Question 1

Which of the following best describes the structure of DNA?

Accepted Answer

A double helix composed of two antiparallel strands held together by hydrogen bonds between complementary nitrogenous bases.

Question 2

During DNA replication in prokaryotes, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to the 3' end?

Accepted Answer

DNA polymerase

Question 3

Which of the following best explains why broad-spectrum antibiotics are more likely to cause the development of opportunistic pathogens?

Accepted Answer

They disrupt normal microbiota, reducing competition and allowing opportunistic pathogens to thrive.

Question 4

A patient is prescribed an antibiotic that inhibits cell wall synthesis. Which of the following is the most likely mechanism of action for this drug?

Accepted Answer

It prevents the cross-linking of peptidoglycan chains, weakening the bacterial cell wall.

Question 5

Which of the following statements about bacterial conjugation is correct?

Accepted Answer

It involves the direct transfer of genetic material through a pilus from one bacterium to another.

Question 6

A hospital is trying to decide between using disinfection and sterilization for surgical instruments. Which of the following best distinguishes these two processes?

Accepted Answer

Sterilization destroys all forms of microbial life, including endospores, while disinfection eliminates most pathogens but not necessarily endospores.

Question 7

Which of the following equations correctly represents the exponential growth of a bacterial population?

Accepted Answer

$N = N_0 	imes 2^n$

Question 8

A microbiologist is testing the effectiveness of a new disinfectant. Which of the following is a major limitation of many disinfectants?

Accepted Answer

They are often inactivated by organic matter such as blood or feces.

Question 9

Which of the following best describes the function of bacterial endospores?

Accepted Answer

They allow bacteria to survive harsh environmental conditions by entering a dormant state.

Question 10

Which of the following is a correct comparison between eukaryotic and prokaryotic chromosomes?

Accepted Answer

Eukaryotic chromosomes are linear and located in a nucleus, while prokaryotic chromosomes are typically circular and found in the nucleoid region.

Question 11

A patient is infected with a bacterium that is resistant to multiple antibiotics. Which genetic element is most likely responsible for the rapid spread of this resistance among bacteria?

Accepted Answer

Plasmids carrying resistance genes

Question 12

Which of the following best describes the lytic cycle of a bacteriophage?

Accepted Answer

The phage injects its DNA, replicates inside the host, and causes cell lysis to release new phages.

Question 13

Which of the following is a key difference between naked and enveloped viruses?

Accepted Answer

Enveloped viruses have a lipid membrane derived from the host cell, while naked viruses lack this envelope.

Question 14

Which of the following best explains why some microorganisms can be resistant to antimicrobial drugs?

Accepted Answer

They possess genes that encode enzymes capable of inactivating the drug.

Question 15

Which of the following is a correct statement about prions?

Accepted Answer

They are infectious proteins that cause neurodegenerative diseases.

Question 16

A scientist is using the Kirby-Bauer test to evaluate antibiotic effectiveness. What is being measured in this test?

Accepted Answer

The diameter of the zone of inhibition around an antibiotic disk on an agar plate.

Question 17

Which of the following best describes the process of bacterial transformation?

Accepted Answer

Uptake of naked DNA from the environment by a bacterial cell.

Question 18

Which of the following is a common limitation of using UV light as a disinfectant?

Accepted Answer

It has poor penetration and is only effective on exposed surfaces.

Question 19

Which of the following best describes the function of the viral capsid?

Accepted Answer

It protects the viral genetic material and aids in attachment to host cells.

Question 20

A patient is diagnosed with a disease caused by a prion. Which of the following is a characteristic feature of prion diseases?

Accepted Answer

They involve the accumulation of misfolded proteins in neural tissue.

Microbiology Exam 2 Study Guide: Chapters 7–13

Study Guide - Practice Questions

Study Guide - Flashcards