For Examiner’s use only

QuestionMarksNumber

1

2

3

4

5

6

7

8

9

TIME

1hour30minutes.

TotalMarks

71

Centre Number

Candidate Number

AB111

6398.13R

ADVANCED SUBSIDIARY (AS)General Certificate of Education

2011

Biology

AssessmentUnitAS1assessing

MoleculesandCells

[AB111]

MONDAY 13 JUNE, AFTERNOON

INSTRUCTIONS TO CANDIDATES

WriteyourCentreNumberandCandidateNumberinthespacesprovidedatthetopofthispage.Writeyouranswersinthespacesprovidedinthisquestionpaper.Answerall nine questions.YouareprovidedwithPhotograph 1.4forusewithQuestion4inthispaper.Donotwriteyouranswersonthisphotograph.

INFORMATION FOR CANDIDATES

Thetotalmarkforthispaperis75.SectionAcarries60marks.SectionBcarries15marks.Figuresinbracketsprinteddowntheright-handsideofpagesindicatethemarksawardedtoeachquestionorpartquestion.YouareremindedoftheneedforgoodEnglishandclear

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

111070

6398.13R 2 [Turn over

Examiner Only

Marks RemarkSection A

1 Thefollowingstatementsdescribeeventswithinstagesofmeiosis.

Identifythestageineachcase.

• Bivalentsareformedwhenhomologouschromosomespair

______________________________________

• Chromatidsseparateandarepulledtooppositepoles

______________________________________

• Fourhaploidnucleiareformed

______________________________________

• Chiasmataoccur

______________________________________ [4]

6398.13R 3 [Turn over

Examiner Only

Marks Remark2 Fungiarecomposedofeukaryoticcells,similartobothplantandanimal

cells.Thecellularstructureofafungusisrepresentedinthediagram.

glycogen granules nuclei

vacuole

endoplasmic reticulum cytoplasm cell wall

mitochondrion

(a) Identifywhichstructureslabelledinthediagramabovearealsofound

• inbothplantandanimalcells

__________________________________________________________

__________________________________________________________

• inplantcellsbutnotinanimalcells

__________________________________________________________

• inanimalcellsbutnotinplantcells

__________________________________________________________[3]

(b) Identifyonefeaturewhichisuniquetothecellsoffungi.

___________________________________________________________[1]

6398.13R 4 [Turn over

Examiner Only

Marks Remark

Examiner Only

Marks Remark

3 Usingaseriesoftests,akeywasproducedtoidentifythefollowingcarbohydrates:

cellulose, glucose, maltose, starch and sucrose.

UsingthekeyidentifyeachofthecarbohydratesAtoE.

A ______________________________________

B ______________________________________

C ______________________________________

D ______________________________________

E ______________________________________ [5]

Solubility in water

Insoluble Soluble

negativeresult

positiveresult

negativeresult

positiveresult

negative result

positiveresult

Iodine test Benedict’s test

Clinistix test

ED

A B C

6398.13R 5 [Turn over

Examiner Only

Marks Remark4 Photograph 1.4isasectionthroughpartoftheileum.

(a) IdentifythestructureslabelledAtoE.

A__________________________________________

B__________________________________________

C__________________________________________

D__________________________________________

E__________________________________________ [5]

(b) SuggestaninterpretationforthearealabelledF.

_____________________________________________________________

___________________________________________________________ [1]

(c) Describetheroleofthelactealwithineachvillusoftheileum.

_____________________________________________________________

___________________________________________________________ [1]

6398.13R 6 [Turn over

Examiner Only

Marks Remark5 (a) ThediagrambelowrepresentsthestructureofDNA.

X

IdentifythepartoftheDNAstructureshownintheboxX.

___________________________________________________________ [1]

(b) Inaclassicexperiment,MatthewMeselsöhnandFrankStahlgrewbacteriainamediumwherethenitrogensourcecontainedthe‘light’nitrogenisotope,14N.Thebacteriawerethenplacedinamediumwithanitrogensourcecontainingthe‘heavy’nitrogenisotope,15N,andallowedtoreproduce.Aftermanygenerations,allDNAinthebacteriacontainedthis‘heavy’15Nisotope.ThisDNAwastermed‘heavy’DNA.

DNAextractedfrombacterialcellswascentrifugedandobservedunderultra-violetlight.TheDNAappearedasablackbandinthecentrifugetube.Thebandproducedby‘heavy’DNAwasmuchlowerinthecentrifugetubethanthatproducedby‘light’DNA.Theyareshowninthediagramsbelow.

light DNA

heavy DNA

6398.13R 7 [Turn over

Examiner Only

Marks Remark Thebacteriacontaining‘heavy’DNAwerethentransferredtoa

mediumwithanitrogensourcecontainingthe‘light’nitrogenisotope,14Nandallowedtoreproduce.Afteronegeneration,samplesofthebacteriawereremovedandtheirDNAwasextractedandcentrifuged.Thisprocesswasrepeatedafterafurthergeneration.

(i) CompletethediagramsbelowtoshowthepositionoftheextractedDNAbydrawing appropriate bands.

after onegeneration

after twogenerations

[2]

(ii) Explaintheresultproducedafteronegeneration.

__________________________________________________________

__________________________________________________________

__________________________________________________________

_______________________________________________________[2]

6398.13R 8 [Turn over

Examiner Only

Marks Remark6 Enzymescanbeimmobilisedforuseinbiotechnology.

(a) Outlinetwomethodsusedtoimmobiliseenzymes.

1.___________________________________________________________

_____________________________________________________________

2.___________________________________________________________

___________________________________________________________ [2]

(b) ThegraphbelowshowstheeffectofpHontheenzymesucrasewheninsolutionandwhenimmobilised.

03 5 7 9

pH

4 6 8 10

10

20

Suc

rase

act

ivity

/arb

itrar

y un

its 30

40sucrase in solutionimmobilised sucrase

(i) ThegraphshowsthatenzymeimmobilisationreducestheactivityofsucraseattheoptimumpH.Calculatethepercentagereductionintherateoftheactivityforthisimmobilisedsucrase.

Answer_______________________ [3]

6398.13R 9 [Turn over

Examiner Only

Marks Remark (ii) Explainthereductionintheactivityoftheimmobilisedsucrase.

__________________________________________________________

__________________________________________________________

__________________________________________________________

_______________________________________________________[2]

(iii)Usingtheinformationinthegraph,describeandexplainoneotherdifferenceintheactivityofthesucraseinsolutionandwhenimmobilised.

__________________________________________________________

__________________________________________________________

__________________________________________________________

_______________________________________________________[2]

6398.13R 10 [Turn over

Examiner Only

Marks Remark7 Anexperimentwascarriedoutontherateofabsorptionoftwomonosaccharidesugarsbylivingintestinalcellsandintestinalcellsthathavebeenpoisonedwithcyanide(achemicalwhichinhibitsproductionofATPincellsbyinhibitingcellrespiration).Theresultsareshowninthetablebelow.

MonosaccharideRate of absorption/arbitrary units

Living intestinal cellsCyanide-treated intestinal cells

Glucose 1.00 0.33

Arabinose 0.29 0.29

(a) Describethetrendsevidentinthedataabove.

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

___________________________________________________________ [3]

(b) Identifywhichofthetwomonosaccharidesisentirelyabsorbedbydiffusion.Explainyouranswer.

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

___________________________________________________________ [3]

6398.13R 11 [Turn over

Examiner Only

Marks Remark (c) Onceabsorbedintotheintestinalcells,glucosemaybeconverted

intoapolysaccharideforstorage.Namethepolysaccharidestoredinanimalcellsanddescribehowitissynthesisedfromglucose.

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

___________________________________________________________ [4]

(d) Cyanide,whichwasusedinthisinvestigationtoinhibitcellrespiration,canbedescribedasanon-competitiveenzymeinhibitor.Explainwhatismeantbytheterm‘non-competitive’.

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

___________________________________________________________ [2]

6398.13R 12 [Turnover

ExaminerOnly

Marks Remark8 (a) Thewaterpotentialofacell(ψcell)hastwocomponents,thesolute

potential(ψs)andthepressurepotential(ψp).

(i) Explainwhythesolutepotentialofacell’scontentsisalwayslessthanzero.

__________________________________________________________

_______________________________________________________[1]

(ii) Statethetermwhichisusedtodescribeaplantcellwhenitspressurepotential(ψp)iszero.

_______________________________________________________[1]

(b) Thesoluteandpressurepotentialsofcarrottissueweredeterminedafterimmersioninfiveexternalsolutions(differingintheirsolutepotential).Theseareshowninthegraphbelow.

–400

–600

–200

0

200

400

Pot

entia

l/kP

a

–1200 –1000 –800 –600 –400 –200

solute potential ( s) of external solution/kPa

pressure potential psolute potential

6398.13R 13 [Turn over

Examiner Only

Marks Remark (i) Thewaterpotentialofthecarrottissuewascalculatedusingthe

valuesforsoluteandpressurepotentialsshowninthegraphopposite.Threeofthevaluesareshowninthetablebelow.

Complete the tablebycalculatingthetwomissingvalues.

Solute potential of the external solution /kPa

Water potential of the carrot tissue /kPa

–200 0

–400 –150

–600 –370

–800

–1000

[2]

(ii) Plotthewaterpotentialvalues,includingthoseyouhavecalculated,onthegraphoppositeanddrawanappropriatelineofbestfit. [2]

Fullturgoroccurswhennomorewatercanenterthetissue.

(iii)Usingthegraph,determinethesolutepotentialoftheexternalsolutionatthepointoffullturgor.

_______________________________________________________[1]

6398.13R 14 [Turn over

Examiner Only

Marks Remark (c) Aweighingmethodcanbeusedtodeterminetheaveragewater

potential(ψcell)ofplanttissues,suchaspotato.

(i) Brieflydescribetheprocedurefortheweighingmethod.

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

_______________________________________________________[3]

(ii) Explainhowyouwouldanalysetheresultstoobtainanestimateofthewaterpotentialofpotatocells.

__________________________________________________________

__________________________________________________________

__________________________________________________________

_______________________________________________________[2]

(iii)Explainthebiologicalbasisoftheweighingmethodasameansofdeterminingtheaveragewaterpotentialofthecellsinaplanttissue.

__________________________________________________________

__________________________________________________________

__________________________________________________________

_______________________________________________________[2]

6398.13R 15 [Turn over

Examiner Only

Marks RemarkSection B

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

9 Giveanaccountofthestructureofproteinsandtheirrolesinthecell-surfacemembrane. [13]

___________________________________

Structureofproteins.

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

6398.13R 16 [Turn over

Examiner Only

Marks Remark _________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

Roleofproteinsinthecell-surfacemembrane.

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

Examiner Only

Marks Remark

6398.13R 17

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

6398.13R 18 [Turn over

THIS IS THE END OF THE QUESTION PAPER

Permissiontoreproduceallcopyrightmaterialhasbeenappliedfor.Insomecases,effortstocontactcopyrightholdersmayhavebeenunsuccessfulandCCEAwillbehappytorectifyanyomissionsofacknowledgementinfutureifnotified.

111070

AB

111I

NS

1

GCE Biology Advanced Subsidiary (AS)

Assessment Unit AS 1: Molecules and Cells

Summer 2011

Photograph 1.4

(For use with Question 4)

6398.02111071

© School of Anatomy and Human Biology, The University of Western Australia

A

B

C

D

E

F

ileumlumen

AB

111I

NS

1