Portage Microbiology BIOD171 Exam 5 Questions and
Answers
Question 1
Define the concept of universal precautions.
Correct Answer
Universal precautions means any and all samples, whether known or unknown, are to be treated as potentially hazardous
(or pathogenic) materials.
Question 2
List at least 3 observations a researcher would be sure to note while assessing an unknown microbial sample.
Correct Answer
A lab researcher would be certain to note:
Size and shape
Any observable motility
Gram status (positive or negative)
The presence of any chemical reactions
Changes in color localized to the organism or the surrounding media
Capture (or draw) images of any of the characteristics described above
Page 1 of 13
, Question 3
While observing an unknown sample of limited amounts, a researcher must determine the following observations: (1) the
presence of any motility and (2) its Gram status using the same sample—the liquid sample cannot be divided. Which would
you determine first and why?
Correct Answer
You must determine motility before determining the Gram status. Motility requires a wet mount, while Gram staining
requires heat fixing the sample. If one were to begin with the Gram stain the heat fixation process would kill the
organism, making any observations regarding motility impossible. The correct approach would be to place the liquid
culture on a glass slide and determine its motility status. Next, the same liquid culture can be heat fixed and Gram
stained.
Question 4
A facultative anaerobe is a microorganism capable of growth under what conditions?
Correct Answer
A facultative anaerobe is capable of growth under aerobic (with oxygen) and anaerobic (without oxygen) conditions.
Question 5
As Streptococcus is catalase negative would it thrive or die in the presence of peroxides? Why?
Correct Answer
Streptococcus is catalse negative which means it cannot break down peroxides and if any peroxides are present it would
die.
Page 2 of 13
Answers
Question 1
Define the concept of universal precautions.
Correct Answer
Universal precautions means any and all samples, whether known or unknown, are to be treated as potentially hazardous
(or pathogenic) materials.
Question 2
List at least 3 observations a researcher would be sure to note while assessing an unknown microbial sample.
Correct Answer
A lab researcher would be certain to note:
Size and shape
Any observable motility
Gram status (positive or negative)
The presence of any chemical reactions
Changes in color localized to the organism or the surrounding media
Capture (or draw) images of any of the characteristics described above
Page 1 of 13
, Question 3
While observing an unknown sample of limited amounts, a researcher must determine the following observations: (1) the
presence of any motility and (2) its Gram status using the same sample—the liquid sample cannot be divided. Which would
you determine first and why?
Correct Answer
You must determine motility before determining the Gram status. Motility requires a wet mount, while Gram staining
requires heat fixing the sample. If one were to begin with the Gram stain the heat fixation process would kill the
organism, making any observations regarding motility impossible. The correct approach would be to place the liquid
culture on a glass slide and determine its motility status. Next, the same liquid culture can be heat fixed and Gram
stained.
Question 4
A facultative anaerobe is a microorganism capable of growth under what conditions?
Correct Answer
A facultative anaerobe is capable of growth under aerobic (with oxygen) and anaerobic (without oxygen) conditions.
Question 5
As Streptococcus is catalase negative would it thrive or die in the presence of peroxides? Why?
Correct Answer
Streptococcus is catalse negative which means it cannot break down peroxides and if any peroxides are present it would
die.
Page 2 of 13
