Laboratory Practice Flashcards
7 cards from real STP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Laboratory Practice flashcards as text
What is the primary purpose of a fume hood in a chemistry laboratory?
Answer: To protect the worker from inhaling hazardous vapors, gases, and aerosols
A fume hood protects laboratory personnel by drawing hazardous airborne contaminants away from the breathing zone.
According to Good Laboratory Practice (GLP), when must a laboratory notebook entry be corrected?
Answer: By drawing a single line through the error, initialing, dating, and writing the correction
GLP requires that errors be crossed out with a single line so the original entry remains legible, then initialed, dated, and corrected.
When centrifuging samples, what is the most important safety consideration regarding tube placement?
Answer: Tubes must be balanced in the rotor to prevent vibration and potential rotor failure
Unbalanced rotors create dangerous vibrations that can cause catastrophic rotor failure and release of aerosols or hazardous materials.
A laboratory technician is asked to validate a new analytical method. Which parameter assesses how close the measured value is to the true value?
Answer: Accuracy
Accuracy measures the closeness of a result to the true or accepted reference value, while precision measures reproducibility.
What does the term 'chain of custody' refer to in a laboratory context?
Answer: The documented record of who handled a sample and all transfers, storage, and processes it underwent
Chain of custody is the chronological documentation that tracks possession, handling, and location of a sample to ensure its integrity and admissibility.
Which autoclave cycle parameter is most critical for achieving sterilization of a liquid media load?
Answer: Temperature held at 121°C for sufficient time (typically 15–20 minutes)
Sterilization requires maintaining 121°C (at 15 psi) for at least 15 minutes to ensure complete destruction of microorganisms including spores.
A researcher obtains an R² value of 0.998 for a standard curve. What does this indicate?
Answer: The linear relationship between concentration and signal is very strong
An R² (coefficient of determination) close to 1.000 indicates that the data points fit the linear model very well, confirming a strong linear relationship.