Q. What is the minimum inhibitory concentration (MIC) of a drug that inhibits 90% of a bacterial population at a concentration of 2 mg/L?
A.1 mg/L
B.2 mg/L
C.3 mg/L
D.4 mg/L
Solution
The MIC is defined as the lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation. In this case, the MIC is 2 mg/L.
Correct Answer: B — 2 mg/L
Q. What is the minimum temperature and time required for effective autoclaving?
A.121°C for 15 minutes
B.100°C for 30 minutes
C.134°C for 10 minutes
D.160°C for 1 hour
Solution
The minimum temperature and time for effective autoclaving is 121°C for 15 minutes.
Correct Answer: A — 121°C for 15 minutes
Q. What is the most effective method for sterilizing heat-sensitive medical instruments?
A.Autoclaving
B.Ethylene oxide gas
C.Boiling water
D.Hydrogen peroxide vapor
Solution
Ethylene oxide gas is commonly used for sterilizing heat-sensitive medical instruments as it effectively penetrates materials without damaging them.
Correct Answer: B — Ethylene oxide gas
Q. What is the primary advantage of using hydrogen peroxide as a disinfectant?
A.It is non-toxic to humans
B.It leaves no residue
C.It is effective against spores
D.It is inexpensive
Solution
Hydrogen peroxide is effective against spores, making it a strong disinfectant for various applications.
Correct Answer: C — It is effective against spores
Q. What is the primary advantage of using UV light for disinfection?
A.It is effective against all pathogens
B.It does not leave chemical residues
C.It is inexpensive
D.It penetrates surfaces effectively
Solution
The primary advantage of using UV light for disinfection is that it does not leave chemical residues, making it safe for use in sensitive environments.
Correct Answer: B — It does not leave chemical residues
Q. What is the primary difference between disinfection and sterilization?
A.Disinfection kills all microorganisms, sterilization does not
B.Sterilization kills all microorganisms, disinfection does not
C.Disinfection is faster than sterilization
D.Sterilization is only for surgical instruments
Solution
The primary difference is that sterilization kills all microorganisms, while disinfection reduces the number of viable organisms but may not eliminate all.
Correct Answer: B — Sterilization kills all microorganisms, disinfection does not
Q. What is the primary disadvantage of using glutaraldehyde as a disinfectant?
A.It is ineffective against viruses
B.It requires long exposure times
C.It is corrosive to metals
D.It has a strong odor
Solution
The primary disadvantage of glutaraldehyde is its strong odor, which can be unpleasant and may pose health risks to users.
Correct Answer: D — It has a strong odor
Q. What is the primary disadvantage of using glutaraldehyde for disinfection?
A.It is ineffective against viruses
B.It requires long exposure times
C.It is corrosive to metals
D.It is not environmentally friendly
Solution
Glutaraldehyde is corrosive to metals, which limits its use in certain applications.
Correct Answer: C — It is corrosive to metals
Q. What is the primary function of antibodies in the immune response?
A.To directly kill pathogens
B.To neutralize toxins
C.To enhance phagocytosis
D.To activate complement system
Solution
Antibodies enhance phagocytosis by opsonization, making it easier for phagocytes to engulf pathogens.
Correct Answer: C — To enhance phagocytosis
Q. What is the primary function of B cells in the immune response?
A.Phagocytosis of pathogens
B.Production of antibodies
C.Activation of T cells
D.Release of cytokines
Solution
B cells are primarily responsible for the production of antibodies, which are crucial for the humoral immune response.
Correct Answer: B — Production of antibodies
Q. What is the primary function of neutrophils in the immune response?
A.Antibody production
B.Phagocytosis of pathogens
C.Activation of T cells
D.Release of histamine
Solution
Neutrophils are key players in the innate immune response, primarily responsible for phagocytosing and destroying invading pathogens.
Correct Answer: B — Phagocytosis of pathogens
Q. What is the primary function of T helper cells in the immune response?
A.Directly kill infected cells
B.Activate B cells and cytotoxic T cells
C.Produce antibodies
D.Phagocytize 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: B — Activate B cells and cytotoxic T cells
Q. What is the primary function of the complement system in immunity?
A.Antibody production
B.Pathogen lysis and opsonization
C.T cell activation
D.Cytokine release
Solution
The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens from an organism, primarily through opsonization and lysis.
Correct Answer: B — Pathogen lysis and opsonization
Q. What is the primary function of the complement system in the immune response?
A.To produce antibodies
B.To enhance phagocytosis
C.To directly lyse pathogens
D.To activate T cells
Solution
The complement system enhances phagocytosis through opsonization and can directly lyse pathogens via the formation of the membrane attack complex.
Correct Answer: B — To enhance phagocytosis
Q. What is the primary immune cell type involved in the response to viral infections?
A.B cells
B.T helper cells
C.Cytotoxic T cells
D.Macrophages
Solution
Cytotoxic T cells are primarily responsible for recognizing and killing virus-infected cells.
Correct Answer: C — Cytotoxic T cells
Q. What is the primary laboratory test used to diagnose streptococcal pharyngitis?
A.Blood culture
B.Rapid antigen detection test
C.Urinalysis
D.Chest X-ray
Solution
The rapid antigen detection test is commonly used to diagnose streptococcal pharyngitis by detecting Group A Streptococcus.
Correct Answer: B — Rapid antigen detection test
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 mechanism by which vaccines provide immunity?
A.Inhibition of pathogen replication
B.Stimulation of the immune response
C.Direct destruction of pathogens
D.Blocking pathogen entry
Solution
Vaccines stimulate the immune response by introducing antigens, which prepare the immune system to recognize and fight the actual pathogen.
Correct Answer: B — Stimulation of the immune response
Q. What is the primary mechanism of action for alcohol-based disinfectants?
A.Denaturation of proteins
B.Disruption of cell membranes
C.Inhibition of nucleic acid synthesis
D.Oxidation of cellular components
Solution
Alcohol-based disinfectants primarily work by denaturing proteins, which disrupts cellular functions and leads to cell death.
Correct Answer: A — Denaturation of proteins
Q. What is the primary mechanism of action for chlorine as a disinfectant?
A.Protein denaturation
B.Nucleic acid synthesis inhibition
C.Cell wall disruption
D.Oxidation of cellular components
Solution
Chlorine acts as an oxidizing agent, damaging cellular components and leading to microbial death.
Correct Answer: D — Oxidation of cellular components
Q. What is the primary mechanism of action for chlorine-based disinfectants?
A.Protein denaturation
B.Nucleic acid synthesis inhibition
C.Cell wall disruption
D.Enzyme inhibition
Solution
Chlorine-based disinfectants primarily act by denaturing proteins, which disrupts cellular functions.
Correct Answer: A — Protein denaturation
Q. What is the primary mechanism of action for ethylene oxide in sterilization?
A.Denaturation of proteins
B.Disruption of cell membranes
C.Inhibition of nucleic acid synthesis
D.Oxidation of cellular components
Solution
Ethylene oxide primarily acts by denaturing proteins, which disrupts cellular functions and leads to microbial death.
Correct Answer: A — Denaturation of proteins
Q. What is the primary mechanism of action for glutaraldehyde as a disinfectant?
A.Oxidation of cellular components
B.Denaturation of proteins
C.Disruption of nucleic acids
D.Inhibition of cell wall synthesis
Solution
Glutaraldehyde acts primarily by denaturing proteins, which leads to the inactivation of microorganisms.
Correct Answer: B — Denaturation of proteins
Q. What is the primary mechanism of action for quaternary ammonium compounds as disinfectants?
A.Oxidation of cellular components
B.Disruption of cell membranes
C.Inhibition of protein synthesis
D.Interference with nucleic acid synthesis
Solution
Quaternary ammonium compounds primarily act by disrupting cell membranes, leading to cell lysis and death of the microorganism.
Correct Answer: B — Disruption of cell membranes
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 mode of transmission for the influenza virus?
A.Vector-borne
B.Airborne
C.Fecal-oral
D.Direct contact
Solution
The influenza virus is primarily transmitted through airborne droplets when an infected person coughs or sneezes.
Correct Answer: B — Airborne
Q. What is the primary purpose of sterilization in a clinical setting?
A.To reduce microbial load
B.To eliminate all forms of microbial life
C.To disinfect surfaces
D.To enhance immune response
Solution
Sterilization aims to eliminate all forms of microbial life, including bacteria, viruses, fungi, and spores.
Correct Answer: B — To eliminate all forms of microbial life
Q. What is the primary purpose of sterilization in microbiology?
A.To reduce microbial load
B.To eliminate all forms of microbial life
C.To inhibit microbial growth
D.To enhance microbial growth
Solution
Sterilization aims to eliminate all forms of microbial life, including bacteria, viruses, fungi, and spores.
Correct Answer: B — To eliminate all forms of microbial life
Q. What is the primary purpose of the complement system in immunity?
A.To produce antibodies
B.To enhance phagocytosis and lyse pathogens
C.To activate T cells
D.To stimulate B cells
Solution
The complement system enhances phagocytosis and can directly lyse pathogens, playing a significant role in the immune response.
Correct Answer: B — To enhance phagocytosis and lyse pathogens
Q. What is the primary purpose of using a biological indicator in sterilization processes?
A.To measure the temperature of the sterilizer
B.To confirm the presence of pathogens
C.To verify the effectiveness of the sterilization process
D.To assess the chemical composition of the sterilant
Solution
The primary purpose of using a biological indicator is to verify the effectiveness of the sterilization process by demonstrating that spores have been killed.
Correct Answer: C — To verify the effectiveness of the sterilization process