Bio P3 Crash Course

Errorcategories Example ImprovementInconsistenciesinbiologicalsamples Differentpotatostripfromdifferentpotatosourceswouldgiverighttodifferentstartingwaterpotentials EnsureallpotatostripsperformedintheexperimentwastakenfromthesamepotatoJudgmentofcolourchangescanbesubjective ColourchangeinBenedict’stestmightbesubjectiveasitisaffectedbydifferencesinindividualperception Useacolorimeterthatprovidesaquantitativevaluetothecolourdetected.Environmentalfactors Fanswitchon,withoutlidsonpetridishes,cancauseevaporationofwaterfromsaltsolutions,hencecausingchangesinconcentrationtothesolutions Usealid,switchoffthefan Limitationsinmeasuringinstruments Rulerdoesnotmeasurelengthasaccurateasapairofverniercallipersasaruleriscorrectonlyto1dp. Useverniercallipersinstead. Experimentsthatrequiretemperaturetobecontrolled Havinganenzymeinatesttubeheatedtoaparticulartemperature.Thetemperaturecannotbekeptconstantasthetemperaturemaychangeoverthecourseoftheexperiment InsulatethetesttubewithaStyrofoamwraporabubblewraptoreduceheatlosstotheenvironment.Othervariablesbesidestheindependentvariablebeingchanged Ininvestigatingtheeffectofwindspeedonrateoftranspiration,otherfactorsliketemperature,humidity,andlightintensitywasnotensuredtobeconstant Ensureotherfactorsareconstantby … PlanningQuestionsExample Aproteaseisaddedto5cm 3 ofeggwhiteandthetimetakenforthesuspensiontoturnclearismeasured.Plananexperimenttoshowhowtheactivityoftheproteaseisaffectedbytemperature. [Describeanapproachtoyourinvestigation] Todeterminetheeffectoftemperatureonproteaseactivity,aninvestigationcanbedonebyallowingenzymereactionstotakeplaceatvaryingtemperatures,thenmeasuringitseffectontimetakenforcompletionofthereaction. Thiswillbefurtherdescribedindetail. [Stateindependentvariablewithunits] Theindependentvariableisthetemperature,inoCelsius,atwhichreactiontakesplace. [Staterangeandincrementsofindependentvariabletobeused]

Place2cm3ofenzymeproteaseinabeakeroficefor5minutes.Thisistoallowtimefortheproteasetoacclimatisetothetemperatureof0 ◦ C.Dothesameforothertemperatures. Usingiceandhotwater,maintainbeakersofwaterbathsat10 ◦ C, 20 ◦ C, 30 ◦ C, 40 ◦ C, 50 ◦ Cand60 ◦ C.(atleast5differentdatapoints). [Statedependentvariable,withunits] Thedependentvariableisthetimetaken, inseconds,forsuspensiontoturnclear. [Statetwocontrolvariablesandhowtheycanbecontrolled] Thevariablestocontrolarethevolumeofproteaseusedandtheamountofmixinginvolved. [Statehowyourdatacollectedcanbeusedtoreachaconclusion(refertoaim)] Pourtheproteaseintothetesttubecontaining5cm3ofeggwhitesolutionandstartthestopwatchimmediately.Stopthestopwatchassoonastheeggwhitesolutionturnsclear.Repeattheexperimentatalltemperaturesstated. Usingthedataobtained, plotagraphtoshowhowtheaveragetimetakenvarieswithtemperature. [Statehowtoensurereliabilityoftheinvestigation] Toensurereliability oftheinvestigation,repeattheexperimentthreetimes,using3samplesateachtemperatureeachtime.Then,obtainaveragereadings.