Quality control, laboratory safety and biomedical waste

55 Lab technician recruitment practice questions on Quality control, laboratory safety and biomedical waste, part of Laboratory Management and Safety. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Medium

   Which error arises before the sample reaches the analyser?

   1. AHaemolysed sample from a narrow needle
   2. BExpired reagent on the analyser
   3. CWrong wavelength set on a photometer
   4. DTranscription error in a report

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   Answer: A · Haemolysed sample from a narrow needle

   Pre-analytical errors arise before testing, from patient preparation, collection, labelling, transport and storage. They account for most laboratory errors. A haemolysed sample raises potassium and LDH and must be recollected.

   • B: An expired reagent is an analytical error.
   • C: A wrong wavelength is an analytical error.
   • D: Transcription is a post-analytical error.

2. Question 2 · Easy

   In internal quality control, the 1-2s Westgard rule is used as a:

   1. ARejection rule
   2. BLinearity check
   3. CCalibration rule
   4. DWarning rule

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   Answer: D · Warning rule

   One control beyond plus or minus 2 SD happens by chance in about 1 in 20 runs, so in the classic multirule scheme 1-2s is only a warning that triggers inspection of the other rules. The run is rejected only if another rule is violated.

   • A: Rejecting on 1-2s alone gives too many false rejections.
   • B: Linearity is checked with a dilution series, not a QC rule.
   • C: It says nothing about calibration.

3. Question 3 · Easy

   A Westgard 1-3s violation shows mainly which type of error?

   1. AClerical error
   2. BRandom error
   3. CPre-analytical error
   4. DProportional bias

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   Answer: B · Random error

   A single control beyond plus or minus 3 SD is very unlikely by chance and mostly reflects random error, such as a bubble, a pipetting fault or a clot. It is a rejection rule. Systematic errors are shown by rules such as 2-2s and 10x.

   • A: Clerical errors are not what QC rules are designed to detect.
   • C: Pre-analytical errors affect patient samples, not the control run.
   • D: Bias is shown by shift rules such as 2-2s and 10x.

4. Question 4 · Medium

   Why are concentrated acids stored on low shelves rather than above eye level?

   1. ACooler air near the floor slows fuming
   2. BA dropped bottle splashes below the face
   3. CIt keeps them out of direct sunlight
   4. DIt allows easier labelling

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   Answer: B · A dropped bottle splashes below the face

   Corrosive liquids stored above eye level can splash onto the face and eyes if a bottle slips while being taken down. They are kept low, in trays, and acids are stored apart from alkalis and oxidisers.

   • A: Floor-level temperature makes little practical difference.
   • C: Sunlight is controlled by cabinets, not shelf height.
   • D: Labelling is not the reason for low storage.

5. Question 5 · Hard

   A source patient is HBsAg-positive. A technician who completed hepatitis B vaccination has an anti-HBs titre of 150 mIU/mL. What is needed after her needle-stick?

   1. AHepatitis B immunoglobulin and vaccine
   2. BNo hepatitis B treatment is needed
   3. CAntiviral PEP for 28 days
   4. DA full new course of vaccine

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   Answer: B · No hepatitis B treatment is needed

   An anti-HBs titre of 10 mIU/mL or more shows protection, so a responder needs no HBIG or vaccine for hepatitis B. The wound is still washed, the injury reported and HIV and HCV status of the source checked.

   • A: HBIG with vaccine is for non-responders or the unvaccinated.
   • C: Antiviral PEP is for HIV exposure, not hepatitis B.
   • D: A new course is for those without protective antibody.

6. Question 6 · Hard

   During a run, the normal control is at +1.2 SD and the high control at +3.4 SD. Patient samples were run between them. What should the technician do?

   1. ARepeat only the high control
   2. BReject the run and repeat after correcting the fault
   3. CReport only normal-range patient results
   4. DReport patients, since the normal control passed

   Answer and explanation in LearnFree account

7. Question 7 · Hard

   A technician spills about 20 mL of a Mycobacterium tuberculosis culture suspension outside the biosafety cabinet. What is the correct first step?

   1. AWipe it up at once with dry tissue
   2. BLeave the room, close the door and wait 30 minutes
   3. CSwitch on a fan to clear the air
   4. DSpray alcohol and continue the work

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8. Question 8 · Medium

   Within a single run, the low control reads +2.3 SD while the high control reads -2.1 SD. Which rule fails and what error does it suggest?

   1. A10x, systematic error
   2. B2-2s, systematic error
   3. CR-4s, random error
   4. D1-2s, warning only

   Answer and explanation in LearnFree account

9. Question 9 · Medium

   An HEPA filter in a biosafety cabinet removes particles of about 0.3 µm with what efficiency?

   1. AAt least 50%
   2. BAbout 80%
   3. CAbout 90%
   4. DAt least 99.97%

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10. Question 10 · Easy

    Which biosafety level suits work with Mycobacterium tuberculosis cultures?

    1. ABSL-2
    2. BBSL-4
    3. CBSL-3
    4. DBasic bench, BSL-1

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11. Question 11 · Medium

    Under the BMW Rules 2016, laboratory bags for waste must be:

    1. ARecycled paper
    2. BChlorinated PVC
    3. CNon-chlorinated plastic
    4. DBlack polythene

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12. Question 12 · Medium

    The coefficient of variation of a control is calculated as:

    1. A(SD / mean) x 100
    2. B(Mean - SD) / mean
    3. C(Mean / SD) x 100
    4. DSD x mean / 100

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13. Question 13 · Medium

    Pick the INCORRECT statement regarding India's biomedical waste rules of 2016.

    1. AUntreated waste is kept up to 48 hours
    2. BPre-treatment of lab waste is required
    3. CChlorinated bags are phased out
    4. DBar-coding of bags is optional

    Answer and explanation in LearnFree account

14. Question 14 · Easy

    Used needles and syringe needles are discarded in which BMW category container?

    1. AWhite translucent puncture-proof
    2. BYellow non-chlorinated bag
    3. CBlue cardboard box
    4. DRed non-chlorinated bag

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15. Question 15 · Hard

    Twenty days of cholesterol control give a mean of 200 mg/dL and an SD of 6 mg/dL. What is the CV?

    1. A3%
    2. B1.2%
    3. C33%
    4. D6%

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16. Question 16 · Easy

    The best first-aid for a concentrated acid splash in the eye is:

    1. ANeutralise it with a sodium bicarbonate rinse
    2. BApply a dry eye pad at once
    3. CInstil antibiotic eye drops
    4. DFlush with running water for 15 minutes

    Answer and explanation in LearnFree account

17. Question 17 · Easy

    Which colour bag takes expired or discarded medicines and chemical waste from the laboratory?

    1. ARed
    2. BWhite
    3. CYellow
    4. DBlue cardboard

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18. Question 18 · Easy

    External quality assessment (EQAS) mainly checks a laboratory's:

    1. ATurnaround time
    2. BAccuracy against other laboratories
    3. CDay-to-day precision
    4. DStorage temperature of its reagents

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19. Question 19 · Easy

    A Levey-Jennings chart plots control results against:

    1. APatient result values
    2. BReagent lot number
    3. CAnalyte concentration
    4. DTime or run number

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20. Question 20 · Easy

    The international biohazard symbol must be shown on:

    1. ADoors of rooms handling infectious agents
    2. BFire extinguisher points
    3. CEmergency exit doors
    4. DEvery chemical reagent bottle on the shelves

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21. Question 21 · Medium

    Two consecutive control results exceed +2 SD on the same side of the mean. Which Westgard rule is violated?

    1. A2-2s
    2. B4-1s
    3. CR-4s
    4. D1-3s

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22. Question 22 · Medium

    Liquid chemical waste from the laboratory that is not infectious should be:

    1. AStored indefinitely on site
    2. BMixed with yellow-bag waste
    3. CNeutralised before discharge to drains
    4. DBurnt in an open pit

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23. Question 23 · Easy

    Which disinfectant is used at 1% available chlorine for a blood spill?

    1. ACetrimide
    2. BSodium hypochlorite
    3. CEthyl alcohol
    4. DPhenol

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24. Question 24 · Easy

    Under the BMW Rules 2016, a hospital that cannot treat its waste within the allowed time must:

    1. AGet permission from the prescribed authority
    2. BBurn the waste in an open pit
    3. CStore it for up to one month without approval
    4. DMix it with general municipal waste

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25. Question 25 · Medium

    Antiretroviral prophylaxis for a lab worker splashed by HIV-positive blood is best begun within what time?

    1. A7 days
    2. B24 hours
    3. C2 hours
    4. D72 hours

    Answer and explanation in LearnFree account