Question 1

Which of the following best describes the basic structure of a virus?

Accepted Answer

A nucleic acid genome enclosed in a protein coat, sometimes surrounded by a membranous envelope

Question 2

Which statement about viral replication is correct?

Accepted Answer

Viruses use host cell machinery to replicate their genome and produce proteins

Question 3

A bacteriophage infects a bacterial cell and integrates its DNA into the host genome without killing the cell. What is this viral DNA called?

Accepted Answer

Prophage

Question 4

Which of the following is a key difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle results in the destruction of the host cell, while the lysogenic cycle allows the host cell to survive with integrated viral DNA

Question 5

Which of the following best explains why antibiotics are ineffective against viral infections?

Accepted Answer

Viruses lack cell walls and metabolic pathways targeted by antibiotics

Question 6

A retrovirus such as HIV uses which enzyme to copy its RNA genome into DNA?

Accepted Answer

Reverse transcriptase

Question 7

Which of the following equations best represents the Central Dogma of molecular biology, and how do retroviruses challenge it?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$, but retroviruses use $$RNA \rightarrow DNA$$ via reverse transcriptase

Question 8

Which of the following is a characteristic of viral genomes?

Accepted Answer

They may be double- or single-stranded DNA or RNA

Question 9

Which of the following best describes the function of viral envelopes in animal viruses?

Accepted Answer

They contain glycoproteins that bind to specific host cell receptors

Question 10

A new strain of influenza virus emerges and causes a global pandemic. Which of the following factors most likely contributed to this event?

Accepted Answer

The virus mutated its H and N proteins, allowing it to infect new hosts

Question 11

Which of the following is true about the host range of viruses?

Accepted Answer

Most viruses infect specific cell types in specific host species

Question 12

Which of the following best describes the role of bacteriophages in aquatic ecosystems?

Accepted Answer

They free up organic matter by lysing bacteria, making nutrients available to other organisms

Question 13

Which of the following is a correct statement about prions?

Accepted Answer

Prions are slow-acting infectious proteins that cause brain diseases by converting normal proteins into the prion form

Question 14

A plant virus is most likely to spread through vertical transmission if:

Accepted Answer

It is inherited from the parent plant

Question 15

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

Accepted Answer

Vaccines stimulate the immune system to recognize and respond to the pathogen

Question 16

Which of the following is a plausible reason why emerging viruses can cause pandemics?

Accepted Answer

They often arise from genetic recombination and can infect hosts with little or no immunity

Question 17

Which of the following is a unique feature of retroviruses compared to other viruses?

Accepted Answer

They integrate a DNA copy of their RNA genome into the host genome

Question 18

Which of the following best describes the process by which a temperate phage can switch from the lysogenic to the lytic cycle?

Accepted Answer

An environmental signal triggers the excision of the viral genome from the host chromosome

Question 19

Which of the following is NOT a way that viruses can cause disease symptoms in their hosts?

Accepted Answer

By directly synthesizing antibiotics

Question 20

Which of the following statements about viroids is correct?

Accepted Answer

Viroids are small circular RNA molecules that infect plants and disrupt their growth

Viruses: Structure, Replication, and Impact (Chapter 19 Study Notes)

Study Guide - Practice Questions