2015 TYS Answers (ThatBioTutor)

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) TYSAnswers2015(ThatBioTutorEdition) IMPTNOTE:- Fordifferencesbetween2023and2024syllabus,seethislisthere.- *Shadedblack=outofsyllabusfrom2024onwards Question Ans Question Ans1 B 21 B2 C 22 D3 B 23 B4 B 24 A5 B 25 D6 B 26 A7 D 27 C8 B 28 B9 D 29 A10 C 30 D11 B 31 C12 C 32 B13 C 33 B14 B 34 A15 B 35 A16 A 36 D17 D 37 A18 C 38 A19 C 39 A20 C 40 B Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q1.(a)● A:Starch● B:Maltose● C:Salivaryamylase (b)● (i)Temperature● (ii)pH (c)● Gallstonespreventbilefrombeingsecretedintothesmallintestine,bilesaltsinbilecannotemulsifylargefatdropletsintosmallerones,● Theirsurfaceareatovolumeratioistoosmallforlipasetoeffectivelydigesttriglyceridesintoglycerolandfattyacids,● Sofatdigestionisslowed/impaired. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q2.(a)● Theprocessthatinvolvesthefusionofnucleiofmaleandfemalegametes● toformadiploidzygote,● producinggeneticallydifferentoffspring. (b)● Thepollengrainisroughandspiky,whichhelpsittogettrappedbetweenthefursonbodiesofinsectpollinatorssuchasbees.● Whenaninsectrubsanantherwhenvisitingaflowerthepollengrainswillsticktothemandbecarriedtootherflowerswhentheinsectleaves. (c)(i) ● Pollentube. (ii)● Thepollentubegrowsfromthepollengrain,secretingenzymestodigestapaththroughthestigma,styleandovarywall.● Thepollentubeentersanovuleviathemicropyle.● Thepollentube(absorbssapand)bursts,releasingtwoamalesexnuclei,oneofwhichfuseswiththeovum,formingadiploidzygote. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q3.(a)● 40-16=+24 (b)● Theinsectdoesnothavehomeostasisofitsinternalbodytemperatureanddoesnotregulateit.● Theinsectcansurviveatawiderangeoftemperatures/enzymesinvolvedinmetabolicreactionsintheinsectcanfunctionatawiderangeoftemperatures. (c)● (Drawahorizontallineat37°Cfrom20°Cto36°Cofairtemperature) (d)● Whenbodytemperatureincreasesabovenormal,sweatglandssecretemoresweat,● Morewaterinsweatevaporates,hencemorelatentheatislost,decreasingbodytemperaturebacktonormal.● Whenbodytemperaturedecreasesbelownormal,sweatglandssecretlesssweat,reducingheatlosstohelpbodytemperatureincreasebacktonormal. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q4.(a)● A:Aorta● B:Pulmonaryvein (b)● Cisasemi-lunarvalve,itclosesduringventriculardiastoletopreventbackflowofbloodfromthepulmonaryarterybacktotherightventricle. (c)● Bloodfrombodyorgansreturnstotheheartviathevenacava,thenenterstherightatrium.● Rightatriumcontractsduringatrialsystole,bloodpressureisnowhigherthanthatoftherightventriclehencebloodmovesintothere,openingthetricuspidvalve.● Rightventriclecontractsduringventricularsystole,bloodpressureisnowhigherthanthatofthepulmonaryarteryhencebloodmovesintothere,closingthetricuspidvalvetopreventbackflow.● Ventricularsystolealsocausespulmonarysemi-lunarvalvetoopen,forcingbloodintothepulmonaryarterytowardsthelungs. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q5.(a)● Itdecreasedfrom100to10units,adecreaseof90units. (b)● Whilefasting,thepersonhasnoteatenamealwithcarbohydratesforalongperiodoftime,● Bloodglucosefallsbelownormal,whicharedetectedbythecellsofisletsofLangerhansinthepancreas,● Whichrespondbyreducingsecretionofinsulinintothebloodstream,asthereislessneedtoconvertglucoseintoglycogeninliverandmusclecells. (c)● Duringexercise,emotionsofexcitementandstressarearoused,whicharedetectedbythehypothalamus,● Whichsendsnerveimpulsestotheadrenalglands,causingthemtosecreteadrenalineintothebloodstream,preparingthebodyforafight-or-flightresponse.● Heartrateincreasesandbloodglucoselevelsincrease,supplyingoxygenandnutrientstomusclesfaster, sothepersoncanmeetthehigherenergydemandfortheexercise. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q6. (b)● I A andI B 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) ● Consumersareorganismsthatobtainfoodbyfeedingonotherorganisms. (ii)● Thefeedingpositionthatanorganismoccupiesinafoodchain. (b)(i) Plankton →Smallfish →Largefish →Fishermen (ii)● Whenchemicalwasteisexpelledintoseawater,seawaternowcontains2p.p.b.ofmercury.● Planktontakeinmercurycompoundsbutcannotexcretethem,henceitaccumulatesinplankton,bioaccumulationhasoccurred.● Smallfishwhichfeedonplanktonnowingestthemercurytoo,anditaccumulatesinthemtooupto200p.p.b. 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) (b)(i) ● 0.040–0.014=0.026 Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) (ii)● Carbondioxide(CO2 )concentrationdecreasesatadecreasingratefrom0.040at04:00to0.014at14:00.● Thesunisrisingfrom04:00,increasinglightenergytobeabsorbedbychlorophyllandconvertedintochemicalenergy.● Photosynthesisrateincreases,amountofCO2 takeninbythericeplantstobeusedtoproduceglucoseandreducedintoglucoseincreases,● ThusconcentrationofCO2 intheairabovethericeplantsfallsuntilthelowestpointat14:00whenthesunishighestintheskyandphotosynthesisrateisgreatest. (iii)● Lightintensityisincreasing,photosynthesisratemayexceedrateofaerobicrespiration,henceanetmovementofO2 outofleavestotheairabovethericeplants. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor