Q: Which viral genome type can be immediately translated by host ribosomes upon entry into the cell?

$$\text{ssRNA}^+ ($$single-stranded positive-sense RNA)$

Question 1

Which of the following best describes why viruses are considered obligate intracellular pathogens?

Accepted Answer

They require host cell machinery to reproduce and cannot multiply outside a host cell.

Question 2

A virus with a helical capsid structure would most likely appear as:

Accepted Answer

A hollow tube-like structure

Question 3

Which of the following statements about viral envelopes is CORRECT?

Accepted Answer

Enveloped viruses acquire their envelope by budding from the host cell membrane.

Question 4

Which viral genome type can be immediately translated by host ribosomes upon entry into the cell?

Accepted Answer

$$	ext{ssRNA}^+ ($$single-stranded positive-sense RNA)$

Question 5

Which process is responsible for the rapid emergence of new influenza strains capable of causing pandemics?

Accepted Answer

Antigenic shift

Question 6

A patient is diagnosed with a persistent viral infection that periodically flares up with symptoms and then enters a dormant phase. Which virus family is most likely responsible?

Accepted Answer

Herpesviridae

Question 7

Which of the following best explains why RNA viruses mutate more rapidly than DNA viruses?

Accepted Answer

RNA polymerases lack proofreading activity.

Question 8

Which laboratory method is used to quantify the number of infectious bacteriophages in a sample?

Accepted Answer

Plaque assay

Question 9

A virus is classified as a retrovirus. Which enzyme is essential for its replication?

Accepted Answer

Reverse transcriptase

Question 10

Which of the following is a medically important consequence of phage conversion in bacteria?

Accepted Answer

Bacteria acquire new pathogenicity factors, such as toxin genes.

Question 11

Which antiviral drug mechanism is correctly matched with its target?

Accepted Answer

Acyclovir: inhibits DNA replication

Question 12

Which of the following best describes a prion?

Accepted Answer

An infectious protein with no genetic material

Question 13

Which of the following is a distinguishing feature of the lysogenic cycle in bacteriophages?

Accepted Answer

Integration of phage DNA into the host genome as a prophage

Question 14

A virus is found to infect only human T cells and not other cell types. This is an example of:

Accepted Answer

Narrow host range and narrow tropism

Question 15

Which of the following best explains why vaccines are effective in preventing viral infections?

Accepted Answer

They train the immune system to recognize viral antigens and mount a rapid response.

Question 16

Which of the following is a limitation of ELISA and agglutination assays for viral detection?

Accepted Answer

They require the antigen to be well characterized and may miss viruses that have undergone antigenic shift.

Question 17

Which of the following viruses is associated with the development of cancer in humans?

Accepted Answer

Human papillomavirus (HPV)

Question 18

Which step in the animal virus replication cycle is unique compared to bacteriophage replication?

Accepted Answer

Uncoating of the viral capsid

Question 19

A patient sample is tested for a viral infection using PCR. What is the main advantage of this method?

Accepted Answer

It can detect very low levels of viral nucleic acids with high specificity.

Question 20

Which of the following best describes the effect of antigenic drift in influenza viruses?

Accepted Answer

It results in minor changes to HA and NA spikes, leading to seasonal epidemics.

Viruses and Prions: Structure, Classification, Replication, and Clinical Aspects

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