2018 TYS Answers (ThatBioTutor)

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) TYSAnswers2018(ThatBioTutorEdition) IMPTNOTE:- Fordifferencesbetween2023and2024syllabus,seethislisthere.- *Shadedblack=outofsyllabusfrom2024onwards Question Ans Question Ans1 A 21 B2 A 22 D3 B 23 A4 B 24 D5 C 25 C6 D 26 C7* C 27 D8 A 28 B9 B 29 B10 A 30 A11 C 31* C12 B 32* D13 C 33* A14 D 34 C15 A 35 D16 B 36 A17 C 37 C18 C 38 B19* B 39 D20 D 40 D *Q31:Homologouschromosomes“formpairsinmitosisandmeiosis”isoutofsyllabus,buttherestoftheoptionsareinsyllabus. 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) ● Chromosome/chromatid (ii)● 3:Metaphase● 4:Anaphase (b)(i) ● Plant2. (ii)● Plant1:AA● Plant3:aa Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q2.(a)(i)Any3:● Thelivercarriesoutdetoxification,whereharmfulsubstancessuchasalcoholareconvertedintoharmlessones.● Hormonesarebrokendownattheliveraftertheyhavecausedtargetorganstocarryouttheresponse.● Theliverproducesbile,whichisthenstoredinthegallbladder. Bileaidsinfatdigestion.● Theliverstoresironfromthebreakdownofhaemoglobinofoldredbloodcells,tobeusedformakingnewredbloodcells.● Thelivercarriesoutdeamination,whereaminogroupsareremovedfromexcessaminoacidsandconvertedintourea.● Theliveraidsinbloodglucoseregulation,convertingglucosetoglycogenwhenbloodglucoseconcentrationistoohigh,andviceversawhenglucoselevelsaretoolow.● Theliversynthesisesbloodproteinssuchasprothrombinandfibrinogen. (ii)● C(pancreas) (iii)Name:● Bile Function:● Bilesaltsinbileemulsifylargefatdropletsintosmallerones,● increasingthesurfaceareatovolumeratioforpancreaticlipaseandintestinallipasetodigestfatsintoglycerolandfattyacids. (b)(i) ● 40°C (ii)● At60°C, thehightemperaturehasdenaturedrennin,theactivesiteisnolongercomplementarytoitssubstratehenceitisnolongerabletocausethemilktoformlumps. (c)● Whenmilkformslumps,itstaysinthestomachlongerforpepsinproteasetodigestmoremilkproteinsintoshortpolypeptides.● Moreshortpolypeptidesarebrokenintoaminoacidsinthesmallintestine,hencemoreaminoacidsareabsorbedintothebloodstreamforassimilationforthegrowthoftheyoungcow. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q3.(a)(i) ● 3minutes. (ii)● Astemperatureincreasesfrom15to19°C, timetakenforbloodtoclotdecreasessharplyfrom24to13min.● Astemperatureincreasesfurtherfrom19to35°C, timetakendecreasesgraduallyfrom13to3min. (b)● Topreventfurtherlossofbloodfromdamagedbloodvesselsbysealingthewound● Topreventtheentryofharmfulmicroorganismsintothewoundfromoutsidethebody. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q4.(a)Any3:● Thealveolarwallisone-cell-thick,minimisingthedistanceoxygen(O2 )andcarbondioxide(CO2 )havetotravel,increasingdiffusionrate.● Alveoliaresmallandnumerous,increasingtheirsurfaceareatovolumeratio, henceincreasingtherateofdiffusionofgases.● Theyarealsosurroundedbyanetworkofcapillaries,whichprovideacontinuousbloodsupply, sooxygenatedbloodisquicklycarriedawaytomaintaintheconcentrationgradientsfordiffusionO2 andCO2 .● Thereisathinfilmofmoistureliningthealveolarairspace,allowinggasestodissolveinitbeforediffusingacross. (b)● Whencarbondioxide(CO2 )producedbycellsdiffusesintoredbloodcells,thereislesscarbonicanhydrasetocombineitwithwater,forminglesscarbonicacid.● LesscarbonicaciddissociatesintolessH + andlessbicarbonateions,whichiscarriedinthebloodplasmatothelungs.● Atthelungs,lessbicarbonateionsareconvertedbacktoCO2 ,concentrationgradientbetweenbloodplasmaandalveolarairspaceislesssteep,decreasingtherateofCO2 thatdiffusesoutoftheblood. (c)● Whenthepersonisbreathingin,pressureinalveolidecreasesfrom0.0to-1.0unitsfrom0to1seconds,● Thenincreasesbackto0.0unitsfrom1to2seconds. (d)● Duringinspiration,thediaphragmcontractsandflattensdownwards.● Theinternalintercostalmusclesrelax,whileexternalintercostalmusclescontract,movingtheribcageupandout.● Asaresult,thoracicvolumeincreasesandthevolumeofthelungsincrease. 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) ● 173.5 (ii)● (180.0-175.5)/180.0=2.5% (iii)● Urea (b)● Aistheglomerulus,andthelumenofefferentarterioleissmallerthantheafferentarteriole,● Generatinghigh(hydrostatic)bloodpressurewhichforcesoutmostofthebloodplasmaanditsdissolvedsubstancesduringultrafiltration.● Bisavenule,bringingsubstancesthathavebeenselectivelyreabsorbedalongthenephronsuchasglucoseandaminoacidstotherenalveinandbacktotherestofthebody. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q6.(a)● Aisaleafvein,anditcontainsthevascularbundleconsistingofxylemandphloem.● Thexylemcarrieswaterandmineralsaltsfromtherootstotheleafcells,andphloemcarriesmanufacturedfoodsubstancessuchassucroseandaminoacidsfromtheleaftotherestoftheplant. (b)(i) ● Sucrose (ii)● Phloem (iii)● 65cm/2.5h=26cm/h Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q7.(a)● Pisaerobicrespiration,wherecarboncompoundssuchasglucosearebrokendown,releasingcarbondioxidetotheatmospheresoitcanbere-usedforphotosynthesis.● QisPhotosynthesis,wherecarbondioxideintheatmosphereisconvertedintocarboncompoundssuchasglucose,whichcanthenbetransferredtootherconsumerswhicheattheseproducersinfoodchains.● Siscombustionoffossilfuels,releasingenergyforhumanuse,andcarbondioxideintotheatmospherewhichcanlaterbeusedbyplantsforphotosynthesis. (b)● Theyaredecomposerswhichbreakdownorganicmattersuchasfaecesanddeadorganisms,releasingcarbontrappedinthecarboncompoundstotheatmosphereascarbondioxide,● soitcanbere-usedforphotosynthesis,makingcarbonavailableforotherorganismsinthefoodchainonceagain. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q8.(a)(i) (ii)● 100-15=85units (iii)● Aswavelengthoflightincreasesfrom420to500nm,sensitivityofretinaincreasesrapidlyfrom5to100units.● Aswavelengthoflightincreasesfrom500to600nm,sensitivityofretinadecreasesrapidlyfrom100to5units. (iv)● Fromgraph:66(orsimilarvalues,basedonyourgraph) (b)● Aslightwasshinedintheperson’seye,theincreasedlightintensitywasdetectedbyphotoreceptorsintheretina,whichsentnerveimpulsestothebrain,● Whichinturnsentnerveimpulsestotheirismuscles.Circularmusclescontracted,radialmusclesrelaxed,● Causingthepupiltoconstrict,hencethedecreaseinpupildiameter. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:Writtenbythecollectiveeffortofourtutor