AQA A LEVEL BIOLOGY TOPIC 3 EXAM QUESTIONS AND ANSWERS

AQA A LEVEL BIOLOGY TOPIC 3
EXAM QUESTIONS AND ANSWERS

Thexchydrostaticxcpressurexcfallsxcfromxcthexcarteriolexcendxcofxcthexccapillaryxctoxcthexcven
ulexcendxcofxcthexccapillary.xcExplainxcwhyxc-xcanswer--Lossxcofxcwater

Highxcbloodxcpressurexcleadsxctoxcanxcaccumulationxcofxctissuexcfluid.xcExplainxchowxc[3]xc-
xcanswer--Highxcbloodxcpressurexc=xchighxchydrostaticxcpressure;

Increasexcoutwardxcpressurexcfromxc(arterial)xcendxcofxccapillary;
(So)xcmorexctissuexcfluid

Thexcwaterxcpotentialxcofxcthexcbloodxcplasmaxcisxcmorexcnegativexcatxcthexcvenulexcendxcofx
cthexccapillaryxcthanxcatxcthexcarteriolexcendxcofxcthexccapillary.xcExplainxcwhyxc[3]xc-

xcanswer--Waterxchasxcleftxcthexccapillary;

Proteinsxctooxclargexctoxcleavexccapillary;
Increasingxchigherxcconcentrationxcofxcbloodxcproteins;

Describexcandxcexplainxcthexcmechanismxcthatxccausesxcforcedxcexpirationxc[4]xc-
xcanswer--Contractionxcofxcinternalxcintercostalxcmuscles;

Relaxationxcofxcdiaphragmxcmuscles;
Causesxcdecreasexcinxcvolumexcofxcthoracicxccavity;
Airxcpushedxcdownxcpressurexcgradient;

Onexctheoryxcofxctranslocationxcstatesxcthatxcorganicxcsubstancesxcarexcpushedxcfromxcaxc
highxcpressurexcinxcthexcleavesxctoxcaxclowerxcpressurexcinxcthexcroots.

Describexchowxcaxchighxcpressurexcisxcproducedxcinxcthexcleaves.xc[3]xc-xcanswer--
Waterxcpotentialxcbecomesxclower;
Waterxcentersxcphloemxcbyxcosmosis;
Increasedxcvolumexc(ofxcwater)xccausesxcincreasedxcpressure;

Duringxctheirxcexperiment,xcthexcscientistsxcensuredxcthexcratexcofxcphotosynthesisxcofxcthe
irxcplantsxcremainedxcconstant.

Explainxcwhyxcthisxcwasxcimportantxc[2]xc-xcanswer--
Ratexcofxcphotosynthesisxcrelatedxctoxcratexcofxcsucrosexcproduction;
Ratexcofxctranslocationxchigherxcwhenxcsucrosexcconcentrationxcisxchigher;

Describexchowxcoxygenxcinxcthexcairxcreachesxccapillariesxcsurroundingxcalveolixcinxcthexclu
ngs.xcDetailsxcofxcbreathingxcarexcnotxcrequired.xc[5]
xc-xcanswer--Tracheaxcandxcbronchixcandxcbronchioles;

Downxcpressurexcgradient;
Downxcdiffusionxcgradient;
Acrossxcalveolarxcepithelium;
Acrossxccapillaryxcendothelium;

, Thexcoxygenxcdissociationxccurvexcforxchaemoglobinxcshiftsxctoxcthexcrightxcduringxcvigorou
sxcexercise.xcExplainxcthexcadvantagexcofxcthisxcshift.xc[3]xc-xcanswer--
Lowerxcaffinityxcforxcoxygen;
(To)xcmuscles;
(For)xcrapidxcrespiration;

ExplainxchowxcthexcbodyxcshapexcofxcaxcWeddelxcsealxcisxcanxcadaptationxctoxclivingxcinxcaxcc
oldxcenvironmentxc[2]xc-xcanswer--SmallxcSA:Vol;
reducesxcheatxcloss;

Describexcthexcrolexcofxcenzymesxcinxcthexcdigestionxcofxcproteinsxcinxcaxcmammal.xc[5]xc-
xcanswer--(Referencexcto)xchydrolysisxcofxcpeptidexcbonds;

Endopeptidasexcactxcinxcthexcmiddlexcofxcprotein/polypeptidexcOR
Endopeptidasexcproducesxcshort(er)xcpolypeptides/xcincreasexcnumberxcofxcends;
Exopeptidasesxcactxcatxcendxcofxcprotein/polypeptidexc
OR
Exopeptidasexcproducesxcdipeptides/aminoxcacids;
Dipeptidasexcactsxconxcdipeptide/aminoxcacids
OR
Dipeptidasexcproducesxc(single)xcaminoxcacids;

Describexcthexcprocessesxcinvolvedxcinxcthexcabsorptionxcandxctransportxcofxcdigestedxclipi
dxcmoleculesxcfromxcthexcileumxcintoxclymphxcvessels.xc[5]xc-xcanswer--
Micellesxccontainxcbilexcsaltsxcandxcfattyxcacids/monoglycerides;
Makexcfattyxcacids/monoglyceridesxc(more)xcsolublexc(inxcwater)
OR
Maintainxchigh(er)xcconcentrationxcofxcfattyxcacids/monoglyceridesxctoxccell/
liningxc(ofxcthexcileum);
Fattyxcacids/monoglyceridesxcabsorbedxcbyxcdiffusion;
Triglyceridesxc(re)formedxc(inxccells);
Vesiclesxcmovexctoxccellxcmembrane;

Cellsxcliningxcthexcileumxcofxcmammalsxcabsorbxcthexcmonosaccharidexcglucosexcbyxcco-
transportxcwithxcsodiumxcions.xcExplainxchow.xc[3]xc-xcanswer--
Sodiumxcionsxcactivelyxctransportedxcfromxcileumxccellxctoxcblood;
Maintains/
formsxcdiffusionxcgradientxcforxcsodiumxctoxcenterxccellsxcfromxcgutxc(andxcwithxcit,xcglucose)
;
Glucosexcentersxcbyxcfacilitatedxcdiffusionxcwithxcsodiumxcions;

ExplainxcthexcadvantagesxcofxclipidxcdropletxcandxcMichellexcformationxc[3]xc-xcanswer--
Dropletsxcincreasexcsurfacexcareasxc(forxclipase/xcenzymexcaction);
(So)xcfasterxchydrolysis/xcdigestionxc(ofxctriglycerides/xclipids);
Micellesxccarryxcfattyxcacidsxcandxcglycerol/
xcmonoglyceridesxccarryxcfattyxcacidsxcandxcglycerol/monoglycerides xcto/

throughxcmembrane/xctoxc(intenstinalxcepithelial)xccell;

Describexcthexcrolexcofxcmicellesxcinxcthexcabsorptionxcofxcfatsxcintoxcthexccellsxcliningxcthexcil
eum.xc[3]xc-xcanswer--Micellesxcincludexcbilexcsaltsxcandxcfattyxcacids;