Biod 171 Essential Microbiology Exam Prep Bundle Complete
Questions and Verified Solutions | UPDATED ACTUAL Exam
Questions and CORRECT Answers
Question 1.
A nanometer is defined as:
Answer: 10 -9 or one-billionth of a meter
Question 2.
True or False: A nanometer is longer than a micrometer
Answer: False
A nanometer is 1000x smaller than a micrometer
Question 3.
Resolution and contrast are two critical factors that influence your ability to see an
object. Explain each.
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. 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.
Question 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.
Answer: Iris diaphragm
Question 5.
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.
Answer: 60x objective x 10x ocular = 600x magnification
, Question 6.
True or False: Staining is often required to image a cell that is adherent and flat (thin).
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.
Question 7.
True or False: A cell that is adherent, flat (thin), and unstained is easily identified using
bright field microscopy
Answer: False: Adherent, flat cells are almost invisible due to the limits on
both resolution and contrast
Question 8.
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
Answer: 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
Question 9.
Which of the following could NOT 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
Answer: A. Bacteria with diameter of 24 μm
C. Virus with a diameter of 0.2 μm The unaided eye can, on average, clearly
resolve objects > 100 μm
Question 10.
Label the following unmarked microscope components (numbered arrows) by matching
it with the components provided
(letters).
Questions and Verified Solutions | UPDATED ACTUAL Exam
Questions and CORRECT Answers
Question 1.
A nanometer is defined as:
Answer: 10 -9 or one-billionth of a meter
Question 2.
True or False: A nanometer is longer than a micrometer
Answer: False
A nanometer is 1000x smaller than a micrometer
Question 3.
Resolution and contrast are two critical factors that influence your ability to see an
object. Explain each.
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. 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.
Question 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.
Answer: Iris diaphragm
Question 5.
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.
Answer: 60x objective x 10x ocular = 600x magnification
, Question 6.
True or False: Staining is often required to image a cell that is adherent and flat (thin).
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.
Question 7.
True or False: A cell that is adherent, flat (thin), and unstained is easily identified using
bright field microscopy
Answer: False: Adherent, flat cells are almost invisible due to the limits on
both resolution and contrast
Question 8.
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
Answer: 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
Question 9.
Which of the following could NOT 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
Answer: A. Bacteria with diameter of 24 μm
C. Virus with a diameter of 0.2 μm The unaided eye can, on average, clearly
resolve objects > 100 μm
Question 10.
Label the following unmarked microscope components (numbered arrows) by matching
it with the components provided
(letters).
