A technologist is subculturing positive blood culture broths in a Class II A2 biological safety cabinet, wearing a gown and gloves. Several open plates and tubes are on the work surface. A tube holding about 10 mL of broth that grew gram-positive cocci in clusters falls over. The broth spreads across the work surface, and some runs through the front grille into the drain pan below. Her gloves are splashed, but her gown and skin are not, and the cabinet's airflow alarm has not sounded. The most appropriate response is to:

Keep the cabinet running and disinfect it, including the drain pan

Switch the cabinet off and leave the room for 30 minutes

Close the sash and run the UV lamp before any cleaning

Wipe the surface with alcohol and carry on working

A tube breaks while spinning in a centrifuge that has no sealed buckets. After switching off the motor, what should the technologist do first?

Leave the lid closed for about 30 minutes

Open the lid at once and spray 70% alcohol

Open the lid and pick out the glass with gloves

Restart the run to finish separating the samples

Which feature is required in a BSL-3 laboratory but not in a BSL-2 laboratory?

Sustained inward airflow, exhausted without recirculation

A handwashing sink near the laboratory exit

Biohazard signs posted at the laboratory entrance

An eyewash station available in the laboratory

A Class I biological safety cabinet protects:

The worker and environment, but not the sample

The worker, the environment and the sample

The sample, but not the worker or environment

Only the environment, through its HEPA exhaust

Under standard precautions, a face shield, or a mask with eye protection, is needed when:

Splashes or sprays of body fluid are likely

The patient is known to have HIV

Work is done inside a Class II cabinet

Any patient specimen is handled

Biosafety levels, biosafety cabinets and PPE

10 DOH Abu Dhabi (HAAD) lab licensing practice questions on Biosafety levels, biosafety cabinets and PPE, part of General Laboratory, Quality and Safety. The first 10 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
A technologist is subculturing positive blood culture broths in a Class II A2 biological safety cabinet, wearing a gown and gloves. Several open plates and tubes are on the work surface. A tube holding about 10 mL of broth that grew gram-positive cocci in clusters falls over. The broth spreads across the work surface, and some runs through the front grille into the drain pan below. Her gloves are splashed, but her gown and skin are not, and the cabinet's airflow alarm has not sounded. The most appropriate response is to:
1. ASwitch the cabinet off and leave the room for 30 minutes
2. BClose the sash and run the UV lamp before any cleaning
3. CKeep the cabinet running and disinfect it, including the drain pan
4. DWipe the surface with alcohol and carry on working
Show answerHide answer
Answer: C · Keep the cabinet running and disinfect it, including the drain pan
A spill inside a working cabinet is already contained: the inflow and downflow keep aerosols away from the operator, so the cabinet is left running. She closes the open plates and tubes, changes gloves, covers the spill with absorbent material soaked in a suitable disinfectant, leaves it for the stated contact time, and wipes the work surface, walls and items inside. Because broth ran through the grille, the drain pan is also flooded with disinfectant, left for the contact time and drained before the surface is wiped again. The cabinet then runs for several minutes before work restarts.
- A: Switching the cabinet off stops the airflow that keeps aerosols inside; leaving the room is for spills outside a cabinet.
- B: UV light does not disinfect liquid spills or shaded areas such as the drain pan.
- D: Alcohol alone is poor on a large protein-rich spill, and the drain pan would stay contaminated.
Question 2 · Medium
A tube breaks while spinning in a centrifuge that has no sealed buckets. After switching off the motor, what should the technologist do first?
1. ALeave the lid closed for about 30 minutes
2. BOpen the lid at once and spray 70% alcohol
3. COpen the lid and pick out the glass with gloves
4. DRestart the run to finish separating the samples
Show answerHide answer
Answer: A · Leave the lid closed for about 30 minutes
Breakage during centrifugation creates aerosols, so the lid is kept closed for about 30 minutes to let them settle, as the WHO biosafety manual advises. The technologist then wears gloves, removes broken glass with forceps, and disinfects the buckets, rotor and bowl with a suitable non-corrosive disinfectant. If sealed safety cups are used, they are opened inside a biological safety cabinet instead. Broken glass is never picked up by hand, even with gloves.
- B: Opening at once releases the aerosol into the technologist's face.
- C: Broken glass is removed with forceps, never by hand, and only after the aerosol settles.
- D: Restarting spreads the broken glass and aerosol further.
Question 3 · Medium
Which feature is required in a BSL-3 laboratory but not in a BSL-2 laboratory?
1. AA handwashing sink near the laboratory exit
2. BBiohazard signs posted at the laboratory entrance
3. CSustained inward airflow, exhausted without recirculation
4. DAn eyewash station available in the laboratory
Show answerHide answer
Answer: C · Sustained inward airflow, exhausted without recirculation
BSL-3 laboratories handle agents that can cause serious disease by inhalation, such as Mycobacterium tuberculosis and Brucella. Their ventilation draws air from clean areas into the laboratory, and the exhaust is not recirculated to other areas; entry is through two self-closing doors, often with an anteroom. Handwashing sinks, eyewash stations and biohazard signs are already required at BSL-2. These requirements follow the CDC/NIH BMBL; the WHO manual applies equivalent heightened controls through risk assessment.
- A: A handwashing sink is required from BSL-1 upward.
- B: A biohazard sign is posted at BSL-2 whenever infectious agents are present.
- D: An eyewash station is already required at BSL-2.
Question 4 · Easy
A Class I biological safety cabinet protects:
1. AThe worker, the environment and the sample
2. BThe worker and environment, but not the sample
3. CThe sample, but not the worker or environment
4. DOnly the environment, through its HEPA exhaust
Show answerHide answer
Answer: B · The worker and environment, but not the sample
In a Class I cabinet, room air is drawn in through the front opening, past the worker and over the work, then exhausted through a HEPA filter. The inward airflow protects the worker and the filtered exhaust protects the environment, but unfiltered room air passes over the sample, so the sample is not protected from contamination. Class II cabinets add HEPA-filtered downflow air to protect the work as well. A horizontal clean bench protects only the product and is never used for infectious material.
- A: Protecting the sample as well needs a Class II or Class III cabinet.
- C: Protecting only the sample describes a clean bench, not a safety cabinet.
- D: The inward airflow at the front opening also protects the worker.
Question 5 · Easy
Under standard precautions, a face shield, or a mask with eye protection, is needed when:
1. AThe patient is known to have HIV
2. BSplashes or sprays of body fluid are likely
3. CWork is done inside a Class II cabinet
4. DAny patient specimen is handled
Show answerHide answer
Answer: B · Splashes or sprays of body fluid are likely
Standard precautions choose PPE by the expected exposure, not by the patient's diagnosis: gloves for contact with body fluids, and eye, nose and mouth protection when splashes or sprays are likely. In the laboratory this includes uncapping tubes without a splash shield, pouring off samples and cleaning up spills. Every specimen is treated as potentially infectious, so a known diagnosis does not change the PPE. The front window of a working Class II cabinet already shields the face.
- A: PPE depends on the task, since every specimen is treated as infectious.
- C: The cabinet's front window already protects the face from splashes.
- D: Handling a capped tube needs gloves and a coat, not face protection.
Question 6 · Hard
A nasopharyngeal swab from a patient with suspected MERS-CoV infection arrives for RT-PCR. According to WHO laboratory guidance, how should it be handled?
1. AOpen it on the bench with a surgical mask; culture at BSL-2
2. BAutoclave it unopened and report it as unsuitable
3. CProcess it only in a Class III cabinet at BSL-4
4. DOpen and inactivate it in a BSC; culture virus only at BSL-3
Answer and explanation in LearnFree account
Question 7 · Hard
A blood culture from a livestock herder with fever and joint pain flags positive on day 4. The Gram stain shows tiny gram-negative coccobacilli, and a technologist has already subcultured it on the open bench. What is the most appropriate handling from now on?
1. AContinue on the bench wearing a surgical mask
2. BIdentify it on the bench with an automated ID panel
3. CDo all further work in a BSC with BSL-3 practices
4. DSniff the plates to look for a typical odor
Answer and explanation in LearnFree account
Question 8 · Medium
A procedure involves infectious material together with volatile toxic chemicals. The suitable biological safety cabinet is:
1. AClass I, with an open front and no downflow
2. BClass II type B2, hard-ducted with total exhaust
3. CClass II type A2, which recirculates most of its air
4. DA horizontal laminar-flow clean bench
Answer and explanation in LearnFree account
Question 9 · Medium
Where should cultures of Mycobacterium tuberculosis be handled?
1. AIn a Class II cabinet in a BSL-3 laboratory
2. BOn an open bench, wearing a surgical mask
3. CIn a horizontal laminar-flow clean bench
4. DIn a chemical fume hood with the sash down
Answer and explanation in LearnFree account
Question 10 · Easy
How should a blood spill on a laboratory bench be decontaminated?
1. APour 70% alcohol straight onto the spill without absorbing it
2. BAbsorb it, then apply fresh 1:10 bleach for the contact time
3. CWipe it with soap and water only, then let it dry
4. DMix undiluted bleach with an ammonia cleaner and wipe
Answer and explanation in LearnFree account

More General Laboratory, Quality and Safety questions

Answer them one by one, keep your score and see your weak topics in Learn. Signed-out visitors try 25 per exam; sign in with Google to see them all.

Study General Laboratory, Quality and Safety

Biosafety levels, biosafety cabinets and PPE

A tube breaks while spinning in a centrifuge that has no sealed buckets. After switching off the motor, what should the technologist do first?

Which feature is required in a BSL-3 laboratory but not in a BSL-2 laboratory?

A Class I biological safety cabinet protects:

Under standard precautions, a face shield, or a mask with eye protection, is needed when:

A nasopharyngeal swab from a patient with suspected MERS-CoV infection arrives for RT-PCR. According to WHO laboratory guidance, how should it be handled?

A blood culture from a livestock herder with fever and joint pain flags positive on day 4. The Gram stain shows tiny gram-negative coccobacilli, and a technologist has already subcultured it on the open bench. What is the most appropriate handling from now on?

A procedure involves infectious material together with volatile toxic chemicals. The suitable biological safety cabinet is:

Where should cultures of Mycobacterium tuberculosis be handled?

How should a blood spill on a laboratory bench be decontaminated?