MCB2010L Final Exam with Questions and
Correct Answers 2025
What ,is ,fluid ,thioglycollate ,broth ,(FTB)? ,- ,CORRECT ,ANSWER-It ,is ,prepared ,as ,a
,basic ,medium ,or ,with ,a ,variety ,of ,substances, ,depending ,on ,the ,needs ,of ,the
,organism ,being ,cultivated. ,It ,is ,appropriate ,for ,a ,broad ,variety ,of ,aerobic ,and
,anaerobic, ,and ,fastidious ,(requiring ,specific ,nutrients ,to ,grow) ,and ,non ,fastidious
,organisms. ,Well ,adapted ,for ,strict ,anaerobes ,and ,microaerophiles.
What ,are ,the ,key ,components ,of ,FTB? ,- ,CORRECT ,ANSWER-Yeast ,extract,
,pancreatic ,digest ,of ,casein, ,dextrose, ,sodium ,thioglycollate, ,L-cystine, ,and ,resazurin.
-yeast ,extract ,and ,casein ,provide ,nutrients
-sodium ,thioglycollate ,and ,L-cystine ,reduce ,oxygen ,to ,water
-resazurin ,is ,an ,indicator ,of ,oxygen
What ,purpose ,does ,resazurin ,dye ,serve ,in ,FTB? ,- ,CORRECT ,ANSWER-Oxygen
,indicator. ,Pink ,when ,oxidized, ,colorless ,when ,reduced.
What ,is ,the ,application ,of ,FTB? ,- ,CORRECT ,ANSWER-Can ,be ,modified ,to ,promote
,growth ,of ,a ,wide ,variety ,of ,fastidious ,to ,non ,fastidious ,microorganisms. ,It ,can ,be
,used ,to ,illustrate ,microbial ,growth ,representing ,all ,levels ,of ,oxygen ,tolerance.
,However, ,it ,generally ,is ,associated ,with ,the ,cultivation ,of ,anaerobic ,and
,microaerophilic ,bacteria.
Why ,is ,it ,preferred ,to ,use ,fresh ,FTB ,medium ,over ,old ,medium? ,- ,CORRECT
,ANSWER-Oxygen ,removed ,during ,autoclaving ,will ,diffuse ,back ,into ,the ,medium ,as
,the ,tubes ,cool ,to ,room ,temperature. ,This ,produces ,a ,gradient ,of ,concentrations ,from
,aerobic ,(comparable ,to ,air) ,at ,the ,top ,to ,anaerobic ,at ,the ,bottom. ,Fresh ,media ,will
,appear ,clear ,to ,straw ,coloured ,with ,a ,pink ,region ,at ,the ,top, ,where ,the ,dye ,has
,,become ,oxidized. ,The ,use ,of ,old ,medium ,will ,cause ,the ,aerobic ,region ,of ,the ,tube ,to
,grow, ,indicating ,widespread ,oxidation ,throughout ,the ,tube.
Where ,would ,you ,expect ,to ,see ,growth ,on ,FTB ,medium ,of ,a ,strict ,aerobe, ,anaerobe,
,microaerophile, ,facultative ,anaerobe, ,and ,an ,aerotolerant ,anaerobe? ,- ,CORRECT
,ANSWER--Strict ,aerobe: ,at ,the ,top ,of ,the ,broth, ,where ,oxygen ,is ,abundant
-Anaerobe: ,at ,the ,bottom ,of ,the ,broth, ,where ,oxygen ,is ,not ,present
-Microaerophile: ,in ,the ,middle ,of ,the ,broth ,where ,oxygen ,is ,present, ,but ,not ,in ,large
,amounts
-Facultative ,anaerobe: ,concentrated ,at ,the ,top ,(grows ,best ,when ,most ,oxygen ,is
,present), ,but ,spread ,throughout ,(can ,grow ,anaerobically)
-Aerotolerant ,anaerobe: ,growth ,relatively ,evenly ,throughout ,(anaerobic, ,but ,tolerates
,oxygen ,presence)
Consider ,resazurin ,dye. ,Considering ,the ,major ,application ,of ,this ,medium, ,which ,is
,more ,desirable, ,a ,thick ,coloured ,or ,a ,thin ,coloured ,band? ,- ,CORRECT ,ANSWER-A
,thin ,coloured ,band ,would ,be ,more ,desirable, ,as ,it ,would ,indicate ,that ,the ,medium ,is
,more ,fresh. ,The ,older ,the ,medium, ,the ,more ,oxidation ,occurs ,within ,the ,media,
,creating ,the ,indicator ,band ,to ,expand. ,Certain ,bacteria ,will ,not ,be ,able ,to ,grow ,or ,the
,results ,of ,their ,growth ,will ,become ,skewed.
Where ,is ,the ,resazurin ,located ,in ,the ,broth ,column? ,- ,CORRECT ,ANSWER-At ,the
,very ,top ,of ,the ,broth, ,forming ,a ,band.
Why ,is ,the ,FTB ,broth ,pink ,at ,the ,surface ,of ,the ,medium? ,- ,CORRECT ,ANSWER-
This ,is ,where ,the ,most ,oxygen ,is ,present.
Which ,type ,of ,organism ,would ,most ,likely ,be ,affected ,negatively ,by ,the ,use ,of ,old
,FTB ,media? ,- ,CORRECT ,ANSWER-Strict ,(obligate) ,anaerobes; ,these ,organisms ,are
,inhibited ,by ,the ,presence ,of ,oxygen, ,therefore ,an ,abundance ,of ,oxygen ,in ,the ,tube
,may ,produce ,limited ,growth ,by ,these ,organisms.
Which ,type ,of ,organism ,would ,most ,likely ,be ,positively ,affected ,by ,the ,use ,of ,old
,FTB ,media? ,- ,CORRECT ,ANSWER-Strict ,(obligate) ,aerobes; ,the ,abundance ,of
,oxygen ,in ,the ,media ,will ,provide ,a ,tremendous ,advantage ,to ,these ,organism's
,growth, ,as ,they ,need ,sufficient ,amounts ,of ,oxygen ,to ,produce.
Which ,type ,of ,organism ,would ,be ,least ,affected ,by ,the ,use ,of ,old ,FTB ,media? ,-
,CORRECT ,ANSWER-Aerotolerant ,anaerobes; ,these ,bacteria ,continue ,their
,production ,anaerobically ,in ,the ,presence ,of ,oxygen. ,Oxygen ,presence ,will ,neither
,inhibit, ,nor ,fuel ,their ,growth.
What ,is ,the ,GasPak ,Anaerobic ,System? ,- ,CORRECT ,ANSWER-A ,plastic ,jar ,in ,which
,we ,create ,anaerobic, ,microaerophilic, ,or ,CO2 ,enriched ,conditions, ,depending ,on ,the
,specific ,needs ,of ,the ,bacteria ,being ,cultivated.
, What ,components ,are ,required ,for ,the ,anaerobic ,jar? ,- ,CORRECT ,ANSWER-
Chemical ,gas ,generator ,packet ,containing ,sodium ,borohydride ,and ,sodium
,bicarbonate, ,and ,a ,paper ,indicator ,strip ,saturated ,in ,methylene ,blue ,and ,resazurin.
,Palladium ,acts ,as ,a ,catalyst ,for ,the ,reaction ,that ,will ,produce ,the ,necessary
,conditions ,within ,the ,jar.
What ,is ,the ,purpose ,of ,the ,indicator ,strip? ,How ,is ,oxygen ,presence ,indicated? ,-
,CORRECT ,ANSWER-To ,confirm ,the ,presence ,or ,absence ,of ,oxygen ,within ,the ,jar.
,Methylene ,blue ,and ,resazurin ,are ,colorless ,when ,reduced, ,but ,are ,blue ,and ,pink,
,respectively, ,when ,oxidized.
What ,does ,the ,gas ,generator ,packet ,do ,within ,the ,anaerobic ,jar? ,- ,CORRECT
,ANSWER-Water ,is ,added ,to ,the ,envelope. ,Sodium ,borohydride ,and ,sodium
,bicarbonate ,react ,with ,the ,water ,to ,produce ,hydrogen ,and ,carbon ,dioxide ,gases.
,Palladium ,catalyzes ,a ,reaction ,between ,hydrogen ,and ,free ,oxygen ,in ,the ,jar ,to
,produce ,water.
How ,long ,does ,it ,take ,for ,the ,gas ,generator ,packet ,to ,create ,anaerobic ,conditions?
,What ,is ,the ,evidence ,of ,this? ,- ,CORRECT ,ANSWER-Removal ,of ,the ,free ,oxygen
,produces ,anaerobic ,conditions ,in ,the ,jar ,in ,approximately ,one ,hour; ,this ,is ,evidenced
,by ,the ,white ,indicator ,strip ,and ,moisture ,inside ,of ,the ,jar.
Suppose ,that ,after ,incubation, ,you ,examine ,the ,jar ,before ,opening ,it ,and ,see ,that ,the
,methylene ,blue ,strip ,is ,blue ,(or ,the ,resazurin ,strip ,is ,pink). ,What ,would ,you ,guess
,the ,internal ,environment ,to ,be- ,aerobic ,or ,anaerobic? ,- ,CORRECT ,ANSWER-
Aerobic; ,the ,indicator ,strips ,should ,be ,white ,when ,within ,the ,jar, ,representing ,an
,anaerobic ,environment. ,If ,these ,strips ,are ,oxidized, ,they ,change ,colour, ,indicating
,the ,presence ,of ,oxygen ,within ,the ,system.
Suppose ,that ,after ,incubation, ,you ,examine ,the ,jar ,before ,opening ,it ,and ,see ,that ,the
,methylene ,blue ,strip ,is ,blue ,(or ,the ,resazurin ,strip ,is ,pink). ,How ,would ,you ,expect
,the ,growth ,on ,the ,plates ,inside ,the ,jar ,to ,differ ,from ,the ,plates ,incubated ,outside ,of
,the ,jar? ,- ,CORRECT ,ANSWER-The ,plates ,inside ,of ,the ,jar ,would ,reflect ,inhibited
,growth ,of ,anaerobic ,organisms, ,while ,aerobic ,organisms ,would ,be ,positively ,affected.
,These ,results ,will ,be ,skewed ,towards ,favouring ,aerobic ,organisms. ,Plates ,outside ,of
,the ,jar ,will ,remain ,unaffected.
Suppose ,that ,after ,incubation, ,you ,examine ,the ,jar ,before ,opening ,it ,and ,see ,that ,the
,methylene ,blue ,strip ,is ,blue ,(or ,the ,resazurin ,strip ,is ,pink). ,Which ,organisms ,would
,be ,most ,affected ,by ,the ,conditions ,described? ,- ,CORRECT ,ANSWER-Obligate
,anaerobes ,would ,be ,most ,affected ,as ,they ,require ,no ,oxygen ,present ,in ,order ,to
,grow. ,The ,presence ,of ,oxygen ,within ,the ,anaerobic ,environment ,will ,stunt ,their
,growth. ,Obligate ,aerobes ,will ,benefit ,from ,the ,influx ,of ,oxygen, ,causing ,these
,organisms ,to ,flourish ,in ,an ,aerobic ,environment. ,If ,the ,conditions ,are ,just ,right,
,microaerophiles ,may ,be ,permitted ,to ,grow ,where ,they ,once ,would ,not ,with ,a ,small
,amount ,of ,oxygen ,present.
Correct Answers 2025
What ,is ,fluid ,thioglycollate ,broth ,(FTB)? ,- ,CORRECT ,ANSWER-It ,is ,prepared ,as ,a
,basic ,medium ,or ,with ,a ,variety ,of ,substances, ,depending ,on ,the ,needs ,of ,the
,organism ,being ,cultivated. ,It ,is ,appropriate ,for ,a ,broad ,variety ,of ,aerobic ,and
,anaerobic, ,and ,fastidious ,(requiring ,specific ,nutrients ,to ,grow) ,and ,non ,fastidious
,organisms. ,Well ,adapted ,for ,strict ,anaerobes ,and ,microaerophiles.
What ,are ,the ,key ,components ,of ,FTB? ,- ,CORRECT ,ANSWER-Yeast ,extract,
,pancreatic ,digest ,of ,casein, ,dextrose, ,sodium ,thioglycollate, ,L-cystine, ,and ,resazurin.
-yeast ,extract ,and ,casein ,provide ,nutrients
-sodium ,thioglycollate ,and ,L-cystine ,reduce ,oxygen ,to ,water
-resazurin ,is ,an ,indicator ,of ,oxygen
What ,purpose ,does ,resazurin ,dye ,serve ,in ,FTB? ,- ,CORRECT ,ANSWER-Oxygen
,indicator. ,Pink ,when ,oxidized, ,colorless ,when ,reduced.
What ,is ,the ,application ,of ,FTB? ,- ,CORRECT ,ANSWER-Can ,be ,modified ,to ,promote
,growth ,of ,a ,wide ,variety ,of ,fastidious ,to ,non ,fastidious ,microorganisms. ,It ,can ,be
,used ,to ,illustrate ,microbial ,growth ,representing ,all ,levels ,of ,oxygen ,tolerance.
,However, ,it ,generally ,is ,associated ,with ,the ,cultivation ,of ,anaerobic ,and
,microaerophilic ,bacteria.
Why ,is ,it ,preferred ,to ,use ,fresh ,FTB ,medium ,over ,old ,medium? ,- ,CORRECT
,ANSWER-Oxygen ,removed ,during ,autoclaving ,will ,diffuse ,back ,into ,the ,medium ,as
,the ,tubes ,cool ,to ,room ,temperature. ,This ,produces ,a ,gradient ,of ,concentrations ,from
,aerobic ,(comparable ,to ,air) ,at ,the ,top ,to ,anaerobic ,at ,the ,bottom. ,Fresh ,media ,will
,appear ,clear ,to ,straw ,coloured ,with ,a ,pink ,region ,at ,the ,top, ,where ,the ,dye ,has
,,become ,oxidized. ,The ,use ,of ,old ,medium ,will ,cause ,the ,aerobic ,region ,of ,the ,tube ,to
,grow, ,indicating ,widespread ,oxidation ,throughout ,the ,tube.
Where ,would ,you ,expect ,to ,see ,growth ,on ,FTB ,medium ,of ,a ,strict ,aerobe, ,anaerobe,
,microaerophile, ,facultative ,anaerobe, ,and ,an ,aerotolerant ,anaerobe? ,- ,CORRECT
,ANSWER--Strict ,aerobe: ,at ,the ,top ,of ,the ,broth, ,where ,oxygen ,is ,abundant
-Anaerobe: ,at ,the ,bottom ,of ,the ,broth, ,where ,oxygen ,is ,not ,present
-Microaerophile: ,in ,the ,middle ,of ,the ,broth ,where ,oxygen ,is ,present, ,but ,not ,in ,large
,amounts
-Facultative ,anaerobe: ,concentrated ,at ,the ,top ,(grows ,best ,when ,most ,oxygen ,is
,present), ,but ,spread ,throughout ,(can ,grow ,anaerobically)
-Aerotolerant ,anaerobe: ,growth ,relatively ,evenly ,throughout ,(anaerobic, ,but ,tolerates
,oxygen ,presence)
Consider ,resazurin ,dye. ,Considering ,the ,major ,application ,of ,this ,medium, ,which ,is
,more ,desirable, ,a ,thick ,coloured ,or ,a ,thin ,coloured ,band? ,- ,CORRECT ,ANSWER-A
,thin ,coloured ,band ,would ,be ,more ,desirable, ,as ,it ,would ,indicate ,that ,the ,medium ,is
,more ,fresh. ,The ,older ,the ,medium, ,the ,more ,oxidation ,occurs ,within ,the ,media,
,creating ,the ,indicator ,band ,to ,expand. ,Certain ,bacteria ,will ,not ,be ,able ,to ,grow ,or ,the
,results ,of ,their ,growth ,will ,become ,skewed.
Where ,is ,the ,resazurin ,located ,in ,the ,broth ,column? ,- ,CORRECT ,ANSWER-At ,the
,very ,top ,of ,the ,broth, ,forming ,a ,band.
Why ,is ,the ,FTB ,broth ,pink ,at ,the ,surface ,of ,the ,medium? ,- ,CORRECT ,ANSWER-
This ,is ,where ,the ,most ,oxygen ,is ,present.
Which ,type ,of ,organism ,would ,most ,likely ,be ,affected ,negatively ,by ,the ,use ,of ,old
,FTB ,media? ,- ,CORRECT ,ANSWER-Strict ,(obligate) ,anaerobes; ,these ,organisms ,are
,inhibited ,by ,the ,presence ,of ,oxygen, ,therefore ,an ,abundance ,of ,oxygen ,in ,the ,tube
,may ,produce ,limited ,growth ,by ,these ,organisms.
Which ,type ,of ,organism ,would ,most ,likely ,be ,positively ,affected ,by ,the ,use ,of ,old
,FTB ,media? ,- ,CORRECT ,ANSWER-Strict ,(obligate) ,aerobes; ,the ,abundance ,of
,oxygen ,in ,the ,media ,will ,provide ,a ,tremendous ,advantage ,to ,these ,organism's
,growth, ,as ,they ,need ,sufficient ,amounts ,of ,oxygen ,to ,produce.
Which ,type ,of ,organism ,would ,be ,least ,affected ,by ,the ,use ,of ,old ,FTB ,media? ,-
,CORRECT ,ANSWER-Aerotolerant ,anaerobes; ,these ,bacteria ,continue ,their
,production ,anaerobically ,in ,the ,presence ,of ,oxygen. ,Oxygen ,presence ,will ,neither
,inhibit, ,nor ,fuel ,their ,growth.
What ,is ,the ,GasPak ,Anaerobic ,System? ,- ,CORRECT ,ANSWER-A ,plastic ,jar ,in ,which
,we ,create ,anaerobic, ,microaerophilic, ,or ,CO2 ,enriched ,conditions, ,depending ,on ,the
,specific ,needs ,of ,the ,bacteria ,being ,cultivated.
, What ,components ,are ,required ,for ,the ,anaerobic ,jar? ,- ,CORRECT ,ANSWER-
Chemical ,gas ,generator ,packet ,containing ,sodium ,borohydride ,and ,sodium
,bicarbonate, ,and ,a ,paper ,indicator ,strip ,saturated ,in ,methylene ,blue ,and ,resazurin.
,Palladium ,acts ,as ,a ,catalyst ,for ,the ,reaction ,that ,will ,produce ,the ,necessary
,conditions ,within ,the ,jar.
What ,is ,the ,purpose ,of ,the ,indicator ,strip? ,How ,is ,oxygen ,presence ,indicated? ,-
,CORRECT ,ANSWER-To ,confirm ,the ,presence ,or ,absence ,of ,oxygen ,within ,the ,jar.
,Methylene ,blue ,and ,resazurin ,are ,colorless ,when ,reduced, ,but ,are ,blue ,and ,pink,
,respectively, ,when ,oxidized.
What ,does ,the ,gas ,generator ,packet ,do ,within ,the ,anaerobic ,jar? ,- ,CORRECT
,ANSWER-Water ,is ,added ,to ,the ,envelope. ,Sodium ,borohydride ,and ,sodium
,bicarbonate ,react ,with ,the ,water ,to ,produce ,hydrogen ,and ,carbon ,dioxide ,gases.
,Palladium ,catalyzes ,a ,reaction ,between ,hydrogen ,and ,free ,oxygen ,in ,the ,jar ,to
,produce ,water.
How ,long ,does ,it ,take ,for ,the ,gas ,generator ,packet ,to ,create ,anaerobic ,conditions?
,What ,is ,the ,evidence ,of ,this? ,- ,CORRECT ,ANSWER-Removal ,of ,the ,free ,oxygen
,produces ,anaerobic ,conditions ,in ,the ,jar ,in ,approximately ,one ,hour; ,this ,is ,evidenced
,by ,the ,white ,indicator ,strip ,and ,moisture ,inside ,of ,the ,jar.
Suppose ,that ,after ,incubation, ,you ,examine ,the ,jar ,before ,opening ,it ,and ,see ,that ,the
,methylene ,blue ,strip ,is ,blue ,(or ,the ,resazurin ,strip ,is ,pink). ,What ,would ,you ,guess
,the ,internal ,environment ,to ,be- ,aerobic ,or ,anaerobic? ,- ,CORRECT ,ANSWER-
Aerobic; ,the ,indicator ,strips ,should ,be ,white ,when ,within ,the ,jar, ,representing ,an
,anaerobic ,environment. ,If ,these ,strips ,are ,oxidized, ,they ,change ,colour, ,indicating
,the ,presence ,of ,oxygen ,within ,the ,system.
Suppose ,that ,after ,incubation, ,you ,examine ,the ,jar ,before ,opening ,it ,and ,see ,that ,the
,methylene ,blue ,strip ,is ,blue ,(or ,the ,resazurin ,strip ,is ,pink). ,How ,would ,you ,expect
,the ,growth ,on ,the ,plates ,inside ,the ,jar ,to ,differ ,from ,the ,plates ,incubated ,outside ,of
,the ,jar? ,- ,CORRECT ,ANSWER-The ,plates ,inside ,of ,the ,jar ,would ,reflect ,inhibited
,growth ,of ,anaerobic ,organisms, ,while ,aerobic ,organisms ,would ,be ,positively ,affected.
,These ,results ,will ,be ,skewed ,towards ,favouring ,aerobic ,organisms. ,Plates ,outside ,of
,the ,jar ,will ,remain ,unaffected.
Suppose ,that ,after ,incubation, ,you ,examine ,the ,jar ,before ,opening ,it ,and ,see ,that ,the
,methylene ,blue ,strip ,is ,blue ,(or ,the ,resazurin ,strip ,is ,pink). ,Which ,organisms ,would
,be ,most ,affected ,by ,the ,conditions ,described? ,- ,CORRECT ,ANSWER-Obligate
,anaerobes ,would ,be ,most ,affected ,as ,they ,require ,no ,oxygen ,present ,in ,order ,to
,grow. ,The ,presence ,of ,oxygen ,within ,the ,anaerobic ,environment ,will ,stunt ,their
,growth. ,Obligate ,aerobes ,will ,benefit ,from ,the ,influx ,of ,oxygen, ,causing ,these
,organisms ,to ,flourish ,in ,an ,aerobic ,environment. ,If ,the ,conditions ,are ,just ,right,
,microaerophiles ,may ,be ,permitted ,to ,grow ,where ,they ,once ,would ,not ,with ,a ,small
,amount ,of ,oxygen ,present.
