Question 1

Which of the following characteristics is shared by viruses and living organisms, but is NOT sufficient to classify viruses as alive?

Accepted Answer

Possession of genetic material (DNA or RNA)

Question 2

A scientist is studying a virus that can infect both humans and chimpanzees, but not other mammals. Which concept best describes this phenomenon?

Accepted Answer

Host range

Question 3

Which of the following best describes the composition of a virion?

Accepted Answer

Proteins and nucleic acids

Question 4

A virus has a genome made of single-stranded RNA and a helical capsid. Which of the following statements is TRUE regarding its genome compared to cellular organisms?

Accepted Answer

Cellular organisms only have double-stranded DNA genomes

Question 5

During the lytic cycle of a bacteriophage, which step directly results in the destruction of the host cell?

Accepted Answer

Lysis

Question 6

Which of the following best explains why viruses are obligate intracellular parasites?

Accepted Answer

They lack genes for many products needed for reproduction and must exploit host cell genomes to reproduce.

Question 7

A viral envelope is acquired during which process, and what is it composed of?

Accepted Answer

During budding; composed of a phospholipid membrane from the host cell

Question 8

Which step is unique to the lysogenic cycle of a temperate bacteriophage compared to the lytic cycle?

Accepted Answer

Integration of viral genome into the host chromosome

Question 9

A patient is diagnosed with HIV. Which enzyme is responsible for converting the viral RNA genome into DNA, and what is the resulting DNA called once integrated into the host genome?

Accepted Answer

Reverse transcriptase; provirus

Question 10

Which of the following best describes viral latency and its significance in cancer development?

Accepted Answer

Latency is when viruses remain dormant inside cells, making it difficult to determine the cause and prevent certain cancers.

Question 11

A laboratory technician is quantifying the number of virions in a sample. Which term describes this measurement?

Accepted Answer

Viral titer

Question 12

Why are viruses more difficult to study and identify in the laboratory compared to bacteria?

Accepted Answer

Viruses require a living host cell for replication and cannot be grown on artificial nutrient media.

Question 13

Which molecular technique uses primers to amplify specific viral DNA sequences for identification?

Accepted Answer

Polymerase Chain Reaction (PCR)

Question 14

An Enzyme Immunoassay (EIA) detects viral infections by:

Accepted Answer

Using antibodies tagged with enzymes to bind antigens, producing a color change upon substrate addition

Question 15

Which of the following is TRUE regarding viroids?

Accepted Answer

Viroids are acellular particles consisting of a short strand of circular RNA capable of self-replication.

Question 16

A patient is infected with Hepatitis Delta Virus (HDV). Which statement best describes the replication requirements of this virus?

Accepted Answer

HDV requires co-infection with Hepatitis B virus to replicate.

Question 17

Which of the following best describes a prion and its effect on the nervous system?

Accepted Answer

A misfolded protein that accumulates in brain tissue, causing spongy degeneration and loss of motor coordination.

Question 18

Which equation would best represent the exponential increase in viral titer during the lytic cycle, assuming each infected cell releases $$n$$ new virions and $$k$$ cells are infected per cycle?

Accepted Answer

$$V = n 	imes k$$

Question 19

Which of the following diseases is caused by prions, and what is the current treatment available?

Accepted Answer

Mad cow disease; no treatment or cure available

Question 20

Why are prions extremely difficult to destroy using standard sterilization procedures?

Accepted Answer

Prions are resistant to heat, chemicals, and radiation.

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