MICROBIOLOGY FINAL PORTAGE LEARNING COURSE // A+
GRADED PRESENTATION // ESSENTIAL MICROBIAL
PHYSIOLOGY CLINICAL APPLICATIONS LAB
DIAGNOSTICS AND PATHOGEN ANALYSIS FOR STUDENT
MASTERY // ACADEMIC YEAR 2025/2026
True or False: A nanometer is longer than a micrometer. - THE
CORRECT ANSWER -False. A nanometer is 1,000 times smaller than a
micrometer.
Resolution and contrast are two critical factors that influence your ability
to see an object. Explain each. - THE CORRECT ANSWER -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).
Assuming a fixed ocular, identify the part of the microscope you would
adjust to enhance the magnification of a sample.
A. Objective
B. Condenser
C. Iris diaphragm
D. Eye piece - THE CORRECT ANSWER -A. 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.
,What is the total magnification (relative to your eye) of a sample imaged
with a 20x objective and a 15x eyepiece? Show your math. - THE
CORRECT ANSWER -20 x 15 = 300x magnification
True or False: A cell that is adherent, flat (thin) and unstained is easily
identified using bright field microscopy. - THE 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 - THE CORRECT ANSWER -B
and D. The unaided eye can, on average, clearly resolve objects > 100
μm
For each of the following questions select from the list below the single
best answer:
Phase-Contrast
Dark Field
Fluorescence
Confocal
This type of microscope is best suited for visualizing GFP, RFP and YFP
proteins. - THE CORRECT ANSWER -Fluorescence
This type of microscope can provide detailed images of live cells without
staining. - THE CORRECT ANSWER -Phase-Contrast
,This type of microscope is used to greatly increase the contrast between
samples and background by reflecting light off of the specimen. - THE
CORRECT ANSWER -Dark Field
This type of microscope is capable of capturing images in multiple focal
planes, rendering a specimen in 3D - THE CORRECT ANSWER -
Confocal
Gram-Positive cells appear _______ in color due to a ______
peptidoglycan layer in the cell wall. - THE CORRECT ANSWER -Purple;
Thick
Gram-Negative cells appear _______ in color due to a ______
peptidoglycan layer in the cell wall. - THE CORRECT ANSWER -Pink;
Thin
True or False: Following the decolorization step of the Gram stain,
Gram-Negative bacteria will appear colorless. - THE CORRECT
ANSWER -True. Even together, the LPS and thin peptidoglycan layer
are unable to retain the crystal violet dye during decolorization.
Name one substance capable of chemically fixing cells to a slide. - THE
CORRECT ANSWER -Any of the following are true: Paraformaldehyde,
ethanol or methanol.
You want to observe the size and shape of a cell. What is the easiest
staining technique that you could perform? Name at least one dye you
would use during this process. - THE CORRECT ANSWER -Simple
stain. You could use any of the following: methylene blue, crystal violet,
safranin or fuschin.
You suspect a patient may have TB. Once a sample has been obtained
it is sent off to the lab for an acid-fast stain. If the patient were infected
, with TB, describe what you would expect to see on the stained slide. -
THE CORRECT ANSWER -You would expect to see red cells (TB+) on
a blue background (TB negative)
True or False: If a patient is suspected of having malaria, a Giemsa stain
would be an appropriate differential test to perform. - THE CORRECT
ANSWER -True. Giemsa stains are often used in the clinical setting to
aid in the diagnosis of blood parasites.
The distinctions for Lancefield subgroupings lie in its: (select all that
apply)
A. Catalase activity
B. Carbohydrate composition of antigens
C. Hemolytic activity
D. All of the above - THE CORRECT ANSWER -The distinctions for
Lancefield subgroupings lie in its: (select all that apply)
A. Catalase activity
B. Carbohydrate composition of antigens
C. Hemolytic activity
D. All of the above
True or False: Growth media is best suited for distinguishing between
two similar species of bacteria. - THE CORRECT ANSWER -False.
Growth media is designed to simply support (and not restrict) microbial
growth.
A researcher is asked to determine which of two vials contains E coli
and which contains Salmonella. Knowing both are Gram-Negative while
only one of them is capable of fermenting lactose, which type of media
would be best suited:
A. Growth media
GRADED PRESENTATION // ESSENTIAL MICROBIAL
PHYSIOLOGY CLINICAL APPLICATIONS LAB
DIAGNOSTICS AND PATHOGEN ANALYSIS FOR STUDENT
MASTERY // ACADEMIC YEAR 2025/2026
True or False: A nanometer is longer than a micrometer. - THE
CORRECT ANSWER -False. A nanometer is 1,000 times smaller than a
micrometer.
Resolution and contrast are two critical factors that influence your ability
to see an object. Explain each. - THE CORRECT ANSWER -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).
Assuming a fixed ocular, identify the part of the microscope you would
adjust to enhance the magnification of a sample.
A. Objective
B. Condenser
C. Iris diaphragm
D. Eye piece - THE CORRECT ANSWER -A. 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.
,What is the total magnification (relative to your eye) of a sample imaged
with a 20x objective and a 15x eyepiece? Show your math. - THE
CORRECT ANSWER -20 x 15 = 300x magnification
True or False: A cell that is adherent, flat (thin) and unstained is easily
identified using bright field microscopy. - THE 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 - THE CORRECT ANSWER -B
and D. The unaided eye can, on average, clearly resolve objects > 100
μm
For each of the following questions select from the list below the single
best answer:
Phase-Contrast
Dark Field
Fluorescence
Confocal
This type of microscope is best suited for visualizing GFP, RFP and YFP
proteins. - THE CORRECT ANSWER -Fluorescence
This type of microscope can provide detailed images of live cells without
staining. - THE CORRECT ANSWER -Phase-Contrast
,This type of microscope is used to greatly increase the contrast between
samples and background by reflecting light off of the specimen. - THE
CORRECT ANSWER -Dark Field
This type of microscope is capable of capturing images in multiple focal
planes, rendering a specimen in 3D - THE CORRECT ANSWER -
Confocal
Gram-Positive cells appear _______ in color due to a ______
peptidoglycan layer in the cell wall. - THE CORRECT ANSWER -Purple;
Thick
Gram-Negative cells appear _______ in color due to a ______
peptidoglycan layer in the cell wall. - THE CORRECT ANSWER -Pink;
Thin
True or False: Following the decolorization step of the Gram stain,
Gram-Negative bacteria will appear colorless. - THE CORRECT
ANSWER -True. Even together, the LPS and thin peptidoglycan layer
are unable to retain the crystal violet dye during decolorization.
Name one substance capable of chemically fixing cells to a slide. - THE
CORRECT ANSWER -Any of the following are true: Paraformaldehyde,
ethanol or methanol.
You want to observe the size and shape of a cell. What is the easiest
staining technique that you could perform? Name at least one dye you
would use during this process. - THE CORRECT ANSWER -Simple
stain. You could use any of the following: methylene blue, crystal violet,
safranin or fuschin.
You suspect a patient may have TB. Once a sample has been obtained
it is sent off to the lab for an acid-fast stain. If the patient were infected
, with TB, describe what you would expect to see on the stained slide. -
THE CORRECT ANSWER -You would expect to see red cells (TB+) on
a blue background (TB negative)
True or False: If a patient is suspected of having malaria, a Giemsa stain
would be an appropriate differential test to perform. - THE CORRECT
ANSWER -True. Giemsa stains are often used in the clinical setting to
aid in the diagnosis of blood parasites.
The distinctions for Lancefield subgroupings lie in its: (select all that
apply)
A. Catalase activity
B. Carbohydrate composition of antigens
C. Hemolytic activity
D. All of the above - THE CORRECT ANSWER -The distinctions for
Lancefield subgroupings lie in its: (select all that apply)
A. Catalase activity
B. Carbohydrate composition of antigens
C. Hemolytic activity
D. All of the above
True or False: Growth media is best suited for distinguishing between
two similar species of bacteria. - THE CORRECT ANSWER -False.
Growth media is designed to simply support (and not restrict) microbial
growth.
A researcher is asked to determine which of two vials contains E coli
and which contains Salmonella. Knowing both are Gram-Negative while
only one of them is capable of fermenting lactose, which type of media
would be best suited:
A. Growth media
