Question 1

Which of the following best describes the difference between a T4 phage and a Lambda (λ) phage when infecting E. coli?

Accepted Answer

T4 phage only undergoes the lytic cycle, while Lambda phage can undergo both lytic and lysogenic cycles.

Question 2

During the lytic cycle of a bacteriophage, which of the following events occurs LAST?

Accepted Answer

Release of new virions from the host cell.

Question 3

A researcher observes that a bacteriophage infects E. coli and integrates its DNA into the host genome, remaining dormant until triggered by stress. Which type of phage is this?

Accepted Answer

Lysogenic phage

Question 4

Which of the following is a bacterial defense mechanism against phage infection?

Accepted Answer

Losing the receptor required for phage adsorption

Question 5

Which of the following best explains why plant viruses generally have a broad host range?

Accepted Answer

They do not require specific receptors for entry.

Question 6

A virus infects only T4 helper cells in humans. This is an example of which viral property?

Accepted Answer

Narrow tissue tropism

Question 7

Which of the following is TRUE regarding the release of enveloped animal viruses from host cells?

Accepted Answer

They acquire their envelope from the host cell membrane during budding.

Question 8

Neuraminidase is important for the release of influenza virus from host cells because it:

Accepted Answer

Cleaves sialic acid on the host cell surface, preventing hemagglutinin from rebinding.

Question 9

Which of the following is a characteristic of prions?

Accepted Answer

They are infectious proteins that can induce abnormal folding in normal proteins.

Question 10

A patient develops a degenerative neurological disorder after consuming contaminated beef. Which agent is most likely responsible?

Accepted Answer

Prion

Question 11

Which of the following is NOT a criterion used to classify viruses into families?

Accepted Answer

Ribosomal RNA sequence

Question 12

A viroid differs from a typical virus in that it:

Accepted Answer

Lacks protein-encoding genes and a capsid.

Question 13

Which of the following best explains why viruses cannot be placed on the universal phylogenetic tree?

Accepted Answer

They do not have ribosomes and thus lack ribosomal RNA sequences.

Question 14

A virus is classified as a single-stranded, negative-sense RNA virus with a segmented genome. Which of the following is the most likely method for its classification?

Accepted Answer

By nucleic acid type, strandedness, and genome structure

Question 15

Which of the following best describes the eclipse period in the one-step growth curve of viral replication?

Accepted Answer

The period during which no infectious virions are detected, even if the cells are lysed.

Question 16

Which of the following is a real-world example of a virus with a broad tissue tropism?

Accepted Answer

Poliovirus infecting many cell types

Question 17

Which of the following statements about the effects of animal viruses on host cells is CORRECT?

Accepted Answer

Some animal viruses can transform host cells into cancerous cells.

Question 18

A plant virus is unable to enter a plant cell unless the cell wall is damaged. Which of the following is the most likely explanation?

Accepted Answer

The rigid plant cell wall prevents viral entry unless breached by vectors or wounds.

Question 19

Which of the following best describes the function of the CRISPR-Cas system in bacteria?

Accepted Answer

It provides adaptive immunity by storing fragments of phage DNA to target future infections.

Question 20

A patient is diagnosed with a persistent viral infection that lasts for many years. Which of the following viruses is most likely responsible?

Accepted Answer

Epstein-Barr virus

Microbiology Study Notes: Viral Structure, Replication, and Classification

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