BIO 250 STRAIGHTERLINE MICROBIOLOGY PRACTICE TEST PREP STUDY GUIDE 2026 COMPREHENSIVE QUESTIONS AND ACCURATE SOLUTIONS FULL SOLUTION

BIO 250 STRAIGHTERLINE
MICROBIOLOGY PRACTICE TEST
PREP STUDY GUIDE 2026
COMPREHENSIVE QUESTIONS AND
ACCURATE SOLUTIONS FULL
SOLUTION
◉ What does it mean when we say the microscope is parfocal? Answer:
Specimen will remain in focus when the objective lens is
changed.


◉ Which objective lenses require immersion oil? Answer: Only the
100X objective


◉ What is the total magnification of microscope B? Answer: 400X


◉ List the following in decreasing size order: Answer: Stentor,
Red blood cell,
S. aureus,
E. coli,
HIV


◉ What is a disinfectant? Answer: Destroys harmful vegetative
microbes, but not endospores, on inanimate objects.

, ◉ What is an antiseptic? Answer: Destroys harmful vegetative
microbes, but not endospores, on animate objects.


◉ Can a substance be both a disinfectant and an antiseptic? Answer:
Yes, alcohol, iodine, hydrogen peroxide


◉ Identify the labeled substances as disinfectants or antiseptics (A - G).
Answer: A. 70% alcohol - both
B. 10% Lysol - disinfectant
C. Mouthwash - antiseptic
D. Quadricide - disinfectant
E. Wescodine - disinfectant
F. 3% hydrogen peroxide - both
G. Bleach - disinfectant


◉ How can you measure the effectiveness of an antiseptic or
disinfectant? Answer: Disc diffusion assay


◉ What is the name of the technique demonstrated by plate A?
Answer: Kirby-Bauer method


◉ How does this method differ from the method we used to measure
the effectiveness of