Q. In a case study, a hospital outbreak was traced back to improperly sterilized endoscopes. What is the best practice to prevent such outbreaks?
A.Use single-use instruments
B.Increase the frequency of cleaning
C.Implement strict sterilization protocols
D.Use chemical disinfectants only
Solution
Implementing strict sterilization protocols is essential to prevent outbreaks associated with reusable medical instruments.
Correct Answer: C — Implement strict sterilization protocols
Q. In a case study, a surgical instrument was found to be contaminated with Staphylococcus aureus. Which sterilization method would be most effective?
A.Boiling water
B.Ethylene oxide gas
C.Alcohol wipes
D.Ultraviolet light
Solution
Ethylene oxide gas is effective for sterilizing heat-sensitive instruments and can eliminate Staphylococcus aureus.
Correct Answer: B — Ethylene oxide gas
Q. In a clinical trial, a vaccine shows a 70% efficacy rate. If 1,000 individuals are vaccinated, how many are expected to be protected?
A.700
B.300
C.500
D.900
Solution
With 70% efficacy, 70% of 1,000 individuals would be protected, which equals 700 individuals.
Correct Answer: A — 700
Q. In a laboratory diagnosis of tuberculosis, which test is most commonly used to assess cell-mediated immunity?
A.ELISA
B.Mantoux test
C.Blood culture
D.PCR
Solution
The Mantoux test is used to assess cell-mediated immunity to Mycobacterium tuberculosis.
Correct Answer: B — Mantoux test
Q. In a laboratory setting, which method is most appropriate for sterilizing heat-sensitive liquids?
A.Autoclaving
B.Filtration
C.Incineration
D.Chemical sterilization
Solution
Filtration is the most appropriate method for sterilizing heat-sensitive liquids without altering their properties.
Correct Answer: B — Filtration
Q. In a study, 200 patients were infected with a virus. If 40% of them developed symptoms, how many patients showed symptoms?
A.80
B.60
C.40
D.20
Solution
40% of 200 patients is 0.4 * 200 = 80 patients who developed symptoms.
Correct Answer: A — 80
Q. In which scenario would you use a high-level disinfectant?
A.For cleaning floors
B.For sterilizing surgical instruments
C.For disinfecting semi-critical items like endoscopes
D.For routine hand hygiene
Solution
High-level disinfectants are used for semi-critical items that come into contact with mucous membranes, such as endoscopes, where sterilization is not feasible.
Correct Answer: C — For disinfecting semi-critical items like endoscopes
Q. What is herd immunity?
A.Immunity developed by individuals after infection
B.Immunity that protects a population when a large percentage is vaccinated
C.Immunity that occurs naturally in a population
D.Immunity that is passed from mother to child
Solution
Herd immunity occurs when a significant portion of a population is vaccinated, reducing the spread of disease.
Correct Answer: B — Immunity that protects a population when a large percentage is vaccinated
Q. What is the appropriate concentration of hydrogen peroxide for high-level disinfection?
A.3%
B.6%
C.30%
D.50%
Solution
A concentration of 30% hydrogen peroxide is appropriate for high-level disinfection.
Correct Answer: C — 30%
Q. What is the D-value for a microorganism if it takes 5 minutes to reduce the population by 90% at 121°C?
A.1 minute
B.2 minutes
C.5 minutes
D.10 minutes
Solution
The D-value is the time required to reduce the microbial population by 90%, which in this case is 5 minutes.
Correct Answer: C — 5 minutes
Q. What is the function of memory B cells?
A.To produce antibodies immediately
B.To remember past infections
C.To activate T cells
D.To phagocytize pathogens
Solution
Memory B cells are responsible for remembering past infections and can quickly produce antibodies upon re-exposure to the same pathogen.
Correct Answer: B — To remember past infections
Q. What is the function of memory cells in the immune system?
A.To produce immediate immune responses
B.To remember past infections and respond quickly upon re-exposure
C.To activate macrophages
D.To secrete cytokines
Solution
Memory cells are long-lived cells that remember past infections and enable a faster and more effective response upon re-exposure to the same pathogen.
Correct Answer: B — To remember past infections and respond quickly upon re-exposure
Q. What is the function of memory T cells?
A.Immediate response to pathogens
B.Long-term immunity
C.Production of antibodies
D.Activation of macrophages
Solution
Memory T cells provide long-term immunity by remaining in the body after an infection and responding more rapidly upon re-exposure to the same pathogen.
Correct Answer: B — Long-term immunity
Q. What is the function of the complement system in immunity?
A.To produce antibodies
B.To lyse pathogens
C.To activate T cells
D.To enhance inflammation
Solution
The complement system consists of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens, including the lysis of pathogens.
Correct Answer: B — To lyse pathogens
Q. What is the half-life of IgG antibodies in the human body?
A.1-2 days
B.5-7 days
C.21 days
D.23 days
Solution
The half-life of IgG antibodies in the human body is approximately 21 days.
Correct Answer: C — 21 days
Q. What is the main advantage of using steam sterilization over dry heat sterilization?
A.Faster sterilization time
B.Lower temperatures required
C.More effective against spores
D.All of the above
Solution
Steam sterilization has the advantages of faster sterilization time, lower temperatures required, and greater effectiveness against spores compared to dry heat sterilization.
Correct Answer: D — All of the above
Q. What is the main difference between disinfection and sterilization?
A.Disinfection kills all microbes; sterilization does not
B.Sterilization kills all microbes; disinfection reduces microbial load
C.Disinfection is used on inanimate objects; sterilization is not
D.There is no difference
Solution
Sterilization kills all microbes, while disinfection reduces the number of viable organisms but may not eliminate all.
Correct Answer: B — Sterilization kills all microbes; disinfection reduces microbial load
Q. What is the main difference between sterilization and disinfection?
A.Sterilization kills all microbes; disinfection reduces them
B.Disinfection kills all microbes; sterilization reduces them
C.Sterilization is faster than disinfection
D.Disinfection is only for surfaces, sterilization is for instruments
Solution
Sterilization kills all microbes, while disinfection reduces the number of viable microorganisms.
Correct Answer: A — Sterilization kills all microbes; disinfection reduces them
Q. What is the main function of cytotoxic T cells?
A.Produce antibodies
B.Kill infected or cancerous cells
C.Activate B cells
D.Secrete cytokines
Solution
Cytotoxic T cells are primarily responsible for killing infected or cancerous cells.
Correct Answer: B — Kill infected or cancerous cells
Q. What is the main function of phagocytes in the immune system?
A.To produce antibodies
B.To present antigens
C.To engulf and digest pathogens
D.To secrete cytokines
Solution
Phagocytes, such as macrophages and neutrophils, are specialized cells that engulf and digest pathogens, playing a key role in the innate immune response.
Correct Answer: C — To engulf and digest pathogens
Q. What is the main mode of transmission for the influenza virus?
A.Vector-borne
B.Airborne
C.Direct contact
D.Fecal-oral
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 main purpose of a booster vaccine?
A.To initiate the immune response
B.To enhance the immune memory
C.To provide immediate protection
D.To replace the primary vaccine
Solution
Booster vaccines are given to enhance and prolong the immune memory established by the primary vaccination.
Correct Answer: B — To enhance the immune memory
Q. What is the main purpose of the complement system in immunity?
A.To produce antibodies
B.To enhance inflammation and opsonization
C.To directly kill pathogens
D.To activate T cells
Solution
The complement system enhances inflammation and opsonization, aiding in the clearance of pathogens.
Correct Answer: B — To enhance inflammation and opsonization
Q. What is the main purpose of the complement system?
A.To produce antibodies
B.To enhance phagocytosis and lyse pathogens
C.To activate T cells
D.To produce cytokines
Solution
The complement system enhances phagocytosis and can directly lyse pathogens, playing a vital role in the immune response.
Correct Answer: B — To enhance phagocytosis and lyse pathogens
Q. What is the main purpose of the Gram stain in microbiology?
A.To identify viral infections
B.To differentiate bacterial species
C.To determine antibiotic susceptibility
D.To visualize fungal structures
Solution
The Gram stain is used to differentiate bacterial species based on the characteristics of their cell walls.
Correct Answer: B — To differentiate bacterial species
Q. What is the mechanism of action of the vaccine for measles, mumps, and rubella (MMR)?
A.Live attenuated virus
B.Inactivated virus
C.Subunit vaccine
D.Toxoid vaccine
Solution
The MMR vaccine is a live attenuated vaccine, which uses weakened forms of the viruses to stimulate an immune response without causing disease.
Correct Answer: A — Live attenuated virus
Q. What is the minimum effective concentration of alcohol for disinfection?
A.50%
B.70%
C.90%
D.100%
Solution
The minimum effective concentration of alcohol for disinfection is typically around 70%, as it allows for better penetration and efficacy.
Correct Answer: B — 70%
Q. What is the minimum effective concentration of bleach for disinfection?
A.0.5%
B.1%
C.5%
D.10%
Solution
A minimum effective concentration of 1% bleach is recommended for effective disinfection of surfaces.
Correct Answer: B — 1%
Q. What is the minimum effective concentration of ethanol for disinfection?
A.50%
B.70%
C.90%
D.100%
Solution
70% ethanol is the minimum effective concentration for disinfection as it allows for better penetration and denaturation of proteins.
Correct Answer: B — 70%
Q. What is the minimum effective temperature for autoclaving to ensure sterilization?
A.100°C
B.121°C
C.130°C
D.150°C
Solution
The minimum effective temperature for autoclaving to ensure sterilization is 121°C.
