Question 1

Which of the following best describes the process of semiconservative DNA replication in bacteria?

Accepted Answer

Each new DNA molecule consists of one parental strand and one newly synthesized strand.

Question 2

A mutation that changes a codon from UAU (tyrosine) to UAA (stop) is best classified as which type of mutation?

Accepted Answer

Nonsense mutation

Question 3

Which enzyme is responsible for synthesizing RNA primers during DNA replication?

Accepted Answer

Primase

Question 4

A bacterium acquires antibiotic resistance by taking up free DNA from its environment. This process is called:

Accepted Answer

Transformation

Question 5

Which of the following statements about viruses is TRUE?

Accepted Answer

Viruses use host cell machinery for replication.

Question 6

During the lytic cycle of a bacteriophage, what is the fate of the host cell?

Accepted Answer

It is lysed, releasing new phage particles.

Question 7

Which of the following best distinguishes an endotoxin from an exotoxin?

Accepted Answer

Exotoxins are proteins secreted by bacteria; endotoxins are lipid A components of LPS.

Question 8

A patient develops a disease after being bitten by a mosquito carrying a protozoan parasite. What is the mode of transmission?

Accepted Answer

Vector-borne transmission

Question 9

Which of the following is a limitation of Koch's postulates?

Accepted Answer

They cannot be applied to diseases caused by viruses that require living cells for growth.

Question 10

Which of the following best describes the difference between incidence and prevalence?

Accepted Answer

Incidence is the number of new cases over a period; prevalence is the total number of existing cases at a given time.

Question 11

A bacterial strain produces a capsule that inhibits phagocytosis. This trait most directly contributes to which aspect of pathogenesis?

Accepted Answer

Immune evasion

Question 12

Which of the following is a correct sequence of events in the generalized animal-virus replication cycle?

Accepted Answer

Attachment → Entry → Uncoating → Synthesis → Assembly → Release

Question 13

Which of the following best explains why positive-sense RNA viruses can often be directly translated by host ribosomes?

Accepted Answer

Their RNA genome functions as mRNA.

Question 14

A hospital patient develops a urinary tract infection after catheterization. This infection is best classified as:

Accepted Answer

A healthcare-associated infection (HAI)

Question 15

Which of the following is a function of hyaluronidase produced by some pathogenic bacteria?

Accepted Answer

Breaks down hyaluronic acid in connective tissue, aiding spread

Question 16

Which of the following best describes the action of a superantigen?

Accepted Answer

It activates many T cells nonspecifically, causing massive cytokine release.

Question 17

A laboratory uses the Limulus amebocyte lysate (LAL) test to check for contamination in a batch of intravenous fluids. What is this test detecting?

Accepted Answer

Endotoxin (lipid A) from gram-negative bacteria

Question 18

Which of the following is a key difference between prokaryotic and eukaryotic gene expression?

Accepted Answer

In eukaryotes, transcription and translation are separated by the nuclear envelope.

Question 19

Which of the following best describes a viroid?

Accepted Answer

A small, circular, single-stranded RNA molecule with no protein coat

Question 20

A patient is exposed to a pathogen, but does not develop disease because most people in the community are immune. This is an example of:

Accepted Answer

Herd immunity

BIO 150 Module 3 Microbiology Study Guide: Genetics, Viruses, Disease, and Pathogenicity

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