MCB101 Exam III

125 cards

Flashcards are for an introductory microbiology lab. They cover multiple topics form different kinds of bacteria to different biochemical tests, etc. Covers labs 15-19.


 
  
Created Nov 22, 2008
by
kiirarodriguez

 

 
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  Side A   Side B
1
microorganisms that cause illness or disease
 
pathogens
2
3 places foodborne illnesses come from
 
presence of pathogens in IT, the production of a toxin by a path. in the gut, ingestion of...
3
most foodborne illness result in ____, but can be especially dangerous in _____.
 
diarrhea children, elderly and immunocompromised
4
found in animal intestines especially poultry, transmitted in uncooked meat
 
camplyobacter jejuni
5
an infection of camplyobacter jejuni causes:
 
fever, headache, muscle pain, diarrhea, abdominal pain and nausea
6
found in intestines of birds or mammals, transmitted in undercooked eggs,meat, and milk
 
salmonella
7
a salmonells infection causes:
 
fever, chills, aches, abdominal pain, and may be serious if it spreads to blood
8
found in the intestines of mammals(cattle)
 
Escherichia coli
9
an e.coli infection causes:
 
diarrhea, dysentery, kidney failure, blindness, paralysis, death
10
most foodborne illnesses are caused by:
 
fecal-oral cycle pathogens
11
the USDA's standard for maximum permissible number of bacterial cells in hamburger is:10
 
10^7 cells/gram
12
hamburger should be cooked to:
 
160 degrees Farenheit
13
in the hamburger contamination lab, what type of medium did we use?
 
3M petrifilm cultures to get a total aerobic bacteria count and a coliform count
14
What volume of liquid is used to inoculate a 3M Petrifilm culture?
 
1.0 ml
15
A 0.1ml aliquot of a 10-2 dilution of the sample gives 90 colonis.What is the concentration...
 
9.0 x 10^2
16
On a 3M Petrifilm culture for E.coli, a colony of a fecal coliform appears:
 
blue and is associated with gas bubbles
17
What is the term for microorganisms that can grow and cause food spoilage in the refrigerator?
 
psychrophillic
18
What type of microorganism is Penicillium?
 
fungus (mold)
19
The food preservative sodium nitrite is:
 
an inhibitor of pyruvate-ferrodoxin oxidoreductase
20
Nitrites are added to meat because it gives meat a pink color and inhibits:
 
Clostridium botulinum
21
How do propionate and benzoate prevent microbial growth?
 
They increase the proton concentration of the cytoplasm in microbes.
22
Which one of the following substances is not classified as a disinfectant? bleach, alcohol,...
 
alcohol
23
An antiseptic is
 
an antimicrobial substance that is used to kill or inhibit microorganisms on the skin
24
chemical disinfectants are more lethal to bacteria at ______
 
higher concentrations
25
____ was used as a disinfectant in hospitals for many years.
 
phenol
26
The Snyder Test is used to:
 
check for high numbers of glucose-fermenting, acid-tolerant bacteria in saliva.
27
Snyder Test Agar will turn fully yellow only if the pH drops below:
 
3.8
28
In ethanol fermentation yeast produce one molecule of ___ for every molecule of ethanol they...
 
CO2
29
Both ethanol and lactic acid can inhibit:
 
the growth of undesirable microorganisms in food products.
30
The predominant sugar found in grape juice is:
 
sucrose
31
The production of yogurt is an example of:
 
a microbial succession that primarily involves two species of bacteria.
32
process of yogurt production:
 
scald milk to 80C, allow to cool below 65C, add commercial yogurt, incubate at 43C
33
if 100 grams of sugar is converted to ethanol in 100% efficient reaction, the yeast produces:
 
51 grams of ethanol and 49 grams of carbon dioxide
34
Yogurt production primarily involves:
 
the fermentation of milk sugar,lactose, to produce lactic acid.
35
What two bacteria are used to make yogurt?
 
Lactobacillus bulgaricus and Streptococcus thermophilus
36
nitrite converted to nitrate is:
 
an oxidation reaction
37
ammonia converted to nitrite is:
 
an oxidation reaction
38
nitrate converted to elemental nitrogen (N2) is:
 
a reduction reaction
39
elemental nitrogen (N2) converted to ammonia is:
 
a reduction reaction
40
The oxidation of ammonia to nitrate is called:
 
nitrification
41
Nitrosococcus bacteria can produce energy by oxidizing:
 
ammonia to nitrate
42
Some strains of Pseudomonas bacteria can reduce:
 
nitrates to nitrogen gas
43
The enzyme urease breaks down urea to:
 
ammonia and CO2
44
The breakdown of amino acids and other nitrogen-containing organic compounds to release ammonia...
 
mineralization
45
Trommsdorf reagents produce a ____ color when they react with nitrite (NO2-).
 
dark blue inky
46
Trommsdorf reagent ___ can burn your skin or cause holes to appear in your clothing.
 
II
47
For the nitrate reductase test, a color change to blue after the addition of zinc indicates...
 
NEGATIVE test result (nitrate was not reduced by the bacteria).
48
For the ammonia oxidation test, a color change to blue after addition of zinc indicates a:
 
POSITIVE test. (Bacteria oxidized the ammonia completely to nitrate.)
49
Trommsdorf reagents do not react with:
 
ammonium
50
Nitrification is also called:
 
ammonia oxidation
51
Nitrification is a two-step process. ____ carries out the first step while ____ carries out...
 
Nitrosomonas,Nitrosococcus, & Nitrosospirina/ nitrobacter,nitrosococcus, and nitrospira
52
Nitrification is an:
 
aerobic process
53
nitrification ____ energy (ATP)
 
produces
54
Denitrification is an:
 
anaerobic process
55
Mammals excrete excess nitrogen primarily in the form of:
 
urea
56
most bacteria and aquatic animals excrete excess nitrogen in the form of:
 
ammonia
57
The main carbon source in the ammonia broth used in Experiment 19C is:
 
carbonate
58
The carbon source in nitrate broth (Ex. 19b) is:
 
a mixture of organic compounds
59
The only organisms that can convert elemental nitrogen (N2) to organic forms are:
 
certain prokaryotes
60
why is hamburger especially subject to contamination by pathogens?
 
the chopping process mixes anny surface bacteria that are present as well as air in with the...
61
name the bacteria that cause foodborne illness:
 
camplyobacter jejuni, clostridium botulinum, clostridium perfringens, e.coli, salmonella, listeria...
62
for hambuger contamination lab, what tubes did you use for the uncooked meat and what were...
 
three 9.9ml and one 9.0ml tubes of saline, 10^-3, 10^-5, 10^-7, and 10^-6
63
in hamburger contamination lab, what tube did you use for the 120 degree meat and the 160 degree...
 
9.9ml saline tube for the 10^-3 120 degree, and 9.0ml saline tube for the 10^-2 160 degree
64
at what temperature do you incubate the 3M petrifilms?
 
37 degree C
65
how do you calculate the total number of cell/gram of meat?
 
dilution facter X number of colonies
66
spoilage from microorganisms causes a loss of up to ___% of all food grown for human consumption
 
40%
67
small organic acids from carbohydrates can cause food to tast ____.
 
sour
68
longer chain fatty acids made ffrom the breakdown of fats can cause a food to taste ____.
 
rancid
69
the breakdown of proteins can yield ammonia, amines, and hydrogen sulfide that make food ____.
 
putrid
70
physical methods for controlling microbial growth on food:
 
heat (dry,moist, or pasteurization), filtration, desiccation, osmotic pressure and radiation...
71
sulfer-based preservatives
 
sulfites
72
when looking at the diameter of a mold colony:
 
the smaller the diameter, the more effective the preservative was
73
a paper disk is soaked with a substance and placed on the surface of an agar medium that has...
 
disk diffusion test
74
factors that affect the size of the zone of inhibition observed in a disk diffusion test
 
concen. of the antimicrobial agent, substance being tested,species of microorganism tested,rate...
75
what fermentable sugar and pH indicator dye are in the Snyder test agar?
 
dextrose (glucose), bromcresol green
76
difference between snyder test agar and OF-glucose agar
 
starting pH of snyder is more acidic (4.8), snyder will not turn yellow until it reaches a...
77
from of anaerobic metabolism in which the terminal electron acceptor, or oxidizing agent, is...
 
fermentation
78
process in wine production where dead yeast cells settle to bottom and are transferred to different...
 
racking
79
what does scalding the milk do in yogurt production?
 
it will kill any contaminating bacteria, drive off oxygen to enhance anaerobic conditions,...
80
how do you calculate to mass of alcohol produced
 
multiply the mass of carbon dioxide lost by 1.045
81
the conversion of atmospheric nitrogen (N2) to ammonia is caled:
 
nitrogen fixation
82
use of nitrogen or ammonia by incorporating into amino acids or proteins, opposite of mineralization
 
nitrogen assimilation
83
process of reducing nitrate to ammonia except that nitrogen is not lost from the soil
 
assimilatory nitrate reduction
84
nitrogen fixation is catalyzed by the enzyme:
 
nitrogenase
85
chemistry of trommsdorf reagents
 
sulfuric acid in II react with nitrite to produce nitrous acid which then reacts w/ iodide...
86
a yellow-orange result for urea broth indicates:
 
a negative result, does not degrade urea to ammonia
87
a bright pinkish-red result for urea broth indicates:
 
a positive result, degrades urea to ammonia
88
for hamburger lab, TA prepares the 10^-1 sample by:
 
mixing 10G of hamburger with 90ml of sterile saline
89
what organism was used to contaminate hamburger?
 
e.coli
90
for the aerobic plate count petrifilms, you use the ____ side of the spreader to distribute...
 
recessed
91
for the viable plate count, what volume do you spread on the petri plates?
 
0.1ml
92
to estimate the number of colonies on aerobic petrifilms:
 
count the number of colonies in 2 squares, average them, and multiply by 20
93
how many petri plates do you use for ex. 16 (food preservatives)?
 
8
94
how much 2% propionate stock solution should you add tot he petri dish in order to get a final...
 
3.5ml
95
how long do you wait after mixing agar w/ preservatives before moving or inoculating the plate?
 
15 to 20 minutes, then inoculate
96
what technique should be used to inoculate potato dextrose agar w/ penicillium?
 
place a drop in the center of the plate and allow to dry
97
penicillin and tetracycline are:
 
antibiotics
98
alcohol, tincture of iodine, and bactine are:
 
antispetics
99
for ex.17 you prepare two plates of:
 
s.epidermis and e.coli
100
the negative control for ex. 17 is:
 
a drop of water
101
for ex. 17, how much solution do you add to the plates to test?
 
5 microliters
102
for the snyder test, what do you do to distribute sample throughout tube?
 
roll gently between hands
103
snyder test is incubated for:
 
more than 25 hours
104
sugar used in agar medium for growing lactic acid:
 
lactose
105
sugar used in PDA, the agar for growing yeasts, is:
 
glucose
106
how much sugar is present in 8oz. of Welch's grape juice?
 
40 grams
107
how much sugar do you add to the grape juice?
 
30 grams
108
how much warm water do you use to activate the yeast?
 
50ml
109
how much yeast do you put into the grape juice?
 
2-3 grams
110
on day 1 of wine production, you take a sterile loop of the mixture and:
 
streak a PDA plate
111
what days do you check pH for wine production?
 
day 1 and 5
112
what days do you calculate ethanol production for wine ex.?
 
day 5
113
what days do you smell the mixture to detect ethanol production in wine?
 
days 2,3,4 and 5
114
what days do you observe the bottle of wine to detect gas?
 
days 2,3,4 and 5
115
metallic zinc can reduce nitrate to:
 
nitrite
116
when setting up urease test in 19a, you inoculate urea broth with:
 
4 loopfuls
117
used in 19b to inoculate both nitrate and PBE broths but not in 19a:
 
pseudomonas aeuignosa
118
show a positive result in urease test:
 
proteus vulgaris
119
used to inoculate 2 tubes of ammonia broth in 19c, one gets air and one does not:
 
soil
120
shows a negative result in the urease test:
 
serratia marcescens
121
linear plots plot:
 
Log AU vs. time
122
semi-log plots plot:
 
AU vs. time
123
takes over when the pH drops below 5 in yogurt production:
 
lactobacillus bulgaricus
124
gros most udring the late stage of yogurt production:
 
lactobacillus bulgaricus
125
glutamic acid is made from alpha-keto-glutarate plus ammonia:
 
nitrogen assimilation


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