Question 1

Which of the following best describes the difference between a bacterium and a virus, as shown in the Venn diagram?

Accepted Answer

Bacteria are unicellular organisms with a cell wall and cytoplasm, while viruses are acellular agents with either DNA or RNA and lack cytoplasm.

Question 2

In the image of a bacterial lawn with clear plaques, what do the plaques represent?

Accepted Answer

Zones of bacterial lysis caused by viral infection (bacteriophage activity).

Question 3

Which step in the lytic replication cycle of a bacteriophage involves the assembly of new viral particles?

Accepted Answer

Assembly

Question 4

During lysogeny, what is the term for viral DNA that is integrated into the bacterial chromosome?

Accepted Answer

Prophage

Question 5

Which of the following is a unique feature of retroviruses such as HIV?

Accepted Answer

They use reverse transcriptase to synthesize DNA from an RNA template.

Question 6

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

Accepted Answer

Their envelope is easily disrupted by environmental factors, leading to loss of infectivity.

Question 7

Which of the following is a result of lysogenic conversion in bacteria?

Accepted Answer

The bacterium gains new properties, such as toxin production, due to the presence of prophage genes.

Question 8

Which process is illustrated by the following equation: $$	ext{Antigen} + 	ext{Antibody} ightarrow 	ext{Antigen-Antibody Complex}$$?

Accepted Answer

Specific immune response (humoral immunity)

Question 9

Which of the following is a function of the complement protein C3b?

Accepted Answer

Acts as an opsonin to enhance phagocytosis.

Question 10

Which of the following best describes the role of interferon alpha and beta in viral infections?

Accepted Answer

They trigger uninfected neighboring cells to produce antiviral proteins (AVPs).

Question 11

Which of the following is a correct statement about prions?

Accepted Answer

Prions are infectious proteins that replicate by converting normal cellular PrP into the prion form.

Question 12

Which of the following is a characteristic of exotoxins?

Accepted Answer

They are proteins secreted by bacteria that can be highly specific and lethal.

Question 13

A patient develops a secondary infection after a primary viral infection damages respiratory cells. Which term best describes the causative agent of the secondary infection?

Accepted Answer

Opportunistic pathogen

Question 14

Which of the following is NOT a function of normal microbiota?

Accepted Answer

Causing disease in healthy individuals under all circumstances

Question 15

Which of the following best describes the process of agglutination?

Accepted Answer

Antibodies bind to antigens and clump them together, enhancing phagocytosis.

Question 16

Which of the following is a correct pairing of antibody class and function?

Accepted Answer

IgM – first antibody produced during primary response

Question 17

Which of the following is a result of the activation of the classical complement pathway?

Accepted Answer

Activation by antibody-antigen complexes

Question 18

Which of the following is a correct description of the role of helper T cells (TH) in the immune response?

Accepted Answer

They activate B cells and cytotoxic T cells by secreting cytokines such as IL-2 and IL-4.

Question 19

Which of the following best explains why a person who has recovered from chickenpox is usually immune to future infections with the same virus?

Accepted Answer

Memory B and T cells are produced, leading to a faster and more effective secondary immune response.

Question 20

Which of the following is a correct statement about the difference between the primary and secondary immune response?

Accepted Answer

The secondary response is faster and produces more IgG than the primary response.

Comprehensive Study Notes: Viruses, Infectious Disease, and Immunity

Study Guide - Practice Questions

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