BIOD 171 MODULE 3 EXAM QUESTIONS
AND ANSWERS GRADED A+ 2025/2026
A nanometer is defined as: - ANS 10 -9 or one-billionth of a meter
True or False: A nanometer is longer than a micrometer - ANS False
A nanometer is 1000x smaller than a micrometer
Resolution and contrast are two critical factors that influence your ability to see an object.
Explain each. - ANS Resolution refers to the distance between two objects at which the
objects can still be seen as separate. Poor or low resolution means two or more objects may
appear as one.
Contrast on the other hand is the difference in light absorbance between two objects. Poor
contrast gives a high background and makes the visualization of multiple objects difficult. For
instance, trying to identify 2 dark colored objects at
night (low light = low contrast) versus the same 2 objects in the middle of
a sunny afternoon (bright light against 2 dark objects = high contrast).
Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the
magnification of a sample. - ANS Objective
Only the oculars (eyepiece) and the objectives contribute to the magnification of the sample.
Since the eyepiece
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, is fixed, only the objectives could be altered.
Assuming a constant (non-adjustable) light source power, identify the part of the microscope
you would adjust to limit the amount of light entering the microscope. - ANS Iris diaphragm
What is the total magnification on (relative to your eye) of a sample imaged with a 60x objective
and a 10x eyepiece? Show your math. - ANS 60x objective x 10x ocular = 600x magnification
True or False: Staining is often required to image a cell that is adherent and flat (thin). -
ANS True
Adherent, flat and unstained cells are almost invisible due to the limits on both
resolution and contrast. Therefore, cell staining is often required to adequately image
the sample.
True or False: A cell that is adherent, flat (thin), and unstained is easily identified using bright
field microscopy - ANS False: Adherent, flat cells are almost invisible due to the limits on both
resolution and contrast
Which of the following could be seen clearly by the unaided eye? Select all that apply.
A. Bacteria with diameter of 24 μm
B. Protozoa with diameter of 150 μm
C. Virus with a diameter of 0.2 μm
D. Skin cell with diameter of 1500 μm - ANS B. Protozoa with diameter of 150 μm
D. Skin cell with diameter of 1500 μm
The unaided eye can, on average, clearly resolve objects > 100 μm
2. Which of the following could NOT be seen clearly by the unaided eye? Select all that apply.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
AND ANSWERS GRADED A+ 2025/2026
A nanometer is defined as: - ANS 10 -9 or one-billionth of a meter
True or False: A nanometer is longer than a micrometer - ANS False
A nanometer is 1000x smaller than a micrometer
Resolution and contrast are two critical factors that influence your ability to see an object.
Explain each. - ANS Resolution refers to the distance between two objects at which the
objects can still be seen as separate. Poor or low resolution means two or more objects may
appear as one.
Contrast on the other hand is the difference in light absorbance between two objects. Poor
contrast gives a high background and makes the visualization of multiple objects difficult. For
instance, trying to identify 2 dark colored objects at
night (low light = low contrast) versus the same 2 objects in the middle of
a sunny afternoon (bright light against 2 dark objects = high contrast).
Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the
magnification of a sample. - ANS Objective
Only the oculars (eyepiece) and the objectives contribute to the magnification of the sample.
Since the eyepiece
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, is fixed, only the objectives could be altered.
Assuming a constant (non-adjustable) light source power, identify the part of the microscope
you would adjust to limit the amount of light entering the microscope. - ANS Iris diaphragm
What is the total magnification on (relative to your eye) of a sample imaged with a 60x objective
and a 10x eyepiece? Show your math. - ANS 60x objective x 10x ocular = 600x magnification
True or False: Staining is often required to image a cell that is adherent and flat (thin). -
ANS True
Adherent, flat and unstained cells are almost invisible due to the limits on both
resolution and contrast. Therefore, cell staining is often required to adequately image
the sample.
True or False: A cell that is adherent, flat (thin), and unstained is easily identified using bright
field microscopy - ANS False: Adherent, flat cells are almost invisible due to the limits on both
resolution and contrast
Which of the following could be seen clearly by the unaided eye? Select all that apply.
A. Bacteria with diameter of 24 μm
B. Protozoa with diameter of 150 μm
C. Virus with a diameter of 0.2 μm
D. Skin cell with diameter of 1500 μm - ANS B. Protozoa with diameter of 150 μm
D. Skin cell with diameter of 1500 μm
The unaided eye can, on average, clearly resolve objects > 100 μm
2. Which of the following could NOT be seen clearly by the unaided eye? Select all that apply.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
