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BasicScience

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https://www.facebook.com/elzohryxp

May2012


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www.MRCPass.com BasicScience

Dr.Khalid Yusuf Elzohry SohagTeachingHospital 20122

BasicScienceQ001A 30 year old patient develops haemolytic anaemia,which is thought to be due to

penicillintreatment.

Whichisthecorrecttypeofhypersensitivityreactiontodescribethis?

A.TypeIB.TypeII

C.TypeIIID.TypeIVE.TypeV

Answer:b)TypeII.

DruginducedhaemolyticanaemiaisduetoatypeIIhypersensitivityreaction.Thetypes

are:

TypeI AnaphylaxisduetoIgEfrommastcellsandinvolvingbasophils

Type II Cytotoxicdue to freeantibodies in thecirculation (usually IgG, IgMand IgA)

leading to cell lysis due to antigenantibody crosslinking and complement

fixation

TypeIII ImmunecomplexdepositionassociatedwithcirculatingIgG

Type IV Cellmediated due to interaction between T cells and membranebound

antigens


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BasicScienceQ002Which

red

blood

cell

antigen

is

involved

in

entry

of

Plasmodium

vivax

into

red

cells?

A.RhesusSB.RhesusD

C.DuffyD.GP24E.Kell

Answer:C)Duffy

Duffy negative patients are resistant to developing plasmodium vivax infection. The

DuffyantigenreceptorfacilitatesentryofPlasmodiumVivaxintoredbloodcells.


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BasicScienceQ003A20yearoldmanhasbeennewlydiagnosedwithGaucher'sDisease.This

is

associated

withadeficiencyofwhichoneofthefollowingenzymes?

A.GlucocerebrosidaseB.Sphingomyelinase

C.IduronidaseD.HexosaminidaseAE.ArylsulphataseA

Answer:a)Glucocerebrosidase.

Gaucher's disease is associated with the enzyme glucocerebrosidase. As a result,

glucocerebrosideaccumulates,principally in thephagocyticcellsof thebodybutalso

sometimesinthecentralnervoussystemneurones.

Three types of Gaucher disease are described. Common to all three types are the

presence of hepatosplenomegaly and of large glucocerebroside containing

reticuloendothelialhistiocytes,orGauchercells,inthebonemarrow.

Theotherassociationsare:

TaySachsdisease HexosaminidaseAdeficiency

NiemannPickdisease Sphingomyelinasedeficiency

Metachromaticleukodystrophy ArylsulphataseAdeficiency

Hurler'ssyndrome Iduronidasedeficiency


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of

the

following

diseases

is

X

linked

inherited?

A.Alpha1antitrypsindeficiencyB.Haemochromatosis

C.Marfan'ssyndromeD.G6PDdeficiencyE.Wilson'sdisease

Answer:d)G6PDdeficiency.

G6PD deficiency's inheritance is X linked recessive. Duchennemuscular dystrophy is

another example of a disease which has X linked recessive inheritance. X linked

hypophosphataemicricketsisXlinkeddominant.


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BasicScienceQ005

A22yearoldmalewho istallandthin, isfoundtohaveahigharchedpalate,downw

arddislocationoflens,chestwalldeformitiesandlivedoreticularis.

Whichoneofthefollowingisalsoassociatedwiththissyndrome?

A.Fibrillingenedefect

B.PositiveGuthrietest

C.AutosomalDominantinheritance

D.Osteopetrosis

E.Methionineaccumulation

Answer:e)Methionineaccumulation.

Thediagnosisishomocystinuria(Marfan'scausesupwardslensdislocationandfibrillin

genedefect).Homocystinuria is an autosomal recessivedisorder.Reduced activityof

cystathionine synthase results in accumulation of homocysteine methionine.

Osteoporosisandosteopetrosisarealsoseeninhomocystinuria.

MetabolismofHomocysteine


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BasicScienceQ006

ApostgraduatestudentisstudyingHIVreplication.

WhichofthefollowingisimportantinthereplicationortransmissionofHIV1?

A.Trypsin

B.Bax

C.GP120

D.P53

E.MHC

Answer:c)GP120.

HIV reverse transcriptase, integrase and protease are key enzymes essential forHIV

replication.TheHIVgenomecontainsthegenes:tatandrevalongwithnef,env,gagand

pol.TheGP120isthemajorproteinonthesurfaceofHIVthatinteractswithhostcells.

HIVbinds to cell surfaceCD4butenters cells through chemokine receptors including

CXCR4andCCR5.Thymidinekinaseisproducedbytheherpessimplexvirus.


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BasicScienceQ007

Whichof

the

following

anatomical

structures,

if

damaged,

leads

to

choreiform

movementabnormalities?

A.Caudatenucleus

B.Subthalamicnucleus

C.Substantianigra

D.Hippocampus

E.Corpuscallosum

Answer:a)caudatenucleus.

Caudatenucleus,putamenandglobuspallidusareareaswithinthebasalgangliawhich,

when impaired,canleadtochoreiformmovements.Subthalamicnucleuslesioncauses

hemiballismus.Hippocampusinvolvementcancausememoryloss.


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BasicScienceQ008

A35yearoldmanpresentswithbleedingoesophagealvarices.Onexaminationhehas

Kayser Fleischerringsinthecornea.Theinheritanceofthisdisorderis:

A.Polygenicinheritance

B.Xlinkeddominant

C.Xlinkedrecessive

D.Autosomalrecessive

E.Autosomaldominant

Answer:d)Autosomalrecessive.

ThediagnosisisWilsonsdisease,whichhasautosomalrecessiveinheritance.

KayserFlescherRinginWilson'sdisease


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BasicScienceQ009

Whichof

these

is

the

correct

description

of

peptide

bonds?

A.Bondsbetween2carboxylicacidgroupsofaminoacids

B.Hydrogenbondsbetween2sidechainsofaminoacids

C.Bondsbetweenthecarboxylicacidgroupofoneaminoacidandtheaminogroupof

thenext

D.Bondsbetweenalternatingpurineandpyrimidinemolecules

E.Covalentbondsbetweentwoaminoacids

Answer:c)bondsbetweenthecarboxylicacidgroupofoneaminoacidandtheamino

groupofthenext.

Peptidebonds are linkagesbetween the carboxylic acid (COOH) groupofone amino

acidandtheamino(NH2)groupofthenextaminoacid.


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BasicScienceQ010A45yearoldmanwithanewdiagnosisofhepatitisBiskeentoknowmoreaboutthe

prognosisofthedisease.

Whatpercentageofpatientsislikelytodevelopchronicinfection?

A.100%B.80%

C.50%D.10%E.5%

Answer:d)10%.

Theviruscanbefoundinothercelltypesapartfromhepatocytes,suchasrenaltubular

cells. 10% of patients with hepatitis B develop chronic infection as compared tohepatitis C where 80% develop chronic infection. The likelihood of virus clearance

increaseswithbettercellmediatedimmuneresponses.


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BasicScienceQ011A25yearoldmanwithcysticfibrosisisreferredforinvestigationofpoorfertility.

Whatislikelytohavecausedthis?

A.MalabsorptionandvitamindeficiencyB.Abnormaloestrogenmetabolism

C.AcidificationofseminalfluidD.HypopituitarismE.Failureofdevelopmentofvasdeferens

Answer:E)Failureofdevelopmentofvasdeferens

Infertilityincysticfibrosisisduetomaldevelopmentofvasdeferens.


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BasicScienceQ012Achildhasanendocrineconditionwhichhascausedshortstature.

Whichofthefollowingconditionsmaybedetectablebygrowthmonitoring?

A.ThyrotoxicosisB.Pseudohypoparathyroidism

C.HypothyroidismD.InsulindependentdiabetesmellitusE.XYYSyndrome

Answer:c)Hypothyroidism.

Growthmonitoringcanaiddetectionofthefollowingconditions:

hypothyroidism

growthhormoneinsufficiency

Turners&Noonan'ssyndrome,skeletaldysplasias

coeliacdisease,inflammatoryboweldisease

intracranialtumours


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BasicScienceQ013A35yearoldladyhaspsychogenicdiabetesinsipidus.Herbloodresultsshow sodium

124mmol/l;potassium 4.0mmol/l;Urea 5mmol/l;Creatinine 30mmol/l;Glucose 8

mmol/l.

Whatistheserumosmolality[mosmol/Kg]?

A.255B.261

C.264D.278E.284

Answer:b)261.

Serum osmolality is 2 X sodium +Urea +Glucose = 248 + 5 + 8 = 261mOsmol/Kg.

Normalis280to305henceshehaslowserumosmolality.Analternativeformulais1.9x

(Na+K)+Ur+Glucose.


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BasicScienceQ014

Whichone

of

the

following

set

of

offsprings

would

aX

linked

dominant

condition

be

transmittedto?

A.Noneofthesonsofanaffectedwoman

B.Halfofthedaughtersofanaffectedwoman

C.Allofthesonsofanaffectedwoman

D.Allchildrenofanaffectedwoman

E.Allchildrenofanaffectedman

Answer:b)Halfofthedaughtersofanaffectedwoman.

The classical example of an Xlinked dominant inherited condition is familial

hypophosphataemicrickets.RemembertodifferentiatebetweenXlinkedrecessiveand

Xlinkeddominant.

An affectedwoman has the chromosomes XxX andwill transmit this to half of her

daughterswhowilleitherhave

XX or XxX chromosomes. Similarly, half of the sonswill have the disease XxY or XY

chromosomes.

Xlinkeddominantinheritancewithanaffectedmother


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one

of

these

conditions

is

an

Autosomal

Dominant

disorder?

A.AtaxiaTelangiectasiaB.Achondroplasia

C.AlkaptonuriaD.CysticFibtosisE.Phenylketonuria

Answer:b)Achondroplasia.

Thelistofautosomaldominantdisordersare:

achondroplasia

antithrombinIIIdeficiency

EhlersDanlossyndrome

Familialhypercholesterolaemia

Gilbert'sdisease

hereditaryhaemorrhagictelangiectasia

hereditaryelliptocysis,hereditaryspherocytosis

Huntington'sdisease

idiopathichypoparathyroidism

intestinalpolyposis

marblebonedisease

Marfan'ssyndrome

neurofibromatosis

polycystickidneydisease(adult)

proteinCdeficiency

osteogenesisimperfecta

TreacherCollinssyndrome

tuberoussclerosis

VonWillebrand'sdisease


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BasicScienceQ016

Whatis

the

effect

of

leptin

on

body

metabolism?

A.Decreasesenergyusage

B.StimulatesneuropeptideY

C.Increasesappetite

D.Stimulatespancreaticproteases

E.Reducesadiposetissuemass

Answer:E)reducesadiposetissuemass

Leptin is expressed by adipocytes andmediate effects via the hypothalamic centre

which controlshungerandenergyexpenditure. It inhibitsneuropeptideY (which is a

potent appetite stimulator), increases oxygen consumption, body temperature and

reducesadiposetissuemass.


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BasicScienceQ017

A65yearoldmanhasaparietallobeinfarct.

Whichoneofthefollowingisalikelymanifestation?

A.Fingeragnosia

B.Homonymoushemianopia

C.Bitemporalhemianopia

D.Expressivedysphasia

E.Dysdiadochokinesis

Answer:a)fingeragnosia.

Parietallobesignsare:

lossoftwopointdiscrimination

agraphia

fingeragnosia

astereognosis

dyslexia

Gerstmannsyndrome

receptivedysphasia

dressingandconstructionaldyspraxia

Gerstmann syndrome includes four features (acalculia, agraphia, finger agnosia, left

rightdisorientation),andisduetoalesioninthedominanthemisphere.

TestingforFingerAgnosia(inabilitytodiscriminatedifferentfingers)


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BasicScienceQ018An18yearoldballetdancerpresentstoA&Eunwell.Shehaspoordentition.

HerarterialpHis7.44andshehasapCO2of6kPaandpO2of10kPa.Herchlorideis85

(95107)mmol/l,HCO3is30(2028)mmol/l.

Whichofthefollowingdescribesheracidbasebalance?

A.RespiratoryacidosiswithmetaboliccompensationB.Respiratoryalkalosiswithmetaboliccompensation

C.MetabolicacidosiswithrespiratorycompensationD.MetabolicalkalosiswithrespiratorycompensationE.Normalaniongapmetabolicacidosis

Answer:d)metabolicalkalosiswithrespiratorycompensation.

This patient is bulimic and has lost HCl from excessive vomiting. She hasmetabolic

alkalosiswhichiscompensatedbyhypoventilation(hencelowpO2andhighCO2).


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one

of

following

biochemical

abnormalities

would

be

most

commonly

seen

in

a

diagnosisofBartterssyndrome?

A.HypochloraemiaB.Hyperkalemia

C.HyponatraemiaD.HypokalemiaE.Acidosis

Answer:D)Hypokalemia

Bartterssyndromeischracterisedby:

hypokalaemicalkalosis,elevatedreninandaldosteronelevels


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BasicScienceQ020Amanwho has common variable immunodeficiency comes to see thedoctor in the

geneticsclinicwithhisgirlfriend.Theywouldliketostartafamily.

Whatistheprobabilitythathischildrenwillinherithisdisease?

A.


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BasicScienceQ021

TranscriptionRNA (tRNA)has threebasesspecific toaparticularaminoacid,which it

bindstomessengerRNA(mRNA).ThisspecificareaoftRNAknownas:

A.Codon

B.Intron

C.Anticodon

D.Transposon

E.Exon

Answer:c)anticodon.

TransferRNA (tRNA) isasmallRNAchain (7493nucleotides)that transfersaspecific

aminoacid toagrow ingpolypeptidechainat the ribosomal siteofproteinsynthesis

during translation. It has sites for aminoacid attachment and codon (a particular

sequenceof3bases)recognition.ThecodonrecognitionisdifferentforeachtRNAand

isdeterminedbytheanticodonregion,whichcontainsthecomplementarybasestothe

onesencounteredonthemRNA.EachtRNAmoleculebindsonlyonetypeofaminoacid,

butbecausethegeneticcodeisdegenerate,morethanonecodonexistsforeachamino

acid.

AnticodonandCodon


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one

of

these

organelles

have

DNA

which

can

self

replicate?

A.GolgiapparatusB.Nuclearmembrane

C.MitochondriaD.PeroxisomesE.Transcriptionfactors

Answer:c)mitochondria.

OnlymitochondriahaveselfreplicatingDNA


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BasicScienceQ023

A 25 year oldwomanwas referred for investigation of iron deficiency anaemia.Her

motherdiedaged35yearsfromcoloniccarcinomaandhadPeutzJeghersyndrome.

WhichisthelikelymodeofinheritanceofPeutzJegherssyndrome?

A.Autosomaldominant

B.Autosomalrecessive

C.Xlinkeddominant

D.Xlinkedrecessive

E.Mitochondrial

Answer:a)Autosomaldominant.

Peutz Jegher syndrome is an autosomal dominant condition associated with

pigmentation,mainly,ofthelips,buccalmucosa,genitalia,handsandfeet.

Inaddition,therearemultiplehamartogenouspolypsofthegastrointestinaltract most

often in the smallbowelbutmayoccuraffectanyportionof theGI tract.Thepolyps

themselves have a very lowmalignant potential. About 1020% of patients develop

gastrointestinalcarcinoma,butthereisalsoincreasedriskofpancreatic,lungandbreast

carcinoma.

MucosalPigmentationinPeutzJegherSyndrome


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BasicScienceQ024

Themain

histological

abnormality

in

Huntington's

disease

is

seen

in

the:

A.Caudatelobe

B.Midbrain

C.Rednucleus

D.Inferiorcolliculus

E.Hippocampus

Answer:a)Caudatelobe.

Themainhistological abnormality inHuntingtons chorea is seen in the caudate lobe

andputamenwherethereisextensiveneuronalloss.

Caudatenucleus/lobe


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BasicScienceQ025Atsympatheticnerveendingswhat

happens

to

the

majority

of

amount

of

noradrenaline

followingdepolarisation?

A.ReuptakebythenerveterminalendingB.Breakdownbymonoamineoxidase

C.ConversiontoadrenalineD.StaysatthenervejunctionE.RecycledbycatecholOmethyltransferase

Answer:a)reuptakebythenerveterminalending.

Most noradrenaline is taken up back into neurosecretory granules.MAO and COMT

metaboliseNAinsmallamounts.


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BasicScienceQ026A 62 year old man with epigastric pains and weight loss is suspected of having

pancreaticcarcinoma.

Whichoneofthefollowingmarkersisuseful?

A.AlphafetoproteinB.CA19.9

C.CA125D.ProstatespecificantigenE.Carcinoembryonicantigen

Answer:B)CA19.9

CA19.9isfoundin7090%ofpatientswithpancreaticcarcinoma.CA125andCEAmay

alsobepositivebutarelessfrequentlyso.


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BasicScienceQ027The

RET

Proto

oncogene

is

associated

with

which

one

of

the

following?

A.InsulinomaB.Anaplasticthyroidcarcinoma

C.BronchialcarcinomaD.MedullarythyroidcarcinomaE.Pituitarytumour

Answer:D)Medullarythyroidcarcinoma.

The RET protooncogene is associated with multiple endocrine neoplasia MEN2A,

MEN2Bandmedullarythyroidcarcinoma1,Hirschsprungdisease.


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BasicScienceQ028Ayoungmanpresentswithfeversandhasseveralbloodtests.

Whichoneofthefollowing,ifincreased,suggestsinfection?

A.AlbuminB.Transferrin

C.FerritinD.Alpha2macroglobulinE.Leptin

Answer:C)Ferritin.

Ferritiniswellknownasanacutephaseproteinwhichisincreasedinsepsis.


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BasicScienceQ029A62yearmalepresentswithbilateralneuropathic legpains.Therewasrelevantpast

history of excess alcohol use. He is currently on oral thiamine and omeprazole. On

examination, both knee reflexes are reduced and there is reduced sensation to fine

touchinbothfeet.

Whatisthenextbestinvestigationtoconfirmthediagnosis?

A.EMGB.ChestXray

C.CTheadD.CTspineE.Bloodsugar

Answer:E)Bloodsugar

The clinical features are consistent with a diagnosis of peripheral neuropathy and

althoughhehasanotherpossiblecauseduetoalcohol,diabetesneedstobeexcluded.


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BasicScienceQ030

A65yearoldMediterraneanmanwhohaslegcrampsisstartedonquinine.Hepresents

10days later,with ahistoryofdarkenedurine, increasingbreathlessness,backpains

and fatigue. Investigations show a haemoglobin of 6.5 g/dl and raised reticulocyte

count.

Whichofthefollowingbestexplainsthisdrugreaction?

A.Hereditaryspherocytosis

B.Hereditaryelliptocytosis

C.Autoimmunehaemolyticanaemia

D.Pyruvatekinasedeficiency

E.Glucose6phosphatedehydrogenasedeficiency

Answer:e)glucose6phosphatedehydrogenasedeficiency.

Glucose6phosphatedehydrogenasedeficiency(X linkedrecessive) isseen inAfrican,

Mediterranean,Iraqi,JewandSouthEastAsianChinesepeople.

Itpredisposestoahaemolyticanaemiareactiontodrugsandinfection.Implicateddrugs

includeaspirin,sulphonamides,antimalarialsandquinidine.

BloodfilmshowinghaemolysisinG6PDdeficiency


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BasicScienceQ031A40yearold femalepresentswithamovementdisorder.There isa familyhistoryof

Huntingtons chorea and the family is worried that she may be developing this

condition.

Whatisitsinheritance?

A.AutosomalrecessiveB.Autosomaldominant

C.MitochondrialinheritanceD.XlinkedrecessiveE.Xlinkeddominant

Answer:b)Autosomaldominant.

Huntingtonschoreaisinheritedasanautosomaldominanttrait.


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BasicScienceQ032

A60yearoldmanhasnumbnessandtinglingoftheupperouterpartoftheleftthigh.

Onexamination,thereissensoryimpairmentovertheanterolateralaspectofthethigh.

Whereisthelesion?

A.Sacralnerve

B.Lateralcutaneousnerveofthigh

C.Pudendalnerve

D.Femoralnerve

E.Sciaticnerve

Answer:b)Lateralcutaneousnerveofthigh.

The diagnosis is meralgia paraesthetica, an entrapment neuropathy of the lateral

cutaneousnerveofthethighasitpassesundertheinguinal ligament.Obesity isarisk

factorforthecondition.


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BasicScienceQ033Whichofthefollowinghaematologicaldisordersisinheritedasanautosomalrecessive

condition?

A.AcuteintermittentporphyriaB.AntithrombinIIIdeficiency

C.PyruvatekinasedeficiencyD.Glucose6phosphatedehydrogenasedeficiencyE.ProteinCdeficiency

Answer:c)Pyruvatekinasedeficiency.

Pyruvate kinase deficiency is a rare congenital haemolytic anaemia inherited as an

autosomalrecessivemanner.

Theothercondition'sinheritanceare:

Acuteintermittentporphyria autosomaldominant

Antithrombin3(AT3) autosomaldominant

Glucose6phosphatedehydrogenasedeficiency Xlinkedrecessive

ProteinCdeficiency autosomaldominant


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BasicScienceQ034

A22yearold ladyhashadseveralepisodeswheezingwithassociated flushingof the

face,lipsandhandswellingoverthepastfewyears.

Whatinvestigationshouldbedone?

A.C1esteraseinhibitorlevel

B.Skinpatchtestwithlatex

C.Skinpricktestwithlatex

D.SerumANCA

E.Rheumatoidfactor

Answer:A)C1esteraseinhibitorlevel

Hereditary angioneurotic oedema is an autosomal dominantly inherited condition

caused by a deficiency of C1 esterase inhibitor. The main clinical feature is the

intermittentoedemaintheskinaroundtheface,hands,feet,larynxandgastrointestinal

tract.Laryngealoedemamaycausewheezing.TheC2andC4 levelare low inbetween

attacksandC3isnormal.Thereare2varietiesofthedisorder.TypeIismostcommon

andresultsfromanabnormallylowlevelofnormalC1INH.TypeIIresultsfromnormal

orabnormallyelevated levelsofadysfunctionalC1INH. Inboth typesof thedisease,

initialproteolytic componentsof the complement cascade (eg,C1r,C1s)go relatively

unopposedandleadtothecharacteristicpresentationandlaboratoryabnormalities(eg,

lowlevelsofC2andC4).

Swollenlipinhereditaryangioedema


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BasicScienceQ035

A 32 year old lady is admittedwith a history of epistaxis. Investigations reveal iron

deficiencyanaemia.Onexamination,multipletelangiectasiaarenotedaroundher lips

andinhermouth.

Whatisthemodeofinheritanceforthecondition?

A.Polygenicinheritance


C.Autosomaldominant

D.AutosomaldominantXlinkedrecessive

E.Xlinkeddominant

Answer:c)Autosomaldominant.

Thepatienthas the featuresofhereditaryhaemorrhagic telangiectasia (OslerRendu

Webersyndrome)whichhasautosomaldominantinheritance.

Hereditaryhaemorrhagictelangiectasia


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BasicScienceQ036Whichofthefollowingstatementsdescribesthiskaryotype46XX,t(4;8)(q26;p21.3)?

A. Transversion between the long arm of chromosome 4 (q) and the short arm ofchromosome8(p)

B.Transversion between the short arm of chromosome 4 (q) and the short arm of

chromosome8(p)

C. Transversion between the long arm of chromosome 4 (p) and the short arm ofchromosome8(q)

D.Translocation between the short arm of chromosome 4 (q) and the long arm of

chromosome8(p)E.Translocation between the long arm of chromosome 4 (q) and the short arm of

chromosome8(p)

Answer:e)translocationbetweenthelongarmofchromosome4(q)andtheshortarm

ofchromosome8(p).

The karyotype46XX, t (4;8)(q26;p21.3)describes a femalewith anormalnumberof

chromosomesbutatranslocationbetweenthelongarmofchromosome4(q)andthe

shortarmofchromosome8(p).


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BasicScienceQ037A 28 year ladypresentsmultiple caf au lait spots.Adiagnosisofneurofibromatosis

type1made.

WhichofthefollowingistrueregardingtheNF1genesinheritanceandlocation?

A.InheritedinanautosomalrecessivefashionB.InheritedinanXlinkedfashion

C.Foundonchromosome17D.FoundinthemitochondrialgenomeE.IsidenticaltotheNF2gene

Answer:C)Foundonchromosome17

NeurofibromatosiscanbeduetoadefectofeithertheNF1orNF2gene.

TheNF1geneisfoundonchromosome17inheritedinanautosomaldominantfashion.

TheNF2geneisfoundonChromosome22.


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BasicScienceQ038Regarding two loci A and B, which are in linkage disequilibrium, which

one

of

the

followingstatementsistrue?

A.TheinheritanceofanalleleatAwillalmostcertainlyexcludetheinheritanceofoneoftheallelesatB

B.Thedegreeoflinkagedisequilibriumcanbehighlyvariable

C.ThefourallelesatAandBareinheritedindependentlyprovidedthatthepopulationisofsufficientsize

D.ThelociAandBarenotlinkedE.Itisarandomassociationofallelesinabreedingpopulation

Answer:b)Thedegreeoflinkagedisequilibriumcanbehighlyvariable.

Linkagedisequilibriumisanonrandomassociationofallelesinabreedingpopulation.The lociAandBare likelytobe linked.Hence inheritanceofanalleleAusuallyoccurs

withtheinheritanceofalleleB(ratherthanexcluded).Theinheritanceisstilldependent

despitepopulationsize.Linkagedisequilibriumalmostalwaysoccursbetweenallelesat

geneticlocithatarecloselylinkedinthegenome.Thedegreeoflinkageequilibriumcan

however,behighlyvariable.


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BasicScienceQ039

McArdle'sdisease isageneticdefect in thephosphorylaseenzyme,whichaffects the

breakdownofglycogen.

Whatisglycogenmadeupof?

A.Chainsofglucoseresidues

B.Chainsoffructoseresidues

C.Chainsofsucroseresidues

D.Chainsofgalactoseresidues

E.Chainsofalternatinggalactoseandglucoseresidues

Answer:a)Chainsofglucoseresidues.

Thestructureofglycogenconsistsoflongpolymerchainsofglucoseunitsconnectedby

analphaacetal linkage.Chainsofglucoseresiduesare linkedinglycogenbyalpha1,4

glycosidicbonds (i.e.betweenthe firstcarbonatomC1ofoneglucoseand thefourth

carbonatomC4ofthenext).

Glycogen polymerofglucosemolecules


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BasicScienceQ040

ApatientwithAngelman'ssyndromeexpressesgenomicimprinting.

Whatdoesthismean?

A.Thattwogenesareinheritedtogether

B.Thatageneismitochondriallyinherited

C.Theseverityofadiseaseworsensfromgenerationtogeneration

D.Thatonealleleofageneisnotexpressed

E.Thedifferentialexpressionofallelesisdependentontheirparentalorigin

Answer:e)thedifferentialexpressionofallelesisdependentontheirparentalorigin.

Genomic imprinting is the termused to refer to thedifferentialexpressionofalleles

dependentontheirparentalorigin.

Anexample iswhen the samegenehavingdifferentphenotypicexpression isdue to

eithermaternalinheritance(e.g.PraderWillisyndrome)orduetopaternal inheritance

(e.g.Angelmanssyndrome).

GenomicImprinting thesamegenehasdifferentphenotypicexpressiondependingon

whetheritismaternallyorpaternallyinherited


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BasicScienceQ041

A 25 year old patient with acquired Factor VIII deficiency was given a monoclonal

antibodydrugfollowinganepisodeofseverebleeding.

Whichoneoftheseisthelikelydrug?

A.Prednisolone

B.Cyclosporin

C.Enoxaparin

D.Rituximab

E.Cyclophosphamide

Answer:d)Rituximab.

Rituximabisachimeric,humanIgG1monoclonalantibodyspecificfortheCD20antigen

expressedon the surfaceofB lymphocytes.Theantibody isknown to induce rapid in

vivodepletionofbothnormalBlymphocytesandlymphomaBcells.Thedrug's limited

toxicity has led to the recent use of rituximab for the treatment of autoimmune

disorders, anticipating adecrease in antibodyproductionbyCD20+B cells. Examples

include ITP, autoimmune hemolytic anaemia, and acquired hemophilia A (factor VIII

deficiency).

Monoclonal antibodies aremade by fusing a mouse B cell withmyeloma cell line.

Antibodiescanbepurifiedandcelllinesaregrowninvitro.Theantibodiescanbeused

tomeasurehormonelevelswithimmunoassays.

ProducingMonoclonalAntibodies


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BasicScienceQ042A55yearoldcarpenterhaspaininhisshoulder.Onexamination,therewaspainduring

resistanceofabduction.

Whichmuscleislikelytobeinvolved?

A.InfraspinatusB.Supraspinatus

C.PectoralismajorD.TeresminorE.Latissimusdorsi

Answer:B)supraspinatus.

Supraspinatus tendonitis is also known as rotator cuff syndrome. Supraspinatus

tendinitistypicallyaffectspatientsbetween40and60yearsofagefollowingprolonged

orexcessiveuseoftheshoulder.Painisusuallymoreseverebutofshorterdurationin

youngerpatientsduetoamorevigorousrepairprocess.Painisfeltintheshoulderand

over the deltoidmuscle but there is no obvious outw ard sign of inflammation or

swelling.Thereispainonactiveorresistedabduction.


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BasicScienceQ043

A25yearoldmanhastheconditionMELAS.

Whichoneofthefollowingisafeatureofthedisease?

A.Cardiacarrhythmia

B.Colourblindness

C.Hirsutism

D.Lacticacidosis

E.Ketoacidosis

Answer:d)lacticacidosis.

Mitochondrial disorders such as MELAS (Mitochondrial myopathy, encephalopathy,

lactic acidosis, stroke) and MERRF have muscle, brain, nerve and pancreatic

involvement.Withpancreaticandmuscleinvolvement,diabetesand lacticacidosiscan

occur,butketoacidosisisinfrequent.

Scatteredabnormal,vacuolatedfiberswithclearriminMELAS:H&Estain


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BasicScienceQ044

Whichnerve

lesion

causes

weakness

of

biceps,

coraco

brachialis

and

brachialis

and

sensorylossoverthelateralaspectoftheforearm?

A.Radialnerve

B.Brachialnerveroot

C.Axillarynerve

D.C5andC6root

E.Musculocutaneousnerve

Answer:e)Musculocutaneousnerve.

The musculocutaneous nerve suppleis the biceps, coracobrachialis and brachialis

muscles.Italsosuppliessensationoverthelateralaspectoftheforearm.


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BasicScienceQ045

A35yearoldmalepresentswithoralandgenitalmucocutaneousulcerations.Healso

has associated polyarthritis affecting the lower limbs. He is currently on an recent

episodeofpulmonaryembolism.

Whichofthegeneticassociationiscommonwithsuchapresentation?

A.HLAA3

B.HLADR2

C.HLADR3

D.HLAB27

E.HLAB5

Answer:e)HLAB5.

The features of genital and oral ulceration, as well as prothrombotic states are

consistentwithBehcet'sdisease.Familialoccurrencehasbeenreportedanditseemsto

occurinpatientsfromeasternMediterraneancountriesandJapan.Thediseaseappears

tobelinkedtoHLAB5,HLA B51andHLADR5alleles.

OralUlcerationinBehcet'sDisease


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BasicScienceQ046A65yearoldmanwasadmittedwithanexacerbationofchronicobstructivepulmonary

disease.

His arterial blood gases on air showed pH 7.29, Paco2 8.5 kPa, Pao2 8.0 kPa, and

standardbicarbonate30.5mmol/l.

Whatistheacidbasedisturbance?

A.MetabolicalkalosisB.Highaniongapmetabolicacidosis

C.NormalaniongapmetabolicacidosisD.RespiratoryalkalosisE.Respiratoryacidosis

Answer:e)Respiratoryacidosis.

This patient had an acidosis with a high PaCO2 and normal standard bicarbonate

respiratory acidosis. This is a common finding in acute exacerbations of chronic

obstructivepulmonarydisease,especiallywithtypeIIrespiratoryfailure.


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BasicScienceQ047

Whichof

the

following

anatomical

structures

is

likely

to

cause

chorea,

ifdamaged?

A.Hippocampus

B.Subthalamicnucleus

C.Thalamus

D.Caudatenucleus

E.Substantianigra

Answer:d)caudatenucleus.

Damage to the caudate nucleus is most likely to cause chorea. This is involved in

Huntington'schorea.


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BasicScienceQ048A60yearoldwomanhashyponatraemia.Followinginvestigation,shewasdiagnosedas

havingSIADH.

Whichofthefollowingisthemostlikelycause?

A.RamiprilB.Ibuprofen

C.ChlorpromazineD.AlcoholE.Atenolol

Answer:c)chlorpromazine.

SIADH can be caused bymany drugs (mnemonic starting with C) carbamazepine,chlorpropramide, cyclophosphamide, chlorpromazine and clomipramine (i.e.

neurolepticsandantidepressantsincludingSSRIs).AlcoholdecreasesADHrelease.


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BasicScienceQ049A40yearolddiabeticpatientoverdosedon30tabletsofanunknownmedication.

ShehasbloodgasesshowingapHof7.32,pO2of16kPaandpCO2of3kPa.HerHCO3

is8mmol/landbaseexcessis 5.

Whatisthelikelyscenario?

A.MetabolicacidosiswithrespiratorycompensationB.Metabolicalkalosiswithrespiratorycompensation

C.RespiratoryacidosiswithmetaboliccompensationD.RespiratoryalkalosiswithmetaboliccompensationE.Normalaniongapmetabolicacidosis

Answer:a)metabolicacidosiswithrespiratorycompensation.

Thepatientislikelytohaveoverdosedonmetforminandhasmetabolicacidosis.ThepH

isacidoticandsheishyperventilatingforrespiratorycompensationofacidbasebalance,

hencethelowCO2andhighO2


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BasicScienceQ050

A50yearoldladyhaspaininherrightleg.Onexamination,therewasweaknessofher

rightankleandabsentrightanklejerk.Shealsohadsensorylossoverthelateralaspect

ofherankle.

Whichofthesenervelesionsislikely?

A.Deepperonealnerve

B.Femoralnerve

C.Sciaticnerve

D.Lumbosacralplexus

E.Inferiorglutealnerve

Answer:c)sciaticnerve.

Thesciaticnervebranchesintothetibialnerveandcommonperonealnerve.Damageto

thesebrancheswillcausealmosttotalweaknessaroundtheankleandabsentanklejerk.


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BasicScienceQ051

Whichform

of

nerve

damage

leads

to

complete

inability

to

raise

the

arm

at

the

shoulder

withsensorylossoverthedeltoid?

A.Lateralcutaneousnerve

B.Axillarynerve

C.Radialnerveintheaxilla

D.Suprascapularnerve

E.C5andC6ofthebrachialnerveplexus

Answer:b)Axillarynerve.

The axillary nerve supplies the deltoid and teresminor aswell as the skin over the

deltoid.


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BasicScienceQ052A40yearoldmanpresented2yearsagowithaninheritedneurologicaldisordercausing

weakness.Hisfatherdevelopedthediseaseinhis70sandhisdaughterwasborn5years

agowithasevereformofthecondition.Hismother,sister,wifeandsonareunaffected.

Whatisthelikelymodeofinheritance?

A.AutosomaldominantB.Autosomalrecessive

C.XlinkedinheritanceD.TrinucleotiderepeatdiseaseE.Mitochondrialinheritance

Answer:d)Trinucleotiderepeatdisease.

The inheritance showing increasing disease severitywith earlier onset of disease in

subsequent generations is called anticipation. This is typical of trinucleotide repeatdiseasewherethereisexpansionofrepetitivesequenceofthreenucleotideswitheach

generation.

Typicalexamplesare:

Huntington'sdisease,myotonicdystrohpy,fragileXsyndrome&Friedriech'sataxia.


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BasicScienceQ053A20yearoldpatienthasbeenkickedintheshinduringanaggressivefootballmatch.He

isunabletoeverthisfootanddorsiflexhisankle.

Whichnerveisinjured?

A.FemoralnerveB.Saphenousnerve

C.GlutealnerveD.CommonperonealnerveE.Anteriortibialnerve

Answer:d)commonperonealnerve.

Theperonealmuscles around the lateralpartof the shinhelp todorsiflex the ankle,

extendthetoesandevertthefoot.Theyaresuppliedbythecommonperonealnerve.

Thecommonperonealnerve isabranchofthesciaticnerve.Themanner inwhichthe

commonperonealnervesnakesaroundthefibularheadexposesittoinjury.


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BasicScienceQ054A10yearoldboywithblue scleraeand recurrent fractureshasbeendiagnosedwith

Osteogenesisimperfecta.

Whatabnormalitypredisposestobonefragility?

A.MetalloproteinaseB.Type1collagen

C.FibronectinD.LamininE.Elastin

Answer:B)type1collagen.

Osteogenesis imperfecta (OI) is a condition resulting from abnormality in the type I

collagen,whichmostcommonlymanifestsasfragilityofbones.


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BasicScienceQ055A65yearoldmanhasfamilialhypercholesterolaemia.

Whichoneofthefollowingisacharacteristicfeatureofthecondition?

A.PalmarxanthomasB.Autosomalrecessiveinheritance

C.ReducedexpressionofLDLreceptorsD.HypertriglyceridaemiaE.Elevatedchylomicrons

Answer:c)ReducedexpressionofLDLreceptors.

Thecharacteristicsoffamilialhypercholesterolaemiaare:autosomaldominantcondition

increasedLDLconcentrations

reducedHDLconcentrations

reducednumbersofLDLreceptor

cardiovasculardisease

tendonxanthomatas


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BasicScienceQ056A65yearoldmanhasarightsidedhomonymoushemianopiaandrightsidedupperand

lower limb weakness. His reflexes are brisk on the right side. There is no sensory

abnormalities.

Whichofthefollowingareacouldbeinfarcted?

A.LefttemporalB.Leftparietal

C.LeftcingulategyrusD.RightmedialthalamusE.Leftfrontallobe

Answer:b)leftparietal.

Thecingulategyrusformspartofthelimbicsystem,whichisassociatedwithmoodandemotions.Frontallobelesionsarenotusuallyassociatedwithhomonymoushemianopia


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BasicScienceQ057

A50yearoldwomanhasrightsidedweakness,headacheandvomiting.Onexamination

she has a hemiplegia affecting the right face, arm and leg. She also has unilateral

internuclearophthalmoplegiawithfailureofadductiontotheleftandnystagmustothe

left.Fundoscopyrevealspapilloedema.

Inthispatient,thepapilloedemaisduetoobstructionat:

A.TheforamenofMonro

B.TheforamenofMorgagni

C.TheforamenofMagendie

D.TheaqueductofSylvius

E.TheforamenofLuschka

Answer:d)theaqueductofSylvius.

Theaqueductofthemidbrain (theaqueductofSylvius)runs inthetegmentumofthe

midbrain andjoins the third and fourth ventricles.Compressionof the aqueduct can

resultinobstructivehydrocephalusandpapilloedema.

Headacheandvomitingcanoccurbecauseofraisedintracranialpressure.Malignantor

benign intracranialtumors,colloidalcysts,arachnoidcysts,andneurocysticercosiscan

alsocausecompressionandneedtoberuledout.

CSFdrainage


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BasicScienceQ058

A75 yearoldmanhas aposterior cerebralartery territory infarct.Whichoneof the

followingislikeytooccur?

A.Bitemporalhemianopia

B.Expressivedysphasia

C.Receptivedysphasia

D.Colourblindness

E.Corticalblindness

Answer:e)corticalblindness.

The posterior cerebral artery supplies the occipital lobe and the inferior portion of

temporal lobe. Homonymous hemianopia, cortical blindness, verbal dyslexia and

hemivisualneglectcanoccur.

PosteriorCerebralArtery


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BasicScienceQ059A30yearoldladyhaspalpitationsandissubsequentlyconfirmedtohavethyrotoxicosis

duetoGrave'sdisease.

Whichofthefollowingstatementsistrue?

A.Grave'sdiseaseisassociatedwithmusculardystrophyB.Propylthiouracilispreferredovercarbimazoleinpregnancy

C.RadioactiveiodinealwaysimprovesGrave'sdiseaseD.SmokinghistoryisirrelevantE.SteroideyedropsaretypicallyusedtotreatGrave'seyedisease

Answer:b)propylthiouracilispreferredovercarbimazoleinpregnancy.

Grave'sdiseaseisassociatedwithotherautoimmuneconditionse.g.myastheniagravis.

Propylthiouracil ispreferred toCarbimazole inpregnancybecausecarbimazolecrosses

theplacentaandcancausenail/fingerabnormalities(aplasiacutis)inthebaby.

Radioactive iodine can worsen Grave's disease. Smoking is a risk factor for Grave's

disease.

HighdoseoralorivsteroidsarerequiredinGrave'seyedisease.


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BasicScienceQ060Whichoneofthefollowingconditionshasautosomaldominantinheritance?

A.OculocutaneousalbinismB.Betathalassaemia

C.Marfan'ssyndromeD.Wilson'sdiseaseE.XerodermaPigmentosa

Answer:c)Marfan'ssyndrome.

Marfan'ssyndrome inheritance isautosomaldominant.The restof theconditionsare

autosomalrecessive.

Thelistofautosomalrecessiveconditionsare:

oculocutaneousalbinism

alkaptonuria

Bartter'ssyndrome

cysticfibrosis

endemicgoitrouscretinism

galactosaemia

Gaucher'sdisease

glycogenstoragedisease

phenylketonuria

Wilson'sdisease

xerodermapigmentosa


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BasicScienceQ061Activationofthecomplementcomponentsisassociatedwithpotentbiologicalfunctions

tocounteractinfections.

Whichofthefollowingactivatesratherthaninhibitsthecomplementpathway?

A.DAFB.CR1

C.C3bD.FactorIE.MCP

Answer:c)C3b.

C3b isanactive fragmentofC3,andcanactivate thealternativepathway.DAF,CR1,

FactorIandMCParecomplementpathwayinhibitors.


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BasicScienceQ062The thymus gland contains 3 major cell populationsepithelial, hemopoietic, and

accessorycells.

Whichofthefollowingcellsdevelopinthethymus?

A.MacrophagesB.Tcells

C.ErythrocytesD.BcellsE.Hairycells

Answer:b)Tcells.

Bcellsarenotonlyproducedinthebonemarrowbutalsomaturethere.However,the

precursorsofTcellsleavethebonemarrowandmatureinthethymus.


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BasicScienceQ063A55yearoldmalehasbeenaheavy smokerandhashadpreviousexposure tosilica

dust.HepresentstoA&Ewithworseninglongstandingbreathlessness.

HisarterialpHis7.36.pCO2of7.7kPaandpO2of7.7kPa.HisHCO3is32(2028)mmol/l

andBaseexcessis2.

Whichistheaccuratedescriptionofhisacidbasebalance?

A.MetabolicacidosiswithrespiratorycompensationB.Metabolicalkalosiswithrespiratorycompensation

C.RespiratoryacidosiswithmetaboliccompensationD.RespiratoryalkalosiswithmetaboliccompensationE.Normalaniongapmetabolicacidosis

Answer:c)respiratoryacidosiswithmetaboliccompensation.

There is chronic type2 respiratory failure causing respiratoryacidosisbecauseof the

hypoxiaandhypercapnia.ThisiscompensatedmetabolicallybyHCO3retentionandpH

isrestoredtowithinanormalrange.


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BasicScienceQ064

Whichis

the

structure

formed

by

the

roots

of

the

lumbar

and

sacral

nerves?

A.Falxcerebri

B.Amygdala

C.Cisterns

D.Medullaoblongata

E.Caudaequina

Answer:e)caudaequina.

Thecordistaperedatthelowerendtoformtheconusmedullaris.

Therootsofthelumbarandsacralnervesarelongandtheyformthecaudaequina.


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BasicScienceQ065A40yearoldwomanhasMELAS.

Whichofthefollowingiscorrectregardingtheriskofthegrandsonsandgranddaughters

havingthedisease?

A.Sonschildren100%,Daughterschildren100%B.Sonschildren0%,Daughterschildren100%

C.Sonschildren50%,Daughterschildren100%D.Sonsdaughters100%,Sonssons100%E.Daughtersdaughters100%,Daughterssons0%

Answer:B)Sonschildren0%,Daughterschildren100%.

Kearn Sayre's, MELAS, MERRF, progressive external opthalmoplegia, Leber's optic

atrophy aremitochondrially inherited diseases. Themitochondrial DNA is passed on

onlyfromthemothertoallchildren.


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BasicScienceQ066A 35 year old lady presentswithw asting of the quadriceps andweakness of knee

extension.There is lossof thekneejerkandsensory impairmentover thefrontofthe

thighandoverthesubcutaneoussurfaceofthetibia.

Thelikelylesionis:

A.PeronealnerveB.Brachialnerve

C.ObturatornerveD.FemoralnerveE.Sacralnerve

Answer:d)Femoralnerve.

Thefemoralnervesuppliesthe iliacusandpectineus,andthemusclesontheanteriorthigh.Thenervealsoprovidescutaneous filaments to the frontand inner sideof the

thighandtothelegandfoot(viasaphenousnerve).


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BasicScienceQ067

Whichone

of

the

following

features

is

found

in

Neurofibromatosis

Type

1(NF1)?

A.Webbedneck

B.Calcinosis

C.Lensdislocation

D.LischNodules

E.Rothsspots

Answer:d)LischNodules.

Lischnodules (pigmented spots)of the iris arepresent inmore than90%ofpatients

withneurofibromatosis type1.Bilateralacousticneuromasareahallmark featureof

neurofibromatosistype2.

Thediagnosis issuggestedbysixormorecafau laitspots.Althoughthecondition is

autosomaldominant,almosthalfofallcasesarenewmutations.

LischNodules


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BasicScienceQ068

A17yearoldladyhassmall,raisedlesionsonhertrunkandalsohasaxillaryfreckles.

Whatisthelikelymodeofinheritanceofthiscondition?

A.Autosomaldominant


C.Trinucleotiderepeats

D.Xlinkedrecessive

E.Xlinkeddominant

Answer:a)Autosomaldominant.

Theconditiondescribedisneurofibromatosis.Inheritanceisautosomaldominant.

ThegenedefectforNF1isonchromosome17,andforNF2isonchromosome22.

Neurofibromas


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BasicScienceQ069

A35yearolddiabeticmanhas lossofsensationintheanteriorand lateralpartofthe

thigh.

Whichnerveislikelytobeaffected?

A.Sciaticnerve

B.Lateralcutaneousnerve

C.Glutealnerve

D.Pudendalnerve

E.Femoralnerve

Answer:b)lateralcutaneousnerve.

Traumaaroundtheinguinalligamentcanleadtodamageinthelateralcutaneousnerve

supplying the anterolateral portion of the thigh. It is a purely sensory nervewhich

travelslateraltothepsoasmuscle.

LateralCutaenousNerve(markedNCL)


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of

the

following

enzymes

converts

glucose

to

glucose

6phosphate?

A.PhosphofructokinaseB.Glucokinase

C.HexokinaseD.FructokinaseE.Glucose6phosphatase

Answer:c)Hexokinase.

Hexokinase catalyses the conversion of glucose to glucose6phosphate, using a

phosphategroupdonatedfromATP.


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of

the

following

is

true

regarding

the

role

of

restriction

enzymes?

A.AnnealDNAtogetherB.SynthesizeDNA

C.AreinvolvedinthecellcyclearrestD.CutDNAE.DegradeDNA

Answer:d)CutDNA.

Restriction enzymes cut DNA at nucleotide sequences specific to each restrictionenzyme.

HindIIIandEcoRIareexamplesofrestrictionenzymes.DNA ligaseandpolymeraseare

involvedinjoiningandlinkingDNAtogether.

EcoR1asanexampleofarestrictionenzyme


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BasicScienceQ072Respiratory distress syndrome can be associated with reduction of lung surfactant.

Surfactantisproducedinwhichcellinthelung?

A.AlveoliwhitecellsB.Vesselendothelium

C.TypeIIpneumocyteD.SmallcellE.Keratinocytes

Answer:c)typeIIpneumocyte.

LungsurfactantisproducedbytypeIIpneumocytes.


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BasicScienceQ073

A 22 year old cricket player presents with an injury to his right upper limb. On

examinationof the rightupper limb there is incompleteanddefectivepronation.The

wristflexorsareparalysedwhenexaminedagainstresistance.

Whenthisistestedthetendonofflexorcarpiulnarisstandsoutandthehandbecomes

ulnardeviated.FlexionoftheulnarTwofingers ispossiblealthough it isweakerthan

normal.Abductionandoppositionofthethumbisdefective.Thereissensorylossover

thelateralthreeandahalfdigitsofthehandandthelateralaspectofthepalm.

Theinjuryislocatedat:

A.Ulnarnerveatthewrist

B.Ulnarnerveattheelbow

C.Brachialnerve

D.Musculocutaneousnerve

E.Mediannerveattheelbow

Answer:e)Mediannerveattheelbow.

An injurytothemediannerveattheelbowcausesweaknessofpronatorteres,radial

flexorsof thewrist, the long finger flexorsexcept theulnarhalfof thedeep flexors,

mostofthemusclesofthethenareminenceandtheTworadiallumbricals.

Sensory lossoccursover the lateralthreeandahalfdigitsofthehandandthe lateral

aspectofthepalm.Theremayalsobevasomotorandtrophicchanges.


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of

the

following

is

true

regarding

autosomal

recessive

inheritance

involving

parentsandchildren?

A.Forparentswithoneaffectedchild,theriskofhavinganotheraffectedchildis1in2B.Forparentswithoneaffectedchild,theriskofhavinganotheraffectedchildis1in8

C.Unaffectedsiblingsofanaffectedchildhavea1in3chanceofbeingcarriersD.Unaffectedsiblingsofanaffectedchildhavea2in3chanceofbeingcarriersE.Unaffectedsiblingsofanaffectedchildaredefinitecarriers

Answer:d)unaffectedsiblingsofanaffectedchildhavea2in3chanceofbeingcarriers.

Thebestwaytounderstandistodrawafamilytreewiththeparentsbothbeingcarriers

oftherecessivegene[AAxandBBx]andfourpossibleinheritedcombinations[AB,AxB,

AxBandAxBx].

Forparentswithoneaffectedchild,theriskofhavinganotheraffectedchildis1in4.

Unaffectedsiblingshavea2in3chanceofbeingcarriersbecausethelastpossibilityof

bothrecessivegenesiseliminated(AxBx).


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BasicScienceQ075WhichONEofthefollowingorganelleshaveselfreplicatingDNA?

A.EndoplasmicReticulumB.Golgiapparatus

C.PeroxisomeD.MitochondriaE.Lysosomes

Answer:d)Mitochondria.

Mitochondria have DNA, which can pass on inherited mitochondrial diseases (e.g.

MELAS/MERRF).


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BasicScienceQ076

APlasmidbestdescribedas

A.ArecombinantsectionofDNA

B.BacterialDNAseparatefromchromosome

C.Multipleoriginsofreplication

D.ViralRNA

E.Consistofmultiplecopiesofasinglegene

Answer:b)bacterialDNAseparatefromchromosome.

Plasmids are circular molecules of bacterial DNA separate from the bacterial

chromosome.Theyareusuallysmall,consistingofafewthousandbasepairs.Theycarry

oneofafewgenesandhaveasingleoriginofreplication.


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BasicScienceQ077A30yearoldmanhasLipoproteinlipasedeficiency.Whichoneofthefollowingfeatures

ismostlikely?

A.MarkedhypercholesterolaemiaB.Reducedchylomicrons

C.MarkedhypertriglyceridaemiaD.FamilialHypercholesterolaemiaE.Combinedhyperlipidaemia

Answer:c)Markedhypertriglyceridaemia.

MutationsintheLPLgenecausefamiliallipoproteinlipasedeficiency.Thebreakdownofchylomicronsreleasesfatmoleculesforstorageinfat(adipose)cells

orforenergyuse.

Inheritanceisautosomalrecessive.Thebreakdownofchylomicronsreleasestriclyceride

molecules for storage in adipose cells or for energy use.Mutations in the LPL gene

preventlipoproteinlipasefrombreakingdownchylomicronseffectively,leadingtohigh

triglyceridelevelsintheplasma.


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BasicScienceQ078

Whichone

of

the

following

is

true

regarding

mitochondrial

DNA

diseases?

A.MitochondrialDNAisinheritedfromthefather

B.MitochondrialDNAiscomposedofacircularloopofdoublestrandedDNA

C.Mitochondrialgenomeencodesfornuclearproteins

D.MutationsofmitochondrialDNAoccursinmultiplesclerosisrelatedopticatrophy

E.SimvastatindepletesmusclemitochondrialDNA

Answer:b)MitochondrialDNAiscomposedofacircularloopofdoublestrandedDNA.

MitochondrialDNAisinheritedfromthemother.MitochondrialDNAcodesforproteins

in theoxidativephosphorylation /electron transportchain. Leber'sopticatrophy isa

formofmitochondrialdisease.AZT (zidovudine) is anexampleof adrugwhichdoes

depletemusclemitochondrialDNA.

MitochondrialDNA


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BasicScienceQ079

Whichof

the

following

is

degraded

to

uric

acid?

A.Uracil

B.Thymine

C.Cytosine

D.Guanine

E.Oroticacid

Answer:d)Guanine.

The purine bases adenine and guanine are degraded to uric acid. Adenosine and

Xanthinearealsometabolisedtouricacid.Uracil,thymine,cytosineandoroticacidare

pyrimidinebases.

PurineMetabolism


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BasicScienceQ080Whichoneofthefollowingfeaturesdoestrinucleotiderepeatdisordersexhibit?

A.AnticipationB.Linkage

C.MethylationD.ReductionE.Genomicimprinting

Answer:A)anticipation.

Trinucleotiderepeatdisorderstypicallyworsenifthereareexpansioninthenumbersof

repeats.This is labeledanticipation.Therepeatsmaybe involved incodingsequences

ofproteinse.g.inHuntingtons.FragileXsyndromecausescognitiveimpairment.


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BasicScienceQ081

A35yearoldpatienthasahigharchedpalateandaortic regurgitation.Hehasa tall

stature,andupwardslensdislocation.

Whichgeneabnormalitydoeshehave?

A.Myosin

B.Actin

C.Fibrillin

D.Spectrin

E.Ankyrin

Answer:c)fibrillin.

InMarfan'ssyndrome,amutationinagenecausesadefectinthebody'sproductionof

fibrillin,animportantbuildingblockofconnectivetissue.Inmanyfamilieswithinherited

Marfan'ssyndrome,themutationaffectstheFBN1geneonchromosome15.


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BasicScienceQ082

A30yearoldwomanhas recentlydeliveredababy.Shecomplainsofgroinpains.On

examination,shehasweaknessofadductionand internalrotationofthehip.There is

sensoryimpairmentoverthemedialaspectofthethigh.

Whichnerveisaffected?

A.Femoralnerve

B.Sciaticnerve

C.Sacralnerve

D.Obturatornerve

E.Lateralcutaneousnerveofthethigh

Answer:d)Obturatornerve.

Theobturatornervesuppliesgracilis,theadductor(longus,brevis,magnus)andtheskin

overthemedialaspectofthethigh.


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BasicScienceQ083Astudyrevealsanimmediateriseinbloodpressurefollowinginfusionofahormoneina

groupofvolunteers.

Whichofthefollowinghormonesislikelytohavebeenused?

A.AngiotensinIB.AngiotensinII

C.GrowthhormoneD.AtrialnatriureticpeptideE.Brainnatriureticpeptide

Answer:b)angiotensinII.

ThefinalactivemessengerofthereninangiotensinpathwayisangiotensinII.

AngiotensinIIbindstoAT1receptorstocausevasoconstrictionandfluidretention,both

ofwhich lead toan increase inbloodpressure.Angiotensin II receptorblockers lower

bloodpressurebyblockingtheAT1receptors.


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BasicScienceQ084A36yearoldmanhasgynaecomastiasecondarytocirrhoticliverdisease.

Whatislikelytohavecausedthegynaecomastia?

A.ReducedtestosteroneproductionB.Increasedtestoteronemetabolism

C.IncreasedoestrogenproductionD.ReducedoestrogenmetabolismE.IncreasedLHlevels

Answer:D)reducedoestrogenmetabolism.

Gynaecomastiainliverdiseaseisduetoanimbalanceinandrogenandoestrogenlevels,

themaincontributorbeingreducedoestrogenmetabolism.


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BasicScienceQ085

A30 yearoldmalepresentshas intermittentjaundice and anaemia.He isdiagnosed

withglucose6phosphatedehydrogenase(G6PD)deficiency.HiswifehasnormalG6PD

activity.

Whatisthelikelihoodoftheirchildrendevelopingtheconditionphenotypically?

A.Alltheirchildrenwillbeaffected

B.Alltheirsonswillbeaffected

C.Alltheirdaughterswillbeaffected

D.50%oftheirdaughterswillbeaffected

E.Noneoftheirchildrenwillbeaffected

Answer:e)Noneoftheirchildrenwillbeaffected.

Glucose6phosphatedehydrogenase (G6PD)deficiencyhasX linked inheritance.The

affectedpatienthasachromosomeXxYandwife isXX.Thereforealldaugherswillbe

carriersXxXandallsonsnormalXY.NoneofthesepatientswillhavephenotypicalG6PD

deficiency.


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BasicScienceQ086A40yearoldmanhasG6PDdeficiency.

Whichoneofthefollowingsubstancesislikelytoleadtoredcellhaemolysis?

A.ChloroquineB.Paracetamol

C.TrimethoprimD.ErythromycinE.Bakedbeans

Answer:a)chloroquine.

Oxidativestresscanbecausedbydrugssuchaschloroquine,quinine,primaquineand

sulphonamide (sulfomethoxazole), nitrofurantoin, NSAIDs, dapsone and aspirin. Fava

beanscanalsocausehaemolysis.


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one

of

the

following

cells

secretes

intrinsic

factor?

A.PancreaticisletcellsB.Panethcells

C.GastricparietalcellsD.HepatocytesE.Myocytes

Answer:C)gastricparietalcells.

Intrinsicfactorissecretedbythegastricparietalcells.Itisaglycoproteinwhichbindsto

vitaminB12best inanacidenvironment. It then releasesvitaminB12 in the terminal

ileumwhereproteasesdigestthebindingproteinsand vitaminB12isabsorbed


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BasicScienceQ088A33yearoldmanhasmyotonicdystrophy.

Whichoneofthefollowingfeaturesisthediseaselikelytoexhibit?

A.DecreasingincidencewithgenerationsB.Skipsgenerations

C.AnticipationD.ApoptosisE.Mutation

Answer:c)Anticipation.

Anticipationreferstoincreasingseveritywithsubsequentgenerations.ItiscommonintrinucleotiderepeatdisorderslikeHuntington'sdisease,myotonicdystrophyandfragile

Xsyndrome,wheretripletrepeatmutationsinDNAareimplicated.

Themechanismbehind theexpansionof the triplet repeats is littleunderstood.One

theoryisthattheincreasingnumberofrepeatsinfluencetheoverallshapeoftheDNA,

which can have an effect on its interaction with DNA polymerase and thus the

expressionofthegene.


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BasicScienceQ089A46yearoldwomancomplainsofnumbness inher lefthand.Onexamination, there

was loss of sensation over the thumb and first 2 fingerswith paralysis of abductor

pollicisandopponenspollicis.

Whichnerveisinjured?

A.MedianB.Ulnar

C.RadialD.PosteriorinterosseousE.Anteriorinterosseous

Answer:A)median

Themediannervesuppliesthefollowingsmallmusclesinthehands:

Abductorpollicisbrevis

Opponenspollicis

Flexorpollicisbrevis

1st&2ndlumbricals

Thesensorysupplyistopalmarsurfaceofthumb,2nd,3rd&lateral1/2of4thfinger


91/173



BasicScienceQ090

Whichofthefollowingisatumoursuppressorgene?

A.Ras

B.Cmyc

C.Nmyc

D.P53

E.Src

Answer:d)p53.

Mutatedprotooncogenesthatcausecancerarecalledoncogenes.Alloftheaboveare

oncogenes except forp53.Ras oncogene is involved in sporadic tumours (colon and

lung) and rhabdomyosarcomas. cmyc translocationoccurs in Burkitt's lymphoma.N

myc protooncogene is seen in neuroblastoma. SRC oncogene is associated with

sarcoma.p53isatumoursuppressorgene.


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BasicScienceQ091A 18 year oldman presents to casualty complaining of difficulty breathing. He had

collapsedshortlyafterbeingstungonthe legbyawasp.Onexamination,hispressure

was80/40mmHg,andtherewassignificantfacialswelling.

Whichoneofthefollowinginvestigationsislikelytoconfirmthenatureofreaction?

A.WasptoxinlevelsB.SerumcomplementC3level

C.SerumcomplementC4levelD.SerumtotalIgElevelE.Plasmatryptaseactivity

Answer:d)SerumtotalIgElevel.

This is a form of Type I hypersensitivity, also known as immediate anaphylactic

hypersensitivity. It usually takes 15 to 30minutes from the time of exposure to the

antigen.ThereactioninvolvesproductionofIgE, inresponsecertainantigens,whichin

turninitiatesasequenceofevents.


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BasicScienceQ092

Whichone

of

the

following

conditions

exhibit

genomic

imprinting?

A.Abetalipoproteinaemia

B.Patau'ssyndrome

C.PraderWillisyndrome

D.Down'ssyndrome

E.MotorNeurondisease

Answer:c)PraderWillisyndrome.

Genomicimprintingisexhibitedbythefollowingconditions:

PraderWillisyndrome

Angelmansyndrome

BeckwithWiedemannsyndrome

Genomicimprinting Diseaseseveritydependsonwhetheritispaternallyormaternally

inherited.


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BasicScienceQ093

Whichof

these

receptors

helps

as

areceptor

to

allow

HIV

to

enter

activated

Tcells?

A.CD4

B.CD8

C.CXCR4

D.CCR4

E.CCR3

Answer:c)CXCR4.

CCR5andCXCR4arecoreceptorswhichhelpHIVbinding (gp120 toCD4 receptor) to

activatedTcells.

CD4moleculesareknown toplayacentral role,butCXCR4 (fusin)andCCR5arealso

involved,possiblybyremovinggp120fromtheHIVparticle,thusexposinggp41,which

isnecessaryforthemembraneattachmentofHIV.


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BasicScienceQ094A 40 year old man with pleurisy for five days was assessed. A moderately sized

pneumothoraxwasseeninachestradiograph.

HisarterialbloodgasesonairshowedpH7.44,PaCO23.0kPa,PaO230.5kPa,standard

bicarbonate16mmol/l.

Howcantheclinicalpicturebeexplained?

A.RespiratoryacidosisB.Compensatedmetabolicalkalosis

C.CompensatedmetabolicacidosisD.CompensatedrespiratoryalkalosisE.Compensatedrespiratoryacidosis

Answer:d)compensatedrespiratoryalkalosis.

ThispatienthadanormalpHbuthadbothalowPaCO2andalowstandardbicarbonate.

Thehistoryindicatesfivedaysofhyperventilation,sothisislikelytobeacompensated

respiratoryalkalosis.


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BasicScienceQ095

An18yearoldmalewithmeningococcalmeningitishas further investigations. Itwas

foundthathehadlowproperdinlevelsmeasuredbytheELISAtest.

Howisthislikelytohavebeeninherited?

A.Autosomaldominant


C.Xlinkedrecessive

D.Xlinkeddominant

E.Mitochondrialinheritance

Answer:C)Xlinkedrecessive.

Thepathwaysincludetheclassicpathway(C1qrs,C2,C4)andthealternativepathway

(C3, factor B, properdin). Properdin is a protein encoded on the X chromosome.

ProperdinstabilizestheC3convertase(C3bBb)ofthealternativepathway, involvedin

opsonisation. Meningococcal disease is a prominent manifestation in a significant

fractionofreportedcasesinallclinicalpatternsofcomplementdeficiency,particularly

those where opsonisation is defective. Properdin deficiency states are Xlinked

recessive, while other genetic defects within the complement system appear to be

transmittedasautosomalrecessivetraits.

ComplementPathways


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BasicScienceQ096Northernblottingisaprocesswhichinvolvesdetectionofwhichofthefollowing?

A.ImmunoglobulinsB.Proteins

C.VirusesD.RNAE.DNA

Answer:d)RNA.

NorthernblottingdetectsRNA,whilstSouthernblottingdetectsDNA.


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BasicScienceQ097

Amedicalstudentreviewsthephysiologyoftheoxygendissociationcurve.

WhichoneofthefollowingisassociatedwithincreasedaffinityofHbforoxygen?

A.Chronichypoxia

B.Anaemia

C.Increased2,3DPG

D.Coldtemperature

E.Diabeticketoacidosis

Answer:d)coldtemperature.

Acidosis,raised2,3DPG,raisedtemperature,hypoxiaandanaemiaallshifttheO2Hb

dissociationcurvetotheright,leadingtoreducedaffinitytoO2.

OxygenDissociationCurve


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BasicScienceQ098ApatientwithCrohnsdiseaseandanileostomyhasthefollowingresults:

Na134(135145mmol/l)

K3.1(3.55mmol/l)

Cl112(92107mmol/l)

Bicarbonate12(2030mmol/l)

Urea13(3.28.1mmol/l)

Creatinine120(70110mmol/l)

pH7.25(7.357.45kPa)

PaCo23.1(3.55kPa)

Thediagnosisislikelytobe:

A.NormalaniongapmetabolicacidosisB.Metabolicalkalosis

C.RespiratoryalkalosisD.RespiratoryacidosisE.Hypochloraemicmetabolicacidosis

Answer:a)Normalaniongapmetabolicacidosis.

Aniongap=(Na+K) (Cl+HCO3),[normalrange1018mmol/L].Inthiscase(134+3.2)

(112+12)=13.1.

Lowbicarbonate in thepresenceofacidosissuggestsametaboliccause, theprobable

causeinthiscaseisgastrointestinalbicarbonateloss.


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BasicScienceQ099A 40 year old patient has had EMGs done to investigate a cause of peripheral leg

weakness.

Whichofthefollowingfeaturessuggestsaxonalneuropathy?

A.LatencyB.Reducedconductionvelocity

C.ReducedmuscleactionpotentialamplitudeD.DecreasedfrequencyofconductionsignalsE.Conductionblock

Answer:c)reducedmuscleactionpotentialamplitude.

Reduced amplitude of action potential is seen in axonal neuropathy. Reduced

conductionvelocityorconductionblockisseenindemyelination.


101/173




of

the

following

are

found

in

both

eukaryotic

AND

prokaryotic

cells?

A.LinearDNAB.Ribosomes

C.ChromosomesD.NuclearmembraneE.Introns

Answer:b)Ribosomes.

Eukaryotes (higher organisms) have muliple chromosomes in a genome which is

separated from the rest of the cell by a nuclear membranes. Prokaryotes lack a

membrane bound nucleus, their DNA occurs in a circular form. Transcription of

eukaryoticgenesrequiresnoncodingsequences(introns) inthemRNAwhich isspliced

out before translation at the ribosome. Both eukaryotes and prokaryotes have

ribosomes.


102/173




of

the

following

is

characteristically

inherited

in

an

autosomal

recessive

manner?

A.AdultpolycystickidneydiseaseB.C1esteraseinhibitordeficiency

C.SicklecelldiseaseD.AchondroplasiaE.Familialhypercholesterolaemia

Answer:c)Sicklecelldisease.

Sickle cell disease is inherited in an autosomal recessive manner (sickle cell trait is

inheritedinanautosomaldominantmanner).

Achondroplasia, adult polycystic kidney disease, C1 esterase inhibitor deficiency

(hereditaryangiooedema)andfamilialhypercholesterolaemiaareusuallyinheritedinan

autosomaldominantmanner.


103/173



BasicScienceQ102

Whichone

of

the

following

statements

describes

genomic

imprinting?

A.Expansionofrepeatswithtime

B.Genotypicvariabilityfrommaternalandpaternalchromosomes

C.Phenotypicpresentationdependsoneithermaternalorpaternalchromosome

D.Imprintingofmutationsongenomes

E.Mendelianinheritance

Answer: c) phenotypic presentation depends on either maternal or paternal

chromosome.

Genomic imprinting refersto thedifference inphenotypicpresentationdependingon

theoriginofthediseasechromosomefromeithermaternalorpaternal.

Genomic imprinting The imprinting"mark" isrepresentedbyastippledbox,and the

imprintedstateisindicatedwithanX.


104/173



BasicScienceQ103

Phosphorylationofproteintyrosineresiduesisassociatedwithwhichofthefollowing?

A.Proteinsynthesis

B.DNAreplication

C.Proteosomaldegradation

D.Cellsignalingpathways

E.Proteindegradation

Answer:D)cellsignalingpathways.

Protein tyrosine kinases (PTKs) are enzymes which catalyze the phosphorylation of

tyrosine residues. These enzymes are involved in cellular signalling pathw ays and

regulatekeycellfunctionssuchasproliferation,differentiation,antiapoptoticsignalling

andneuriteoutgrowth.Unregulatedactivationoftheseenzymes,throughmechanisms

suchaspointmutationsoroverexpression,canleadtovariousformsofcanceraswell

asbenignproliferativeconditions.Indeed,morethan70%oftheknownoncogenesand

protooncogenesinvolvedincancercodeforPTKs.

TyrosineKinaseReceptor


105/173



BasicScienceQ104

Amanwithmildbleedingdisorder isbeing considered for aspirin for acute coronary

syndrome.

Whichoneoftheeffectsofaspirinisbeneficialincoronaryarterydisease?

A.ReductioninthromboxaneA2synthesis

B.Increaseintheprostaglandins

C.GlycoproteinIIBIIIAreceptorinhibition

D.ADPreceptorantagonism

E.IncreaseinCOXenzymes

Answer:a)reductioninthromboxaneA2synthesis.

AspirinblocksthesynthesisofCOX1andCOX2enzymes.

This leads to a reduction in the prostaglandin PGG2, PGH2 thromboxane TXA2

synthesis .Thisleadsto plateletaggregation.

Aspirinaction(salicylates)


106/173



BasicScienceQ105A 12 year old child is investigated for multiple skin abscesses. Swabs grow

staphylococcusaureus.Hiscousinhaddiedfromaserioussepticillnessafewyearsago.

Whatformofimmunedeficiencyisthechildlikelytohave?

A.EosinophilB.Neutrophil

C.ComplementD.LymphocyteE.ImmunoglobulinA

Answer:B)neutrophil.

Primary neutrophil deficiencies are rare and are due to an abnormality, usually

inherited,oftheneutrophil itself.Theproblemcanaffectphagocytosis(e.g.deficiency

ofanadhesionmolecule,CD18/LFAdeficiency,ontheneutrophilsurface).Patientswith

neutrophil defects suffer from recurrent chest infections with bacteria or fungi,

recurrent skin abscesses often caused by Staphylococcus aureus and poor wound

healing.


107/173



BasicScienceQ106

A40yearoldmanattendsafertilityclinic.Examinationshowsthathe istall,thinand

hasbilateralgynaecomastia.

Investigationshowhighlevelsofurinarygonadotrophins.

Whatisthelikelydiagnosis?

A.Homocystinuria

B.Marfansyndrome

C.Testicularfeminisationsyndrome

D.Noonan'ssyndrome

E.Klinefelter'ssyndrome

Answer:e)Klinefelter'ssyndrome.

Klinefelter's syndrome is the most common chromosomal disorder associated with

malehypogonadismand infertility. It isdefinedclassicallybya47,XXYkaryotypewith

variantsdemonstratingadditionalXandYchromosomes.

The syndrome is characterized by hypogonadism (small testes,

azoospermia/oligospermia), gynecomastia at late puberty, psychosocial problems,

hyalinization and fibrosis of the seminiferous tubules, and elevated urinary

gonadotropins.


108/173




one

of

the

following

amino

acids

is

thyroxine

derived

from?

A.LeucineB.Glycine

C.CystathioneD.TryptophanE.Tyrosine

Answer:e)Tyrosine.

Eachmoleculeof thyroxine isderived fromTwo tyrosinemoleculesand three (T3)or

four(T4)iodinemolecules.


109/173



BasicScienceQ108

A30yearmanhasacuteonsetofpainaroundhislefteye.Onexamination,hehasaleft

ptosisandasmallleftpupilbutbothreactnormallytolight.Visualacuity,fieldsandeye

movementsarenormal.Thesiteofinjuryistowhichofthefollowing?

A.Midbrain

B.Superiorcervicalganglion

C.Stellateganglion

D.Pons

E.Geniculateganglion

Answer:b)superiorcervicalganglion.

The diagnosis is Horner's syndrome. The sympathetic nerve fibres from the

hypothalamus travel throughbrainstemandcervicalcord toT1/T2.These synapseon

preganglionic sympathetic fibres, travel up sympathetic chain to superior cervical

ganglion,and then synapseontopostganglionic fibreswhich travelwithcommonand

internalcarotidarteries.


110/173



BasicScienceQ109Two strainsofStaphaureusare isolatedandbothare resistant toampicillin.Strain1

retains its resistance to amplicillin when grown from multiple generations in the

absenceofampicillin.Howeverstrain2losesitsresistancewhengrownintheabsence

ofampicillin.

Whichofthefollowingbestexplainsthelossofantibioticresistanceinstrain2?

A.AmpicillinhaseliminatedresistantbacteriaB.Variabilitywithgenerations

C.TranspositionofanothersequenceintotheresistancegeneD.ChangesinbacterialDNAligaseE.Lossofaplasmidcontainingtheresistancegene

Answer:e)Lossofaplasmidcontainingtheresistancegene.

Bacteria develop resistance to antibiotics by gaining genes which encode particular

proteinswhich offer protectionorganism. Sometimes this occursbymutation but at

other times gene may be acquired from another bacterial species. The genes are

containedinplasmids(circularsegmentsofDNA)separatefrombacterialchromosome.Plasmidscaneasilyspreadfromonebacteriaorequally lost.Transfer, lossandgainof

plasmidsarerelativelycommoncomparedtosinglemutations.


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BasicScienceQ110Apatienthasthefollowingbloodresults.

sodium131mmol/l

potassium4.5mmol/l

urea5mmol/l

creatinine100 mol/l

glucose12mmol/l

Whatisherplasmaosmolality?

A.262B.267

C.279D.280E.290

Answer:C)279.

Plasmaosmolalityisestimatedbythefollowingformula2xNa+Urea+glucose.262+5

+12=279(mmol/kg).Anexample:highserumosmolalitycouldbecausedbyHONK.


112/173



BasicScienceQ111

Thelevel

of

cellular

telomerase

activity

will

affect

which

of

the

following?

A.Celldeath

B.Thenumberofpotentialcelldivisions

C.RNAsynthesis

D.Therateofcellgrowth

E.Cellsurvival

Answer:b)Thenumberofpotentialcelldivisions.

The telomere is a DNA sequence at end of each chromosome which becomes

progressivelyshorterwitheachdivisionthecellundergoes.Theenzymetelomerase is

ablethelengthentelomerethuspreventingthelimitationtowardscelldivision.

TelomeraseActivity


113/173



BasicScienceQ112

Whichof

these

areas

is

involved

in

the

pupillary

reflex?

A.Occipitalcortex

B.Stellateganglion

C.Trochlearganglion

D.Vestibularnucleus

E.Ciliaryganglion

Answer:e)ciliaryganglion.

Thepathwayofthepupillarylightreflexconsistsof:retinalreceptorcells,bipolarcells,

ganglion cells,opticnerveand tract, lateral geniculatebodies, superior colliculus and

pretectal nucleus of the high midbrain, EdingerWestphal nucleus, efferent Two

neuronepathw ay via theoculomotornerve (IIIrdnerve), ciliary ganglion, constrictor

muscleoftheiris.


114/173




one

of

the

following

is

the

best

indicator

of

osteoblastic

activity?

A.AspartateaminotransferaseB.Calcium

C.AlbuminD.AlkalinephosphataseE.Leucocytes

Answer:D)alkalinephosphatase.

Bonealkalinephosphatase(BALP) isproducedbytheosteoblast It isan indexofearly

os

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