Question 1

Which of the following best describes the mechanism of action of penicillin?

Accepted Answer

It prevents the synthesis of peptidoglycan, weakening the cell wall and causing lysis.

Question 2

Why do some antibiotics that inhibit protein synthesis in bacteria also affect mitochondria in eukaryotic cells?

Accepted Answer

Mitochondria have ribosomes similar in size and composition to prokaryotic ribosomes (70S).

Question 3

Which of the following antibiotics acts by inhibiting the 50S ribosomal subunit in bacteria?

Accepted Answer

Erythromycin

Question 4

A patient is diagnosed with a urinary tract infection caused by a Gram-negative bacterium. Which structural feature of the bacterium makes it more resistant to penicillin?

Accepted Answer

Outer membrane containing lipopolysaccharides and porins

Question 5

Which of the following best explains why broad-spectrum antibiotics can lead to superinfections?

Accepted Answer

They kill a wide range of normal microbiota, reducing competition and allowing opportunistic pathogens to thrive.

Question 6

Which of the following is a mechanism by which bacteria can become resistant to antibiotics?

Accepted Answer

Production of enzymes such as beta-lactamase that inactivate the antibiotic

Question 7

A disk-diffusion test is performed to evaluate the efficacy of a new antibiotic. What does a large clear zone around the disk indicate?

Accepted Answer

The bacterium is highly susceptible to the antibiotic.

Question 8

Which of the following statements about sulfonamides is correct?

Accepted Answer

They act as antimetabolites by competitively inhibiting the enzyme that uses para-aminobenzoic acid (PABA) to synthesize folic acid.

Question 9

Which of the following is a benefit of using antibiotic combinations in therapy?

Accepted Answer

They can broaden the antibacterial spectrum and prevent the emergence of resistant organisms.

Question 10

A patient with sickle cell trait is less likely to develop severe malaria. This is an example of which genetic phenomenon?

Accepted Answer

Heterozygous advantage

Question 11

Which of the following drugs is most appropriate for treating a fungal infection?

Accepted Answer

Ketoconazole

Question 12

Which of the following best describes the action of quinolones?

Accepted Answer

They inhibit DNA gyrase, blocking DNA replication.

Question 13

Which of the following is a reason why chemotherapeutic agents must have selective toxicity?

Accepted Answer

To minimize damage to host cells while targeting microbial cells.

Question 14

Which of the following is a common side effect of antifungal drugs that target ergosterol synthesis?

Accepted Answer

Renal toxicity

Question 15

Which of the following statements about plasmids is correct?

Accepted Answer

They often carry genes for antibiotic resistance and can be transferred between bacteria.

Question 16

Which of the following is a real-world consequence of excessive use of triclosan?

Accepted Answer

Development of bacterial resistance to multiple antibiotics

Question 17

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics than Gram-positive bacteria?

Accepted Answer

They possess an outer membrane that acts as a barrier to many antibiotics.

Question 18

Which of the following is the primary target of aminoglycoside antibiotics such as gentamicin?

Accepted Answer

30S ribosomal subunit

Question 19

Which of the following statements about the disk-diffusion method is correct?

Accepted Answer

It evaluates the efficacy of a chemical agent by measuring the zone of inhibition around a disk.

Question 20

Which of the following is a correct pairing of an antimicrobial drug and its primary target?

Accepted Answer

Praziquantel – flukes (helminths)

Chapter 20: Antimicrobial Drugs – Comprehensive Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards