CMLA Laboratory Equipment Operation & Maintenance 5

Question 1

Which action protects pipette accuracy when aspirating volatile reagents such as acetone?

Accepted Answer

Pre-wet the pipette tip with the reagent before aspirating the target volume

Answer

Pre-wetting saturates the dead air space inside the tip, reducing evaporation and improving volume accuracy for volatile liquids.

Question 2

How often should the HEPA filter in a Class II Type A2 biological safety cabinet typically be certified?

Accepted Answer

Annually or whenever the cabinet is moved or serviced

Answer

NSF/ANSI 49 requires annual certification of BSCs, plus recertification after relocation or major service, to verify airflow and HEPA filter integrity.

Question 3

What does the term 'carry-over' mean in the context of automated laboratory analyzers?

Accepted Answer

Residual analyte from a previous sample contaminating the next sample result

Answer

Carry-over occurs when residual analyte from a high-concentration sample contaminates the subsequent sample, falsely elevating or affecting that result.

Question 4

A freezer storing frozen plasma is found at –15°C instead of the required ≤–20°C. What is the primary concern?

Accepted Answer

Labile coagulation factors in the plasma may have degraded

Answer

Temperatures above –20°C accelerate degradation of labile coagulation factors such as Factor V and Factor VIII in frozen plasma.

Question 5

Why should a centrifuge rotor be inspected for cracks or corrosion before each use?

Accepted Answer

A compromised rotor can fail catastrophically at high speed, causing injury

Answer

Cracks or corrosion weaken the rotor structure and can lead to explosive rotor failure under centrifugal force, posing serious risk to laboratory personnel.

(CMLA) Certified Medical Laboratory Assistant Practice Test

(CMLA) Certified Medical Laboratory Assistant Practice Test

CMLA Laboratory Equipment Operation & Maintenance 5