BIOD 171: FINAL EXAM
LATEST QUESTIONS AND
ANSWERS 2025 2026
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. 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
2. 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
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
1. Label the following unmarked microscope components (numbered
arrows) by matching it with the components provided
(letters).
1F- eyepiece
2D- neck
3B- fine adjustment knob
4G- objective
5A- stage
6H- base
This type of microscope is best suited for visualizing GFP, RFP, and YFP
proteins.
Fluorescence
This type of microscope utilizes ultraviolet (UV) light to illuminate stained
objects.
Fluorescence
This type of microscope uses a specialized condenser and objective to
amplify the slight differences between cells and background.
Phase-contrast
This type of microscope enhances contrast between specimen and
background but does not permit the visualization of intracellular
structures.
Dark Field
,This type of microscope uses neither halogen nor UV light sources but
rather lasers to illuminate stained cells in high resolution.
Confocal
This type of microscope is capable of capturing images in multiple focal
planes, rendering a specimen in 3-D
Confocal
Identify what type of electron microscope was used to capture the following
image and explain your choice.
(picture labeled B)
The image was captured using a Scanning Electron Microscope (SEM). The
above image shows the trademark 'shell' image (no subcellular organelles are
visible) reminiscent of SEM. Only TEM is capable of visualizing subcellular
substrucutres.
Identify what type of electron microscope was used to capture the following
image and explain your choice.
(picture labeled A)
The above image is captured via a Transmission Electron Microscope (TEM).
Even at 20nm resolution (inset image), subcellular substructures are still visible.
The image lacks the outside 'shell' only appearance of SEM.
Gram-Positive cells appear [answer1] in color due to a [answer2]
peptidoglycan layer in the cell wall.
1. Purple
2. Thick
Gram-Negative cells appear [answer1] in color due to a [answer2]
peptidoglycan layer in the cell wall.
1. Pink
2. Thin
True or False: A Giemsa stain can be used to determine the presence of
pathogenic bacteria.
, True
Pathogenic bacteria would appear pink while non-pathogenic bacteria would
appear purple.
True or False: The distinguishing characteristic of Gram-Negative bacteria
is the presence of LPS in the outer membrane.
True
True or False: Following the decolorization step of the Gram stain, Gram-
Negative bacteria will appear colorless.
True
True or False: If you wish to study the motiity of an organism you cannot
heat fix, but you can chemically fix the specimen
False
Both heat and chemical fixation strategies will kill the cell, making motility
observation impossible
Name one substance capable of chemically fixing cells to a slide.
Any of the following are true: Paraformaldehyde, ethanol or methanol.
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.
I would expect to see red cells (TB+) on a blue background (TB negative).
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.
Simple stainining and crystal violet could be used.
True or False: If a patient is suspected of having malaria, a Giemsa stain
would be an appropriate differential test to perform.
LATEST QUESTIONS AND
ANSWERS 2025 2026
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. 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
2. 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
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
1. Label the following unmarked microscope components (numbered
arrows) by matching it with the components provided
(letters).
1F- eyepiece
2D- neck
3B- fine adjustment knob
4G- objective
5A- stage
6H- base
This type of microscope is best suited for visualizing GFP, RFP, and YFP
proteins.
Fluorescence
This type of microscope utilizes ultraviolet (UV) light to illuminate stained
objects.
Fluorescence
This type of microscope uses a specialized condenser and objective to
amplify the slight differences between cells and background.
Phase-contrast
This type of microscope enhances contrast between specimen and
background but does not permit the visualization of intracellular
structures.
Dark Field
,This type of microscope uses neither halogen nor UV light sources but
rather lasers to illuminate stained cells in high resolution.
Confocal
This type of microscope is capable of capturing images in multiple focal
planes, rendering a specimen in 3-D
Confocal
Identify what type of electron microscope was used to capture the following
image and explain your choice.
(picture labeled B)
The image was captured using a Scanning Electron Microscope (SEM). The
above image shows the trademark 'shell' image (no subcellular organelles are
visible) reminiscent of SEM. Only TEM is capable of visualizing subcellular
substrucutres.
Identify what type of electron microscope was used to capture the following
image and explain your choice.
(picture labeled A)
The above image is captured via a Transmission Electron Microscope (TEM).
Even at 20nm resolution (inset image), subcellular substructures are still visible.
The image lacks the outside 'shell' only appearance of SEM.
Gram-Positive cells appear [answer1] in color due to a [answer2]
peptidoglycan layer in the cell wall.
1. Purple
2. Thick
Gram-Negative cells appear [answer1] in color due to a [answer2]
peptidoglycan layer in the cell wall.
1. Pink
2. Thin
True or False: A Giemsa stain can be used to determine the presence of
pathogenic bacteria.
, True
Pathogenic bacteria would appear pink while non-pathogenic bacteria would
appear purple.
True or False: The distinguishing characteristic of Gram-Negative bacteria
is the presence of LPS in the outer membrane.
True
True or False: Following the decolorization step of the Gram stain, Gram-
Negative bacteria will appear colorless.
True
True or False: If you wish to study the motiity of an organism you cannot
heat fix, but you can chemically fix the specimen
False
Both heat and chemical fixation strategies will kill the cell, making motility
observation impossible
Name one substance capable of chemically fixing cells to a slide.
Any of the following are true: Paraformaldehyde, ethanol or methanol.
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.
I would expect to see red cells (TB+) on a blue background (TB negative).
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.
Simple stainining and crystal violet could be used.
True or False: If a patient is suspected of having malaria, a Giemsa stain
would be an appropriate differential test to perform.
