March 1st PL Quiz

Question 1

what is phenol red broth

Answer 1

a differential test medium prepared as a base to which a carbohydrate is added

Question 2

what is included in the base medium

Answer 2

peptone and phenol red

Question 3

what does phenol red do

Answer 3

it is a pH indicator

Question 4

when is phenol red yellow

Answer 4

when the pH is below 6.8

Question 5

when is phenol red pink

Answer 5

when the pH is above 7.4

Question 6

what is added to each tube as an indicator of gas production

Answer 6

an inverted durham tube

Question 7

what is indicated by a bubble in the tube where the broth was displaced

Answer 7

gas production from fermentation

Question 8

what is PR broth used for

Answer 8

to differentiate members of Enterobacteriaceae and to distinguish them from other gram negative rods
also differentiates between gram positive fermenters

Question 9

the metabolic process by which an organic molecule acts as an electron donor and one or more of its organic products acts as the final electron acceptor

Answer 9

carbohydrate fermentation

Question 10

what does the fermentation of glucose begin with

Answer 10

the production of pyruvate

Question 11

what do MR and VP stand for

Answer 11

Methyl red and Voges-Proskauer broth

Question 12

what are MR and VP

Answer 12

combination medium

Question 13

what do MR and VP contain

Answer 13

peptone, glucose and phosphate buffer

Question 14

what is the MR test designed to do

Answer 14

detect organisms capable of performing a mixed acid fermentation ad produce stable end products

Question 15

what is unique about the acids produced by organisms capable of performing a mixed acid fermentation

Answer 15

they tend to be stable whereas acids produced by other organisms tend to be unstable

Question 16

what is mixed acid fermentation verified by

Answer 16

the addition of methyl red indicator dye following incubation

Question 17

at what pH is methyl red actually red

Answer 17

at pH 4.4

Question 18

what was the VP test designed for

Answer 18

organisms that are able to ferment glucose but quickly convert their acid products to acetoin and butanediol

Question 19

how does adding the VP reagents determine the result

Answer 19

they oxidize the acetoin to diacetyl which reacts with guanidine nuclei and produces a red color

Question 20

what color is a positive VP result

Answer 20

red

Question 21

what was the citrate utilization test designed for

Answer 21

to differentiate members of the Enterobacteriaceae

Question 22

what are all facultative anaerobes

Answer 22

Eneterobacteriaceae

Question 23

this means they have the ability to ferment carbohydrates, aerobically respire, and have a citric acid cycle

Answer 23

facultative anaerobes

Question 24

what does the citrate utilization test tell us

Answer 24

about the ability of organisms to use citrate as their sole carbon source and perform citrate fermentation

Question 25

what does it mean to be a defined medium

Answer 25

the amount and source of all ingredients are carefully controlled

Question 26

what is an example of a defined medium

Answer 26

simmons citrate agar

Question 27

what will happen t bacteria that do not possess citrate permease

Answer 27

they will not grow on this medium(ammonium)

Question 28

citrate positive bacteria hydrolyze citrate into oxaloacetate and acetate using what

Answer 28

citrate lyase

Question 29

what is oxaloacetate converted to

Answer 29

pyruvate

Question 30

what can some bacterial fermentation pathways make

Answer 30

ATP and reducing power

Question 31

why do citrate positive organisms occasionally grow on the simmons citrate slant without producing a change in color

Answer 31

due to incomplete incubation

Question 32

what are citrate slants typically inoculated with

Answer 32

lightly with inoculating needle

Question 33

this is used to determine the ability of an organism to use citrate as its sole source of carbon

Answer 33

citrate utilization test

Question 34

how do you know if citrate is utilized(positive)

Answer 34

it will turn blue

Question 35

what is the SIM medium used for

Answer 35

determination of three bacterial activities: | sulfur reaction, indole production from tryptophan, and motility

Question 36

both systems produce what

Answer 36

hydrogen sulfide gas

Question 37

what is an indication of a sulfur reaction and a positive test

Answer 37

any blackening of the medium

Question 38

what is indole production in the medium made possible by

Answer 38

the presence of tryptophan

Question 39

what can be detected by the addition of kovac's reagent

Answer 39

tryptophan hydrolysis in the SIM medium

Question 40

what indicates a positive reaction and the presence of tryptophanase

Answer 40

the formation of red color in the reagent layer

Question 41

what is determination of motility in SIM medium made possible by

Answer 41

the reduced agar concentration and the method of inoculation

Question 42

what does hazziness/fuzziness usually indicate

Answer 42

motility

Question 43

what does TSIA stand for

Answer 43

triple sugar iron agar

Question 44

TSIA is a rich medium designed to differentiate bacteria on the basis of what

Answer 44

glucose fermentation, lactose fermentation, sucrose fermentation, and sulfur reduction

Question 45

what is the pH indicator

Answer 45

Phenol red

Question 46

what is the hydrogen sulfide indicator

Answer 46

iron in the ferrous sulfate

Question 47

when TSIA is inoculated with a glucose only fermenter what happens

Answer 47

acid products lower the pH ad turn the entire medium yellow within a few hours

Question 48

what is reversion

Answer 48

the process that occurs in the slant when organisms break down available amino acids which raises the pH

Question 49

what does a TSIA with a red slant and yellow butt indicate

Answer 49

the organism ferments glucose but not lactose or sucrose.

Question 50

what color do organisms turn that are able to ferment glucose and sucrose/lactose

Answer 50

yellow throughout