AQA A-LEVEL BIOLOGY PAPER 2 EXAM COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!

AQA A- x




LEVEL BIOLOGY PAPER 2 EXAM COMPLET
x x x x x




E QUESTIONS AND CORRECT DETAILED A
x x x x x




NSWERS (VERIFIED ANSWERS) |ALREADY
x x x x




GRADED A+||BRAND NEW!! x x




Allelesxthatxarexneitherxdominantxnorxrecessivextoxonexanother,xsoxbothxallelesxarexalwaysx
expressedxinxthexphenotype.x-xAnswerx-xCodominant

Thexinheritancexofxaxsinglexgenex-xAnswerx-xMonohybridxinheritance

Physical,xbehavioural,xbiochemicalxexpressionxofxanxorganismsxgenotypex-xAnswerx-
xPhenotype




Thextypexofxgenesxanxindividualxhasx-xAnswerx-xGenotype

Allesxthatxisxalwaysxexpressedxinxthexphenotypex-xAnswerx-xDominant

Onlyxexpressedxinxthexphenotypexwhenxhomozygousx-xAnswerx-xRecessive

bothxallelesxarexthexsamex-xAnswerx-xHomozygous

Bothxallelesxforxaxspecificxgenexarexdifferentx-xAnswerx-xHeterozygous

Positionxofxaxgenexonxaxchromosomex-xAnswerx-xLoci

Axsetxofxinstructionsxforxaxspecificxpolypeptidex-xAnswerx-xGene

Differentxformsxofxaxgenex-xAnswerx-xAllele

1.xExpectedxratiosxarexprobabilityx
2.xSexualxreproductionxisxrandomxduextoxrandomxfusionxofxgametesxandxrandomxassortme
ntxhomologousxchromosomes.
3.xSmallxsamplexsizex

,4.xLinkedxgenesx-xAnswerx-
xSuggestxfourxreasonsxwhyxobservedxratiosxarexnotxthexsamexasxexpectedxratiosx(4).




1.xHomologousxchromosomesxpairxupx
2.xCrossingxoverx/xchiasmataxform;
3.xProducesxnewxcombinationxofxalleles
4.xChromosomesxseparatexatxrandom
5.xThisxproducesxvaryingxcombinationsxofxgenes
6.xChromatidsxseparatedxatxmeiosisxIIx-xAnswerx-
xMeiosisxresultsxinxcellsxthatxhavexthexhaploidxnumberxofxchromosomesxandxshowxgeneticxv


ariation.xExplainxhow.x(6)

1.xReferxtoxthexspecificxindividualsx(usingxtheirxnumber)
2.xExplainxwhatxhappenedxwithxthexgenesx(passedxonxrecessive/dominant)
3.xDescribexthexgenotypexofxyourxexamplesxandxmentionxtheirxphenotypex(homozygous/he
terozygousxetc)x-xAnswerx-xPedigreexQuestionsxMarkxSchemex(3)

Groupxofxorganismsxofxthexsamexspeciesxoccupyingxaxparticularxspacexatxaxparticularxtimext
hatxcanxpotentiallyxinterbreedxtoxproducexfertilexoffspring.x-xAnswerx-xPopulations

Thextotalxnumberxofxgenesxofxeveryxindividualxinxanxinterbreedingxpopulation.x-xAnswerx-
xGenexpool




Howxoftenxanxallelexappearsxinxaxpopulation.

desiredxallele/totalxallelesx=xallelexfrequencyx(decimalxform)x-xAnswerx-
xAllelexfrequencyx[definition][Equation]x(2)




Noxemigrationxorximmigration
Noxmutationsx
Matingxisxrandomx
Noxnaturalxselectionx-xAnswerx-xHardy-WeingbergxAssumptionsx(4)

1.xSelectionxpressurexexistsxinxanxenvironmentx(namexit)
2.xVariationxexistsxinxstatedxphenotypexofxorganism/xmutationxoccursxcreatingxnewxallelesx(
namexthexallelexifxapplicable)
3.xSomexindividualsxhavexthexselectivexadvantagex(describexit)
4.xProducesxdifferentialxsurvival/xorganismsxwithxsuccessfulxallelesxmorexlikelyxtoxsurvivex
5.xNaturalxselectionxoccursxviaxdirectionalxselection
6.xSurvivorsxbreedxandxpassxonxallelesxtoxoffspringx

, 7.xOverxtime,xtherexisxaxchangexinxallelexfrequencyx-xAnswerx-xNaturalxselectionxMSx(7)

Favoursxthexmeanxphenotype.x(Normalxdistributionxbecomesxnarrower)x-xAnswerx-
xStabilisingxselection




Favoursxonexextremexend.x(Normalxdistributionxtranslatesxthatxway)x-xAnswerx-
xDirectionalxSelection




Favoursxbothxextremexphenotypes.xMeanxisxatxdisadvantagexandxdies.xCanxcreatextwoxne
wxspeciesx-xAnswerx-xDisruptivexSelection

1.xNaturalxdisasterx
2.xFewxsurvivex
3.xNewxpopulationxdevelopsxwithxdifferentxallelex
4.xFrequencyxtoxthexoriginalx-xAnswerx-xGeneticxDrift:xBottleneckxEffectx(4)

Geneticxdriftxthatxoccursxafterxaxsmallxnumberxofxindividualsxcolonizexaxnewxarea.xAllelexfre
quencyxisxdifferentxtoxthexoriginalx-xAnswerx-xFounderxeffect

1.xPopulationsxgeographicallyxseparatedx(formationxofxaxriver)x(AllopatricxSpeciation)
2.xSeparatedxpopulationsxnowxunablextoxreproduce
3.xDifferentxenvironmentsxhavexdifferentxselectivexpressuresxsoxeachxpopulationxwillxaccu
mulatexdifferentxbeneficialxmutationsxoverxtimextoxhelpxthemxsurvivexsoxchangexinxallelexfre
quencyx
4.xTwoxpopulationsxbecomexsoxgeneticallyxdifferentxthatxtheyxcannotxreproducextoxformxfert
ilexoffspring,xsoxarexnowxclassedxasxdifferentxspeciesx-xAnswerx-xAllopatricxspeciationx(4)

Populationsxlivexinxthexsamexregionxbutxoccupyxdifferentxhabitatsx-xAnswerx-
xReproductivexisolation:xEcological




Samexareaxbutxarexsexuallyxmaturexatxdifferentxtimesx-xAnswerx-
xReproductivexisolation:xSeasonal




Differentxspeciesxensurexsuccessfulxmatingxbyxspecificxcourtshipx(birdxdances).xAsxthisxisxg
enetic,xmutationxcanxchangexthisx-xAnswerx-xReproductivexIsolation:xBehavioural

Plantsxexhibitxpheromonesxtoxanyxmatexwithxtheirxownxspeciesx-xAnswerx-
xReproductivexisolation:xIncompatibility