Question 1

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

Accepted Answer

They can only reproduce by using the metabolic machinery of a host cell.

Question 2

A scientist discovers a new infectious agent that contains only RNA, lacks a protein coat, and infects plants. Based on these characteristics, how should this agent be classified?

Accepted Answer

Viroid

Question 3

Which of the following statements about viral host specificity is correct?

Accepted Answer

Viral surface proteins must have an affinity for complementary proteins on the host cell surface.

Question 4

A virus with a capsid but no envelope is described as:

Accepted Answer

Naked

Question 5

Which of the following best describes the genetic material found in viruses?

Accepted Answer

It can be either DNA or RNA, single-stranded or double-stranded, and may be linear or circular.

Question 6

During the lytic replication cycle of a bacteriophage, what is the primary cause of host cell death?

Accepted Answer

Lysis of the cell due to the release of newly assembled virions.

Question 7

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, while bacteriophages typically inject their genome.

Question 8

A virus with a (+)ssRNA genome infects an animal cell. Which of the following statements about its replication is correct?

Accepted Answer

The viral RNA can act directly as mRNA for protein synthesis.

Question 9

Which of the following best explains why enveloped viruses are generally more fragile than naked viruses?

Accepted Answer

Their phospholipid envelope is sensitive to desiccation, heat, and detergents.

Question 10

A patient is infected with a virus that integrates its genome into the host cell's DNA and remains dormant for several generations before becoming active. This type of viral replication is known as:

Accepted Answer

Lysogenic cycle

Question 11

Which of the following is NOT a property that distinguishes viruses from living cells?

Accepted Answer

Ability to carry out metabolic pathways independently

Question 12

A researcher is studying a virus with a helical capsid and a phospholipid envelope. Which of the following statements is most likely true about this virus?

Accepted Answer

It acquires its envelope from the host cell membrane during replication or release.

Question 13

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

Accepted Answer

They mediate attachment to specific host cell receptors.

Question 14

A virus is found to have a genome size of 30,000 nucleotides. Compared to a typical bacterial genome, this viral genome is:

Accepted Answer

Much smaller

Question 15

Which of the following steps is unique to the replication of animal viruses compared to bacteriophages?

Accepted Answer

Uncoating of the capsid after entry into the host cell

Question 16

A virus infects a host cell and uses the following process: its single-stranded DNA genome folds back on itself to form double-stranded DNA, which is then replicated by host enzymes. Which type of virus is this?

Accepted Answer

ssDNA virus

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

A virus is described as having an icosahedral capsid. What does this mean about its structure?

Accepted Answer

It has a capsid with 20 triangular faces.

Question 19

Which of the following is a correct statement about the size of viruses compared to other biological structures?

Accepted Answer

Most viruses are smaller than bacterial cells and red blood cells.

Question 20

A patient is diagnosed with a disease caused by a prion. Which of the following best describes a prion?

Accepted Answer

An infectious protein that lacks nucleic acids

Characterizing and Classifying Viruses, Viroids, and Prions

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