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 original strand and one newly synthesized strand.

Question 2

A patient is diagnosed with a genetic disease caused by a point mutation that changes a codon from UAU (tyrosine) to UAA. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 3

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

Accepted Answer

Primase

Question 4

A researcher is studying a bacterial strain that can transfer antibiotic resistance genes to other bacteria through direct cell-to-cell contact. Which mechanism is responsible for this gene transfer?

Accepted Answer

Conjugation

Question 5

Which of the following best explains why retroviruses require the enzyme reverse transcriptase?

Accepted Answer

To synthesize DNA from an RNA template

Question 6

A hospital patient develops a urinary tract infection after catheterization. Which term best describes this infection?

Accepted Answer

Nosocomial infection

Question 7

Which of the following is a function of the 5’ cap added to eukaryotic mRNA during post-transcriptional modification?

Accepted Answer

It protects mRNA from degradation and assists in ribosome binding during translation.

Question 8

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause spongiform encephalopathies.

Question 9

A patient is infected with a virus that enters the host cell by membrane fusion. Which type of virus is most likely responsible?

Accepted Answer

Enveloped virus

Question 10

Which of the following best describes the role of Toll-like receptors (TLRs) in innate immunity?

Accepted Answer

They recognize pathogen-associated molecular patterns (PAMPs) and activate immune responses.

Question 11

A mutation changes the DNA sequence from $$	ext{ATG GAA TCC} to$$ $$	ext{ATG GAT TCC}. $$What type of mutation has occurred, and what is its likely effect?

Accepted Answer

Point mutation; may result in a missense mutation if the codon change alters the amino acid.

Question 12

Which of the following is a key difference between the replication of positive-sense single-stranded RNA viruses and double-stranded DNA viruses in animal cells?

Accepted Answer

Positive-sense RNA viruses can be directly translated by host ribosomes, while dsDNA viruses must first be transcribed into mRNA.

Question 13

Which of the following best describes the function of the bacterial F factor?

Accepted Answer

It enables bacteria to form sex pili and transfer genetic material during conjugation.

Question 14

A patient is exposed to a pathogen through a contaminated surgical instrument. Which mode of transmission does this represent?

Accepted Answer

Indirect contact transmission via a fomite

Question 15

Which of the following is a hallmark of inflammation?

Accepted Answer

Edema (swelling) due to increased vascular permeability

Question 16

A laboratory technician is growing viruses using a continuous cell culture. What is a key advantage of this method compared to using diploid cell cultures?

Accepted Answer

Continuous cell cultures can be maintained and subcultured indefinitely.

Question 17

Which of the following best explains the difference between incidence and prevalence in epidemiology?

Accepted Answer

Incidence is the number of new cases in a given time period, while prevalence is the total number of cases at a specific time.

Question 18

Which of the following statements about the complement system is correct?

Accepted Answer

Activation of the complement system can lead to the formation of the membrane attack complex, which lyses bacterial cells.

Question 19

A patient is found to have a latent viral infection. Which of the following best describes this condition?

Accepted Answer

The virus remains in the host without causing symptoms, but can reactivate later.

Question 20

Which of the following best describes the role of interferon alpha ($$\alpha) $$and beta ($$\beta) in $$the immune response to viral infections?

Accepted Answer

They induce the production of antiviral proteins in neighboring cells, limiting viral spread.

Microbial Genetics, Virology, Infectious Diseases, and Innate Immunity: Study Guide

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