BIOD 171 EXAM MODULE 3
. 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.
Exam Page 2
Answer Key
False. A nanometer is 1,000 times smaller than a micrometer.
1. 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 seenas 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, tryingto identify 2 dark colored
objects at night (low light = low contrast) versus the same 2 objectsin the middle of a sunny afternoon
(bright light against 2 dark objects = high contrast).
Exam Page 3
Answer Key
1. 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 objectivelens. Thus, it
can be adjusted (opened or closed) to alter the amount of light.
2. What is the total magnification (relative to your eye) of a sample imaged with a 60x objective anda
10x eyepiece? Show your math.
Exam Page 4
Answer Key magnification
60 x 10 = 600x
1. 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 andcontrast.
2. 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. ThePage
Exam 5 can, on average, clearly resolve objects > 100 μm
unaided eye
Answer Key
1. Label the following unmarked microscope components (numbered arrows) by matching it with the
components provided (letters).
. 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.
Exam Page 2
Answer Key
False. A nanometer is 1,000 times smaller than a micrometer.
1. 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 seenas 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, tryingto identify 2 dark colored
objects at night (low light = low contrast) versus the same 2 objectsin the middle of a sunny afternoon
(bright light against 2 dark objects = high contrast).
Exam Page 3
Answer Key
1. 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 objectivelens. Thus, it
can be adjusted (opened or closed) to alter the amount of light.
2. What is the total magnification (relative to your eye) of a sample imaged with a 60x objective anda
10x eyepiece? Show your math.
Exam Page 4
Answer Key magnification
60 x 10 = 600x
1. 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 andcontrast.
2. 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. ThePage
Exam 5 can, on average, clearly resolve objects > 100 μm
unaided eye
Answer Key
1. Label the following unmarked microscope components (numbered arrows) by matching it with the
components provided (letters).
