BIOD 171
BIOD 171 MODULE 3 EXAM 2025
A nanometer is defined as: -Correct Answer ✔10 -9 or one-billionth of a meter
True or False: A nanometer is longer than a micrometer -Correct Answer ✔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. -Correct Answer ✔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. -Correct Answer ✔Objective
Only the oculars (eyepiece) and the objectives contribute to the magnification of the
sample. Since the eyepiece
is fixed, only the objectives could be altered.
BIOD 171
, BIOD 171
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. -
Correct Answer ✔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. -Correct Answer ✔60x objective x 10x
ocular = 600x magnification
True or False: Staining is often required to image a cell that is adherent and flat (thin). -
Correct Answer ✔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 -Correct Answer ✔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 -Correct Answer ✔B. Protozoa with diameter of
150 μm
D. Skin cell with diameter of 1500 μm
BIOD 171
BIOD 171 MODULE 3 EXAM 2025
A nanometer is defined as: -Correct Answer ✔10 -9 or one-billionth of a meter
True or False: A nanometer is longer than a micrometer -Correct Answer ✔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. -Correct Answer ✔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. -Correct Answer ✔Objective
Only the oculars (eyepiece) and the objectives contribute to the magnification of the
sample. Since the eyepiece
is fixed, only the objectives could be altered.
BIOD 171
, BIOD 171
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. -
Correct Answer ✔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. -Correct Answer ✔60x objective x 10x
ocular = 600x magnification
True or False: Staining is often required to image a cell that is adherent and flat (thin). -
Correct Answer ✔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 -Correct Answer ✔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 -Correct Answer ✔B. Protozoa with diameter of
150 μm
D. Skin cell with diameter of 1500 μm
BIOD 171
