QLS 2026 STUDY GUIDE Qualification
Laboratory Safety Practice Questions with
Answer Explanations Biosafety • Chemical Safety
• Risk Management • Compliance • Laboratory
Operations • Exam Preparation
SECTION 1: BIOLOGICAL SAFETY (Questions 1–30)
Question 1. According to the CDC/NIH Biosafety in Microbiological and
Biomedical Laboratories (BMBL) manual, which biosafety level is appropriate for
working with Mycobacterium tuberculosis?
A) BSL-1
B) BSL-2
C) BSL-3
D) BSL-4
E) BSL-2 with enhanced precautions
Rationale: Mycobacterium tuberculosis requires BSL-3 containment because it is
transmitted via the airborne route and can cause serious disease. BSL-3
laboratories have controlled access, directional airflow, and respiratory protection
requirements. BSL-2 is for moderate-risk agents, and BSL-4 is for
dangerous/exotic agents that pose a high individual and community risk.
Question 2. Which of the following is a PRIMARY containment barrier in a
microbiology laboratory?
A) Biological safety cabinet (BSC)
B) Laboratory door
C) Eyewash station
D) Fume hood
E) Fire extinguisher
,Rationale: Primary containment barriers protect personnel and the immediate
laboratory environment from exposure to infectious agents. The biological safety
cabinet (BSC) is the primary containment device that uses HEPA filtration and
directional airflow to protect the operator and environment. Secondary
containment includes laboratory design features (e.g., doors, walls, ventilation).
Question 3. What is the primary function of a Class II biological safety cabinet?
A) To protect the environment only
B) To protect the product only
C) To protect the operator, the environment, and the product
D) To protect the operator only
E) To protect against chemical vapors only
Rationale: Class II biological safety cabinets provide protection for the operator,
the environment, and the product (sample). They use HEPA-filtered downward
airflow and inward airflow to create an air barrier. Class I BSCs protect personnel
and environment but not the product. Class III BSCs are gas-tight and provide
maximum protection.
Question 4. Which of the following is TRUE regarding the use of a biological
safety cabinet?
A) The BSC should be certified annually and after any major repair or
relocation
B) The BSC does not require certification
C) The BSC should be used with the sash fully open
D) The BSC should be turned off when not in use
E) The BSC can be used for chemical vapors without ventilation
Rationale: Biological safety cabinets should be certified annually by a qualified
technician and after any major repair, relocation, or filter change. The sash should
be at the correct operating height (typically 8–10 inches). The BSC should be left
running (or turned on before use) to maintain airflow. Chemical vapors should not
be used in a BSC unless it is connected to an exhaust system.
,Question 5. What is the recommended method for decontaminating a biological
safety cabinet after use?
A) Wipe all surfaces with 70% ethanol or an appropriate disinfectant
B) Rinse with water only
C) Use bleach without rinsing
D) Leave the BSC untreated
E) Use a dry cloth only
Rationale: After use, all surfaces of the BSC should be wiped with 70% ethanol or
an appropriate disinfectant. Bleach can be corrosive to stainless steel and should be
rinsed with water if used. The BSC should be left running to maintain airflow.
Proper decontamination prevents cross-contamination and protects personnel.
Question 6. Which of the following is a requirement for a BSL-2 laboratory?
A) Limited access to the laboratory and use of a biological safety cabinet for
aerosol-generating procedures
B) Controlled access with directional airflow
C) Positive pressure airflow
D) Sealed centrifuge cups
E) Full-body positive pressure suits
Rationale: BSL-2 requirements include limited access to the laboratory, use of a
biological safety cabinet for procedures that may generate aerosols, appropriate
PPE, and biohazard signage. Controlled access with directional airflow is a BSL-3
requirement. Positive pressure airflow is not a BSL-2 requirement. Sealed
centrifuge cups and positive pressure suits are used in BSL-3 and BSL-4
laboratories.
Question 7. What is the recommended method for handling a spill of infectious
material in a centrifuge?
A) Open the centrifuge immediately
B) Wait 30 minutes before opening the centrifuge to allow aerosols to settle
C) Use a broom to clean the spill
D) Ignore the spill
E) Use a vacuum cleaner
, Rationale: If a spill occurs in a centrifuge, the centrifuge should be left closed for
30 minutes to allow aerosols to settle. Then, appropriate PPE should be worn, and
the spill should be cleaned with disinfectant. Opening the centrifuge immediately
can release infectious aerosols. Brooms and vacuum cleaners can aerosolize
infectious material.
Question 8. Which of the following is the correct procedure for disposing of
contaminated sharps?
A) Recap the needle and place it in the regular trash
B) Place the needle directly into a sharps container without recapping
C) Break the needle off and place it in the regular trash
D) Place the needle in a biohazard bag
E) Leave the needle on the tray
Rationale: Contaminated sharps should be placed directly into a sharps container
without recapping, breaking, or bending. Recapping, breaking, or placing sharps in
regular trash or biohazard bags increases the risk of needlestick injuries. Sharps
containers should be replaced when they are three-quarters full.
Question 9. What is the FIRST action after a needlestick injury?
A) Report the injury at the end of the shift
B) Wash the wound with soap and water immediately
C) Ignore the injury if it is minor
D) Cover the wound with a bandage
E) Continue working
Rationale: The first action after a needlestick injury is to wash the wound with
soap and water immediately. This should be followed by reporting the injury to the
supervisor, seeking medical evaluation, and completing incident reports. Ignoring
the injury or delaying reporting can have serious consequences.
Question 10. Which of the following is a recommended immunization for
laboratory personnel?
Laboratory Safety Practice Questions with
Answer Explanations Biosafety • Chemical Safety
• Risk Management • Compliance • Laboratory
Operations • Exam Preparation
SECTION 1: BIOLOGICAL SAFETY (Questions 1–30)
Question 1. According to the CDC/NIH Biosafety in Microbiological and
Biomedical Laboratories (BMBL) manual, which biosafety level is appropriate for
working with Mycobacterium tuberculosis?
A) BSL-1
B) BSL-2
C) BSL-3
D) BSL-4
E) BSL-2 with enhanced precautions
Rationale: Mycobacterium tuberculosis requires BSL-3 containment because it is
transmitted via the airborne route and can cause serious disease. BSL-3
laboratories have controlled access, directional airflow, and respiratory protection
requirements. BSL-2 is for moderate-risk agents, and BSL-4 is for
dangerous/exotic agents that pose a high individual and community risk.
Question 2. Which of the following is a PRIMARY containment barrier in a
microbiology laboratory?
A) Biological safety cabinet (BSC)
B) Laboratory door
C) Eyewash station
D) Fume hood
E) Fire extinguisher
,Rationale: Primary containment barriers protect personnel and the immediate
laboratory environment from exposure to infectious agents. The biological safety
cabinet (BSC) is the primary containment device that uses HEPA filtration and
directional airflow to protect the operator and environment. Secondary
containment includes laboratory design features (e.g., doors, walls, ventilation).
Question 3. What is the primary function of a Class II biological safety cabinet?
A) To protect the environment only
B) To protect the product only
C) To protect the operator, the environment, and the product
D) To protect the operator only
E) To protect against chemical vapors only
Rationale: Class II biological safety cabinets provide protection for the operator,
the environment, and the product (sample). They use HEPA-filtered downward
airflow and inward airflow to create an air barrier. Class I BSCs protect personnel
and environment but not the product. Class III BSCs are gas-tight and provide
maximum protection.
Question 4. Which of the following is TRUE regarding the use of a biological
safety cabinet?
A) The BSC should be certified annually and after any major repair or
relocation
B) The BSC does not require certification
C) The BSC should be used with the sash fully open
D) The BSC should be turned off when not in use
E) The BSC can be used for chemical vapors without ventilation
Rationale: Biological safety cabinets should be certified annually by a qualified
technician and after any major repair, relocation, or filter change. The sash should
be at the correct operating height (typically 8–10 inches). The BSC should be left
running (or turned on before use) to maintain airflow. Chemical vapors should not
be used in a BSC unless it is connected to an exhaust system.
,Question 5. What is the recommended method for decontaminating a biological
safety cabinet after use?
A) Wipe all surfaces with 70% ethanol or an appropriate disinfectant
B) Rinse with water only
C) Use bleach without rinsing
D) Leave the BSC untreated
E) Use a dry cloth only
Rationale: After use, all surfaces of the BSC should be wiped with 70% ethanol or
an appropriate disinfectant. Bleach can be corrosive to stainless steel and should be
rinsed with water if used. The BSC should be left running to maintain airflow.
Proper decontamination prevents cross-contamination and protects personnel.
Question 6. Which of the following is a requirement for a BSL-2 laboratory?
A) Limited access to the laboratory and use of a biological safety cabinet for
aerosol-generating procedures
B) Controlled access with directional airflow
C) Positive pressure airflow
D) Sealed centrifuge cups
E) Full-body positive pressure suits
Rationale: BSL-2 requirements include limited access to the laboratory, use of a
biological safety cabinet for procedures that may generate aerosols, appropriate
PPE, and biohazard signage. Controlled access with directional airflow is a BSL-3
requirement. Positive pressure airflow is not a BSL-2 requirement. Sealed
centrifuge cups and positive pressure suits are used in BSL-3 and BSL-4
laboratories.
Question 7. What is the recommended method for handling a spill of infectious
material in a centrifuge?
A) Open the centrifuge immediately
B) Wait 30 minutes before opening the centrifuge to allow aerosols to settle
C) Use a broom to clean the spill
D) Ignore the spill
E) Use a vacuum cleaner
, Rationale: If a spill occurs in a centrifuge, the centrifuge should be left closed for
30 minutes to allow aerosols to settle. Then, appropriate PPE should be worn, and
the spill should be cleaned with disinfectant. Opening the centrifuge immediately
can release infectious aerosols. Brooms and vacuum cleaners can aerosolize
infectious material.
Question 8. Which of the following is the correct procedure for disposing of
contaminated sharps?
A) Recap the needle and place it in the regular trash
B) Place the needle directly into a sharps container without recapping
C) Break the needle off and place it in the regular trash
D) Place the needle in a biohazard bag
E) Leave the needle on the tray
Rationale: Contaminated sharps should be placed directly into a sharps container
without recapping, breaking, or bending. Recapping, breaking, or placing sharps in
regular trash or biohazard bags increases the risk of needlestick injuries. Sharps
containers should be replaced when they are three-quarters full.
Question 9. What is the FIRST action after a needlestick injury?
A) Report the injury at the end of the shift
B) Wash the wound with soap and water immediately
C) Ignore the injury if it is minor
D) Cover the wound with a bandage
E) Continue working
Rationale: The first action after a needlestick injury is to wash the wound with
soap and water immediately. This should be followed by reporting the injury to the
supervisor, seeking medical evaluation, and completing incident reports. Ignoring
the injury or delaying reporting can have serious consequences.
Question 10. Which of the following is a recommended immunization for
laboratory personnel?
