BIOD 171 ESSENTIAL MICROBIOLOGY PORTAGE
LEARNING MODULE 4 EXAM 50 QUESTIONS AND
ANSWERS UPDATED 2026 2027 COURSE VERIFIED
ANSWERS ACTUAL UPDATED PRACTICE
QUESTIONS HIGH-YIELD STUDY GUIDE GRADED
A+
In an attempt to detect the presence of the pathogenic strain of
E. coli O157:H7, a researcher spread a culture onto a
MacConkey agar with failed results. What type of agar should
they (correctly) try next? Why? - CORRECT ANSWER
-The SMAC should be tried next because it can be
differentiated by lactose fermentation and sorbitol fermentation,
both of which can be fermented by the non-pathogenic strain
What is the Gram status (positive or negative) of microbes
growing on Eosin
Methylene Blue (EMB) agar plates? - CORRECT ANSWER -
Gram-
negative because gram positive bacteria growth is restricted by
EMB plates Mannitol salt agar will turn what in color in the
presence of the pathogenic
strain Staphylococcus aureus? - CORRECT ANSWER -Yellow
What is the process of spreading a bacterial culture onto a petri
dish called? -
CORRECT ANSWER -Plating
, Describe the primary advantage of using a petri dish over
growing a liquid culture - CORRECT ANSWER -The primary
advantage is that cells are held into place. When grown in a
nutrient broth, bacterial cells can multiply but are free to move
around in the solution. When grown on agar within a petri dish
they are fixed in a way to form colonies.
T/F: The visualization of colonies on a petri dish represents
bacterial cells that have often multiplied a million times over -
CORRECT ANSWER -True
To form a bacterial colony the initial cell must have
multiplied many "times over, ofen greater than a million, in
order for the naked eye to resolve it.
T/F: The purpose of a quadrant streak is to expand a bacterial
population -
CORRECT ANSWER -False
The purpose of the quadrant streak is to generate individual
colonies such that a single bacterial sample can be isolated
To be considered a pure culture, the sample (1) can be traced
back to a single cell and (2)__________ - CORRECT
ANSWER -free of external contaminants
When performing a quadrant streak, the ample is spread across
the plate in such a way to form what? - CORRECT ANSWER -
A dilution gradient.
LEARNING MODULE 4 EXAM 50 QUESTIONS AND
ANSWERS UPDATED 2026 2027 COURSE VERIFIED
ANSWERS ACTUAL UPDATED PRACTICE
QUESTIONS HIGH-YIELD STUDY GUIDE GRADED
A+
In an attempt to detect the presence of the pathogenic strain of
E. coli O157:H7, a researcher spread a culture onto a
MacConkey agar with failed results. What type of agar should
they (correctly) try next? Why? - CORRECT ANSWER
-The SMAC should be tried next because it can be
differentiated by lactose fermentation and sorbitol fermentation,
both of which can be fermented by the non-pathogenic strain
What is the Gram status (positive or negative) of microbes
growing on Eosin
Methylene Blue (EMB) agar plates? - CORRECT ANSWER -
Gram-
negative because gram positive bacteria growth is restricted by
EMB plates Mannitol salt agar will turn what in color in the
presence of the pathogenic
strain Staphylococcus aureus? - CORRECT ANSWER -Yellow
What is the process of spreading a bacterial culture onto a petri
dish called? -
CORRECT ANSWER -Plating
, Describe the primary advantage of using a petri dish over
growing a liquid culture - CORRECT ANSWER -The primary
advantage is that cells are held into place. When grown in a
nutrient broth, bacterial cells can multiply but are free to move
around in the solution. When grown on agar within a petri dish
they are fixed in a way to form colonies.
T/F: The visualization of colonies on a petri dish represents
bacterial cells that have often multiplied a million times over -
CORRECT ANSWER -True
To form a bacterial colony the initial cell must have
multiplied many "times over, ofen greater than a million, in
order for the naked eye to resolve it.
T/F: The purpose of a quadrant streak is to expand a bacterial
population -
CORRECT ANSWER -False
The purpose of the quadrant streak is to generate individual
colonies such that a single bacterial sample can be isolated
To be considered a pure culture, the sample (1) can be traced
back to a single cell and (2)__________ - CORRECT
ANSWER -free of external contaminants
When performing a quadrant streak, the ample is spread across
the plate in such a way to form what? - CORRECT ANSWER -
A dilution gradient.
