MCB 101 FINAL EXAM QUESTIONS WITH VERIFIED
ANSWERS
Lab 7 hw: Which biochemical test media requires that you remove a specific amount of
culture to a new tube prior to reading the result?
1.) lysine decarboxylase
2.) methyl red
3.) indole
4.) urease - Answers - methyl red
Which sugar fermentation test utilizes a Durham tube?
1.) mannitol
2.) glucose
3.) lactose
4.) raffinose
5.) sucrose - Answers - glucose
Which biochemical test requires a larger inoculum than other the other tests?
1.) esculin
2.) urease
3.) citric acid
4.) raffinose
5.) lysine decarboxylase - Answers - urease
Match the appropriate developing reagent with the biochemical tests listed below.
1.) methyl red
2.) voges- proskauer
3.) indole
4.) macConkey
5.) phenylalanine deaminase
6.) catalase - Answers - 1.) methyl red
2.) VPI/VPII
3.) kovac reagent
4.) none
5.) 10% ferric chloride
6.) hydrogen peroxide
Agar Plate vs Agar Slant vs Broth Media
For each fo the media listed below, is it an agar plate, an agar slant, or a broth medium?
,1.) phenylalanine deaminase
2.) lysine decarboxylase
3.) mannitol
4.) MacConkey
5.) phenylethanol
6.) kilgers test - Answers - 1.) agar slant
2.) broth media
3.) broth media
4.) agar plate
5.) agar plate
6.) agar slant
Why does Kovac Reagent contain isoamyl alcohol?
1.) Isolamyl alcohol oxidizes acetoin to diacetyl.
2.) Isomayl alcohol concentrates the hydrgoen sulfide allowing to react with iron salts.
3.) Isoamyl alcohol reacts with the products of mixed acid fermentation to turn red.
4.) Isoamyl alcohol concentrates indole allowing it to react with p-
dimethylaminobenzaldehyde.
5.) Isoamyl alcohol reacts with phenylpyruvic acid so that it can bind ferric ions. -
Answers - Isoamyl alcohol concentrates indole allowing it to react with p-
dimethylaminobenzaldehyde.
You run a Kligler's test on the Gram-negative organism, Serratia marcescens, to see if it
produces hydrogen sulfide when grown in the presence of sulfur-containing amino
acids. After 48 h, you score the test and find that S. marcescens gives a positive result.
What is the most likely appearance of the Kligler's test agar slant when you score it?
1.) the entire slant is red and there is dense growth on the slant surface
2.) the bottom of the slant is yellow, the slant/air interface is red, and there is an obvious
black precipitate in the agar
3.) the entire slant is yellow, and the agar is cracked from excessive gas production
4.) the bottom of the slant is yellow while the slant/air interface is red
5.) the bottom of the slant is orange while the slant/air interface is red - Answers - the
bottom of the slant is yellow, the slant/air interface is red, and there is an obvious black
precipitate in the agar
Biochemical tests can be used to...
1.) obtain a pure culture of an organism
2.) determine the identity of a particular acid waste product
3.) determine exactly how an acid waste product is produced
4.) measure a specific biochemical capability
5.) distinguish between different groups of bacteria - Answers - distinguish between
different groups of bacteria
, A durham tube is used for...?
1.) ability to use a nitrogen source
2.) acid production
3.) a color change
4.) production of alkaline waste products
5.) H2 production - Answers - H2 production
All the biochemical tests we perform in this exercise should be incubated at _________
for _________ .
1.) 37C, 24 hours
2.) 30C, 48 hours
3.) 30C, 24 hours
4.) 37C, 48 hours - Answers - 37C, 48 hours
Which component(s) in MacConkey agar restrict the growth of Gram-positive bacteria?
1.) Peptone and sodium chloride
2.) Mannitol
3.) Esculin and peptone
4.) Bile salts and crystal violet - Answers - Bile salts and crystal violet
Lab 8: Which media will you use to start your isolation of E. coli?
1.) MacConkey agar
2.) MRS agar
3.) Chromocult Coliform agar
4.) EMB agar - Answers - EMB agar
How many isolated colonies will you streak onto your Chromocult Coliform agar plate?
1.) 4
2.) 2
3.) 8
4.) 1 - Answers - 4
How many isolated colonies will you streak onto your MacConkey agar plate?
1.) 4
2.) 8
3.) 2
ANSWERS
Lab 7 hw: Which biochemical test media requires that you remove a specific amount of
culture to a new tube prior to reading the result?
1.) lysine decarboxylase
2.) methyl red
3.) indole
4.) urease - Answers - methyl red
Which sugar fermentation test utilizes a Durham tube?
1.) mannitol
2.) glucose
3.) lactose
4.) raffinose
5.) sucrose - Answers - glucose
Which biochemical test requires a larger inoculum than other the other tests?
1.) esculin
2.) urease
3.) citric acid
4.) raffinose
5.) lysine decarboxylase - Answers - urease
Match the appropriate developing reagent with the biochemical tests listed below.
1.) methyl red
2.) voges- proskauer
3.) indole
4.) macConkey
5.) phenylalanine deaminase
6.) catalase - Answers - 1.) methyl red
2.) VPI/VPII
3.) kovac reagent
4.) none
5.) 10% ferric chloride
6.) hydrogen peroxide
Agar Plate vs Agar Slant vs Broth Media
For each fo the media listed below, is it an agar plate, an agar slant, or a broth medium?
,1.) phenylalanine deaminase
2.) lysine decarboxylase
3.) mannitol
4.) MacConkey
5.) phenylethanol
6.) kilgers test - Answers - 1.) agar slant
2.) broth media
3.) broth media
4.) agar plate
5.) agar plate
6.) agar slant
Why does Kovac Reagent contain isoamyl alcohol?
1.) Isolamyl alcohol oxidizes acetoin to diacetyl.
2.) Isomayl alcohol concentrates the hydrgoen sulfide allowing to react with iron salts.
3.) Isoamyl alcohol reacts with the products of mixed acid fermentation to turn red.
4.) Isoamyl alcohol concentrates indole allowing it to react with p-
dimethylaminobenzaldehyde.
5.) Isoamyl alcohol reacts with phenylpyruvic acid so that it can bind ferric ions. -
Answers - Isoamyl alcohol concentrates indole allowing it to react with p-
dimethylaminobenzaldehyde.
You run a Kligler's test on the Gram-negative organism, Serratia marcescens, to see if it
produces hydrogen sulfide when grown in the presence of sulfur-containing amino
acids. After 48 h, you score the test and find that S. marcescens gives a positive result.
What is the most likely appearance of the Kligler's test agar slant when you score it?
1.) the entire slant is red and there is dense growth on the slant surface
2.) the bottom of the slant is yellow, the slant/air interface is red, and there is an obvious
black precipitate in the agar
3.) the entire slant is yellow, and the agar is cracked from excessive gas production
4.) the bottom of the slant is yellow while the slant/air interface is red
5.) the bottom of the slant is orange while the slant/air interface is red - Answers - the
bottom of the slant is yellow, the slant/air interface is red, and there is an obvious black
precipitate in the agar
Biochemical tests can be used to...
1.) obtain a pure culture of an organism
2.) determine the identity of a particular acid waste product
3.) determine exactly how an acid waste product is produced
4.) measure a specific biochemical capability
5.) distinguish between different groups of bacteria - Answers - distinguish between
different groups of bacteria
, A durham tube is used for...?
1.) ability to use a nitrogen source
2.) acid production
3.) a color change
4.) production of alkaline waste products
5.) H2 production - Answers - H2 production
All the biochemical tests we perform in this exercise should be incubated at _________
for _________ .
1.) 37C, 24 hours
2.) 30C, 48 hours
3.) 30C, 24 hours
4.) 37C, 48 hours - Answers - 37C, 48 hours
Which component(s) in MacConkey agar restrict the growth of Gram-positive bacteria?
1.) Peptone and sodium chloride
2.) Mannitol
3.) Esculin and peptone
4.) Bile salts and crystal violet - Answers - Bile salts and crystal violet
Lab 8: Which media will you use to start your isolation of E. coli?
1.) MacConkey agar
2.) MRS agar
3.) Chromocult Coliform agar
4.) EMB agar - Answers - EMB agar
How many isolated colonies will you streak onto your Chromocult Coliform agar plate?
1.) 4
2.) 2
3.) 8
4.) 1 - Answers - 4
How many isolated colonies will you streak onto your MacConkey agar plate?
1.) 4
2.) 8
3.) 2
