2015 HSC Biology - Board of Studies group of students wanted to test whether water purifying tablets were effective in making creek water free from bacteria. ... 2015 HSC Biology

2015 HIGHER SCHOOL CERTIFICATE EXAMINATION

1000

Biology

General Instructions

•Readingtime–5minutes

•Workingtime–3hours

•Writeusingblackpen

•Drawdiagramsusingpencil

•Board-approvedcalculatorsmaybeused

Total marks – 100

Section I Pages2–28

75 marks

Thissectionhastwoparts,PartAandPartB

PartA–20marks

•AttemptQuestions1–20

•Allowabout35minutesforthispart

PartB–55marks

•AttemptQuestions21–31

•Allowabout1hourand40minutesforthispart

Section II Pages29–43

25 marks

•AttemptONEquestionfromQuestions32–36

•Allowabout45minutesforthissection

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Section I75 marks

Part A – 20 marksAttempt Questions 1–20Allow about 35 minutes for this part

Usethemultiple-choiceanswersheetforQuestions1–20.

1 What is the name of the theory which describes evolution as patterns of rapid firstappearancesorextinctionsfollowedbyperiodsoflittleornochange?

(A) Gradualism

(B) Convergence

(C) Adaptiveradiation

(D) Punctuatedequilibrium

2 Whatarealternativeformsofgenescalled?

(A) Alleles

(B) Autosomes

(C) Chromatids

(D) Chromosomes

3 Whichadaptationwoulddecreasewaterlossfromaplantinaregionwithlowrainfall?

(A) Broadleaves

(B) Surfaceroots

(C) Sunkenstomates

(D) Looselypackedepidermalcells

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4 WhichofthefollowingdoesNOTplayaroleinmaintainingthehealthofanorganism?

(A) Mitosis

(B) Celldeath

(C) Geneexpression

(D) Sexualreproduction

5 Thediagramshowsamodelforenzymeaction.

Whichletterindicatesthesubstrateinthisdiagram?

(A) W

(B) X

(C) Y

(D) Z

6 Anextremelyhighconcentrationofcarbondioxideisundesirableinactivemuscletissuebecauseitwill

(A) increasethepH.

(B) causeenzymestodenature.

(C) increasecellularreactionrates.

(D) causehaemoglobintoreleaseoxygen.

Awaiting copyright

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RefertothefollowinginformationtoanswerQuestions7and8.

Thediagramshowsahomeostaticmechanisminamammal.

Core bodytemperature

below normal

Return tonormal core body

temperatureX

Muscles of skin

Arteriole wallsin skin

NEGATIVE FEEDBACK

7 WhatdoesX representinthediagram?

(A) Theheart

(B) Thebrain

(C) Athermoreceptorintheskin

(D) Apressurereceptorinabloodvessel

8 Whichofthefollowingdescribeswhathappenstothemusclesandthearteriolewallsintheskinwhenthecorebodytemperatureisbelownormal?

Muscles of skin Arteriole walls in skin

(A) Relaxtolowerepidermalhairs Expand

(B) Contracttoraiseepidermalhairs Contract

(C) Relaxtoraiseepidermalhairs Expand

(D) Contracttolowerepidermalhairs Contract

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9 Apathogenandaredbloodcellaredrawntothesamescale,withsomefeaturesindicated.

Pathogen

Cell wallMembrane

Membrane

Red blood cell

Whattypeofpathogenisthis?

(A) Avirus

(B) Aprion

(C) Afungus

(D) Abacterium

10 ATPisanorganicmoleculecommontothemetabolismofeveryspeciesonEarth.

Which of the following statements explains why this fact is considered evidence forevolution?

(A) AllspecieshaveevolvedtobesuitedtotheenvironmentofEarth.

(B) ATPmoleculesweretransferredbetweenorganismsearlyinthehistoryoflife.

(C) ThegeneforATPdeveloped in theearliestorganismsandhasbeenretainedbysubsequentspecies.

(D) All species on Earth developed the same gene for ATP as a consequence ofconvergentevolution.

11 EnvironmentcanaffectphenotypebyalteringthesequenceofbasesinDNA.

Whichofthefollowingisanexampleofthis?

(A) Highproteindietsmakingchildrentallerthantheirparents

(B) Stresscausingtheexpressionofonesetofgenesinsteadofanother

(C) Languageandmusiclessonsimprovingintelligenceinyoungchildren

(D) Nuclearfalloutfromatomicbombsincreasingbirthdefectsinpopulations

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The larvae of fruit flies damage fruit in Western Australia. To control theproblem,growersareadvisedtosprayfruittreeswithpesticides.Anyalreadydamaged fruit is boiled anddisposedof as chicken foodor landfill.Anothercontrol measure is the release of genetically engineered infertile flies of thisspecies.

12 Whichreasonbestexplainswhythecorrespondingcontrolmeasurereducesthisproblem?

Control measure Reason

(A) Releaseofinfertileflies Infertilefliesdonoteatthefruit

(B) Releaseofinfertileflies Thenumberoffliesinthenextgenerationisdecreased

(C) Boilingfruitandfeedingtochickens

Chickensareunaffectedbythedamagedfruit

(D) Boilingfruitandfeedingtochickens

Theamountofwasteforlandfillisreduced

13 The following measures could be used to prevent the spread of this fruit fly acrossAustralia.

1. Australia-widereleaseofinfertilefruitflies

2. Aerialsprayingoforchardsthroughoutthecountry

3. SpotsprayingofnewlyaffectedorchardsinWesternAustralia

4. StoppingthetransportoffruitfromWesternAustraliatootherstates

TopreventthespreadofthisfruitflyacrossAustralia,whichcombinationofmeasureswouldbemostpracticaltouse?

(A) 1and2

(B) 1and4

(C) 2and3

(D) 3and4

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14 ThetableshowsthebasetripletsinmRNAforaminoacids.

Fromthetable,theaminoacidSerine(Ser)canbecodedforbythebasetripletUCG.

Base triplets found in messenger RNA

SecondbaseU C A G

Firs

tbas

eU

Phe Ser Tyr Cys U

Thi

rdb

ase

Phe Ser Tyr Cys CPhe Ser Stop Stop APhe Ser Stop Trp G

C

Leu Pro His Arg ULeu Pro His Arg CLeu Pro Gln Arg ALeu Pro Gln Arg G

A

lle Thr Asn Ser Ulle Thr Asn Ser Clle Thr Lys Arg A

Met Thr Lys Arg G

G

Val Ala Asp Gly UVal Ala Asp Gly CVal Ala Glu Gly AVal Ala Glu Gly G

© California Department of Education

WhichbasetripletcouldcodefortheaminoacidTyrosine(Tyr)?

(A) CCU

(B) CAU

(C) UAA

(D) UAC

15 Inacertainplantspecies,individualplantshaveeitheryellow,redororangeflowers.

Twoplants,eachwithadifferentflowercolour,werecrossedinabreedingexperimentlike thosecarriedoutbyMendel.TheF2resultswere:6 red,11orangeand5yellowfloweredplants.

Whatwerethegenotypesoftheoriginalparentplants?

(A) RYandRY

(B) RRandrr

(C) RRandYY

(D) RrandRY

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16 Whymightepidemiologybeconsideredmoreessentialforthestudyofnon-infectiousdiseasesthanforthestudyofinfectiousdiseases?

(A) Thecausesofinfectiousdiseaseshavealreadybeendetermined.

(B) Onlynon-infectiousdiseasesareaffectedbypatternsofbehaviour.

(C) Epidemiologycannotbeusedtofindthecausesofinfectiousdiseases.

(D) Koch’spostulatesarenotusefulinfindingthecausesofnon-infectiousdiseases.

17 Thediagramshowsaninteractionbetweencellsoftheimmunesystem.

Antigen

Surfacereceptors

T Cell

Cytokine

Illustration from Anatomy & Physiology, Connexions Website by OpenStax College. http://cnx.org/content/col11496/1.6/, Jun 19, 2013.

Whatspecificprocessisshowninthediagram?

(A) Bcellencounteringanantigen

(B) ActivationofamacrophagebyahelperTcell

(C) StimulationofaBcelltobecomeaplasmacell

(D) CytotoxicTcelldestroyingavirus-infectedcell

18 Studentsconductedalargefirst-handinvestigationintoenzymeactivity.

Theaiminthereportisshown.

Aim: To determine the optimum pH of four different enzymes.

Howmanyindependentvariableswereinthisfirst-handinvestigation?

(A) 1

(B) 2

(C) 4

(D) 5

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Theintestinaltractofahumanfoetusissterile.

After birth, microflora from the mother are transferred to the baby’s mouththroughclosecontact.Afterayear,themicrofloraofthebabyissimilartothemother’s,withthebaby’simmunesystemignoringthesemicrobes.

Also during the first year of life, breast milk from the mother providesantibodies to the baby for any disease the mother has already experienced.Whenbreastfeedingceases,theseantibodylevelsinthebabystarttofall.

Afterthefirstyear,anynewspeciesofinvadingbacteriaistreatedasapathogenbythebaby’simmunesystem.

19 A medical consequence for six-month-old babies that have only been bottle-fed withformulamilkandnotbreastfedisthat

(A) theywillnotdevelopmicroflora.

(B) theirimmunesystemwillbedamaged.

(C) theirconsumptionofmilkcannotbequantified.

(D) theywillbeatincreasedriskofinfectiousdisease.

20 Stricthygienepracticesarefollowedinthecareofnewborns,whereashygienepracticesinthecareofolderbabiesarelessemphasised.

Whichofthefollowingisthebestreasonforthisdifference?

(A) Vaccinationsrenderpersonalhygieneunnecessaryforolderbabies.

(B) Procaryoticcellsarenotidentifiedasantigensinearlydevelopment.

(C) Antibiotictreatmentskillbacterialpopulationsinthedigestivesystem.

(D) Earlyexposuretopathogenshelpstobuildastrongimmunesystem.

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© 2015 Board of Studies, Teaching and Educational Standards NSW

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Centre Number

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Biology

Section I (continued)

Part B – 55 marksAttempt Questions 21–31Allow about 1 hour and 40 minutes for this part

Answer the questions in the spacesprovided. These spaces provideguidance for the expected length ofresponse.

Extra writing space is provided onpages27and28.Ifyouusethisspace,clearly indicate which question youareanswering.

Write your Centre Number andStudent Number at the top of thispage.

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Question 21 (2marks)

ExplainONEcontrolmeasureformalaria.

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Explainwhyinsectsexcreteuricacidastheirprincipalnitrogenouswaste.

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ThediagramshowsamodelinvolvingDNA.

(a) Whatprocessisbeingmodelled?

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(b) IdentifyTWOstructuralfeaturesoftheDNAmoleculewhichareNOTshowninthismodel.

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Datacanbeprovidedbyapulseoximeterpeggedtoaperson’sfinger,asshowninthediagram.

PULSE OXIMETER

97% bpm

78

(a) Whatistheoxygensaturationforthisperson?

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(b) OutlineTWOlimitationsofusingonlytheinformationprovidedinthediagramtodeterminethe‘health’ofaperson.

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(c) Explain TWO advantages in using a pulse oximeter to measure oxygensaturationcomparedtousinganothernamedtechnologyinaspecificsetting.

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Agroupofstudentswantedtotestwhetherwaterpurifyingtabletswereeffectiveinmakingcreekwaterfreefrombacteria.

They conducted an experiment using a water sample collected from the creek andfoundthatthetabletswereeffective.

(a) Describe a means of addressing ONE identified hazard relevant to thisinvestigation.

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(b) Illustratetheresultsofthisexperimentindiagrammaticform.

Uselabelstoclearlyidentifythedatacollected.

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Sugaristransportedinvasculartissuesinplantsandanimals.

Contrast the structure and workings of ONE named plant tissue and ONE namedanimaltissueusedtotransportsugar.

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(a) OutlineTWOdifferencesbetweenwholebloodandplasma.

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(b) ThestepsbelowshowthepreparationanduseofbloodproductsinthetreatmentofEbolaVirusDisease.Thisdiseaseischaracterisedbysignificantbloodloss.

World Health Organisation Protocol

1. ApatientrecoversfromEbolaVirusDisease.

2. Thesamepatientisdisease-freefor28days.

3. Bloodistakenfromthepatientandscreenedfortransmissiblediseases.

4. Plasmaisseparatedfromthewholeblood.

5. PlasmaistransfusedintoanotherpersonwithearlysignsofEbolaVirusDisease.

Explain why this protocol produces an effective treatment for Ebola VirusDisease.

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Use of convalescent whole blood or plasma collected from patients recovered from Ebola virus disease http://www.who.int/csr/resources/publications/ebola/convalescent-treatment/en/

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Agroupofstudentshypothesisedthattheheightofplantsdecreaseswithincreasedelevation.

Thestudentsplantedtenplantcuttingsfromthesameplantateachoffivelocations.Thelocationswereatvaryingelevationsinthesamemountainrange.Allthecuttingswere provided with the same volume of water on planting, and no fertiliser wasapplied.Thestudentsreturnedafterthesamegrowthperiodandmeasuredtheheightoftheplants.

Thecross-sectionshownindicatestheaverageheightoftheplantsinmetresafterthegrowthperiodateachlocationinthemountainrange.

1

2

3

0

Ele

vatio

n(1

02 m)

prevailing wind

Mountain range cross-section

N

(10 m) (15 m)

(4 m)

(7 m)

(12 m)

(a) Evaluatethevalidityoftheexperiment.

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Question28(continued)

(b) Completebothcolumnsofthetabletobestpresentthedatafortheanalysisofanytrend.

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‘The application of modern reproductive techniques in plant and animal breedinglimitsgeneticdiversity.’

Discussthisstatement.

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Thegraphshowsthehistoryoftherelativenumbersofthreevarietiesofbird(X,YandZ )withinabirdspecies,onaremoteislandinthePacificOcean.

Thebirdspeciesarrivedontheislandinamigrationevent.Beforemigration,thebirdspecieswasnotpresentontheisland.

Thegraphrecordofbirdnumbersontheislandisdividedintotwosections(1and2).Overthetimedatawererecorded,theenvironmentoftheislanddidnotchange.

0 50 100Time (Number of generations after migration event)

Num

ber o

f bird

s

Variety X

Variety Y

Variety Z

150 200

21

(a) Whatbirdvarietiesoriginallymigratedtotheisland?

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(b) Using the Darwin/Wallace theory of evolution, and making reference(s) to thedatainthegraph,explainthechangestothepopulationofeachvarietyofbirdin

(i) section 1 ofthegraph. 2

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‘Renal dialysis and kidney transplants are very different treatments for the samemedicalcondition.Eachtreatmentwasdevelopedfromanewapplicationofbiologicalknowledge.’

Justifythesestatements.

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Section I Part B extra writing space

If you use this space, clearly indicate which question you are answering.


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Biology

Section II

25 marksAttempt ONE question from Questions 32–36Allow about 45 minutes for this section

Answerparts(a)–(e)ofonequestionintheSectionIIWritingBooklet.Extrawritingbookletsareavailable.

Pages

Question32 Communication......................................................................30–31

Question33 Biotechnology........................................................................33–35

Question34 Genetics:TheCodeBroken?.................................................37–39

Question35 TheHumanStory.................................................................. 40–41

Question36 Biochemistry..........................................................................42–43

– 30–

Question 32 — Communication (25marks)

Answerparts(a),(b)and(c)ofthequestiononpages2–4oftheSectionIIWritingBooklet.Starteachpartofthequestiononanewpage.

(a) Thediagramshowschangesinmembranepotentialinaneuroneafterastimulusisappliedattimet.

t

–70

–60

+30

Time (ms)

Mem

bran

e po

tent

ial (

mV

)

Adapted from Art Connection graph: Figure 3. http://cnx.org/contents/72cfcf6f-e196-4e0b-9bcf-45f4853993e4@5/How-Neurons-Communicate

(i) Whatistherestingmembranepotentialofthisneurone? 2

(ii) With reference to this diagram, explain why some stimuli would notgenerateanactionpotentialinaneurone.

2

(b) Differentspeciesofanimalscanseethesameenvironmentdifferently.

Explainthisintermsofthewavelengthsoftheelectromagneticspectrumthatanimalscandetect.Usespecificexamplesinyouranswer.

4

(c) Account for the diversity of senses in humans, in terms of receptors andcorrespondingregionsofthebrain.SupportyouranswerwithTWOexamples.

4


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Answer parts (d) and (e) of the question on pages 6–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.

(d) Asoundshadowisproducedwhenthewavelength(l)ofasoundisshorterthanthelengthofthehumanhead(l).Whenasoundofwavelengthlongerthantheheadisused,nosoundshadowoccurs.SeeFigure1.

l<

l>

0.25

0.50

0.75

1.00

1.75

2.00

1.25

1.50

0 1000 2000Frequency (Hz)

3000 4000 5000

Wav

elen

gth

(m)

Figure 1

Figure 2

(i) Predictadifferenceintheloudnessofthesoundineachearifthesoundhasawavelengthshorterthanthelengthofthehead.Justifyyouranswer.

2

(ii) Aperson’sheadis25cmlong.UsingFigures1and2,andshowingthe steps, determine the frequency range of sound for which a soushadowoccursforthisperson.

allnd

4

(e) ‘Scienceisusedtosolveproblemsforthebenefitofsociety.’

JustifythisstatementwithreferencetothescientificknowledgeusedtosolveONEprobleminhearingandONEprobleminvisualaccommodation.

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End of Question 32

©Thomas Haslwanter

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–33–

Question 33 — Biotechnology (25marks)


(a) Thefermentationreactionshownoccursasyeastbiomassincreases.

Glucose X + Y

(i) IdentifytheproductsXandY. 2

(ii) Describehow,after the18thcentury, the fermentationofglucosewasmodifiedtoincreasetheyieldofyeastbiomass.

2

(b) DNAcanbeextractedinaschoollaboratory.

Describeseparatelythemethodusedtoget theDNAoutof thecells,andthemethodusedtoisolatetheDNAfromothercellcomponentsinthissetting.

4

(c) Explain why the domestication of species for agriculture is described as abiotechnology.Inyouranswer,refertoONEspecificdomesticatedorganism.


4

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(d) (i) Whyislacticacidfermentationusedinthetransformationofmilkintocheese?

2

(ii) Severalgroupsofstudentsinaclassinvestigatedtheoptimumconditionsfor the transformation of milk into cheese using a common bacterialstarterculture.

Each group conducted experiment 1 and the class obtained averagevaluesof their results.Theclass thendesignedexperiment2andeachgroupconductedtheexperiment,againobtainingaveragevaluesoftheirresults.Theaveragevaluesforeachexperimentareshownbelow.

4

Experiment 1–The effect of temperature on lactic acid production inmilkatpH5

Time after bacteria added

(hours)

Average lactic acid concentration in substrate

(%)Fermentationtemperature

2°C

Fermentationtemperature

25°C

Fermentationtemperature

35°C

0 0.1 0.1 0.1

10 0.1 0.2 0.2

20 0.1 0.3 0.2

30 0.2 0.8 0.4

40 0.3 1.8 0.7

50 0.4 2.2 1.0

60 0.6 2.3 1.3


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Experiment 2–TheeffectofpHonlactoseconversioninmilkat25°C

1

1.5

2

2.5

4

4.5

3

3.5

0 20 40

Time (hours)

60

pH 8

pH 5

pH 2

Aver

age

Lact

ose

Con

cent

ratio

n (%

)

Thestudentsconcludedthattheresultswerecontradictoryandthattheycouldnotdefinetheoptimumconditionsfortheircheeseproduction.

Evaluatethestudents’conclusionwithreferencetotheirdatafrombothexperiments.


Justify this statement with reference to the scientific knowledge behindDNAtechnology,usingONEexamplefrommedicineandONEfromforensics.

7

End of Question 33

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Question 34 — Genetics: The Code Broken? (25marks)


(a) Thediagramshowstwocellstakenfromthesameorganism.

(i) WhattypeofcellisCell B? 1

(ii) Explain the potential effects on this species of a disadvantageousmutationineachofthesecelltypes.

3

(b) Describe how the current models of the structure of tRNA and mRNA havehelpedusunderstandtheproductionofasequenceofaminoacids.

4

(c) Describehowtheactionofgenescanexplainfeaturesofembryonicdevelopment.


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(d) A biology class searched the internet for published results of cross-breedingexperimentsonthesamethreetraitscontrolledbygenesknowntobelinked.

Theyfoundtwobreedingexperimentsonthesamespeciesoffloweringplant,involvingthegenesforstamenlength,flowercolourandfruitcolour.

Eachexperimentinvestigatedtwoofthethreegenes.Theexperimentalresultswerepresentedindifferentformats.

Experiment 1: AaEe × aaee

Raw data: Phenotypicratiosinoffspring

–27longstamen,redflowers

–3longstamen,yellowflowers

–3shortstamen,redflowers

–27shortstamen,yellowflowers

Experiment 2: BbEe × bbee

After data analysis: Resultindicatedonareferencegraph.

5

0

10

15

20

25

0 5 10

Distance between genes (map units)

15 20 25

Deg

ree

of re

com

bina

tion

(%)


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The class concluded that the distance between Gene A and Gene E is less than thedistancebetweenGeneBandGeneE.

(i) Show,withworking,thatGeneAis10mapunitsfromGeneE. 2

(ii) Evaluatetheconclusionsdrawnbytheclass. 2

(iii) Whatfurtherdatawouldneedtobecollectedtodrawaquantitativemapof the chromosome showing the relative positions of all these genes?Justifyyouranswer.

2


Justify this statement with reference to the scientific knowledge behindDNAtechnology,usingONEexamplefrommedicineandONEfromforensics.

7

End of Question 34

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Question 35 — The Human Story (25marks)


(a) (i) Thediagramshowstwoprimates. 2

BIOZONE, Human Evolution OHT Masters Set No. 8, 1998, BIOZONE International. Reproduced with permission

Provide the word that describes the tail for the classification of eachprimate.

(ii) Spider monkeys and baboons are members of the same order. Usethe hierarchical classification system to explain whether they wouldnecessarilybeinthesamephylumandthesamegenus.

2

(b) Explain ONE piece of evidence for, and ONE piece of evidence against, thetheoryofregionalcontinuity.

4

(c) Account for identified differences in the cultural development ofAustralopithecines and Homo neanderthalensis in relation to their cranialcapacities.


4

Figure 1 Figure 2

Spider monkey Baboon

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(d) (i) Distinguishbetweenrelativedatingandabsolutedatingoffossils. 2

(ii) Studentsfoundthreefossils(A,BandC)atanarchaeologicalsite. 4

Thedepthofeachfossilbelowthesurfacewasrecordedandthestrataofrocksatthesiteweremapped.

Figure 1

Figure 2

Number of half-lives

Fossil C

Fossil B

Fossil A

0 1 2 3 4 5

0

20

40

Dep

th (m

)R

atio

of C

14: C

12

livingtree

A

C

B

××

×

×

×

×

ThefossilswereanalysedinthelaboratoryforratiosofC14toC12,andtheresultswerepresentedonaC14half-lifecurve.

Figure 1

Figure 2

Number of half-lives

Fossil C

Fossil B

Fossil A

0 1 2 3 4 5

0

20

40D

epth

(m)

Rat

io o

f C14

: C12

livingtree

A

C

B

××

×

×

×

×

Thestudentsconcludedthattheirdatawereconflictingandtheycouldnotdeterminetherelativeagesofthefossils.

Evaluatethestudents’conclusionwithreferencetothedatapresented.

(e) ‘Sciencehasbeenusedtosolveproblemsintheinvestigationofevolutionaryrelationships between humans and other primates, and so has providedinformationofinteresttosociety.’

JustifythisstatementintermsofthescientificknowledgebehindDNA–DNAhybridisationANDkaryotypeanalysis.

7

End of Question 35

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Question 36 — Biochemistry (25marks)


(a) (i) Thediagramshowsamodelofaphotosyntheticunit. 1

WhatisanappropriatelabelforthecomponentsX?

(ii) ExplainwhyhavingphotosystemIandphotosystemIIacting togetherincreasestheefficiencyofphotosynthesis.

3

(b) From their experiments, Blackman and Mathgel hypothesised thatphotosynthesiswasatwo-stepprocessasfollows:

lightdependentreaction

temperaturedependentreaction

4

Explain how their results led them to hypothesise that photosynthesis beginswithalightdependentreaction.

(c) Explain the location of the light and dark reactions within the chloroplast,withreferencetoaspecificfeatureoftheorganelleateachlocation.


4

Awaiting copyright

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(d) (i) Outlinehowpigmentscanbeextractedfromleaves. 2

(ii) Studentsinvestigatedthepigmentsintheleavesofanewly-discoveredplant,andcomparedtheirresultstoresultsfromexperimentsonknownpigmentsfromafamiliarplant.Allexperimentalresultsareshown.

4

Distance travelled

(cm)

New plantFamiliar plant

Results of chromatography with the same solvent

Solvent front

Dark green lineLight green line

5.0

4.252.89

Pigment

Chlorophyll b

Chlorophyll a

Distance travelled by

pigment(cm)

Distance travelled by

solvent(cm)

6.2

9.1

10.7

10.7

Thestudentsconcludedthatthenewplanthasauniquepigmentsystem.

Evaluatethestudents’conclusionwithreferencetothedatapresented.

(e) ‘Sciencehasbeenusedtosolveproblemsintheinvestigationofphotosynthesis,andsohasprovidedinformationofbenefittosociety.’

Justify this statement with reference to the scientific knowledge behindradioactivetracersforthestudyofphotosynthesis.

7

End of paper

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