BIOD171 EXAM | Questions and
Answers | 100% Correct (Latest Update
)
1. True or False. The purpose of a quadrant streak is to
produce individual colonies of a bacterial population.
ANS True
2. What is the Gram status (positive or negative) of
microbes growing on Eosin Methylene Blue (EMB) agar
plates? ANS Gram-negative because gram positive
bacteria growth is restricted by EMB plates
3. True or False. The visualization of colonies on a petri
dish represents bacterial cells that have multiplied ~2-3
times. ANS False. When an individual colony is visible
on agar, the bacterial cell has multiplied often a million
times over
4. What is the process of spreading a bacterial culture
onto a petri dish called? ANS Plating
5. True or False. Following the decolorization step of the
Gram stain, Gram-Negative bacteria will appear
colorless. ANS True
6. True or False. A cell that is adherent, flat (thin), and
unstained is easily identified using bright field
1
,microscopy. ANS False. Adherent, flat cells are almost
invisible due to the limits on both resolution and contrast
7. 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. ANS 60x objective x 10x
ocular = 600x magnification
8. True or False. A nanometer is longer than a
micrometer. ANS False. A nanometer is 1000x smaller
than a micrometer
9. This type of microscope uses a specialized condenser
and objective to amplify the slight differences between
cells and background. ANS Phase-contrast
10. True or False. The distinguishing characteristic of
Gram-Negative bacteria is the presence of LPS in the
outer membrane. ANS True
11. In order to visualize individual colonies of bacteria
would you culture your sample in a liquid media or on a
solid (agar) media? Why? ANS Solid (agar) media
because the primary advantage is that cells are held into
place. When grown on agar in a petri dish, it’s fixed in a
way to form colonies. In a nutrient broth, bacterial cells
can multiply but are able to freely move around in the
solution
12. True or False. LB agar is classified as a non-
selective, non-differential media. ANS True
13. This type of microscope is capable of capturing
2
, images in multiple focal planes, rendering a specimen in
3-D. ANS Confocal
14. True or False. If you wish to study the motility of an
organism you cannot heat fix, but you can chemically fix
the specimen. ANS False. Both heat and chemical
fixation strategies will kill the cell, making motility
observation impossible
15. Mannitol salt agar will turn what color in the presence
of the pathogenic strain Staphylococcus aureus? ANS
Yellow
16. True or False. All multicellular microorganisms
classified as Animalia are heterotrophic. ANS True
17. Which type of agar media is best suited to support
the growth of Staphylococcus? ANS Mannitol salt agar
18. True or False. When performing a dilution streak a
new (or sterilized) loop is not required for each phase as
long as the bacterial culture is pure. ANS False. A new
or sterilized loop is absolutely required for each phase
19. In Eosin Methylene Blue (EMB) agar, what color
indicates the presence of E. coli? ANS Metallic Green
20. True or False. A Giemsa stain can be used to
determine the presence of pathogenic bacteria. ANS
True. Pathogenic bacteria would appear pink while non-
pathogenic bacteria would appear purple
21. The function of the lysosome is (select all that apply):
3
Answers | 100% Correct (Latest Update
)
1. True or False. The purpose of a quadrant streak is to
produce individual colonies of a bacterial population.
ANS True
2. What is the Gram status (positive or negative) of
microbes growing on Eosin Methylene Blue (EMB) agar
plates? ANS Gram-negative because gram positive
bacteria growth is restricted by EMB plates
3. True or False. The visualization of colonies on a petri
dish represents bacterial cells that have multiplied ~2-3
times. ANS False. When an individual colony is visible
on agar, the bacterial cell has multiplied often a million
times over
4. What is the process of spreading a bacterial culture
onto a petri dish called? ANS Plating
5. True or False. Following the decolorization step of the
Gram stain, Gram-Negative bacteria will appear
colorless. ANS True
6. True or False. A cell that is adherent, flat (thin), and
unstained is easily identified using bright field
1
,microscopy. ANS False. Adherent, flat cells are almost
invisible due to the limits on both resolution and contrast
7. 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. ANS 60x objective x 10x
ocular = 600x magnification
8. True or False. A nanometer is longer than a
micrometer. ANS False. A nanometer is 1000x smaller
than a micrometer
9. This type of microscope uses a specialized condenser
and objective to amplify the slight differences between
cells and background. ANS Phase-contrast
10. True or False. The distinguishing characteristic of
Gram-Negative bacteria is the presence of LPS in the
outer membrane. ANS True
11. In order to visualize individual colonies of bacteria
would you culture your sample in a liquid media or on a
solid (agar) media? Why? ANS Solid (agar) media
because the primary advantage is that cells are held into
place. When grown on agar in a petri dish, it’s fixed in a
way to form colonies. In a nutrient broth, bacterial cells
can multiply but are able to freely move around in the
solution
12. True or False. LB agar is classified as a non-
selective, non-differential media. ANS True
13. This type of microscope is capable of capturing
2
, images in multiple focal planes, rendering a specimen in
3-D. ANS Confocal
14. True or False. If you wish to study the motility of an
organism you cannot heat fix, but you can chemically fix
the specimen. ANS False. Both heat and chemical
fixation strategies will kill the cell, making motility
observation impossible
15. Mannitol salt agar will turn what color in the presence
of the pathogenic strain Staphylococcus aureus? ANS
Yellow
16. True or False. All multicellular microorganisms
classified as Animalia are heterotrophic. ANS True
17. Which type of agar media is best suited to support
the growth of Staphylococcus? ANS Mannitol salt agar
18. True or False. When performing a dilution streak a
new (or sterilized) loop is not required for each phase as
long as the bacterial culture is pure. ANS False. A new
or sterilized loop is absolutely required for each phase
19. In Eosin Methylene Blue (EMB) agar, what color
indicates the presence of E. coli? ANS Metallic Green
20. True or False. A Giemsa stain can be used to
determine the presence of pathogenic bacteria. ANS
True. Pathogenic bacteria would appear pink while non-
pathogenic bacteria would appear purple
21. The function of the lysosome is (select all that apply):
3
