文稿成果讲稿biology paper sl markscheme

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M16/4/BIOLO/SP2/ENG/TZ0/XX/M

SectionA

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1.

a

nervecellsincreasetheleast

OR

controlcellsthemost

«endodermalandcontrolcellsarethesameat48hours»butthecontrolcellsincreaseexponentially/muorethanendodermalcellsby96hours

OR

last48hours/from48hoursto96hours,constant«small»increaseincellnumbersfornerve,butgreater/increasedchangeforcontrolandendodermal

from48to96hoursmuoreincreaseincellnumberincontrolthaninendodermal

Donotacceptnumberswithoutdistinguishingterms.

Award[1max]ifallthree(nerve,endodermalandcontrolcells)notmentionedatsomepointintheanswerasstemrequiresallthree.

2max

b

celldifferentiationslowsdown/retards/decreasespopulationgrowth

OR

populationgrowthisslowerindifferentiating/differentiatedcelllines

Acceptconverseeg:nondifferentiationacceleratesgrowth.

1

c

thepercentageof«cellsin»G1innerveisgreaterthanincontrol

OR

theSphasehasgreater«percentageofcells»incontrolthaninnerve

G2phaseissimilarinboth

OR

least/lowerpercentageofcellsofthephasesinbothlines

Donotacceptnumberswithoutdistinguishingterms.

2

d

morecellsinG1«ofcelllines/nerves»withslowpopulationgrowth

morecellsinS«ofcellline/control»withfastpopulationgrowth/«significantly»fewercellsinSinbothslowgrowthlines/nervesandendodermalcells

G2seemsnottoberelatedwithpopgrowthasitisverysimilarinthethreecelllines

Acceptconversestatements.

2max

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e

twogeneticallyidenticaldaughternuclei/cells

OR

twoidenticaldaughternuclei

1

f

cyclinD1islessincontrol

OR

cyclinD2isnotpresent/veryfaintincontrol,butpresentinlargetyinnerve

OR

cyclinD3moreinnerve

cyclinD1ispresentinboth

OR

cyclinD3issimilar/sameinboth

OWTTE

2

g

cyclinD1issimilarinbothnerveandendodermalANDmorethanincontrolsobothmayberesponsibleforgeneral/earlydifferentiation

Bothneeded.OWTTE

b.thereismuorecyclinD2innerve«celllines»somaybespecificfornervedifferentiation

OR

maynegativelyaffect/reducecelldivision/growthcapacityinnerve

OWTTE

3max

c.cyclinD2ismostlikelywhatcausesdifferentiationascontrolgroupcontainsnoneofit

OWTTE

d.thereisslightlymorecyclinD3inendodermal«celllines»somayberelatedtoendodermaldifferentiation

OWTTE

e.limiteddatatodeterminerolesofcyclinsasverycomplexprocesses

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2.

a

i

60kg

Unitneeded.

1

ii

coronaryheartdiseaseorcoronaryarterydiseaseorthrombosisorstrokeorhypertensionorhighbloodpressureoratheromaorfattydepositsinarteriesorque«inarteries»orarteriosclerosisoratherosclerosis

1

b

[CH2]norhydrocarbonchainwithsinglebondsandatleastfourcarbons

COOHheadatoneendANDthreehydrogensonotherend

Thefourcarbonscanincludethecarboxylcarbon.

Bothneeded.

2

c

a.hormoneproducedbyadipose/fatcells/adiposetissue

b.actson/targetcellsareinthehypothalamus«ofthebrain»

Donotaccept“pituitary”or“fat”.

c.inhibits/reducesappetite

OR

inhibitshunger

OR

causesfeelingofsatiety

OR

makesyoufeelfull/makesyoueatless

3max

d.moreleptinwithmoreadiposetissue

e.decreases/reducesfoodintake

OR

inhumansobesepeoplecanhaveleptin

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3.

a

i

boilingpointofwaterisgreaterthanmethane

meltingpointofwaterisgreaterthanmethane

latentheatofvaporizationofwaterisgreaterthanmethane

OR

specificheatcapacityofwaterisgreaterthanmethane

2max

ii

waterispolar

OR

Oatommorenegative

OR

Hatomsmorepositive

thiscauses«strong»hydrogenbondstoformbetweenthemolecules

whichrequiremore/highamountofenergytobreak

whichincreasesthemelting/boiling/latentheatproperties

2max

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b

shortwaveradiation/UV«shownas»havingitsoriginintheSungivesofflightasshortradiation

shortwaveradiation/UV«shownas»passingthroughthegreenhousegases«somereflected»

someshortwaveradiation/UVisabsorbedbytheEarthandsomeisreflected

thereflectedradiationislongwaveradiation«reflectedasheat»

longwaveradiation/IR«shownas»beingunabletopassthrough/beingabsorbed/reflectedbythegreenhousegases

Awardmarksfordiagr ticexnationsofthesemarkingpoints.

AcceptUVandIRaslongastheyaredrawnwiththecorrectwavelength.

3max

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4.

a

I:nitrogenousbase

OR

adenine

OR

purinebase

II:deoxyribose

III:phosphate

3

b

A:gillsorfinsorscalesornolimbsorexternalfertilization

B:homeothermicorendothermicorwarm-bloodedorlungsor

tetrapodorfourlimbsorpentadactyllimbsorinternalfertilization

C:hairorfurorm ryglandsormilk

3

c

eukaryotes

1

SectionB

Clarityofcommunication:[1]

Thecandidate’sanswersareclearenoughtobeunderstoodwithoutre-reading.Thecandidatehasansweredthequestionsuccinctlywithlittleornorepetitionorirrelevantmaterial.

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5.

a

catalyse/speedup«biological»reactions

aresubstrate-specific

lowertheactivationenergy«ofachemicalreaction»/makesreactiongomoreeasily/increaseslikelihoodofreactionhappening

substratecollideswith/bindstoactivesite

enzyme–substratecomplex/transitionstateformed

OR

bondsinsubstrateweakened

“activationenergy”isnotinSLbutallowmarkingpointifgiven.

Donotawardmarkforstating“lockandkey”unlessobviouslyshowninadiagramwithenzymeandsubstra abelled.

4max

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b

keyortextgivingalleleswithuppercasefordominantalleleandlowercaseforrecessiveallele/allelecausingdisease

Punnettgridshowingthatbothparentscanpassoneitheradominantorarecessivealleleintheirgamete

fourpossiblegenotypesforchildcorrectlyshownongrid

double/homozygousrecessiveshownhavingthedisease

25%or0.25or1chanceofinheritingthedisease

4

Rejectkeyshowingalinkedgenesuchashemophilia.RejectifXorYchromosomesareshownwiththealleles.AcceptAaoranyotherupperandlowercaseletters.

ForexamplerowandcolumnheadingswithAanda.

ThismarkcanbeawardedifXorYchromosomesareshownbuteachparenthasonerecessiveandonedominantalleleasifforautosomalinheritance.

AA,Aa,aAandaaforexample.

ThismarkcanbeawardedifXorYchromosomesareshownbutthegenotypesarecorrectforautosomalinheritance.

Cannotbeawardedwith linkage.

ThismarkcanbeawardedifXorYchromosomesareshownbuttheratioiscorrectforautosomalinheritance.

4max

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M16/4/BIOLO/SP2/ENG/TZ0/XX/M

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c

neurotransmitttachestoreceptorsite,initiatingtransmission

nerveimpulsesareactionpotentialspropagatedalongtheaxonsofneurons

restingpotentialismorenegativeinside/–70mV/morepositiveoutsidethemembrane

OR

arestingpotentialhasgreaterconcentrationofNaionsoutsidethanKionsinsidetheaxon

«voltedgated»channelsopenandNaionsdiffusein

causesdepolarizationofthemembrane/–70mVto+40mV

localcurrentsaffectadjacentchannels/causeactionpotential

depolarizationisfollowedbyrepolarizationoftheneuron

«voltagegated»channelsopenandKionsdiffuseout/repolarizethemembrane

Na-KpumpsrestoreNa/Kbalance/restingpotential

myelinaroundtheneuroninsulatestheaxon

OR

speedsthetransmission

myelinpermitssaltatoryconduction

OR

permitsjumfromnodetonode

Award[6max]ifnomentionoftheroleofmyelin.

7max

(Plusupto[1]forquality)

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6.

a

a.cellwallshownwithtwolinestoindicatethethickness

b.sma/cellmembraneshownasasinglecontinuousline

Acceptinsideofwalllabelled“smamembrane”

asifturgid.

c.nuclearmembrane/nucleusshownwithdoublemembraneandnuclearpores

d.vacuole«membrane»/tonostshownasasinglecontinuousline

4max

e.chlorost/stidshownwithdoubleorsinglemembrane

f.ribosomescorrectlyshown

OR

RERcorrectlyshown

OR

golgicorrectlyshown

OR

mitochondrionshownwithdoublemembrane/cristae

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b

oxygenmustbetakenupANDcarbondioxidemustbereleased

gasespassthroughacellmembranebysimplediffusion

requireaconcentrationgradient

OR

passfromhighconcentrationtolowconcentration

withoutrequiringenergy

OR

passiveprocess

largeSA:volratio

Bothneeded.

3max

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c

evolutionis«cumulative»changeinpopulat