Question 1

Which of the following statements best explains why viruses are considered acellular?

Accepted Answer

They lack a cytoplasmic membrane, cytosol, and organelles.

Question 2

A scientist discovers a new infectious agent that consists of a circular piece of ssRNA, lacks a protein coat, and causes disease in plants. What is this agent most likely to be?

Accepted Answer

A viroid

Question 3

Which of the following best describes the role of glycoprotein spikes on enveloped viruses?

Accepted Answer

They serve as recognition sites for host cell attachment.

Question 4

During the lytic replication cycle of a bacteriophage, what is the primary function of lysozyme?

Accepted Answer

To weaken the bacterial cell wall for genome entry and virion release

Question 5

Which of the following is a key difference between the replication of animal viruses and bacteriophages?

Accepted Answer

Animal viruses may enter host cells by membrane fusion or endocytosis.

Question 6

A virus with a negative-sense single-stranded RNA genome must carry which enzyme within its virion to ensure successful replication in a host cell?

Accepted Answer

RNA-dependent RNA transcriptase

Question 7

Which of the following best explains why enveloped viruses are generally more sensitive to environmental conditions than naked viruses?

Accepted Answer

Their phospholipid envelopes are susceptible to desiccation and detergents.

Question 8

Which of the following is a correct sequence of events in the lytic replication cycle of a bacteriophage?

Accepted Answer

Attachment → Entry → Synthesis → Assembly → Release

Question 9

A patient is diagnosed with a prion disease. Which of the following best describes the molecular mechanism underlying this disease?

Accepted Answer

A misfolded protein induces normal proteins to adopt an abnormal conformation.

Question 10

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes may be DNA or RNA, but never both.

Question 11

A researcher is culturing a virus using a fertilized chicken egg. What is the primary advantage of this method?

Accepted Answer

It provides a large, sterile, and nutrient-rich environment for viral growth.

Question 12

Which of the following best describes lysogenic conversion?

Accepted Answer

A prophage alters the phenotype of its bacterial host.

Question 13

Which of the following is a real-world example of a virus causing cancer in humans?

Accepted Answer

Human papillomavirus (HPV) causing cervical cancer

Question 14

Which of the following is NOT a method by which animal viruses can enter host cells?

Accepted Answer

Tail fiber injection

Question 15

A retrovirus differs from other +ssRNA viruses because it:

Accepted Answer

Synthesizes DNA from its RNA genome using reverse transcriptase.

Question 16

Which of the following best explains why normal sterilization procedures are ineffective against prions?

Accepted Answer

Prions are composed entirely of protein and resist denaturation by heat and chemicals.

Question 17

Which of the following equations best represents the burst size in a lytic viral replication cycle?

Accepted Answer

$$	ext{Burst size} = \frac{	ext{Number of virions released}}{	ext{Number of infected cells}}$$

Question 18

Which of the following is a plausible reason why viruses are not considered alive by some scientists?

Accepted Answer

They cannot carry out metabolic pathways independently.

Question 19

A plant infected with a viroid shows stunted growth and abnormal development. What is the most likely molecular mechanism for this disease?

Accepted Answer

The viroid RNA binds to complementary plant mRNA, forming dsRNA that is degraded by plant enzymes.

Question 20

Which of the following best describes the process of viral budding in enveloped animal viruses?

Accepted Answer

The virus extrudes through the host cell membrane, acquiring an envelope in the process.

Characterizing and Classifying Viruses, Viroids, and Prions: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard