Microorganisms and Disease - Higher Difficulty Problems
Q. What is the primary mechanism by which the influenza virus evades the immune system?
A.Antigenic drift
B.Phagocytosis
C.Complement activation
D.Lysis of host cells
Solution
Antigenic drift refers to the gradual mutation of viral antigens, allowing the influenza virus to evade the host's immune response.
Correct Answer: A — Antigenic drift
Q. What is the primary mode of transmission for the hepatitis B virus?
A.Airborne
B.Fecal-oral
C.Bloodborne
D.Vector-borne
Solution
Hepatitis B virus is primarily transmitted through blood and bodily fluids, making it a bloodborne pathogen.
Correct Answer: C — Bloodborne
Q. What is the primary role of T helper cells in the immune response?
A.Directly kill infected cells
B.Produce antibodies
C.Activate B cells and cytotoxic T cells
D.Phagocytose pathogens
Solution
T helper cells play a crucial role in the immune response by activating B cells to produce antibodies and cytotoxic T cells to kill infected cells.
Correct Answer: C — Activate B cells and cytotoxic T cells
Q. Which laboratory test is most commonly used to diagnose streptococcal pharyngitis?
A.Blood culture
B.Rapid antigen detection test
C.PCR assay
D.Complete blood count
Solution
The rapid antigen detection test is commonly used to quickly diagnose streptococcal pharyngitis by detecting Group A Streptococcus antigens.
Correct Answer: B — Rapid antigen detection test
Q. Which of the following is a characteristic feature of Gram-negative bacteria?
A.Thick peptidoglycan layer
B.Outer membrane containing lipopolysaccharides
C.Staining purple in Gram stain
D.Sensitive to penicillin
Solution
Gram-negative bacteria have an outer membrane that contains lipopolysaccharides, which is a key characteristic distinguishing them from Gram-positive bacteria.
Correct Answer: B — Outer membrane containing lipopolysaccharides
Q. Which pathogen is known for causing a severe form of gastroenteritis, particularly in children?
A.Norovirus
B.Clostridium difficile
C.Salmonella enterica
D.Escherichia coli O157:H7
Solution
Norovirus is a leading cause of gastroenteritis outbreaks, especially in children, due to its high transmissibility and low infectious dose.
Correct Answer: A — Norovirus
Q. Which type of vaccine is composed of live attenuated pathogens?
A.Inactivated vaccine
B.Subunit vaccine
C.Recombinant vaccine
D.Live attenuated vaccine
Solution
Live attenuated vaccines contain live pathogens that have been weakened so they cannot cause disease but still elicit a strong immune response.
