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WorksheetsUnit 3 lab
Total questions: 34
Worksheet time: 27mins
A pure culture _____________.
is sterile
contains no synthetic ingredients
contains only one organism
does not contain genetically modifies organisms
In microbiology, what is a contaminant?
An organisms growing in the media
The organisms that have been inoculated in the media
An unwanted cell growing in the media
An unwanted chemical altering the chemical composition of the media.
Which isolation method is easy, but not quantitative?
Spread plate method
Streak plate method
Pour plate method
None are quantitative
Which isolation method is quantitative, but could kill heat sensitive bacteria?
Pour plate method
Streak plate method
Spread plate method
Autoclave
What is a disadvantage of the spread plate method?
Is quantitative and will be milder on heat sensitive bacteria.
It is not quantitative.
It is too harsh on heat sensitive bacteria.
It uses a lot of material and can increase the chances of contamination.
What can you say from this culture?
It contains two types of cells
It contains at least two types of cells
It is a pure culture
The cells ferment mannitol.
What can you say from this culture?
It contains at least one type of cell
It contains more than one type of cell.
The streak plate technique was unsuccessful.
There are too many colonies to count.
What is the range of colonies that you can use to calculate the original colony forming count on a spread plate?
10-100
50-500
25-250
5-250
Assume you perform a serial 1/10 dilution procedure as we did in the lab.
You have 29 colonies in the second dilution. What is the CFU count in the original sample?
The answer cannot be calculated with the information given
29 CFU/ml
290 CFU/ml
2900 CFU/ml
Assume you perform a serial 1/10 dilution procedure as we did in the lab.
You have 19 colonies in the fourth dilution. What is the CFU count in the original sample?
The answer cannot be calculated with the information given
19 CFU/ml
190,000 CFU/ml
1,900,000 CFU/ml
Assume you perform a serial 1/10 dilution procedure as we did in the lab.
You have 20 red colonies and 30 green colonies in the third dilution. What is the TOTAL CFU count in the original sample?
The answer cannot be calculated with the information given.
50,000 CFU/ml
30 CFU/ml
5,000 CFU/ml
MSA is selective for ___________.
Halophiles
Capnophiles
Thermophiles
Coliforms
What makes MSA differential?
Mannitol and phenol red
Mannitol and congo red
Mannose and congo red
Lactose and Eosin
What makes EMB agar selective?
Eosin and methilene blue
Lactose
Agar
Embosin
If something grows on EMB agar, the cell must be __________.
Halophile
Gram negative
Coliform
Capnophile
Which of the following will grow on MSA but not change the media to yellow?
Staphylococcus aureus
Staphylococcus epidermidis
Bacillus subtillis
Mycobacterium tuberculosis
Blood agar is a(n)____________ media for Streptococcus species.
Selective and differential
Toxic
Enrichment and differential
Enrichment
What type of hemolysis is shown?
Beta hemolysis
Alpha hemolysis
Gama hemolysis
non-hemolytic
We replicated oral conditions when growing mouth microbes in the lab. Which condition is NOT one of them
High CO2
High sugar
High iron and nutrients
High oxygen
Why do high sugar intake facilitate dental decay?
Promotes the formation of plaque
Promotes the production of acids by fermentation.
Enhances attachment by promoting the production of capsules
All are correct
A media supplemented with phenylalanine is needed to grow special strains of E. coli. What type of media is this?
Enrichment
Differential
Selective
Complex
Beta Hemolysis
Alpha Hemolysis
Gamma Hemolysis
Streptococcus mutants
Streptococcus pyogenes
Streptococcus salivarius
Which one is more likely a pathogen causing strep-throat?
A
B
C
D
Normal microbiota _____________.
Is never pathogenic
Can become pathogenic
Is in every part of your body
cannot be cultured in a lab
A media that contains high concentration of NAD+ and coagulation factors to promote the growth of Haemophilus bacteria is a(n) ____________ media.
complex
enrichment
differential
selective
What cell is most likely growing on this MSA plate?
Escherichia coli
Staphylococcus epidermidis
Streptococcus pyogenes
Staphylococcus aureus
What cell grows like the colony on the LEFT side of the EMB agar plate?
Alcaligenes faecalis
Escherichia coli
Bacillus subtilis
Candida albicans
You have a gram positive, endospore forming, lactose fermenter bacterium.
How will it behave in EMB agar?
Will grow and turn media black/green.
Will grow and turn media yellow
Will not grow.
Will grow with no change.
What will make gram negative cells more resistant to the toxicity of EMB agar?
Outer membrane
Endospore
Thick peptidoglycan
Mycolic acid
Gal-x media uses a substrate that turns blue in the presence of the enzyme beta-galactosidase (β-gal). Only β-gal producing cells will turn blue. This is an example of a (n) _________ media
Differential
Selective
Defined
Enrichment.
You want to see if there are psychrophilic bacteria in your samples. What can you do to select for them?
grow them in cold
use MSA agar
use serial dilution
treat with an antibiotic
Take your time. Match the following cells with their growth and fermentation profile.
Does not grow in MSA
Does not grow on EMB
Bacillus subtilis
Grows on EMB, but no change in color
Alcaligenes faecalis
Grows on EMB and changes to black
Escherichia coli
Grows on MSA and turns it yellow
Staphylococcus aureus
Grows on MSA but does not change it
Staphylococcus epidermidis
What is the role of agar in media?
Solidifying agent
Differential agent
Carbon source
All are corect
