Portage Learning
3 MAXE · 171 DOIB
★ ★
P A Division of Geneva College
EST. 2012
ONLINE COURSES FOR COLLEGE CREDIT
Portage Learning BIOD 171 Exam 3
E SS E N T I A L M I C R O B I O LO G Y — M I C R O S CO PY & STA I N I N G
INSTITUTION Portage Learning (Geneva College) PROGRAM Pre-Nursing / Health Sciences
COURSE CODE BIOD 171 COURSE TITLE Essential Microbiology
ACADEMIC YEAR EXAM TITLE Portage Learning BIOD 171 Exam 3
TOTAL QUESTIONS 67 Questions FORMAT Multiple Choice / True-False /
Select All That Apply
EXAMINATION INSTRUCTIONS
▸ Select the single best answer unless "Select all" is specified.
▸ Questions randomized from source material per Component 16.
▸ Topics: Microscopy, Staining Techniques, Gram Staining, Electron Microscopy.
▸ Correct answers and rationales appear below each question.
MICROSCOPY & STAINING — EXAMINATION 3 Questions 1 – 67
1. A nanometer is defined as:
A. 10⁻³
B. 10⁻⁶
C. 10⁻⁹
D. 10⁻¹²
CORRECT ANSWER C — 10⁻⁹ (one billionth of a meter)
RATIONALE 1 nanometer = 10⁻⁹ m = 0.000000001 m. It is 1,000 times smaller than a
micrometer (10⁻⁶ m). Viruses and large molecules are measured in nanometers.
,2. A micrometer is defined as:
A. 10⁻³
B. 10⁻⁶
C. 10⁻⁹
D. 10⁻¹²
CORRECT ANSWER B — 10⁻⁶ (one millionth of a meter)
RATIONALE 1 micrometer (μm) = 10⁻⁶ m. Bacteria are typically 1–10 μm. The unaided eye can
resolve objects >100 μm.
3. True or False: A nanometer is longer than a micrometer.
A. True
B. False
CORRECT ANSWER B — False (1 nm is 1,000 times SMALLER than 1 μm)
RATIONALE 1 μm = 10⁻⁶ m; 1 nm = 10⁻⁹ m. Therefore 1 μm = 1,000 nm. A nanometer is much
smaller.
4. Resolution and contrast are two critical factors in microscopy. Explain each.
A. Resolution = brightness; Contrast = magnification
B. Resolution = distance to distinguish objects as separate; Contrast = difference in light
absorbance
C. Resolution = color; Contrast = focus
D. Both measure the same property
CORRECT ANSWER B — Resolution: distance between two objects where they're still seen as
separate. Contrast: difference in light absorption between objects
RATIONALE Poor resolution = objects blur together. Poor contrast = high background makes
objects hard to distinguish (like seeing dark objects at night vs. daylight).
, 5. What happens if resolution is poor?
A. Objects appear too bright
B. Two or more objects may appear as one
C. Colors are distorted
D. Magnification decreases
CORRECT ANSWER B — Two or more objects may appear as one
RATIONALE Resolution is the ability to distinguish two close objects as separate. Poor
resolution causes them to blur together.
6. What is contrast in microscopy?
A. The magnification power
B. The difference in light absorbance between two objects
C. The thickness of the specimen
D. The color of the stain
CORRECT ANSWER B — The difference in light absorbance between two objects
RATIONALE High contrast = objects stand out clearly against background. Low contrast = high
background makes visualization difficult.
7. What happens if there is poor contrast?
A. Magnification is reduced
B. High background makes visualization of multiple objects difficult
C. Resolution improves
D. The image becomes too bright
CORRECT ANSWER B — Gives high background; makes visualization of multiple objects difficult
RATIONALE Poor contrast = objects blend into background. Like trying to see dark objects at
night (low contrast) vs. daylight (high contrast).
3 MAXE · 171 DOIB
★ ★
P A Division of Geneva College
EST. 2012
ONLINE COURSES FOR COLLEGE CREDIT
Portage Learning BIOD 171 Exam 3
E SS E N T I A L M I C R O B I O LO G Y — M I C R O S CO PY & STA I N I N G
INSTITUTION Portage Learning (Geneva College) PROGRAM Pre-Nursing / Health Sciences
COURSE CODE BIOD 171 COURSE TITLE Essential Microbiology
ACADEMIC YEAR EXAM TITLE Portage Learning BIOD 171 Exam 3
TOTAL QUESTIONS 67 Questions FORMAT Multiple Choice / True-False /
Select All That Apply
EXAMINATION INSTRUCTIONS
▸ Select the single best answer unless "Select all" is specified.
▸ Questions randomized from source material per Component 16.
▸ Topics: Microscopy, Staining Techniques, Gram Staining, Electron Microscopy.
▸ Correct answers and rationales appear below each question.
MICROSCOPY & STAINING — EXAMINATION 3 Questions 1 – 67
1. A nanometer is defined as:
A. 10⁻³
B. 10⁻⁶
C. 10⁻⁹
D. 10⁻¹²
CORRECT ANSWER C — 10⁻⁹ (one billionth of a meter)
RATIONALE 1 nanometer = 10⁻⁹ m = 0.000000001 m. It is 1,000 times smaller than a
micrometer (10⁻⁶ m). Viruses and large molecules are measured in nanometers.
,2. A micrometer is defined as:
A. 10⁻³
B. 10⁻⁶
C. 10⁻⁹
D. 10⁻¹²
CORRECT ANSWER B — 10⁻⁶ (one millionth of a meter)
RATIONALE 1 micrometer (μm) = 10⁻⁶ m. Bacteria are typically 1–10 μm. The unaided eye can
resolve objects >100 μm.
3. True or False: A nanometer is longer than a micrometer.
A. True
B. False
CORRECT ANSWER B — False (1 nm is 1,000 times SMALLER than 1 μm)
RATIONALE 1 μm = 10⁻⁶ m; 1 nm = 10⁻⁹ m. Therefore 1 μm = 1,000 nm. A nanometer is much
smaller.
4. Resolution and contrast are two critical factors in microscopy. Explain each.
A. Resolution = brightness; Contrast = magnification
B. Resolution = distance to distinguish objects as separate; Contrast = difference in light
absorbance
C. Resolution = color; Contrast = focus
D. Both measure the same property
CORRECT ANSWER B — Resolution: distance between two objects where they're still seen as
separate. Contrast: difference in light absorption between objects
RATIONALE Poor resolution = objects blur together. Poor contrast = high background makes
objects hard to distinguish (like seeing dark objects at night vs. daylight).
, 5. What happens if resolution is poor?
A. Objects appear too bright
B. Two or more objects may appear as one
C. Colors are distorted
D. Magnification decreases
CORRECT ANSWER B — Two or more objects may appear as one
RATIONALE Resolution is the ability to distinguish two close objects as separate. Poor
resolution causes them to blur together.
6. What is contrast in microscopy?
A. The magnification power
B. The difference in light absorbance between two objects
C. The thickness of the specimen
D. The color of the stain
CORRECT ANSWER B — The difference in light absorbance between two objects
RATIONALE High contrast = objects stand out clearly against background. Low contrast = high
background makes visualization difficult.
7. What happens if there is poor contrast?
A. Magnification is reduced
B. High background makes visualization of multiple objects difficult
C. Resolution improves
D. The image becomes too bright
CORRECT ANSWER B — Gives high background; makes visualization of multiple objects difficult
RATIONALE Poor contrast = objects blend into background. Like trying to see dark objects at
night (low contrast) vs. daylight (high contrast).
