CABT Laboratory Equipment 4

Question 1

What is the primary purpose of a Coulter counter (impedance-based cell counter) in a clinical lab?

Accepted Answer

Counting and sizing cells by electrical impedance as they pass through an aperture

Answer

A Coulter counter counts and measures cell size by detecting changes in electrical impedance as individual cells pass through a small aperture in an electrolyte solution.

Question 2

Which type of pipette should be used to transfer 0.05 mL of serum for a clinical chemistry assay?

Accepted Answer

50 µL micropipette

Answer

A 50 µL (0.05 mL) micropipette with a calibrated disposable tip provides the accuracy required for small-volume serum transfers in clinical chemistry.

Question 3

During routine maintenance of a microscope, immersion oil is found on the 40× dry objective lens. The correct cleaning agent is:

Accepted Answer

Lens paper moistened with lens cleaner or xylene substitute

Answer

Lens paper moistened with a lens cleaning solution or xylene substitute safely removes immersion oil without damaging optical coatings on dry objectives.

Question 4

What does 'CV%' (coefficient of variation) measure when validating laboratory equipment precision?

Accepted Answer

The percentage of random variability relative to the mean across repeated measurements

Answer

CV% = (standard deviation / mean) × 100, expressing random variability as a percentage of the mean to assess instrument precision.

Question 5

A gas chromatograph (GC) used in toxicology shows baseline noise. Which component is most likely responsible?

Accepted Answer

Detector or detector contamination

Answer

Detector contamination or detector malfunction is the most common cause of elevated baseline noise in gas chromatography systems.

(CABT) Certified Associate in Biomedical Technology Practice Test

(CABT) Certified Associate in Biomedical Technology Practice Test

CABT Laboratory Equipment 4