AQA A Level Biology Exam Questions Paper 1

AQA A LEVEL BIOLOGY
EXAM QUESTIONS
PAPER 1

Describethechemicalreactionsinvolvedintheconversionofpolymerstomonomersandmonomer
stopolymers.Givetwonamedexamplesofpolymersandtheirassociatedmonomerstoillustrateyo
uranswer.-CORRECTANSWERS-MONOMERSTOPOLYMERS

-Condensationreaction

-Waterisreleasedtoformbondbetweenthemonomers

-e.g.Alphaglucosemoleculesarebondedtogetherwithglycosidicbondstoformstarch

POLYMERSTOMONOMERS

-Hydrolysisreaction

-Waterisusedtobreakthebondsbetweentheindividualmonomers

-e.g.thepeptidebondsinproteinsarehydrolysedtoformindividualaminoacids



Whatisamonomer?-CORRECTANSWERS-Smallunitsfromwhichpolymersaremade



Abiochemicaltestforreducingsugarsproducesanegativeresultwithraffinosesolution.Describea
biochemicaltesttoshowthatraffinosesolutioncontainsanon-reducingsugar.-
CORRECTANSWERS--AddHCl,shakeandheat

-Addsodiumbicarbonateandshaketoneutralisetheacid

-AddBenedict'ssolutionandheatgentlyinawaterbath

-Positiveresult=brickredprecipitate

, AprecipitateisproducedinapositiveresultforreducingsugarinaBenedict'stest.Astudentcarriedo
utaBenedict'stest.Suggestamethod,otherthanusingacolorimeter,thatthisstudentcouldusetom
easurethequantityofreducingsugarinasolution.-CORRECTANSWERS--Filteranddryprecipitate

-Findmass/weight



Glycogenandcellulosearebothcarbohydrates.Describeandexplaintwodifferencesbetweenthes
tructureofacellulosemoleculeandaglycogenmolecule.-CORRECTANSWERS--
Glycogenisapolymerofalphaglucosebutcelluloseisapolymerofbetaglucose

-Celluloseisastraightchainbutglycogenisbranched



Describeandexplaintwofeaturesofstarchthatmakeitagoodstoragemolecule.-
CORRECTANSWERS--Insolublesodoesn'taffectosmoticpotential

-Branchedsomoleculeiscompact



Describethestructureofglycogen-CORRECTANSWERS--Polysaccharideofalphaglucose

-Joinedbyglycosidicbonds



Suggesthowglycogenactsasasourceofenergy.Don'tincludetransportacrossmembranesinyoura
nswer.-CORRECTANSWERS--Hydrolysedtoglucose

-Glucoseusedinrespiration



Explainthedifferenceinthestructureofthestarchmoleculeandthecellulosemoleculeshowninthe
diagramabove-CORRECTANSWERS--Starchformedfromalpha-
glucosebutcelluloseisformedfrombeta-glucose

-Positionofhydrogenandhydroxylgroupsoncarbonatom1isinverted



Explainonewayinwhichstarchmoleculesareadaptedfortheirfunctioninplantcells-
CORRECTANSWERS--insolublesodoesn'taffectwaterpotential



Explainhowcellulosemoleculesareadaptedfortheirfunctioninplantcells-CORRECTANSWERS--
Long,straightchains