Question 3

Which biochemical test would you use to differentiate between Staphylococcus aureus and Staphylococcus epidermidis?

Accepted Answer

Coagulase test

Question 4

A patient presents with symptoms of hepatitis. Which virus is most likely responsible if the patient also has a history of intravenous drug use?

Accepted Answer

Hepatitis C virus

Question 5

Which of the following equations correctly represents the calculation of bacterial concentration using the plate count method?

Accepted Answer

$$CFU/mL = \frac{	ext{Number of colonies}}{	ext{Dilution factor} 	imes 	ext{Volume plated (mL)}}$$

Question 6

Which of the following is a correct statement about the role of oxygen in microbial metabolism?

Accepted Answer

Facultative anaerobes can grow with or without oxygen.

Question 7

A streak plate is used in microbiology primarily to:

Accepted Answer

Isolate pure colonies from a mixed culture.

Question 8

Which of the following is the best example of a nosocomial infection?

Accepted Answer

A patient develops pneumonia after being hospitalized for surgery.

Question 9

Which of the following statements about endospores is correct?

Accepted Answer

Endospores are resistant to heat, desiccation, and chemicals.

Question 10

Which of the following is the most effective method for sterilizing heat-sensitive medical equipment?

Accepted Answer

Filtration through a $$0.22 \mu m$$ membrane

Question 11

Which of the following is a correct statement about the biochemical pathway of glycolysis?

Accepted Answer

Glycolysis converts glucose into two molecules of pyruvate, producing a net gain of 2 ATP.

Question 12

A patient is diagnosed with tuberculosis. Which genus of bacteria is responsible for this disease?

Accepted Answer

Mycobacterium

Question 13

Which of the following is the best description of the function of teichoic acids in Gram-positive bacteria?

Accepted Answer

They help anchor the peptidoglycan layer to the cell membrane.

Question 14

Which of the following is a correct equation for calculating the total magnification of a compound microscope?

Accepted Answer

$$	ext{Total Magnification} = 	ext{Objective Lens Magnification} 	imes 	ext{Ocular Lens Magnification}$$

Question 15

Which of the following is a common misconception about antimicrobial drugs?

Accepted Answer

Antibiotics are only effective against bacteria, not viruses.

Question 16

Which of the following is the best example of a facultative anaerobe?

Accepted Answer

Escherichia coli

Question 17

A biochemical test result shows gas production and acid formation in a lactose broth. Which type of bacteria is most likely present?

Accepted Answer

Lactose fermenter

Question 18

Which of the following is the best method to determine the oxygen requirements of an unknown bacterial isolate?

Accepted Answer

Inoculate the bacteria into thioglycollate broth.

Question 19

Which of the following is a correct statement about the role of epidemiology in disease control?

Accepted Answer

Epidemiology studies the distribution and determinants of diseases in populations.

Question 20

Which of the following is the best example of a biochemical test used to identify Gram-negative rods in the family Enterobacteriaceae?

Accepted Answer

IMViC tests (Indole, Methyl Red, Voges-Proskauer, Citrate)

Biology 22 Microbiology: Laboratory and Lecture Syllabus Study Guide

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