Microbiology & Immunology: 2026 Viral
Pathogens
Replication, Host Defense & Diagnostic Frontiers (100 Questions)
1. What is the fundamental structure of a virus?
A) A cell nucleus surrounded by a cell wall
B) Genetic material (DNA or RNA) enclosed in a protein coat (capsid), sometimes surrounded
by an envelope
C) A complex network of organelles and mitochondria
D) A single-stranded DNA molecule without a protein coat
Correct Answer: B) Genetic material (DNA or RNA) enclosed in a protein coat (capsid),
sometimes surrounded by an envelope
2. What is the "Lytic Cycle" of a bacteriophage?
A) The virus integrates its DNA into the host genome and remains dormant
B) The virus replicates within the host cell, destroys the cell, and releases new viral particles
C) The virus converts the host cell into a fungus
D) The virus remains on the surface of the host cell without entering
Correct Answer: B) The virus replicates within the host cell, destroys the cell, and
releases new viral particles
3. What is the "Lysogenic Cycle"?
A) Rapid destruction of the host cell
B) Viral DNA integrates into the host genome and replicates without destroying the host cell
C) Immediate release of viral particles
D) A process of cell repair after viral infection
Correct Answer: B) Viral DNA integrates into the host genome and replicates without
destroying the host cell
4. What is the role of "Reverse Transcriptase" in retroviruses (like HIV)?
A) It synthesizes RNA from a DNA template
B) It synthesizes DNA from an RNA template
C) It cuts viral proteins into functional units
D) It binds to the host cell membrane to initiate entry
Correct Answer: B) It synthesizes DNA from an RNA template
5. What is "Antigenic Drift" in the context of Influenza?
,A) A sudden, massive change in the viral genome
B) Minor mutations in viral surface proteins (HA and NA) that allow the virus to evade the host's
existing immunity
C) The total replacement of the viral RNA genome
D) The process of viral cell death
Correct Answer: B) Minor mutations in viral surface proteins that allow the virus to evade
existing immunity
6. What is "Antigenic Shift"?
A) Small, gradual mutations
B) A major genetic change resulting from the reassortment of genes between different viral
strains (e.g., in Influenza)
C) The process of vaccine development
D) The movement of viruses across continents
Correct Answer: B) A major genetic change resulting from the reassortment of genes
between different viral strains
7. Which type of immunity is triggered immediately by physical barriers and non-specific
white blood cells (e.g., neutrophils)?
A) Adaptive immunity
B) Innate immunity
C) Cell-mediated immunity
D) Humoral immunity
Correct Answer: B) Innate immunity
8. "Humoral Immunity" is primarily mediated by:
A) T-cells
B) B-cells and the production of antibodies
C) Macrophages
D) Dendritic cells
Correct Answer: B) B-cells and the production of antibodies
9. What do "Cytotoxic T-cells" (CD8+) primarily do?
A) Produce antibodies
B) Recognize and destroy infected or cancerous host cells
C) Block viral receptors
D) Ingest viral particles via phagocytosis
Correct Answer: B) Recognize and destroy infected or cancerous host cells
, 10. What are "Memory B-cells"?
A) Cells that trigger the initial inflammatory response
B) Cells that persist after an infection to provide long-term immunity upon re-exposure to the
pathogen
C) Cells that produce viral proteins for research
D) Cells that rapidly degrade during the infection
Correct Answer: B) Cells that persist after an infection to provide long-term immunity
upon re-exposure to the pathogen
11. "PRRs" (Pattern Recognition Receptors) on host cells recognize:
A) Human DNA
B) PAMPs (Pathogen-Associated Molecular Patterns) on viruses and other microbes
C) Host cell proteins
D) Mitochondrial DNA exclusively
Correct Answer: B) PAMPs (Pathogen-Associated Molecular Patterns) on viruses and
other microbes
12. What is the function of "Interferons" in a viral infection?
A) They directly kill viruses
B) They signal neighboring cells to increase antiviral defenses and inhibit viral replication
C) They digest the virus once it enters the cell
D) They suppress the immune system to prevent damage
Correct Answer: B) They signal neighboring cells to increase antiviral defenses and
inhibit viral replication
13. "MHC Class I" molecules are found on:
A) Only white blood cells
B) All nucleated cells in the body
C) Only red blood cells
D) Only macrophages
Correct Answer: B) All nucleated cells in the body
14. What is the role of the "MHC Class I" molecule?
A) To present antigens to Helper T-cells
B) To present internal proteins (or viral peptides) to Cytotoxic T-cells for surveillance
C) To stimulate B-cell proliferation
D) To bind to antibodies directly
Correct Answer: B) To present internal proteins (or viral peptides) to Cytotoxic T-cells for
surveillance
15. "Viral Tropism" refers to:
A) The speed at which a virus replicates
B) The ability of a virus to infect specific cell types, tissues, or host species
Pathogens
Replication, Host Defense & Diagnostic Frontiers (100 Questions)
1. What is the fundamental structure of a virus?
A) A cell nucleus surrounded by a cell wall
B) Genetic material (DNA or RNA) enclosed in a protein coat (capsid), sometimes surrounded
by an envelope
C) A complex network of organelles and mitochondria
D) A single-stranded DNA molecule without a protein coat
Correct Answer: B) Genetic material (DNA or RNA) enclosed in a protein coat (capsid),
sometimes surrounded by an envelope
2. What is the "Lytic Cycle" of a bacteriophage?
A) The virus integrates its DNA into the host genome and remains dormant
B) The virus replicates within the host cell, destroys the cell, and releases new viral particles
C) The virus converts the host cell into a fungus
D) The virus remains on the surface of the host cell without entering
Correct Answer: B) The virus replicates within the host cell, destroys the cell, and
releases new viral particles
3. What is the "Lysogenic Cycle"?
A) Rapid destruction of the host cell
B) Viral DNA integrates into the host genome and replicates without destroying the host cell
C) Immediate release of viral particles
D) A process of cell repair after viral infection
Correct Answer: B) Viral DNA integrates into the host genome and replicates without
destroying the host cell
4. What is the role of "Reverse Transcriptase" in retroviruses (like HIV)?
A) It synthesizes RNA from a DNA template
B) It synthesizes DNA from an RNA template
C) It cuts viral proteins into functional units
D) It binds to the host cell membrane to initiate entry
Correct Answer: B) It synthesizes DNA from an RNA template
5. What is "Antigenic Drift" in the context of Influenza?
,A) A sudden, massive change in the viral genome
B) Minor mutations in viral surface proteins (HA and NA) that allow the virus to evade the host's
existing immunity
C) The total replacement of the viral RNA genome
D) The process of viral cell death
Correct Answer: B) Minor mutations in viral surface proteins that allow the virus to evade
existing immunity
6. What is "Antigenic Shift"?
A) Small, gradual mutations
B) A major genetic change resulting from the reassortment of genes between different viral
strains (e.g., in Influenza)
C) The process of vaccine development
D) The movement of viruses across continents
Correct Answer: B) A major genetic change resulting from the reassortment of genes
between different viral strains
7. Which type of immunity is triggered immediately by physical barriers and non-specific
white blood cells (e.g., neutrophils)?
A) Adaptive immunity
B) Innate immunity
C) Cell-mediated immunity
D) Humoral immunity
Correct Answer: B) Innate immunity
8. "Humoral Immunity" is primarily mediated by:
A) T-cells
B) B-cells and the production of antibodies
C) Macrophages
D) Dendritic cells
Correct Answer: B) B-cells and the production of antibodies
9. What do "Cytotoxic T-cells" (CD8+) primarily do?
A) Produce antibodies
B) Recognize and destroy infected or cancerous host cells
C) Block viral receptors
D) Ingest viral particles via phagocytosis
Correct Answer: B) Recognize and destroy infected or cancerous host cells
, 10. What are "Memory B-cells"?
A) Cells that trigger the initial inflammatory response
B) Cells that persist after an infection to provide long-term immunity upon re-exposure to the
pathogen
C) Cells that produce viral proteins for research
D) Cells that rapidly degrade during the infection
Correct Answer: B) Cells that persist after an infection to provide long-term immunity
upon re-exposure to the pathogen
11. "PRRs" (Pattern Recognition Receptors) on host cells recognize:
A) Human DNA
B) PAMPs (Pathogen-Associated Molecular Patterns) on viruses and other microbes
C) Host cell proteins
D) Mitochondrial DNA exclusively
Correct Answer: B) PAMPs (Pathogen-Associated Molecular Patterns) on viruses and
other microbes
12. What is the function of "Interferons" in a viral infection?
A) They directly kill viruses
B) They signal neighboring cells to increase antiviral defenses and inhibit viral replication
C) They digest the virus once it enters the cell
D) They suppress the immune system to prevent damage
Correct Answer: B) They signal neighboring cells to increase antiviral defenses and
inhibit viral replication
13. "MHC Class I" molecules are found on:
A) Only white blood cells
B) All nucleated cells in the body
C) Only red blood cells
D) Only macrophages
Correct Answer: B) All nucleated cells in the body
14. What is the role of the "MHC Class I" molecule?
A) To present antigens to Helper T-cells
B) To present internal proteins (or viral peptides) to Cytotoxic T-cells for surveillance
C) To stimulate B-cell proliferation
D) To bind to antibodies directly
Correct Answer: B) To present internal proteins (or viral peptides) to Cytotoxic T-cells for
surveillance
15. "Viral Tropism" refers to:
A) The speed at which a virus replicates
B) The ability of a virus to infect specific cell types, tissues, or host species
