2019 TYS Answers (ThatBioTutor)

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) TYSAnswers2019(ThatBioTutorEdition) IMPTNOTE:- Fordifferencesbetween2023and2024syllabus,seethislisthere.- *Shadedblack=outofsyllabusfrom2024onwards Question Ans Question Ans1 B 21 C2 D 22 D3 C 23 B4 B 24 D5 D 25 D6 B 26* A7 B 27 D8 C 28 D9 B 29 A10 A 30 A11 D 31 C12 B 32* C13 B 33* A14 C 34 D15 D 35 D16 A 36 D17 C 37 D18* C 38 A19 C 39 B20 D 40* C Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q1.(a)(i) ● Aistheplasmamembrane.● Itispartiallypermeableandregulatesthemovementofsubstancesinandoutofthecell. (ii)● BisaribosomethatisstuddedontheRoughEndoplasmicReticulum.● ItsynthesisesproteinsattheRoughEndoplasmicReticulumwhicharemeantforsecretionoutofthecell. (b)● Theliverisinchargeofvariousmetabolicprocessessuchasthebreakdownofhormones/excessaminoacidsintourea/harmfulsubstancessuchasalcohol/synthesisofbilesynthesisofbloodproteins,whichrequiresalotofenergy.● Hencelivercellsneedmanymitochondriatogeneratelargeamountsofenergyviaaerobicrespiration. (c)Choose2:● Cellwall● Chloroplasts● Largecentralvacuole (d)● Microvilliincreasesurfaceareatovolumeratioofthesmallintestineincontactwiththecontentsofthelumen,● Forfasterabsorptionofdigestedfoodsubstancessuchasglucoseandaminoacidsfromthelumenintoepithelialcells. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q2.(a)● ChambersAandBhavethethinnestwallsof3mmastheyaretheatriaoftheheart,● Andonlyneedtopumpbloodashortdistanceintotheventricleshencedonotneedtobethatmuscular.● ChamberChasathicknessof5mmasitistherightventricle,andDwhichistheleftventricleisof12mm.● Conlyneedstopumpbloodtothelungs,whereasDneedstopumpitaroundthewholebodytoafurtherdistanceandathigherpressure,hencerequiringthickermuscularwalls. (b)● Thisallowsoxygenatedanddeoxygenatedbloodtomix,sobloodpumpedouttheaortaaroundthebodywillbelessoxygenated,● Cellsaroundthebodyreceivelessoxygenforaerobicrespirationtoreleaseenergy,thepersonwillfeelingeasilyfatigued/weak/shortofbreath/fainting/dizzy. (c)● Adiethighinsaturatedfats/sedentarylifestyle/smoking. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q3.(a)● Aswaterpotentialofmesophyllcellsislowerthanthatofthexylem,● Watermovesfromxylemvesselsat(1)intomesophyllcellsat(2)byosmosistoreplacethewaterlost.● Waterthenmovesoutofmesophyllcells,formingathinfilmofmoisture.● Thisfilmevaporatesintowatervapourintheintercellularairspacesat(3).● Watervapourdiffusesouttheleafviaastomaat(4),downitsconcentrationgradient,tothesurroundingairoutsidetheleafat(5). (b)● Jisanupperepidermalcell.● Itistransparenttoallowasmuchlighttopassthroughandreachthemesophyllcellsbelowsotheycanconductphotosynthesisatthehighestrateallowable. ● Kisapalisademesophyllcell.● Ithasmanychloroplastssomorephotosynthesiscanoccur.● OR:Itislong,cylindricalandverticallyarrangedsomanyofthemcanbepackedtogethersomorephotosynthesiscanoccur. (c)● Indaylight,lightenergyispresentforchloroplastsinplantstophotosynthesise.● Openstomataallowformoregaseousexchange,somorecarbondioxidediffusesintoleaves,andisreducedintomoreglucoseduringphotosynthesis.● Italsoallowsmoreoxygen,theby-product,todiffuseout.● Openstomataincreasestranspirationrate,somorewaterispulledupthexylemtotheleavesreplenishwaterusedbyphotosynthesis. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q4.(a) (b)● Asfertilisationisarandomprocess,thegenotypeofeachchildisbasedonchance/probability.● Thesamplesizeofoffspringisonly2,whichisverysmall,hencethediscrepancyofactualratiofromtheexpectedratio. (c)● Asuddenchangeinthestructureofagene● orchromosomenumber. (d)● Thepresenceofamutagensuchasultravioletradiation/nuclearradiation/toxicchemicals/tarincigarettesmoke. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q5.(a)(i) ● C C G A T A (ii)● Nucleotide (b)Social:● Thiscouldreducethecostofproductionofsuchmedicationsandmakethemmoreaffordabletopeoplewhoneedthem● Companiescouldsetpatentsontheproductionprocessforsuchproteins,andmakemedicinesverycostly,financiallyexploitingthosewhoneedthem. Ethical(Choose2):● Itcouldresultinunforeseenhealthproblemsforthechickens,causingsufferingforchickenswhichismorallywrong● Morallywrongtoviolateanimalrights,byusingchickensasbiologicalfactories● Canbeseenas"playingGod",somemayfeelitismorallywrongtomodifylivingthings. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q6.(a)Choose2:● Energyislostasheattothesurroundingsduetocellularrespiration.● Chemicalenergyisalsotrappedwithincarboncompoundsinundigestedfoodwastethatisegested,andinexcretedsubstancessuchasurine.● Whenanorganismdies,chemicalenergyisalsotrappedintheuneatenparts,suchasitsbones. (b)● (1600–90)/1600=94%(nearestwholenumber) (c) ● As90%ofenergyislostbetweeneachtrophiclevel,suchasduringaerobicrespiration,lessandlessenergyisavailableforeachincreasinglevelofconsumer.● Theenergythatcanbepassedontopredatorsoftertiaryconsumersisextremelylimited,henceitcanonlysupportveryfewofsuchpredators. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q7.(a)(i) (ii)● (Fromgraphworking)–9.0% (b)(i) ● From1993to2003,percentageoffishcaughtwithbodylengths40cmandlongergraduallyincreasesfrom5.0%to5.6%,● Thenincreasesmoreandmoresteeplyuntil16.3%at2013. (i) ● Havingalargeproportionoffishbeing40cmandlongermeansthatthefisharegettingenoughfoodtogrowtothatsizeorlarger,● Sothatmeanstheecosystemisabletosustainalargepopulationoffish,andtheareaisagoodplaceforfishing. ● Itmeansalargeproportionareadults,andtheycanreproduceandhaveoffspring,● ensuringthesurvivalofthepopulationandprovidingmorefishtobecaughtinfuture. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q8.(a)● Duringultrafiltration,mostofthebloodplasmaanddissolvedsubstancesareforcedoutoftheglomerulusintothebowman'scapsulebyhigh(hydrostatic)bloodpressure.● Duringselectivereabsorption,usefulsubstancesareabsorbedfromthefiltratebackintothebloodastheypassthroughthenephron.● Allglucoseandaminoacidsarereabsorbed,whilesomemineralsaltsandsomewaterisreabsorbed.● Theremainingfiltrateinthecollectingductbecomesurinewhichislaterexcretedoutofthebody. (b) ● Duringkidneydialysis,bloodisdrawnfromaveininthepatient'sforearmandpassedintoadialysismachine.● Itflowsthroughapartiallypermeabletubing,whichisbathedindialysisfluid/dialysate● Thedialysatecontainszerowasteproducts,sotheconcentrationgradientisassteepas