BIOD 171 MODULE 3 EXAMINATION TEST
COMPLETE SOLVED QUESTIONS
◉ 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
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
◉ 1. Label the following unmarked microscope components
(numbered arrows) by matching it with the components provided
(letters).
Answer: 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.
Answer: Fluorescence
◉ This type of microscope utilizes ultraviolet (UV) light to
illuminate stained objects.
Answer: Fluorescence
◉ This type of microscope uses a specialized condenser and
objective to amplify the slight differences between cells and
background.
Answer: Phase-contrast
◉ This type of microscope enhances contrast between specimen
and background but does not permit the visualization of
intracellular structures.
Answer: Dark Field
◉ This type of microscope uses neither halogen nor UV light
sources but rather lasers to illuminate stained cells in high
resolution.
Answer: Confocal
,◉ This type of microscope is capable of capturing images in
multiple focal planes, rendering a specimen in 3-D
Answer: Confocal
◉ Identify what type of electron microscope was used to capture
the following image and explain your choice.
(picture labeled B)
Answer: 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)
Answer: 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.
Answer: 1. Purple
2. Thick
, ◉ Gram-Negative cells appear [answer1] in color due to a
[answer2] peptidoglycan layer in the cell wall.
Answer: 1. Pink
2. Thin
◉ True or False: A Giemsa stain can be used to determine the
presence of pathogenic bacteria.
Answer: 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.
Answer: True
◉ True or False: Following the decolorization step of the Gram
stain, Gram-Negative bacteria will appear colorless.
Answer: 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
Answer: False
COMPLETE SOLVED QUESTIONS
◉ 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
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
◉ 1. Label the following unmarked microscope components
(numbered arrows) by matching it with the components provided
(letters).
Answer: 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.
Answer: Fluorescence
◉ This type of microscope utilizes ultraviolet (UV) light to
illuminate stained objects.
Answer: Fluorescence
◉ This type of microscope uses a specialized condenser and
objective to amplify the slight differences between cells and
background.
Answer: Phase-contrast
◉ This type of microscope enhances contrast between specimen
and background but does not permit the visualization of
intracellular structures.
Answer: Dark Field
◉ This type of microscope uses neither halogen nor UV light
sources but rather lasers to illuminate stained cells in high
resolution.
Answer: Confocal
,◉ This type of microscope is capable of capturing images in
multiple focal planes, rendering a specimen in 3-D
Answer: Confocal
◉ Identify what type of electron microscope was used to capture
the following image and explain your choice.
(picture labeled B)
Answer: 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)
Answer: 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.
Answer: 1. Purple
2. Thick
, ◉ Gram-Negative cells appear [answer1] in color due to a
[answer2] peptidoglycan layer in the cell wall.
Answer: 1. Pink
2. Thin
◉ True or False: A Giemsa stain can be used to determine the
presence of pathogenic bacteria.
Answer: 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.
Answer: True
◉ True or False: Following the decolorization step of the Gram
stain, Gram-Negative bacteria will appear colorless.
Answer: 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
Answer: False
