Portage Learning BIOD 171 Module 3
Exam Module 3
1. A micrometer is defined as
A. 10-3
B. 10-6
C.10-9
D. 10-12
B. A micrometer is one-millionth of a meter.
2. True or False: A nanometer is longer than a micrometer.
False. A nanometer is 1,000 times smaller than a micrometer.
3. Resolution and contrast are two critical factors that influence your
ability to see an object. Explain each.
Resolution refers to the distance between two objects at which the
objects still can be seen as separate. Poor or low resolution means two
(or more) objects may appear as one.
Contrast 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).
4. 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.
Select all that apply.
A. Objective
B. Condenser
C. Iris diaphragm
D. Eye piece
C. The iris controls the amount of light that passes through the sample
and into the objective lens. Thus, it can be adjusted (opened or closed)
to alter the amount of light.
, 5. What is the total magnification (relative to your eye) of a sample
imaged with a 60x objective and a 10x eyepiece? Show your math.
60 x 10 = 600x magnification
6. True or False: A cell that is adherent, flat (thin) and unstained is easily
identified using bright field microscopy.
False. Adherent, flat cells are almost invisible due to the limits on both
resolution and contrast.
7. 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
B and D. The unaided eye can, on average, clearly resolve objects >
100 μm
8. Label the following unmarked microscope components (numbered
arrows) by matching it with the components provided (letters).
Exam Module 3
1. A micrometer is defined as
A. 10-3
B. 10-6
C.10-9
D. 10-12
B. A micrometer is one-millionth of a meter.
2. True or False: A nanometer is longer than a micrometer.
False. A nanometer is 1,000 times smaller than a micrometer.
3. Resolution and contrast are two critical factors that influence your
ability to see an object. Explain each.
Resolution refers to the distance between two objects at which the
objects still can be seen as separate. Poor or low resolution means two
(or more) objects may appear as one.
Contrast 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).
4. 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.
Select all that apply.
A. Objective
B. Condenser
C. Iris diaphragm
D. Eye piece
C. The iris controls the amount of light that passes through the sample
and into the objective lens. Thus, it can be adjusted (opened or closed)
to alter the amount of light.
, 5. What is the total magnification (relative to your eye) of a sample
imaged with a 60x objective and a 10x eyepiece? Show your math.
60 x 10 = 600x magnification
6. True or False: A cell that is adherent, flat (thin) and unstained is easily
identified using bright field microscopy.
False. Adherent, flat cells are almost invisible due to the limits on both
resolution and contrast.
7. 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
B and D. The unaided eye can, on average, clearly resolve objects >
100 μm
8. Label the following unmarked microscope components (numbered
arrows) by matching it with the components provided (letters).
