AQA A LEVEL BIOLOGY 7402/1 PAPER 1 QUESTION PAPER AND MARKS SCHEME { MERGED} JUNE 2023 COM, Exams of Biology

Download AQA A LEVEL BIOLOGY 7402/1 PAPER 1 QUESTION PAPER AND MARKS SCHEME { MERGED} JUNE 2023 COM and more Exams Biology in PDF only on Docsity! AQA A LEVEL BIOLOGY 7402/1 PAPER 1 QUESTION PAPER AND MARKS SCHEME { MERGED} JUNE 2023 COMPLETE AND VERIFIED Pleasewriteclearlyinblockcapitals. BIOLOGY Paper1 Wednesday7June 2023 Afternoon Timeallowed:2 hours Materials Forthispaperyoumusthave: • arulerwithmillimetremeasurements • ascientificcalculator. Instructions • Useblackinkorblackball-pointpen. • Fillintheboxesatthetopofthispage. • Answerallquestions. • Youmustanswerthequestionsinthespacesprovided.Donot write outside the box around each page or on blank pages. • Ifyouneedextraspaceforyouranswer(s),usethelinedpagesattheendof this book. Write the question number against your answer(s). • Showallyour working. • Doallroughworkinthisbook.Crossthroughanyworkyoudonot want to be marked. Information • Themarksforthequestionsareshowninbrackets. • Themaximummarkforthispaperis 91. Centrenumber Candidatenumber Surname Forename(s) Candidatesignature Ideclarethisismyownwork. A-level ForExaminer’sUse Question Mark 1 2 3 4 5 6 7 8 9 10 TOTAL 4 Donotwriteo utsidethe *04* IB/M/Jun23/7402/1 8 2Chitinkeepsthetracheaeopeninthetrachealsystemofgasexchangeinaninsect. Gasexchangedoesnotoccurinthetracheae. Explaintheimportanceof oneadaptationofthegasexchangesurfaceinthetracheal system of an insect. box [2 marks] 3Ligninisapolymerfoundinthewallsofxylemvesselsinplants.Ligninkeepsthe xylem vessel open as a continuous tube. Explaintheimportanceofthexylembeingkeptopenasacontinuoustube. [3 marks] 2 . 0 2 . 0 5 Donotwriteo utsidethe *05* IB/M/Jun23/7402/1 Turnoverforthenextquestion DO NOT WRITE ON THIS PAGE ANSWERINTHESPACESPROVIDED box Turnover► 6 Donotwriteo utsidethe *06* IB/M/Jun23/7402/1 1Thehumandisease,malaria,iscausedbyinfectionwithasingle-celledeukaryotic organism. Figure2showsadiagramof Plasmodiumvivax,oneofthespeciesthatcancause malaria. Figure2 box OtherthantheGolgiapparatus,nameonestructureinFigure2which shows that P. vivax is a eukaryote. [1 mark] 2DescribetwofunctionsoftheGolgiapparatusinaeukaryoticcell. [2 marks] 1 2 3 . 0 3 . 0 9 Donotwriteo utsidethe *09* IB/M/Jun23/7402/1 1 Some hospital patients suffer from diarrhoea caused by infection with the bacterium Clostridiumdifficile.TheC.difficilebacteriareleasetoxins.Thesetoxinscausethe diarrhoea. The toxins damage the cells lining the ileum, causing them to lose theirmicrovilli. The damage to the cells reduces the absorption of the products of digestion and reduces the absorption of water, resulting in diarrhoea. box Explainwhythedamagetothecellsliningtheileumreducesabsorptionof the products of digestion and why this reduces absorption of water. [3 marks] Question4continuesonthenextpage Turnover► 4 . 0 10 Donotwriteo utsidethe *10* IB/M/Jun23/7402/1 NotallpatientsinhospitalwithC.difficiledevelopdiarrhoea. Scientistsmeasuredtheanti-toxinantibodyconcentrationinhospitalpatientswith and without C. difficile infection. Theymeasuredtheanti-toxinantibodyconcentrationfourtimes: • onadmissiontohospital(day0) • onday 3 • onday 6 • onthedaythepatientleftthe hospital. Figure4showsthescientists’results. Figure4 box 11 Donotwriteo utsidethe *11* IB/M/Jun23/7402/1 9 2Thescientistssuggestthattheanti-toxinantibodycouldbegiventosomepatientsasa form of passive immunity. box UseFigure4tosuggesthowthispassiveimmunitywouldworkandwhich patients should be offered this anti-toxin antibody. [3 marks] 3Tobeusedaspassiveimmunitytreatment,theanti-toxinantibodywouldbeinjected.If it was given by mouth, it would be digested. Describehowtheanti-toxinantibodywouldbedigested. [3 marks] Turnoverforthenextquestion Turnover► 4 . 0 4 . 0 14 Donotwriteo utsidethe *14* IB/M/Jun23/7402/1 Thestudentkepttheplatesat25°Cfor24hours. Figure5showswhatoneofherplateslookedlikeafter24hours. Figure5 Thestudentmeasuredthediameteroftheclearzonewithnobacterialgrowth around each well. She made these measurements to the nearest whole mm Table1showsherresults. Table1 box Bacterialculture Diameterofclearzone/mm Cinnamonoil Positive Negative control control Bacillusspp. 15 14 0 Staphylococcusaureus 20 17 0 Listeriamonocytogenes 18 12 0 Escherichiacoli 16 12 0 Klebsiellaspp. 14 12 0 Medianforallcultures 0 Meanforallcultures 0 Standarddeviationforallcultures 2.4 2.2 0 15 Donotwriteo utsidethe *15* IB/M/Jun23/7402/1 10 3Suggestexactlywhatthestudentaddedtothewellstogetthepositivecontrol andnegativecontrolresults. [2marks] box 4CompleteTable1toshowthemedianandmean diameters. [1 mark] 5Themean±2standarddeviationsincludesover95%ofthe data. Usethisinformationtoconsiderwhetherthestandarddeviationssuggestthe differences in means are likely to be due to chance. Explainyouranswer,includingatleastonecalculation. [2 marks] Turnoverforthenextquestion Turnover► 5 . 0 5 . 0 5 . 0 16 Donotwriteo utsidethe *16* IB/M/Jun23/7402/1 1Definegenomeandproteome. [2marks] box Genome Proteome Theclassificationsystemusedintheearly20thcenturygroupeddifferentspecies ofbacteria according to the position and shape offlagella on bacterial cellsand bythe number of flagella per cell. These were observed using an optical microscope. Eachspeciesofbacteriumhasacharacteristiccellshapeandarrangementofflagella. These characteristics may be shared with other species within a genus. Flagellaarefragile,difficulttostainandmayextendfromthecellatanyangle. 2Considertheaccuracyandlimitationsoftheearlyclassificationofbacteriausingthe arrangement of flagella. [3 marks] 6 . 0 6 . 0 19 Donotwriteo utsidethe *19* IB/M/Jun23/7402/1 2TheWorldHealthOrganisation(WHO)suggeststhattoavoidlong-termhealtheffects, COHb concentrations should be kept below 2.5%. WHOrecommendsthatpeopleshouldnotbeexposedto: • airwith>10mgm –3 COformorethan8hours • airwith>30mgm –3 COformorethan1hour. Scientistshaveusedamathematicalmodeltocalculatetheexposuretocarbon monoxide that would result in 2.5% COHb in both adults and children. Table2showsthescientists’results. Table2 box COconcentrationintheair/mgm –3 Exposuredurationatrest/ resultingin2.5%COHb hours Child Adult 1 31.2 40.2 8 9.6 10.6 The scientists suggest that the WHO recommendations for carbon monoxideconcentrationsresultingin2.5%COHbshouldbereduced. Evaluatethescientists’conclusion. [3 marks] Turnoverforthenextquestion Turnover► 6 7 . 0 20 Donotwriteo utsidethe *20* IB/M/Jun23/7402/1 1 ScientistsinvestigatedadrugcalledMiTMABasatreatmentforcancer.MiTMAB inhibits cytokinesis. Figure8showsdrawingsofcancercellsseenwithanopticalmicroscopefrom a: • sampletreatedwithMiTMAB • controlsample. Figure8 A B ThecellsindrawingAcanbeidentifiedasthosetreatedwithMiTMAB. box Explainwhy. [2 marks] 8 . 0 21 Donotwriteo utsidethe *21* IB/M/Jun23/7402/1 2 MiTMABactsasanon-competitiveinhibitorofanenzymecalleddynamin. SuggesthowMiTMABcancausedynamintobecomeinactive. [3marks] box Question8continuesonthenextpage Turnover► 8. 0 24 Donotwriteo utsidethe *24* IB/M/Jun23/7402/1 9Denguefeverisahumandiseasecausedbythedenguevirus. ScientistsdesignedanELISAtesttodetectantibodiestothedenguevirusina patient’s blood sample. Figure10showsadiagramofthistestandsomeinformationabouthowitworks. Figure 10 Figure11showsthenegativeandpositiveresultsthatwereproduced20 minutes after the use of the test shown in Figure 10. Figure 11 box 0 25 Donotwriteo utsidethe *25* IB/M/Jun23/7402/1 1 Suggest what isonthetestatlineT andexplainwhatcausesthelinetoappearina positive test. box [2 marks] 2 AlineatCshowsthatthetesthasworked. SuggestonereasonwhyalineatCshowsthetest hasworked. [1 mark] Question9continuesonthenextpage Turnover► 9 . 0 9 . 0 26 Donotwriteo utsidethe *26* IB/M/Jun23/7402/1 Figure12showsaflowchartofhowtheanti-humanantibodieswithenzymeattached are produced. Figure 12 0 9.3Suggestwhythefusedcellsallowcontinuousproductionofmonoclonalantibodies. [2 marks] box 4EvaluatetheethicsoftheproductionprocessshowninFigure 12. [1 mark] 9 . 0 29 Donotwriteo utsidethe *29* IB/M/Jun23/7402/1 11 5Thescientistsrecommendthatthenewtestisusedfortheidentificationofdengue fever in all countries around the world. Discussthisrecommendation.Usealltheinformationgiven. box [3 marks] 6Thedengueviruscausesdamagetocapillariessothatbloodproteinsmoveoutof the capillaries into the tissue fluid. Explainhowthiswouldaffectthereturnoftissuefluidintothecapillaries. [2 marks] Turnoverforthenextquestion Turnover► 9 . 0 9 . 0 30 Donotwriteo utsidethe *30* IB/M/Jun23/7402/1 1Describehowaquaternaryproteinisformedfromitsmonomers. Do not include the process of translation in your answer. [5marks] box 0 . 1 31 Donotwriteo utsidethe *31* IB/M/Jun23/7402/1 2DescribethestructureofDNAandthestructureofachromosome. [6marks] box Question10continuesonthenextpage Turnover► 0 . 1 34 *34* IB/M/Jun23/7402/1 Question number Additionalpage,ifrequired. Writethequestionnumbersintheleft-handmargin. Donotwrite outsidethe box 35 Question number Additionalpage,ifrequired. Writethequestionnumbersintheleft-handmargin. Donotwrite outsidethe box *35* IB/M/Jun23/7402/1 36 Question Additionalpage,ifrequired. number Writethequestionnumbersintheleft-handmargin. MARKSCHEME–A-LEVELBIOLOGY–7402/1–JUNE 2023 Markschemeinstructionstoexaminers 1. General Themarkschemeforeachquestionshows: • themarksavailableforeachpartofthequestion • thetotalmarksavailableforthequestion • thetypicalansweroranswerswhichareexpected • extra information tohelp the examiner make his or herjudgement and help to delineate what is acceptable or not worthy of credit or, in discursive answers, to give an overview of thearea in which a mark or marks may be awarded. The extra information in the ‘Comments’ column is aligned to the appropriate answer in the left-handpart ofthemarkschemeandshouldonlybeappliedtothatiteminthemarkscheme. At the beginning of a part of a question a reminder may be given, for example: where consequentialmarkingneedstobeconsideredinacalculation;ortheanswermaybeon the diagram or at a different place on the script. Ingeneraltheright-handsideofthemarkschemeistheretoprovidethoseextradetails which confuse the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and consistent. 2. Emboldening Inalist of acceptableanswerswheremorethanonemarkisavailable‘any twofrom’is used, with the number of marks emboldened. Each of the following bullet points is a potential mark. Aboldandisusedtoindicatethatbothpartsoftheanswerarerequiredtoawardthe mark. AlternativeanswersacceptableforthesamemarkareindicatedbytheuseofOR. Differenttermsinthemarkschemeareshownbya/;egallowsmooth/free movement. 3. Markingpoints Markingoflists This applies to questions requiring a set number of responses, but for which students haveprovidedextraresponses.Thegeneralprincipletobefollowedinsuchasituation is that ‘right + wrong = wrong’. Eacherror/contradictionnegateseachcorrectresponse.So,ifthenumberoferrors/ contradictions equals or exceeds the number of marks available for the question, no marks can be awarded. However,responsesconsideredtobeneutral(oftenprefacedby‘Ignore’in the ‘Comments’ column of the mark scheme) are not penalised. 3 MARKSCHEME–A-LEVELBIOLOGY–7402/1–JUNE 2023 Markingprocedureforcalculations Full marks can be given for a correct numerical answer, without any working shown. However,iftheanswerisincorrect,mark(s)canusuallybegainedbycorrectsubstitution / workingandthisisshowninthe‘Comments’columnorbyeachstageofa longer calculation. Interpretationof‘it’ Answersusingtheword‘it’shouldbegivencreditonlyif itisclearthatthe‘it’refers to the correct subject. Errorscarriedforward,consequentialmarkingandarithmeticerrors Allowances for errorscarried forwardaremost likely to berestrictedto calculationquestionsandshouldbeshownbytheabbreviationECFor consequential in the mark scheme. An arithmetic error should be penalised for onemark only unless otherwise amplified in the mark scheme. Arithmetic errors may arise from a slip in a calculation or froman incorrect transfer of a numerical value from data given in a question. Phoneticspelling The phonetic spelling of correct scientific terminology should be credited unless there isa possible confusion with another technical term. Brackets (…..)areusedtoindicateinformationwhichisnot essentialforthemarktobeawarded but is included to help the examiner identify the sense of the answer required. Ignore/Insufficient/Donotallow Ignore or insufficient is used when the information given is irrelevant to the question ornot enough to gain the marking point. Any further correct amplification could gain the marking point. Donot allowmeansthatthisisawronganswerwhich,evenifthecorrectanswer is given, will still mean that the mark is not awarded. 4 MARKSCHEME–A-LEVELBIOLOGY–7402/1–JUNE2023 Question MarkingGuidance Mark Comments 01.1 1. Geneticmaterial,capsidandattachmentprotein; 2. Geneticmaterialcodesfor(viral)protein OR Capsidprotectsthegenetic material/RNA/DNA OR Attachmentproteinbindtoreceptors(oncell); 2 (2 x AO1) 1. Accept ‘DNA or RNA’(the‘or’OR‘/’ is needed) OR nucleic acid OR genome for‘genetic material’ 1. Ignoregenetic information 1. and2.Accept glycoprotein for attachmentprotein 1. Accept nucleocapsid for ‘capsidandnucleic acid’ 1. and 2. Accept capsomeresfor capsid 2. Accept DNA OR RNA OR genome for genetic material 2.AcceptcontainsOR stores OR encloses for protects 2.Acceptglycoprotein for receptor 2. Accept ECF for correct function of incorrect viral structuralfeature; eg reversetranscriptase produces DNA from RNA 5 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 02.3 1.(Allowsunbroken)water column 1.Acceptidea of OR continuousflowOR streamof water (So)nobarrierto(water)movement; 1.Ignorechainof 2.CohesionfromHbondsbetween(all)water watermolecules (molecules) OR 3 If1,2or 3arenot Cohesionfrom(polar)attractionbetween(all) awardedaccepta water(molecules); (3 x principlemark for 3. Evaporation/transpirationcreatestension(in AO1) correctreferenceto column) cohesion-tension OR causingwater Watermovesfromxylem(intocells) creates movement tension OR (To)pullupwatercreatestension(inxylem); 8 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 03.1 Membrane-boundorganelle(s) IgnorerERORrough ER OR Accept‘80S Mitochondrion/mitochondria ribosomes’OR ‘large(r)ribosomes’ OR Rejectsmooth Vesicle(s)/lysosomes 1 Rejectnucleolus OR (AO1) Rejectcellmembrane (Rough)endoplasmicreticulum OR Nucleus/(double)nuclearmembrane/pore(s)/ nuclearenvelope; Question MarkingGuidance Mark Comments 03.2 1.Modify/package/transportproteins Acceptprocessesfor modify OR 1.and2.Accept ‘adds Make/transportglycoproteins; carbohydrateto’for modify 2.Modify/package/transportlipids 1.Accept‘addslipid OR to’formodify 1.Accept lipoprotein Make/transportglycolipids; 2 max forglycoprotein 3.Forms/releasesvesicles/lysosomes; (2 x 1 or2.Accept AO1) chylomicronfor glycoprotein/glycolipid 2.Accept phospholipidforlipid Acceptadditional markingpoint, 4.Make/transport polysaccharides,but ignorecellulose Question MarkingGuidance Mark Comments 03.3 Answerkey: 1 India,Europe,EastAsia,CentralAmerica,South (AO3) America 9 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 03.4 Correctanswerof8.3814million/8381400/8.3814 x10 6 1 Acceptanycorrect numericalequivalent OR (AO2) answer 8.4million/8400000/8.4x 10 6 ; Question MarkingGuidance Mark Comments 03.5 1. Mutationproducedallele; 2. Thosewithallele/resistancelesslikelyto/do not get malaria/P vivax OR Thosewithallele/resistancesurvivemalaria/P vivax; 3. (Somorelikelyto)reproduceandpassonthe allele; 4. (Overgenerations)allele frequency increases; 4 (2 x AO1,2 xAO2) Rejectgenefor alleleonlyonce 1. Reject ‘mutation caused by infection/exposure to P. vivax’. 2. Acceptconverse; eg ‘people lacking theallelediefrom malaria’ 4. Acceptdescription of increasingfrequency of allele eg ‘higher proportion’, ‘more common’ but ‘ignore increase in number ofallele’ 10 MARKSCHEME–A-LEVELBIOLOGY–7402/1–JUNE 2023 Question MarkingGuidance Mark Comments 05.1 1.Washhandswith soap 1. Ignoresterilise OR handsORsurfaces 1. Acceptsanitisefor Disinfectsurfaces; disinfect 1. Acceptantiseptic 2.Usesterilepipette/syringe(totransferbacteria); /antimicrobial/alcohol (wipes) 3.(Removebottlelidand)flameneckof bottle; 1.and7Accept a namedtypeof 4.Liftlidof(agar)plateatanangle; disinfectant 2. Reject loop 5.Workclosetoupwardairmovement; 2. Acceptuse unopenedpipette/ 6.Usesterilespreader; syringeforsterile 4. Acceptliftlid 3 max slightlyORkeeplid 7.Placepipette/spreaderintodisinfectant (immediatelyafteruse); (3 x over plate AO1) 4. wi 5 m air 5 cur m 6. spr 6. st eg al ‘di rins Ignore‘work quickly thlidoff’ Reject ‘air ovementssterilise ’ Accept ‘convection rent’ for ‘upward air ovement’ Acceptloopfor eader Examples of erilisingtechnique , flame OR ‘dip in coholandflame’OR pindisinfectantand e(insterilewater)’ 13 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 05.2 Correctanswerinrangeof1.768to1.8 Acommoncorrect OR answerfor2marks is 1.77 2 = 2 marks Acceptfor1mark,evidenceof 28/28.26/28.3(correctcalculation,πx3 2 ) OR 2 28.27433(correctcalculationusingπvalue on (2 x calculator) AO3) Acceptcorrect OR roundingoffigures 0.4423(correctcalculationusingdiameterrather thanradius) OR 1.76(correctcalculationbutincorrectlyrounded); Question MarkingGuidance Mark Comments 05.3 (Positivecontrol) Ifnotspecified,acceptthe first 1. Antimicrobial/antibacterial(solution) answerasbeingforthepositive control OR 1.Accept named Antibiotic 2 antimicrobial/antibacterial/ antibiotic/antiseptic/disinfectant OR (2 x Antiseptic/disinfectant; AO3) (Negativecontrol) 2. (Sterile)water OR Oil(withoutcinnamon); Question MarkingGuidance Mark Comments 05.4 Allfournumberscorrect; 1 (AO2) Accept16.6and13.4asthe mean values (in this order) 14 Medianforallcultures 16 12 Meanforallcultures 17 13 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 1.(Mean±2SD)12.2to21.8and8.6 to 17.4 OR (Mean±2SD)11.8to21.4and9(.0) to 17.8 OR (Mean±1.96SD)12.3to 21.7 and8.7 to 17.3 OR (Mean±1.96SD)11.9to 21.3and 9.1to 17.7; 2.(SD)overlapsodifference (likely to be) due to chance OR (SD) overlap so (likely) no significantdifference(inmeans); 1.Accept ECFfor1mark, correctSDscalculatedusing incorrectmeansin05.4 2. Accept ECFfor1mark, 2 correctexplanationbased oncorrectSDscalculated 05.5 (2 x fromincorrectmeansin05.4 AO3) 2.Rejectresultsaredue tochanceORresultsare significant 15 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 07.1 1.Less(oxygen)loadedathighpO2(compared Ignorereferencesto withnoCO) ‘bindingsites OR occupiedbyCO’ 1.Accept‘inlungs’for MaximumHbsaturationis50%(oxygen); ‘highpO2’ 2.(AtlowpO2)Hbhashigh er affinity(foroxygen); 1.Accept‘levels(off)’ 3.HbhasmoreoxygenatlowpO2 OR‘plateauat 50%’ OR formaximum 3 1Accept‘only50%’ Hbunloadslessoxygenatlow pO2; (1 x for‘maximum(of) AO2,2 50%’ xAO3) 3.Accept‘in (respiring) cells/tissues’for‘low pO2/cells’ 3.Ignore‘more loadingofoxygenat low pO2’ 3.Accept‘lessreadily’ forless 18 MARKSCHEME–A-LEVELBIOLOGY–7402/1–JUNE2023 Question MarkingGuidance Mark Comments (Forscientists’suggestion) 1. Children exposed (to CO) for 8 hours;(Againstscientists’suggestion) 2. Childrenexposed(toCO)for1hour OR Adultsexposed(toCO)for1hourand8hours; (But) 3. Mathsmodelmaynot beaccurate OR Mathsmodeldidnotusepeople; 4. (Recommendationforpeople)onlyatrest OR Unknowneffectsofexercise(onCOuptake); 5. (Peoplevaryin)size/age/ethnicity OR Differentsex; 6. Nostatisticaltesttoshowifdifferences are significant; 7. UnknowneffectsonCOexposureforpeoplewith respiratory disease OR UnknowneffectsonCOexposureforsmokers; 8. MightnotbeabletoreduceCO(concentration) in air below 10(mg m-3); Award3maxonlyif answercontains MP1ORMP2 3.Accept‘(basedon) invalid assumptions’ for ‘may not be accurate’ 3. Accept test OR experiment ORinvestigation for‘mathsmodel’ 3 max 07.2 (3 x AO3) 5.Acceptgender 6.AcceptnoSDsto showifdifferences aresignificant 7.Acceptany namedrespiratory disorder;egasthma ORcoronaryheart disease 19 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 08.1 1. 2nuclei(in cells) OR Cells(stopped)attelophase; 2. Cytokinesisprevented OR Stopped(new)cellmembraneforming OR Stoppedcytoplasmdividing; 2 (2 x AO3) 2. Accept cell membrane not dividing/splitting/ pinching(inthecell) Question MarkingGuidance Mark Comments 08.2 1.(MiTMAB)binds(todynamin)otherthanthe 1.Accept(MiTMAB) activesite; bindstodynaminat 2.Changestheshapeof(dynamin)activesite anallosteric OR inhibitorsite OR 3 2.Acceptdenaturefor Changesthetertiarystructure(of dynamin/ enzyme); (1 x ‘changeinshape’ AO1,2 3.Notcomplementarysosubstratedoesnot bind xAO2) 3.AcceptEScomplex (toactivesite) inthisinstance OR 3.IgnoreESC 3.AcceptfitOR Notcomplementarysono/fewerenzyme- attachforbind substratecomplexes(form); 20 MARKSCHEME–A-LEVELBIOLOGY–7402/1–JUNE 2023 Question MarkingGuidance Mark Comments 09.1 1.Antigen(at Tandsubstrate); 1.Rejectantigen in 2.Enzyme-substratecomplex(producesa 2 blood line/colourchange) 2.Acceptcolourless OR (2 x dyeforsubstrate AO2) 2.AcceptEScomplex Enzyme(binds)withsubstrate(produces inthisinstance line/colourchange); Question MarkingGuidance Mark Comments 09.2 Blood/samplehasmoved/diffused(aboveTin the 1 AcceptBlood/sample test); (AO3) andanti-human antibodyhavemoved (inthe test) Question MarkingGuidance Mark Comments 09.3 1.(Cancer/fusedcells)divide/replicate 1.AcceptmitosisOR reproducefordivide rapidly/uncontrollably; 2.Bcellsproduce(monoclonal)antibody; 1.Accept hybridoma 2 for‘fusedcell’ (2 x 2.Accept ‘plasma AO2) cells’OR‘memory cells’for‘B cells’ 2.AcceptsecreteOR makefor produce Question MarkingGuidance Mark Comments 09.4 Harmfulbutnotkilled Musthaveidea ‘for’ OR andidea‘against’ Harmfulbutonlyused once AcceptstressedOR OR exploitedOR Harmfulbutstopshumansuffering 1 mistreatedOR OR (AO3) abusedfor harmed AcceptillnessOR Harmfulbutproduces(useful)medicine/drugs infectionORdeathfor OR suffering Notharmedbutinjected(withasubstance); 23 MARKSCHEME–A-LEVELBIOLOGY–7402/1–JUNE2023 Question MarkingGuidance Mark Comments 1. Betterthancurrentatdetectingearlybutnot as good as lab-based; 2. New/currenttestbetterthanlab-basedfrom 5 days OR Newtestasgoodascurrentfrom5 days; 3. Newtestandlab-basedbettertotal (of)positivesthancurrent OR Newtesttotal(of)positivesnot(quite)as good as lab-based; 4. Newtest(likelytobe) quicker; 5. Newtest(likelytobe) cheaper; 6. Limited/inaccessiblelabs OR Limitedtrainingofpeopletouselabs; Max2from4,5and6 AcceptELISA test fornewtest 1, 2 and 3 Accept correctcomparative figures from Table3 OR calculations (some examples in table below) 1. and2.Accept higherproportion forbetter 09.5 3 max (3 x AO3) 1. Accept referencetoday(s)in rangeof 1to4daysforearly 1.Acceptidentifies ORfindsORspots for detects 1. and 2. Accept ‘moreaccurate’OR ‘identifiesmore’OR ‘finds more’ OR ‘detects more’ OR ‘ismoresuccessful’ OR ‘is more effective’ for “better than” and the converse of these statements for “not as good as” 2.Acceptafter4days 4.Accept‘more efficient’forquicker Timeafteronsetof symptoms/days Numberofpositiveresults/%(combinedwithearlierresult(s)) Lab-basedtest Current test Newtest 1–2 71 0 43 3–4 74 (73) 16 (12) 63 (58) 5–7 44 (66) 78 (29) 78 (63) 24 MARKSCHEME–A-LEVELBIOLOGY –7402/1–JUNE2023 Question MarkingGuidance Mark Comments 09.6 1.Increaseswaterpotentialofblood/capillary 1. AcceptΨforwater potential OR 1IgnoreWP Decreaseswaterpotentialoftissuefluid; 2 1. Acceptreduces 2.(So)lesswaterreturnstoblood/capillaries(by (2 x water potential osmosis) AO2) gradient OR 2. Ignoretissuefluid (So)morewaterleavesblood/capillaries(by 2. Accept‘no’forless osmosis); 25