Q: According to the central dogma of molecular biology, which of the following correctly represents the flow of genetic information in a typical cell?

$$DNA \rightarrow RNA \rightarrow \text{Protein}$$

Question 1

Which of the following best describes the structural difference between a naked virus and an enveloped virus?

Accepted Answer

A naked virus contains only a nucleic acid genome and a protein capsid, while an enveloped virus has an additional lipid bilayer derived from the host cell membrane.

Question 2

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes can be composed of either DNA or RNA, which may be single-stranded or double-stranded, and can be linear or circular.

Question 3

What is the primary function of tail fibers in bacteriophages or glycoprotein spikes in animal viruses?

Accepted Answer

They mediate attachment to specific receptors on the host cell surface, determining host specificity.

Question 4

Which of the following is NOT one of the three basic shapes of viral particles?

Accepted Answer

Tetrahedral

Question 5

A lytic phage infects a bacterial cell. Which of the following correctly lists the five basic steps of the lytic cycle in order?

Accepted Answer

Attachment, penetration, biosynthesis, maturation, release

Question 6

Which statement best distinguishes a temperate phage from a lytic phage?

Accepted Answer

A temperate phage can integrate its genome into the host chromosome and enter a lysogenic cycle, while a lytic phage only undergoes the lytic cycle.

Question 7

During generalized transduction, which of the following occurs?

Accepted Answer

A phage accidentally packages random fragments of bacterial DNA and transfers them to another bacterium.

Question 8

Which of the following best describes the difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction can transfer any bacterial gene, while specialized transduction transfers only genes adjacent to the prophage integration site.

Question 9

Which step in the animal virus replication cycle is most different from the bacteriophage replication cycle, and why?

Accepted Answer

Entry, because animal viruses can enter by membrane fusion or endocytosis, whereas bacteriophages inject their genome into the host.

Question 10

A scientist is studying a new animal virus. She observes that the virus enters the host cell by fusion with the plasma membrane. Which viral structure is essential for this process?

Accepted Answer

Viral envelope glycoproteins

Question 11

According to the central dogma of molecular biology, which of the following correctly represents the flow of genetic information in a typical cell?

Accepted Answer

$$DNA ightarrow RNA ightarrow 	ext{Protein}$$

Question 12

Which class of viruses must carry their own RNA-dependent RNA polymerase within the virion to replicate inside a host cell?

Accepted Answer

Negative-sense single-stranded RNA viruses

Question 13

Which of the following is a mechanism by which animal viruses are released from host cells?

Accepted Answer

Budding from the plasma membrane

Question 14

A researcher wants to quantify the number of infectious virus particles in a sample. Which laboratory technique should she use?

Accepted Answer

Plaque assay

Question 15

Which of the following best describes a cytopathic effect (CPE) observed in cell cultures?

Accepted Answer

Visible changes or damage to host cells caused by viral infection, such as cell rounding or lysis

Question 16

Which of the following statements about viroids is correct?

Accepted Answer

Viroids are small, circular RNA molecules that lack a protein coat and can cause disease in plants.

Question 17

Which of the following best describes prions and their mechanism of propagation?

Accepted Answer

Prions are misfolded proteins that induce normal proteins to adopt the abnormal conformation, leading to disease.

Question 18

A patient is diagnosed with Creutzfeldt-Jakob disease, a transmissible spongiform encephalopathy. Which of the following is the causative agent?

Accepted Answer

A prion

Question 19

A viral growth curve in a laboratory experiment shows a latent period followed by a sharp increase in viral particles. What does the latent period represent?

Accepted Answer

The time during which viruses are replicating inside host cells but have not yet been released.

Question 20

Which of the following best explains why glycoproteins on the viral envelope are critical for host specificity?

Accepted Answer

Glycoproteins bind to specific receptors on the host cell surface, determining which cells the virus can infect.

Viruses, Viroids, and Prions: Structure, Replication, and Pathogenesis

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