,Microbiology Lab
Practicum Review:
Key Terms, Concepts
& Exam Questions
and Answers with
Rationale 2026–2027
Updated Study Guide
Unit 1: Aseptic Technique, Isolation &
Pure Culture Methods
, Q1. What is the primary purpose of "flaming" an
inoculating loop before and after transferring
bacteria?
A) To warm up the bacteria so they reproduce faster.
B) To dry any liquid clinging to the metal wire.
C) To incinerate existing microbes and ensure the
loop is sterile, preventing contamination.
D) To facilitate the spread of bacteria on an agar
plate.
Answer: C
Rationale: Flaming uses dry heat to incinerate all
living vegetative cells and endospores on the wire
loop before contacting a culture (avoiding
introduction of contaminants) and after transfer
(avoiding introducing the culture into the surrounding
air/worksurface).
Q2. When using the quadrant streak plate technique,
why must you flame the loop between each quadrant?
A) To prevent the agar from melting.
B) To dilute the bacterial cells sequentially to isolate
individual, pure colonies.
C) To ensure the bacteria are killed inside the dish.
D) To change the staining properties of the bacteria.
Answer: B
Rationale: Flaming between quadrants kills residual
bacteria on the loop, allowing you to drag only a
Practicum Review:
Key Terms, Concepts
& Exam Questions
and Answers with
Rationale 2026–2027
Updated Study Guide
Unit 1: Aseptic Technique, Isolation &
Pure Culture Methods
, Q1. What is the primary purpose of "flaming" an
inoculating loop before and after transferring
bacteria?
A) To warm up the bacteria so they reproduce faster.
B) To dry any liquid clinging to the metal wire.
C) To incinerate existing microbes and ensure the
loop is sterile, preventing contamination.
D) To facilitate the spread of bacteria on an agar
plate.
Answer: C
Rationale: Flaming uses dry heat to incinerate all
living vegetative cells and endospores on the wire
loop before contacting a culture (avoiding
introduction of contaminants) and after transfer
(avoiding introducing the culture into the surrounding
air/worksurface).
Q2. When using the quadrant streak plate technique,
why must you flame the loop between each quadrant?
A) To prevent the agar from melting.
B) To dilute the bacterial cells sequentially to isolate
individual, pure colonies.
C) To ensure the bacteria are killed inside the dish.
D) To change the staining properties of the bacteria.
Answer: B
Rationale: Flaming between quadrants kills residual
bacteria on the loop, allowing you to drag only a
