MLS Laboratory Equipment & Techniques 2

Question 1

Which centrifuge type uses a fixed angle rotor where tubes are held at a constant angle during spinning?

Accepted Answer

Fixed-angle centrifuge

Answer

Fixed-angle rotors hold tubes at a set angle (typically 25–45°) throughout the run, causing particles to sediment along the tube wall.

Question 2

When calibrating a spectrophotometer, which solution is used to set 100% transmittance (zero absorbance)?

Accepted Answer

The blank (reagent blank)

Answer

The reagent blank contains all reagents except the analyte and is used to zero the instrument, correcting for reagent color and background absorbance.

Question 3

A laboratory thermometer reads 37.2°C when placed in a 37.0°C reference bath. This difference is best described as:

Accepted Answer

Systematic error (bias)

Answer

A consistent offset from the true value in one direction is systematic error (bias), which can often be corrected by calibration.

Question 4

Which pipette type is designed to deliver a single fixed volume and is NOT adjustable?

Accepted Answer

Volumetric (transfer) pipette

Answer

Volumetric (transfer) pipettes are calibrated to deliver one precise fixed volume and offer the highest accuracy for that volume.

Question 5

In a biosafety cabinet Class II Type A2, the percentage of air recirculated within the cabinet versus exhausted is approximately:

Accepted Answer

70% recirculated, 30% exhausted

Answer

Class II Type A2 BSCs recirculate approximately 70% of air through HEPA filters and exhaust about 30% to the environment (via HEPA or hard-duct).

(MLS) Medical Laboratory Scientist Practice Test

(MLS) Medical Laboratory Scientist Practice Test

MLS Laboratory Equipment & Techniques 2