BACE - Biotechnician Assistant Credentialing Basic Laboratory Equipment Use Questions and Answers

Question 1

A technician needs to accurately transfer 185 µL of a buffer solution. The lab has P20, P200, and P1000 micropipettes available. Which micropipette should be used for the highest accuracy and precision?

Accepted Answer

P200

Answer

The P200 micropipette, with a typical range of 20-200 µL, is the most appropriate choice. Micropipettes are most accurate and precise when used in the middle to upper portion of their specified volume range. Using a P1000 for 185 µL would be at the low end of its range (100-1000 µL or 200-1000 µL), leading to greater potential inaccuracy. A P20 (2-20 µL) cannot handle this volume.

Question 2

Before starting a microcentrifuge, a technician places two 1.5 mL tubes containing samples of unequal mass opposite each other in the rotor. What is the most likely consequence of this action?

Accepted Answer

The centrifuge will generate excessive noise and vibration, potentially damaging the unit.

Answer

Centrifuges must be properly balanced by mass to operate safely and effectively. Placing tubes with unequal masses opposite each other creates an imbalance. At high rotational speeds, this imbalance causes significant vibration, which can damage the motor and rotor, posing a serious safety risk.

Question 3

A biotechnician is preparing to measure the pH of a critical buffer solution. Which of the following is the most important first step to ensure an accurate reading?

Accepted Answer

Calibrating the meter using at least two standard buffers of known pH.

Answer

Before use, a pH meter must be calibrated against standard solutions of known pH (e.g., pH 4.0, 7.0, 10.0). This process adjusts the meter's response to match the known pH values of the standards, ensuring that subsequent measurements of unknown samples are accurate. While other steps are part of good practice, calibration is the prerequisite for accuracy.

Question 4

What are the three critical parameters that an autoclave utilizes to achieve sterilization of laboratory equipment and media?

Accepted Answer

High temperature, high pressure, and steam.

Answer

An autoclave, or steam sterilizer, sterilizes items by subjecting them to high-pressure saturated steam at a high temperature (typically 121°C or higher) for a specific amount of time. The combination of steam, pressure, and heat effectively kills all microorganisms, including resilient bacterial spores.

Question 5

When using a spectrophotometer to measure the absorbance of a colored solution, what is the primary purpose of first inserting a 'blank' cuvette containing only the solvent?

Accepted Answer

To calibrate the instrument by setting the absorbance of the solvent to zero.

Answer

The purpose of a blank is to zero the spectrophotometer. The blank contains all components of the sample except for the analyte being measured. By setting the absorbance of the blank to zero, the instrument subtracts any absorbance caused by the solvent or the cuvette itself, ensuring that the final reading reflects only the absorbance of the analyte.

BACE - Biotechnician Assistant Credentialing Exam Practice Test

BACE - Biotechnician Assistant Credentialing Exam Practice Test

BACE - Biotechnician Assistant Credentialing Basic Laboratory Equipment Use Questions and Answers