Question 1

Which of the following best describes the difference between sterilization and disinfection?

Accepted Answer

Sterilization removes all forms of microbial life, including endospores, while disinfection reduces the number of viable microorganisms but may not eliminate all pathogens or spores.

Question 2

A hospital uses moist heat to sterilize surgical instruments. Which mechanism of action is primarily responsible for microbial destruction in this process?

Accepted Answer

Denaturation of proteins and destruction of cell membranes

Question 3

Which group of microbes is most resistant to antimicrobial agents, and why?

Accepted Answer

Bacterial endospores, because they have thick protective coats and are metabolically inactive

Question 4

A microbiologist is testing the effectiveness of a new disinfectant. Which method is considered the 'gold standard' for measuring disinfectant effectiveness?

Accepted Answer

The phenol coefficient test

Question 5

Which equation represents the Decimal Reduction Time ($$D$$), and what does it signify?

Accepted Answer

The time required to reduce a microbial population by one log (90%) at a given temperature: $$D = \frac{t}{\log N_0$ - \log N}$$

Question 6

Which physical method of microbial control is most effective for sterilizing heat-sensitive liquids, such as vaccines?

Accepted Answer

Filtration

Question 7

Which chemical agent acts by disrupting cell membranes and denaturing proteins, and is commonly used as a skin antiseptic?

Accepted Answer

Alcohols

Question 8

Paul Ehrlich, Alexander Fleming, and Gerhard Domagk made significant contributions to antimicrobial development. Which statement correctly matches each scientist to their contribution?

Accepted Answer

Ehrlich developed the first synthetic antimicrobial (Salvarsan), Fleming discovered penicillin, and Domagk discovered sulfa drugs.

Question 9

Which principle explains why antimicrobial drugs can target bacteria without harming human cells?

Accepted Answer

Selective toxicity

Question 10

A patient is prescribed a broad-spectrum antibiotic. What is a potential disadvantage of this approach?

Accepted Answer

It may disrupt normal microbiota, leading to secondary infections such as Clostridioides difficile.

Question 11

Which mechanism of action is used by beta-lactam antibiotics such as penicillin?

Accepted Answer

Inhibition of cell wall synthesis

Question 12

A bacterial strain acquires resistance to an antibiotic by producing an enzyme that destroys the drug. Which mechanism of resistance is this?

Accepted Answer

Development of enzymes

Question 13

Which equation best represents the calculation of the minimum inhibitory concentration (MIC) in a broth dilution test?

Accepted Answer

MIC is the lowest concentration of drug that prevents visible growth: $$MIC = \min \{C : 	ext{no growth at concentration } C\}$$

Question 14

Which of the following best describes the purpose of Bergey’s Manual of Systematic Bacteriology?

Accepted Answer

It provides a comprehensive classification and identification guide for prokaryotes based on their characteristics.

Question 15

Which prokaryotic cell shape and arrangement is described by chains of spherical cells?

Accepted Answer

Streptococci

Question 16

Which type of extremophile in Domain Archaea thrives in environments with high salt concentrations?

Accepted Answer

Halophiles

Question 17

Which protozoan is responsible for causing African sleeping sickness?

Accepted Answer

Trypanosoma

Question 18

Which equation best represents the number of chromosomes after meiosis in a diploid organism with $$2n$$ chromosomes?

Accepted Answer

After meiosis, each gamete has $$n$$ chromosomes: $$n = \frac{2n}{2}$$

Question 19

A fly lands on dog feces and then on your picnic lunch, transferring bacteria. What type of vector is the fly in this scenario?

Accepted Answer

Mechanical vector

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