2017 TYS Answers (ThatBioTutor)

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) TYSAnswers2017(ThatBioTutorEdition) IMPTNOTE:- Fordifferencesbetween2023and2024syllabus,seethislisthere.- *Shadedblack=outofsyllabusfrom2024onwards Question Ans Question Ans1 C 21 D2 A 22 D3 A 23* B4 D 24 C5 B 25 A6 D 26 A7 C 27 B8 B 28 A9 B 29 B10 C 30 D11 A 31 B12 A 32* C13 C 33* A14 B 34 C15 C 35 C16 A 36 A17 C 37 C18 B 38 D19 A 39 A20 A 40 B *23:OptionA, hairerectormuscles,outofsyllabus,buttheotheroptionsareinsyllabus Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q1.(a)● Itisthemaintenanceofaconstantinternalenvironment,● Usingnegativefeedbacktocounteractchangesinthesystemtorestoretheset-point. (b)● Aductlessglandthatsecreteshormonesdirectlyintobloodstream,● whichtravelto,andalterstheactivityofoneormorespecifictargetorgans. (c)(i) ● A:Glycogen● B:Glucagon (ii)● Duringexercise,muscularcontractionsdemandlargeamountsofenergygeneratedbyaerobicandanerobicrespiration,● Bothofwhichinvolvesoxidisingglucose,hencemusclecellsuseupalotofbloodglucoseandcauseitsconcentrationtofall. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q2.(a)● Cisoneofthelargeintercellularairspacesthatdecreasetheoveralldensityoftheleaf,sothatitislessdensethanwaterandallowstheleaftofloat. (b)● Theyarepositionednearthetopoftheleaf,justbeneaththeupperepidermis,sotheycanreceivemaximumsunlightforphotosynthesis. (c)● Chlorophyllinchloroplastsabsorblightenergyandconvertsitintochemicalenergy,● whichisusedtoconvertcarbondioxideandwaterintoglucoseandoxygen.● Usinghydrogenatomsandchemicalenergy, carbondioxideisreducedtoformglucoseduringphotosynthesis. (d) Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q3.(a)● Ittakesupthefirsttrophiclevelinthefoodweb,itmakesitownfoodfrominorganicmaterialslikecarbondioxide,andpassesenergyupthefoodwebtotherestoftheorganisms. (b)● Trophiclevel2:74(9+36+29)● Trophiclevel3:10(4+6)● Trophiclevel4:2 (c) Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q4.(a)● Beforetheexperiment,weigheachplantusinganelectronicbalance.Afterevery24hours,weigheachplantagain.● Subtracteachday’snewweightfromthepreviousday’sweighttotrackthemasslosteachdayforeachplant. (b)● Transpiration. (c)● PlantEwasentirelyenclosedinaplasticbag,watervapouraccumulatedwithin,increasinghumiditysotranspirationratewasthelowest.● PlantDandFhadtheirleavesexposed,butDhadmoreleaveshencemoretotalsurfaceareaforwaterlossthroughmorestomatainleaves,henceDlosesthemostmass. (d)● Topreventanylossofmassduetoevaporationofwaterfromthesoilinthepotsthemselves,henceensuringanydropinmasswasduetowaterlossviatranspiration. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q5.(a)● Thetypeofreproductioninwhichthereisoneparentwhichproducesgeneticallyidenticaloffspring,● withoutthefusionofnucleiofmaleandfemalegametes. (b)● Afterfertilisation,thezygoteismovedfromtheoviducttowardstheuterus,byperistalticactionoftheoviductwallsandthesweepingactionofcilia.● Meanwhile,thezygotedividesbymitosisintoanembryo,● Whichembedsitselfintotheuterineliningduringimplantation,whereitdevelopsintoafoetus. (alongwithany2morepoints):● Finger-likeprojectionscalledvilli,containingthebloodvesselsfromtheembryo,growintotheuterinelining,formingtheplacenta.● Theplacentasecretesprogesteroneandoestrogen,maintainingthethicknessofuterinelining.● Intheplacenta,oxygenandnutrientsdiffusefrommaternaltofoetalcapillaries,andaredeliveredtothefoetusviatheumbilicalcord,whilemetabolicwasteproductssuchasureaandcarbondioxideareremoved.● Theamnioticsacdevelops,containingamnioticfluidthatprotectsfoetusfromphysicalinjury/allowsformovementformusculardevelopment/trainsthefoetus'digestivesystem. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q6.(i) ● 1400cm 3 (ii)● Asexerciseintensityincreases,thevolumeofeachbreathincreasesgraduallyfrom0.5to1.5au,thenincreasessharplyfrom1.5to3.0au. (iii)● 26breathsperminutex1700cm 3 =44,200cm 3 (b)● Aerobicrespiration. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q7.(a)● Name:Cardiac/Heartmuscle.● Function:Itallowsthehearttocontractandrelax,pumpingbloodaroundthebodyforcellstoreceiveoxygenandnutrientswhilecarbondioxideandmetabolicwasteproductstoberemoved. (b)(i) ● 5.6dm 3 perminute (ii)● 19–7=12minutes (iii)● (168-66)/66=155%(nearestwhole) (iv)● From2to3minutes,heartrateincreasesverysharplyfrom66to140beatsperminute(bpm),anincreaseof74bpm.● From3to6minutes,heartrateincreasesatadecreasingratefrom140to170bpm,andincreaseof30bpm.● From6to7minutes,heartrateremainsconstantatthemaximumheartrateof170bpm. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q8.(a) (b)● Lipasebreaksdownfatsinthemilk,formingglycerolandfattyacids.● Theacidicfattyacidsneutralisethesodiumalkalinecarbonate,loweringthepHofthesolution.● Onceenoughfattyacidsareproduced,thepHwilldropbelow8,causingphenolphthaleintoturnfrompinktocolourless. (c)● At55°C,thehightemperaturesdenaturedlipase,anditlosttheshapeofitsactivesite,itwasnolongerabletocatalysethebreakdownoffats. (d)● Whentimetakenisthelowestpointonthegraphof2.5minutes,temperatureis35°C,whichistheoptimumtemperatureoflipase,● Atthistemperature,reactionratewasthefastestaslipasewasmostactive. Stillwantmore?www.thatbiotutor.com- www.instagram.com/thatbiotutor/-www.youtube.com/@thatbiotutor- www.tiktok.com/@thatbiotutor

Credit:WrittenbythecollectiveeffortofourtutorsatThatBioTutor. Youarewelcometosharethesewithanyoneyou’dlike!Justdon’tsellthemforprofit:) Q9.(a)● 1600+700+200=2500 (b) ● Thewaterformedwithinthebodyasaproductofmetabolicreactions,● suchasduringaerobicrespiration. (c) ● At5°C,sweatglandsbecomelessactiveandsecretelesssweat,hencelesswaterislostthroughsweat.● Duetoanincreaseinmetabolicrateinresponsetointernalbodytemperaturebeingtoocold,higherrateofaerobicrespirationproducesmoremetabolicwater,hencemorewaterislostinurine.● Coldairislesshumidthanwarmair,itdrawsmorewaterfromthethinfilmofmoistureofthealveoli,somorewaterislostthroughbreathingout. ● Waterlostthroughfaeceswillbeunaffectedbythechangeintemperature(asitisdependentondiet). (d)● Whenapersondrinkstoolittlewater,osmoreceptorsinthehypothalamusdetectthedecreaseintheblood'swaterpotential.● ThehypothalamuscausesthepituitaryglandtosecretemoreADH,whichtravelsviathebloodstreamtokidneynephrons,● Causingcellsinthewallsofcollectingductstobecomemorepermeablet