Q: Which of the following equations best represents the burst size in a lytic cycle, given the number of virions released ($$N_{virions}) $$and the number of infected cells ($$N_{cells}$$)?

$$\text{Burst size} = \frac{N_{virions}}{N_{cells}}$$

Question 1

Which of the following statements best describes the extracellular state of a virus?

Accepted Answer

The viral genome is surrounded by a protein coat called a capsid, forming a virion.

Question 2

A virus is classified based on its genetic material. Which of the following is NOT a possible viral genome configuration?

Accepted Answer

Both DNA and RNA present simultaneously

Question 3

What is the primary function of the viral capsid?

Accepted Answer

To provide protection for the viral nucleic acid and facilitate attachment to host cells.

Question 4

Which of the following best explains why most viruses infect only particular host cells?

Accepted Answer

Affinity of viral surface proteins for complementary proteins on the host cell surface.

Question 5

During the lytic replication cycle, what is the correct sequence of events?

Accepted Answer

Attachment → Entry → Synthesis → Assembly → Release

Question 6

A bacteriophage infects a bacterial cell and integrates its genome into the host chromosome, remaining dormant for several generations. This process is known as:

Accepted Answer

Lysogeny

Question 7

Which of the following equations best represents the burst size in a lytic cycle, given the number of virions released ($$N_{virions}) $$and the number of infected cells ($$N_{cells}$$)?

Accepted Answer

$$	ext{Burst size} = \frac{N_{virions}}{N_{cells}}$$

Question 8

Which of the following is a characteristic unique to enveloped viruses compared to naked viruses?

Accepted Answer

They acquire a phospholipid bilayer from the host cell during replication or release.

Question 9

Which mechanism is NOT used by animal viruses to enter host cells?

Accepted Answer

Tail fiber injection

Question 10

A virus that causes persistent infection in animal cells is most likely:

Accepted Answer

An enveloped virus released by budding

Question 11

Which of the following best describes the role of viruses in cancer development?

Accepted Answer

Viruses can carry oncogenes, promote host oncogenes, or interfere with tumor repression, leading to uncontrolled cell division.

Question 12

Which of the following is a correct statement about viroids?

Accepted Answer

Viroids are small, circular pieces of RNA that lack a capsid and are pathogenic in plants.

Question 13

Prion diseases are characterized by which of the following?

Accepted Answer

Fatal neurological degeneration, fibril deposits in the brain, and spongiform encephalopathies.

Question 14

Which method is commonly used to culture viruses in the laboratory and is free of contaminating microbes?

Accepted Answer

Embryonated chicken eggs

Question 15

Which of the following statements about prion proteins (PrP) is correct?

Accepted Answer

Prion PrP induces conformational change in cellular PrP, converting it to the disease-causing form.

Question 16

Which of the following equations best represents the relationship between viral genome size ($$S_{virus}) $$and cellular genome size ($$S_{cell}$$), given that viral genomes are much smaller?

Accepted Answer

$$S_{virus} \ll S_{cell}$$

Question 17

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

Accepted Answer

Viruses cannot carry out any metabolic pathway independently.

Question 18

Which of the following is a correct statement about the replication of animal viruses?

Accepted Answer

DNA viruses often enter the nucleus, while RNA viruses often replicate in the cytoplasm.

Question 19

Which of the following is a correct description of lysogenic conversion?

Accepted Answer

Phages carry genes that alter the phenotype of a bacterium during lysogeny.

Question 20

Which of the following is a correct statement about viral plaques in a bacterial lawn?

Accepted Answer

Viral plaques are clear zones where viruses have lysed bacterial cells.

Study Notes: Chapter 13

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