BIO 171 Bio Test 3.
Question 1
pts
A nanometer is defined
as: A. 10-3
B. 10-6
C. 10-9
D. 10-12
Correct Answer : C
Question 2
Not yet graded / 10 pts
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).
Question 3
pts
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.
Iris diaphragm
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.
, BIO 171 Bio Test 3.
Eye piece
Objective
Condenser
Question 4
Not yet graded / 5 pts
What is the total magnification (relative to your eye) of a sample imaged with
a 20x objective and a 15x eyepiece? Show your math.
Your Answer:
20 x 15 = 300x magnification
Question 5
pts
True or False: Staining is often required to image a cell that is adherent and
flat (thin).
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.
False
Question 6
pts
Which of the following could NOT be seen clearly by the unaided eye?
Select all that apply.
Skin cell with diameter of 1500 μm
Question 1
pts
A nanometer is defined
as: A. 10-3
B. 10-6
C. 10-9
D. 10-12
Correct Answer : C
Question 2
Not yet graded / 10 pts
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).
Question 3
pts
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.
Iris diaphragm
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.
, BIO 171 Bio Test 3.
Eye piece
Objective
Condenser
Question 4
Not yet graded / 5 pts
What is the total magnification (relative to your eye) of a sample imaged with
a 20x objective and a 15x eyepiece? Show your math.
Your Answer:
20 x 15 = 300x magnification
Question 5
pts
True or False: Staining is often required to image a cell that is adherent and
flat (thin).
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.
False
Question 6
pts
Which of the following could NOT be seen clearly by the unaided eye?
Select all that apply.
Skin cell with diameter of 1500 μm
