Microbio 4000 Lab 8 Questions and
Answers.
In exercise 3.3 to examine if biofilm is formed a ____ will be perform
A: stain to envision capsules
B: simple stain
C: differential stain
D: stain to envision endospores - Answer B: simple stain
Bacteria belonging to the genera Bacillus and Clostridium are a problem when it comes to
sterilizing media, equipment, etc., because.....
A: their cell walls contain mycolic acid
B: they have an outer membrane
C: they produce endospores
D: they produce vegetative cells - Answer C: they produce endospores
True or False...Endospores are more resistant to heat and UV irradiation compared to vegetative
cells - Answer true
An organism was to inoculated media containing the various salt concentrations you used in lab.
The organism grew in 0%, 5%, and 10% NaCl. How would you classify this organism?
A: the organism is not salt tolerant
B: the organism is both a halophile and is salt tolerant
C: the organism is not a halophile
D: the organism is salt tolerant - Answer D: the organism is salt tolerant
Which of the three organism do you expect to see growing on PIA medium?
A: both E. coli and P. fluorescens
B: Bacillus subtillis
C: Escherichia coli
D: pseudomonas fluorescens - Answer D: pseudomonas fluorescens
, Which component of MacConkey agar selects against gram positive bacteria?
A: lactose
B: neutral red
C: crystal violet - Answer C: crystal violet
Why should you perform a Grain stain of the pure unknown cultures in this lab period?
A: this is the last change you will have to take a sample of your culture to do gram stain
B: to verify that you have the correct organism with the correct Gram status on the plate
C: to verify that your plate has a pure culture
D: to determine which biochemical tests to use - Answer B: to verify that you have the
correct organism with the correct Gram status on the plate
You have determined that one of your unknown organisms is a Gram-negative bacillus. Lactose
broth would be the best medium to use to begin the identification process of this organism.
A: yes, most organisms can use lactose, so you should get good results
B: yes, since it divides the G G- bacilli into two groups
C: no, there are other tests on the list that would split the G- bacilli into more than two groups
D: no, it is nearly impossible to distinguish acid and gas production from a negative result in this
medium - Answer C: no, there others tests on the on the list that would split G- bacilli into
more than two groups
In which pH-adjusted medium would you expect a neutrophile to grow best?
A: pH 7
B: pH 10
C: should grow equally well in all pH adjusted media
D: pH 4 - Answer A: pH 7
In exercise 6-4, you are asked to use your saline suspension to inoculate a tube of TSB before
you heat the suspension in the water bath. Why?
A: to preserve a sample in case the cells in the saline suspension are killed in the water bath
Answers.
In exercise 3.3 to examine if biofilm is formed a ____ will be perform
A: stain to envision capsules
B: simple stain
C: differential stain
D: stain to envision endospores - Answer B: simple stain
Bacteria belonging to the genera Bacillus and Clostridium are a problem when it comes to
sterilizing media, equipment, etc., because.....
A: their cell walls contain mycolic acid
B: they have an outer membrane
C: they produce endospores
D: they produce vegetative cells - Answer C: they produce endospores
True or False...Endospores are more resistant to heat and UV irradiation compared to vegetative
cells - Answer true
An organism was to inoculated media containing the various salt concentrations you used in lab.
The organism grew in 0%, 5%, and 10% NaCl. How would you classify this organism?
A: the organism is not salt tolerant
B: the organism is both a halophile and is salt tolerant
C: the organism is not a halophile
D: the organism is salt tolerant - Answer D: the organism is salt tolerant
Which of the three organism do you expect to see growing on PIA medium?
A: both E. coli and P. fluorescens
B: Bacillus subtillis
C: Escherichia coli
D: pseudomonas fluorescens - Answer D: pseudomonas fluorescens
, Which component of MacConkey agar selects against gram positive bacteria?
A: lactose
B: neutral red
C: crystal violet - Answer C: crystal violet
Why should you perform a Grain stain of the pure unknown cultures in this lab period?
A: this is the last change you will have to take a sample of your culture to do gram stain
B: to verify that you have the correct organism with the correct Gram status on the plate
C: to verify that your plate has a pure culture
D: to determine which biochemical tests to use - Answer B: to verify that you have the
correct organism with the correct Gram status on the plate
You have determined that one of your unknown organisms is a Gram-negative bacillus. Lactose
broth would be the best medium to use to begin the identification process of this organism.
A: yes, most organisms can use lactose, so you should get good results
B: yes, since it divides the G G- bacilli into two groups
C: no, there are other tests on the list that would split the G- bacilli into more than two groups
D: no, it is nearly impossible to distinguish acid and gas production from a negative result in this
medium - Answer C: no, there others tests on the on the list that would split G- bacilli into
more than two groups
In which pH-adjusted medium would you expect a neutrophile to grow best?
A: pH 7
B: pH 10
C: should grow equally well in all pH adjusted media
D: pH 4 - Answer A: pH 7
In exercise 6-4, you are asked to use your saline suspension to inoculate a tube of TSB before
you heat the suspension in the water bath. Why?
A: to preserve a sample in case the cells in the saline suspension are killed in the water bath
