INSTRUCTIONS TO CANDIDATES

71

Centre Number

Candidate Number

TotalMarks

For Examiner’s use only

QuestionMarks Number

1

2

3

4

5

6

7

8

6397.05R

Thetotalmarkforthispaperis75.SectionAcarries60marks.SectionBcarries15marks.Figuresinbracketsprinteddowntheright-handsideofpagesindicatethemarksawardedtoeachquestionorpartquestion.

YouareremindedoftheneedforgoodEnglishandclearpresentationinyouranswers.Useaccuratescientificterminologyinallanswers.Youshouldspendapproximately20 minutesonSectionB.YouareexpectedtoanswerSectionBincontinuousprose.QualityofwrittencommunicationwillbeassessedinSection B,andawardedamaximumof2marks.

INFORMATION FOR CANDIDATES

WriteyourCentreNumberandCandidateNumberinthespacesprovidedatthetopofthispage.Writeyouranswersinthespacesprovidedinthisquestionpaper.Answeralleightquestions.YouareprovidedwithPhotograph 1.4forusewithQuestion4inthispaper.Donotwriteyouranswersonthisphotograph.

TIME

1hour30minutes.

ADVANCED SUBSIDIARY (AS)General Certificate of Education

January 2011

Biology

AssessmentUnitAS1assessing

MoleculesandCells

[AB111]

TUESDAY 11 JANUARY, MORNING

1115

62

AB

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1

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Section A

1 Thestatementsinthetablebelowrefertosomeofthefeaturesfoundinprokaryoticandeukaryoticcells.Somefeaturesmaybefoundonlyinonetypeofcellorinbothcelltypes.

Ifafeatureispresent,placeatick(✓)intheappropriateboxand,ifthefeatureisabsent,placeacross(✗)intheappropriatebox.(Donotleaveanyboxesempty.)

Feature Prokaryotic cell Eukaryotic cell

Plasmid

Ribosome

Golgiapparatus

[3]

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2 Thediagrambelowrepresentsaplantcellimmersedinabathingsolutionwithasolutepotentialof–1200kPa(ψexternal).Thesolutepotential(ψs)andpressurepotential(ψp)ofthecellarealsoshown.

ψs = –1400 kPa

ψexternal = –1200 kPa

ψp = 500 kPa

(a) Calculatethewaterpotential(ψcell)ofthecell.

Answer________________________[1]

(b) Describeandexplainthemovementofwaterbetweenthecellanditsbathingsolution.

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(c) Drawadiagramofthecelltoshowitsfinalappearanceinthebathingsolution.

[2]

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3 (a) Readthefollowingpassagewhichdescribestheprimarystructureofaproteinandwritethemostappropriateword(s)intheblankspacestocompletetheaccount.

Proteinsarepolymers,consistingoflongchainsof

joinedtogetherby

reactionstoformnumerous bonds.The

sequenceofmonomersinaproteinisknownasitsprimarystructure

andisencodedinthe ofanorganism. [4]

(b) Proteinsarecomplexmoleculeswithaleveloforganisationbeyondtheprimarystructure.Describehowafinaloverallshapeisproducedinaprotein.

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(c) DescribethecolourchangewhichindicatesthepresenceofproteininafoodsamplewhenitistestedwithBiuretreagent.

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4 Photograph1.4 isanelectromicrographofpartsoftwoadjacentspongymesophyllcellsfoundintheleafofageraniumplant.

(a) (i) IdentifythestructureslabelledAtoD.

A_________________________________

B_________________________________

C_________________________________

D_________________________________ [4]

(ii) Explainthepositionofthenucleiinthesemesophyllcells.

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(b) Usethescalebartocalculatethemagnificationofthiselectronmicrograph.(Showyourworking)

Answer________________________[3]

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5 (a) Thediagrambelowrepresentsthefluidmosaicmodelofthecellsurfacemembrane.

A

B

C

D

(i) IdentifythestructureslabelledAtoD.

A_____________________________________

B_____________________________________

C_____________________________________

D_____________________________________ [4]

(ii) PlaceanX on the diagramtoindicatetheoutersurfaceofthemembrane.Giveareasonforyouranswer.

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(b) Thetablebelowshowstheeffectofchangingconditionsonthreedifferentmechanismsofmembranetransport.

Effect of changing conditions on rate of movement

Change in conditions

Mechanism1

Mechanism2

Mechanism3

Increasedoxygenlevels

Rateincreases

significantly

Noeffectonrate

Noeffectonrate

Additionofcyanide(arespiratorypoison)

Ratedecreasessignificantly

Noeffectonrate

Noeffectonrate

Increasednumbersofmembranecarriers

Rateincreases

Rateincreases

Noeffectonrate

Usingtheinformationinthetable,identifyeachmechanismofmembranetransportand,ineachcase,giveareasonforyouridentification.

(i) Mechanism1

Identification _____________________________________________

Reason__________________________________________________

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(ii) Mechanism2

Identification _____________________________________________

Reason__________________________________________________

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(iii)Mechanism3

Identification _____________________________________________

Reason__________________________________________________

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BLANK PAGE

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6 (a) TheenzymeBamHIisarestrictionendonucleasewiththerecognitionsiteGGATCCcuttingDNAintofragmentsbetweenthebasesGG.

ThebasesononestrandofalengthofDNA,120nucleotides,isrepresentedinthethreelinesbelow.

AATGGGTACGCACAGTGGATCCACGTAGTATGCGATGCGT

AGTTGATAGATAGATAGATAGATAGATAGATATTTTATCG

TGCTGTACGGATCCGGAAGTGGCGATGAGGATCCATGCAA

(i) HowmanyfragmentswouldbeproducedifthislengthofDNAwascutwiththerestrictionendonucleaseBamHI?

Answer [1]

(ii) TheDNAstrandabovecontainsamicrosatelliterepeatsequence(MRS).Identifythesequenceandstatethenumberofrepeats.

• Microsatelliterepeatsequence__________________________

• Numberofrepeats__________________________________ [2]

(iii) ExplainwhymicrosatelliterepeatsequencesareusefulforforensicanalysisofDNA.

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(b) DNAsamplesfromthemembersofaparticularfamilywereanalysedforrestrictionfragmentlengthpolymorphisms(RFLPs).ThedarkbandsintheautoradiographbelowrepresentRFLPmarkers.Theautoradiographhas15lanesmanyofwhichareusedforcomparison.

15lanescontainsamplesfromthefollowingsources.

• Lanes8,9,10,12,13and14arefrommembersofthesamefamily

• Lanes1,2,7,11and15containaseriesofDNAfragmentsofdifferentlengthusedforcalibration

• Lane3isacontrolcontainingknownRFLPmarkers(producingbandsatthesamelocationseachtime)

• Lanes4,5and6arefromunrelatedindividuals

(i) ExplainwhythesonanddaughterhavedifferentRFLPmarkers.

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Image of DNA samples has been removed due to copyright issues.

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(ii) Usingtheinformationintheautoradiograph,identifythegrandparentsasthewife’sparents(maternal)orthehusband’sparents(paternal).Explaintheevidenceforyourchoice.

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(iii) Usetheautoradiographtoidentifymatcheswithanyoftheunrelatedindividuals(4,5and6)andanyofthefamilymembers.

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(iv) ExplainwhyRFLPmatchesmaybefoundbetweenunrelatedindividuals.

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7 Thisquestionisaboutthedigestionofjellybyprotein-digestingenzymes.

(a) Jellycontainstheproteingelatine,whichisbrokendowntoaminoacidsbyprotein-digestingenzymes.Statethetypeofreactionwhichtakesplaceduringdigestion.

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(b) TheprocedureusedforaninvestigationoftheeffectofpHontheactivityoftwoprotein-digestingenzymesisoutlinedbelow.

1. FivebuffersolutionswerepreparedatpH4,6.4,7.4,8,and9. 2. 10stripsofjellywerecutfromajellyblock.Eachstripwas

approximately1to2mminthickness. 3. Eachstripwastrimmedtoarectangleof10by20mmandthe

surplusjellydiscarded.TrimmedstripswereplacedinseparatePetridishes.

4. 10cm3ofeachofthefivebuffersolutionswasaddedtotwoofthePetridishes,sothattwoPetridisheshadpH4,twohadpH6.4,etc.ThePetridishesweredividedintotwosets,eachsethavingonedishateachpH.

5. 10cm3ofenzymeAwasaddedtoonesetofthePetridishesand10cm3ofenzymeBwasaddedtothesecondsetofPetridishes.

6. AllPetridisheswereleftatroomtemperaturefor90minutes. 7. Theareaofthejellyremainingwasmeasuredandtheresultsare

showninthetablebelow.

Area of jelly remaining/mm2

pH Enzyme A Enzyme B

4 0 200

6.4 100 190

7.4 171 98

8 190 48

9 200 0

(i) Plottheaboveresults,usinganappropriategraphicaltechnique.(Usethegraphpaperopposite.) [5]

(ii) Describethetrendsevidentinthegraph.

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(c) ExplainwhypHinfluencestheactivityofanenzyme.

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(d) Thereareseveralpotentialproblemswiththedesignofthisexperiment.Suggestfour possibleproblemsintheprocedureused.

1. ___________________________________________________________

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2. ___________________________________________________________

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3. ___________________________________________________________

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4. ___________________________________________________________

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Section B

Quality of written communication is awarded a maximum of 2 marks in this section. [2]

8 (a) Giveanaccountofthestructureofthenucleicacids,DNAandRNA. [8]

(b) DescribetheprocessofDNAreplication. [5]

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(a) Giveanaccountofthestructureofthenucleicacids,DNAandRNA.

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(b) DescribetheprocessofDNAreplication.

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THIS IS THE END OF THE QUESTION PAPER

Permissiontoreproduceallcopyrightmaterialhasbeenappliedfor.Insomecases,effortstocontactcopyrightholdersmayhavebeenunsuccessfulandCCEAwillbehappytorectifyanyomissionsof acknowledgementinfutureif notified.

111562

6397.02

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GCE Biology Advanced Subsidiary (AS)Assessment Unit AS 1: Molecules and CellsJanuary 2011

Photograph 1.4(For use with Question 4)

NUCLEUS

NUCLEUS

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D

C

B

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0.5 Õm © Dr Jeremy Burgess/Science Photo Library