Princeton Review MCAT Practice Test
Questions With Complete Solutions
Sickle-cell nnanemia nn(HbS) nnresults nnfrom nna nnsubstitution nnto nnvaline nnfrom nnglutamic nnacid nnat nnposition nn6
nnof nnthe nnβ nnchain nnof nnhemoglobin. nnWhich nnof nnthe nnfollowing nnbest nnexplains nnwhy nnthe nnisoelectric
nnpoint nnof nnHbS nnis nnhigher nnthan nnthat nnof nnHbA?
nn
A. nnThe nnside nnchain nnof nnglutamic nnacid nnis nnless nnacidic nnthan nnthat nnof nnvaline.
B. nnGlutamic nnacid nnis nnisoelectric nnat nna nnlower nnpH nnthan nnis nnvaline. nn
C. nnValine nnis nnisoelectric nnat nna nnlower nnpH nnthan nnis nnglutamic nnacid. nn
D. nnGlutamic nnacid nnhas nna nnnet nncharge nnof nn0 nnat nnits nnisoelectric nnpoint. nn- nnANSWER: nn✔ nnB. nnGlutamic
nnacid nnis nnisoelectric nnat nna nnlower nnpH nnthan nnis nnvaline.
The nnisoelectric nnpoint nnis nnthe nnpH nnat nnwhich nnan nnamphoteric nnmolecule nnhas nna nnnet nnelectric nncharge
nnof nnzero. nnGlutamic nnacid nnis nnmore nnacidic, nnnot nnless nnacidic nnthan nnvaline nn(A nnis nnwrong). nnGlutamate
nnwould nnrequire nnmore nnacidic nnpH nnto nnneutralize nnits nncharge nn(C nnis nnwrong). nnD nnis nna nntrue, nnbut
nnirrelevant nnstatement. nnThe nnbest nnanswer nnis nnB. nnThe nnnegative nncharge nnof nnglutamic nnacid nnwould
nnrequire nna nnmore nnacidic nnpH nnto nnneutralize, nnmaking nnthe nnisoelectric nnpoint nnof nnHbA nn(with nnglutamic
nnacid) nnlower nnthan nnthat nnof nnHbS nn(with nnvaline).
A nnmixture nnof nnaspartate nnand nnphenylalanine nnis nnseparated nninto nnits nncomponent nnmolecules nnby nnthin
nnlayer nnchromatography nnon nna nnsilica nnplate nneluted nnwith nnbenzene.
Which nnof nnthe nnfollowing nnbest nnexplains nnwhy nnthe nnseparation nnoccurs?
nn
A. nnAspartate nnwill nnmove nnfarther nnwith nnthe nnmobile nnphase, nnbecause nnit nnhas nna nnpolar nnside nnchain.
nnB. nnAspartate nnwill nnmove nnfarther nnwith nnthe nnmobile nnphase, nnbecause nnit nnhas nna nnnonpolar nnside
nnchain.
C. nnPhenylalanine nnwill nnmove nnfarther nnwith nnthe nnmobile nnphase, nnbecause nnit nnhas nna nnpolar nnside nnchain.
D. nnPhenylalanine nnwill nnmove nnfarther nnwith nnthe nnmobile nnphase, nnbecause nnit nnhas nna nnnonpolar nnside
nnchain. nn- nnANSWER: nn✔ nnD. nnPhenylalanine nnwill nnmove nnfarther nnwith nnthe nnmobile nnphase, nnbecause nnit
nnhas nna nnnonpolar nnside nnchain. nn
,The nnside nnchain nnon nnaspartate nnis nn-CH2COO-, nnwhich nnis nnvery nnpolar, nnwhile nnthe nnside nnchain nnon
nnphenylalanine nnis nn-CH2Ph, nnwhich nnis nnnonpolar. nnSince nn"like nndissolves nnlike," nnand nnthe nnmobile nnphase
nnis nnnonpolar, nnthe nnmolecule nnwhich nnis nnless nnpolar nn(phenylalanine, nnin nnthis nncase) nnwill nnmove nnfarther
nnwith nnthe nnmobile nnphase.
SEE nnOTHERSIDE nnFIRST
nn
D. nnThickness nnof nnthe nnmembrane nnCorrect nnAnswer
"Charge nnstored nnper nnunit nnvoltage," nnQ nn/ nnV, nnis nnthe nndefinition nnof nncapacitance, nnC. nnThe nnequation nnfor
nnthe nncapacitance nnof nna nnparallel-plate nncapacitor nnis nnC nn= nnκε0A nn/ nnd, nnwhere nnκ nnis nnthe nndielectric
nnconstant, nnε0 nnis nna nnuniversal nnconstant nn(the nnpermittivity nnof nnfree nnspace), nnA nnis nnthe nnarea nnof nneach
nnplate, nnand nnd nnis nnthe nndistance nnbetween nnthe nnplates. nnOf nnthe nnchoices nngiven, nnonly nnD, nndecreasing
nnthe nnthickness nnof nnthe nnmembrane nn(that nnis, nndecreasing nnd), nnwould nnincrease nnthe nncapacitance, nnC. nn-
nnANSWER: nn✔ nnIon nnflow nnin nnneurons nncan nnbe nncharacterized nnas nnan nnelectrical nncircuit nnfor nnboth nnthe
nnresting nnneuron nn(Figure nn1) nnand nnthe nnactive nnneuron nn(Figure nn2). nnThe nnmembrane nnis nna nncapacitor,
nnslow nnleakage nnchannels nnare nna nn25 nnMΩ nnresistor, nnand nnthe nnNa+/K+ nnpump nnis nna nnvoltage nngenerator.
nnIn nna nnresting nnaxon, nnthere nnis nnno nnnet nntransfer nnof nncharge nnacross nnthe nnaxon nnmembrane. nnFigure nn2
nnincludes nnthe nnadditional nnNa+ nninflux nn(a nn4 nnkΩ nnresistor) nnof nnan nnaction nnpotential. nnOther nnion nnfluxes
nnare nnignored. nnAccording nnto nnthe nnfigures, nndecreasing nnwhich nnof nnthe nnfollowing nnwould nncreate nnthe
nngreatest nnincrease nnin nncharge nnstored nnper nnunit nnvoltage nnon nnan nnaxon nnmembrane nnin nnits nnrest nnstate?
nn
A. nnLeakage nnchannel nnresistance
nn B. nnNa+ nnchannel nnresistance
C. nnArea nnof nnthe nnmembrane nnsurfaces
D. nnThickness nnof nnthe nnmembrane
Across nnthe nnmembrane nnof nnan nnaxon nnin nnits nnrest nnstate:
nn
A. nnthe nnpotential nnis nnhigher nnon nnthe nnoutside nnof nnthe nncell nnthan nnthe nninside, nnand nnelectric nnfield nnlines
nnrun nnfrom nnthe nnoutside nnto nnthe nninside. nn
B. nnthe nnpotential nnis nnhigher nnon nnthe nnoutside nnof nnthe nncell nnthan nnthe nninside, nnand nnelectric nnfield nnlines
nnrun nnfrom nnthe nninside nnto nnthe nnoutside.
C. nnthe nnpotential nnis nnlower nnon nnthe nnoutside nnof nnthe nncell nnthan nnthe nninside, nnand nnelectric nnfield nnlines
nn
run nnfrom nnthe nnoutside nnto nnthe nninside.
nn
,D. nnthe nnpotential nnis nnlower nnon nnthe nnoutside nnof nnthe nncell nnthan nnthe nninside, nnand nnelectric nnfield nnlines
nnrun nnfrom nnthe nninside nnto nnthe nnoutside. nn- nnANSWER: nn✔ nnA. nnthe nnpotential nnis nnhigher nnon nnthe nnoutside
nnof nnthe nncell nnthan nnthe nninside, nnand nnelectric nnfield nnlines nnrun nnfrom nnthe nnoutside nnto nnthe nninside. nn
The nnvoltage nnacross nnthe nnmembrane nnis nn-70 nnmV nnfrom nnthe nnexterior nnto nnthe nninterior nnof nnthe nncell;
nnthus, nnthe nnpotential nnis nnhigher nnon nnthe nnexterior nnof nnthe nncell nn(C nnand nnD nnare nnwrong). nnSince nnthe
nnpotential nnis nnhigher nnon nnthe nnexterior nnthan nnin nnthe nninterior, nnthe nnelectric nnfield nnlines nnmust nnpoint
nnfrom nnthe nnoutside nnto nnthe nninside nn(choice nnA). nnIN nnPHYSICS, nnFIELD nnLINES nnGO nnTOWARD nnTHE nnMORE
nnNEGATIVE nnAREA.
Which nnof nnthe nnfollowing nnstatements nnregarding nnRNA nnmolecules nnis nnNOT nntrue?
nn
A. nnRNAs nncan nnact nnas nnenzymes nnto nncatalyze nnreactions.
B. nnSome nnRNAs nnhave nnmore nnthan nnfour nndifferent nntypes nnof nnbases.
C. nnSome nnRNAs nnare nnsynthesized nnin nnthe nnnucleolus.
D. nnRNAs nnare nninsusceptible nnto nnalkaline nnhydrolysis. nn- nnANSWER: nn✔ nnD. nnRNAs nnare nninsusceptible nnto
nnalkaline nnhydrolysis. nn
RNA nnmolecules nnhave nndecreased nnstability nncompared nnto nnDNA nnin nnpart nnbecause nnof nntheir
nnsusceptibility nnto nnalkaline nnhydrolysis nndue nnto nnthe nnpresence nnof nnhydroxyl nngroup nnat nn2'-C nnposition
nn(choice nnD nnis nnnot nntrue nnof nnRNA nnand nnis nnthe nncorrect nnanswer nnchoice). nnSome nnRNAs nnhave
nnenzymatic nnfunction nn(such nnas nnin nntelomerase) nnand nnthey nnare nntermed nnribozymes nn(A nnis nntrue). nntRNA
nnhas nnunique nnand nnmodified nnbases nnapart nnfrom nnthe nntraditional nnfour nnbases nnA,U,C, nnand nnG nn(such nnas
nninosine, nnB nnis nntrue). nnrRNA nnis nnsynthesized nnin nnthe nnnucleolus nn(C nnis nntrue).
Two nnblocks nnare nnsuspended nnfrom nnthe nnends nnof nna nnmassless nnmeter nnstick; nna nn4kg nnweight nnfrom nnone
nnside nnand nna nn1kg nnweight nnfrom nnthe nnopposite nnside. nnHow nnfar nnfrom nnthe nncenter nnof nnthe nnstick nnmust
nnthe nnrope nnbe nnattached nnin nnorder nnto nnmaintain nnrotational nnequilibrium?
nn
A. nn10 nncm
B. nn20 nncm
C. nn25 nncm
D. nn30 nncm nn- nnANSWER: nn✔ nnD. nn30 nncm
, A nnQ-switched nnlaser nncan nnbe nnused nnto nntreat nnskin nnblemishes nnand nnto nnremove nntattoos. nnThe nnQ
nnswitch nnmomentarily nninterrupts nnthe nninducing nnlight nncreating nna nnbuild-up nnof nnenergy nnwithin nnthe
nncrystal. nnThis nndoes nnnot nnincrease nnthe nnoverall nnenergy nnof nnthe nnlaser, nnbut nnconcentrates nnit nninto
nnshorter nntime nnperiods nnor nnpulses. nnA nnlonger nninterruption nnwith nnthe nnQ-switch nnmost nnlikely nnwould
nnincrease nnthe:
nn
A. nntotal nnamount nnof nnwork nndone nnby nnthe nnlaser.
B. nnpower nnof nneach nnlaser nnpulse.
nn
C. nnwavelength nnof nnthe nnlaser nnlight.
D. nnfrequency nnof nnthe nnlaser nnlight. nn- nnANSWER: nn✔ nnB. nnpower nnof nneach nnlaser nnpulse. nn
Since nnthe nnoverall nnenergy nnof nnthe nnlaser nndoes nnnot nnchange, nnneither nnwill nnthe nnfrequency,
nnwavelength, nnnor nnwork nndone nnby nnthe nnlaser. nnThis nnleaves nnchoice nnB: nnConcentrating nnthe nnenergy nninto
nna nnshorter nntime nnperiod nnincreases nnthe nnpower nnof nneach nnpulse nn(since nnpower nnequals nnenergy
nndelivered nnper nnunit nntime, nnby nndefinition).
A nnCO2 nnlaser nnused nnas nna nnlaser nnscalpel nnproduces nna nnbeam nnof nnlaser nnlight nnwith nna nnwavelength nnof
nn10.6 nnµm. nnCompared nnto nnthe nnexcited nnelectrons nnin nna nnlaser nnwith nna nnwavelength nnof nn1.06um, nnthe
nnexcited nnelectrons nnin nnthe nnCO2 nnlaser nnmost nnlikely nnhave:
nn
A. nngreater nnmass.
B. nnless nnmass.
nn
C. nna nngreater nnenergy nndifference nnbetween nntheir nnnormal nnstate nnand nntheir nnexcited nnstate.
D. nna nnsmaller nnenergy nndifference nnbetween nntheir nnnormal nnstate nnand nntheir nnexcited nnstate. nn- nnANSWER:
nn✔ nnD. nna nnsmaller nnenergy nndifference nnbetween nntheir nnnormal nnstate nnand nntheir nnexcited nnstate. nn
The nnwavelength nnof nnthe nnCO2 nnlaser nnis nn10 nntimes nngreater nnthan nnthe nn1.06 nnwavelength nnlaser.
nnTherefore, nnthe nnfrequency nnand nnthe nnenergy nnof nnthe nnCO2 nnlaser nnare nn10 nntimes nnlower. nnSince nnthe
nnlaser nnlight nnis nnthe nnenergy nnreleased nnby nntransitions nnof nnelectrons nndropping nnto nna nnlower nnenergy
nnlevel, nnless nnemitted nnenergy nnimplies nna nnsmaller nndifference nnbetween nnthe nnenergy nnlevels. nnThe nnmass
nnof nnan nnelectron nnis nnindependent nnof nnits nnatomic nnor nnmolecular nnenergy nnstate nn(A nnand nnB nnare nnwrong).
If nnthe nnfront nnmirror nnin nna nnlaser, nnwhich nnis nnmade nnof nnglass nnof nnrefractive nnindex nn3/2, nnwere
nnrepositioned nnso nnthat nnthe nnlaser nnbeam nnstrikes nnat nnan nnangle nnof nn30° nnto nnits nnnormal, nnwhat nnwould
nnbe nnthe nnangle nnof nnreflection?