Question 1

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

Accepted Answer

They require host cell enzymes and metabolic processes to synthesize new virus particles.

Question 2

A scientist discovers a new virus with a circular, double-stranded RNA genome. Which statement is most accurate regarding this finding?

Accepted Answer

Double-stranded RNA genomes are rare in cells but found in some viruses.

Question 3

Which feature distinguishes enveloped viruses from naked viruses in terms of environmental stability?

Accepted Answer

Naked viruses are more stable in harsh environmental conditions.

Question 4

During the lytic cycle of a bacteriophage, which enzyme is responsible for degrading the bacterial cell wall prior to penetration?

Accepted Answer

Lysozyme

Question 5

A bacteriophage infects a bacterial cell and integrates its genome into the host chromosome. What is the integrated viral DNA called?

Accepted Answer

Prophage

Question 6

Which of the following best explains why viruses do not undergo metabolic activity on their own?

Accepted Answer

They lack ribosomes and functional organelles required for metabolism.

Question 7

A virus is classified as having a helical capsid and a lipid envelope. Which of the following is true regarding its susceptibility to environmental factors?

Accepted Answer

It is more susceptible to desiccation and detergents than naked viruses.

Question 8

Which step in the lytic cycle of bacteriophage replication involves the assembly of viral nucleic acid and proteins into complete virus particles?

Accepted Answer

Maturation

Question 9

What is the primary difference between the lytic and lysogenic cycles of bacteriophage replication?

Accepted Answer

The lysogenic cycle allows the host cell to survive and replicate with the viral genome integrated.

Question 10

A bacterium acquires a new toxin gene after infection by a temperate phage. This phenomenon is best described as:

Accepted Answer

Lysogenic conversion

Question 11

Which of the following equations best represents the burst size in a lytic bacteriophage infection, where $$N_{virions} is $$the number of virions released and $$N_{cells} is $$the number of lysed cells?

Accepted Answer

$$Burst\ Size = \frac{N_{virions}}{N_{cells}}$$

Question 12

Which viral component is most critical for host cell recognition and attachment?

Accepted Answer

Glycoproteins embedded in the capsid or envelope

Question 13

A virus with a positive-sense single-stranded RNA genome enters a host cell. What is the first step in its replication?

Accepted Answer

Direct translation of viral RNA by host ribosomes

Question 14

Which of the following best describes the role of the viral envelope in immune evasion?

Accepted Answer

It is derived from the host cell membrane, helping the virus avoid immune detection.

Question 15

Which scenario best illustrates host specificity in viruses?

Accepted Answer

A bacteriophage infects only a specific strain of E. coli.

Question 16

During the lysogenic cycle, what happens to the viral genome after integration into the host chromosome?

Accepted Answer

It is replicated along with the host genome during cell division.

Question 17

Which of the following is NOT a characteristic of viruses?

Accepted Answer

They possess functional organelles for metabolism.

Question 18

A virus is found to infect many kinds of host cells within one species. This virus is best described as:

Accepted Answer

A generalist

Question 19

Which of the following best explains why viral genomes are generally much smaller than cellular genomes?

Accepted Answer

Viruses do not encode for metabolic enzymes or organelles.

Question 20

Which process triggers a prophage to enter the lytic cycle?

Accepted Answer

Environmental stress or DNA damage in the host cell

Viruses, Viroids, and Bacteriophage Lifecycles: Key Concepts in Microbiology

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