Microbiology: Laboratory Operations and Safety Flashcards
7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Microbiology: Laboratory Operations and Safety flashcards as text
Which biosafety cabinet (BSC) class provides personnel protection only and does NOT protect the product from contamination?
Answer: Class I
Class I BSCs exhaust air through a HEPA filter to protect personnel and the environment but draw unfiltered room air over the work surface, offering no product protection.
A technician must dispose of a culture plate containing a BSL-2 organism. What is the correct first step before placing it in the biohazard waste bag?
Answer: Autoclave the plate at 121°C for at least 15 minutes
BSL-2 biological waste must be autoclaved (decontaminated) before disposal to render the organisms non-viable.
When calibrating a micropipette, which technique produces the most accurate volume delivery for aqueous solutions?
Answer: Air displacement with a pre-wet tip
Pre-wetting the tip with the solution before aspirating the target volume reduces error caused by vapor pressure and minimizes loss on tip walls, improving accuracy for aqueous samples.
The use of personal protective equipment (PPE) is governed by the hierarchy of controls. Where does PPE fall in this hierarchy?
Answer: Last line of defense
PPE is the last line of defense in the hierarchy of controls, used when elimination, substitution, engineering, and administrative controls cannot adequately reduce risk.
A researcher accidentally spills a small volume of a BSL-2 culture on the bench. What is the correct immediate action?
Answer: Cover with paper towels soaked in 10% bleach for 20 minutes, then clean up
A 10% bleach (hypochlorite) solution applied for at least 20 minutes effectively disinfects BSL-2 spills before physical clean-up.
Which type of culture media allows any organism to grow without providing any selective advantage or differential characteristic?
Answer: General-purpose (non-selective) media
General-purpose or non-selective media such as nutrient agar or tryptic soy agar support the growth of a wide variety of organisms without selecting for or distinguishing between them.
During an aseptic transfer, why must the loop or needle be flamed to red-hot before and after each transfer?
Answer: To sterilize the loop and prevent cross-contamination between cultures
Flaming to red-hot incincerates any residual organisms on the loop, ensuring sterility before inoculation and preventing contamination of stock cultures after use.