WJEC Biology for AS: Study and Rev Guide

Exam Practice and Technique The second section of the book covers the key skills for examination success and offers you examples based on suggested model answers to possible examination questions. First, you will be guided into an understanding of how the examination system works, an explanation of Assessment Objectives and how to interpret the wording of examination questions and what they mean in terms of exam answers. This is followed by a selection of examination and specimen questions with actual student responses. These offer a guide as to the standard that is required, and the commentary will explain why the responses gained the marks that they did. It is a good idea to split the course down into manageable chunks, complete revision notes as you go along, and have a go at as many questions as you can. The real key to success is practice, practice, practice past paper questions, so I advise that you look at www.wjec.co.uk for sample papers and past papers. A level is such a big jump from GCSE; you really need to start working for the exams from day 1! Good luck with your revision, Dr Neil Roberts General exam tips Always read thequestion carefully: read thequestion twice! It iseasy toprovide thewronganswer ifyoudon’t givewhat thequestion isasking for.All the informationprovided in thequestion is there tohelpyou toanswer it.Thewordinghasbeendiscussedat lengthbyexaminers toensure that it isas clearaspossible. Lookat thenumberofmarksavailable.Agood rule is tomake at leas tonedifferentpoint foreachmark available.Somakefivedifferentpoints ifyou can fora four-markquestion tobe safe.Make sure thatyoukeep checking thatyouareactuallyanswering thequestion thathasbeenasked– it iseasy todriftoff topic! Ifadiagramhelps, include it:butmake sure it is fullyannotated. Timing On theASWJECexam thereare80marks foreachpaperandyouhave90minutes.Thisgivesyoua senseof howmuch timeyou should spendoneachexamquestion,andagood rule isaboutonemarkperminute.Don’t forget that this timing isnot justaboutwritingbutyou should spend time thinking,and for theextendedanswer someplanning, too. Assessment objectives Examinationquestionsarewritten to reflect theassessmentobjectives (AOs)as laidout in the specification.The threemain skills thatyoumustdevelopare: AO1:Demonstrateknowledgeandunderstandingof scientific ideas,processes, techniquesand procedures. AO2:Applyknowledgeandunderstandingof scientific ideas,processes, techniquesandprocedures. AO3:Analyse, interpretand evaluate scientific information, ideasand evidence, including in relation to issues. Inbothwrittenexaminationsyouwillalsobeassessedonyour: ▪ mathematical skills (minimumof10%) ▪ practical skills (minimumof15%) ▪ ability to select,organiseand communicate informationand ideas coherentlyusingappropriate scientific conventionsandvocabulary. Inanyonequestion,youare likely tobeassessedonall skills to somedegree. It is important to remember that onlyabouta thirdof themarksare fordirect recallof facts.Youwillneed toapplyyourknowledge, too. If this is somethingyoufindhard,practiseasmanypastpaperquestionsasyou can.Manyexamples comeup in slightly different forms fromoneyear toanother. Yourpractical skillswillbedevelopedduring class time sessionsandwillbeassessed in theexaminationpapers. This could include: ▪ plottinggraphs ▪ identifying controlledvariablesand suggestingappropriate controlexperiments ▪ analysingdataanddrawing conclusions ▪ evaluatingmethodsandproceduresand suggesting improvements. 121 Exampractice and technique Isla’sanswer a) Duringprophasethenuclearmembranedisappears ✓ andthe chromosomes condenseappearingastwo distinct chromatids ✓ joinedat centromere. ✓ b) Interphaseoccurs in both experimentsasDNA quantitydoubles. ✓ When placed in the newdrug, there is no halvingofDNAat 20 hoursas seen in the garlic grown inwater. ✓ This shows that there is no cytokinesis because the lackof spindle fibres prevents anaphase. ✓ Examiner commentary Islahas learnt thekeyevents inprophaseandwas able to relate thegraph toherknowledge of cytokinesis. Islaachieves 6/6marks Exam tip Learn thekeyevents inmitosis (andmeiosis)andbeable to recognisedrawings ofeach stage.You shouldbeable tousedatagiven to reach or supporta conclusion. Ceri’sanswer a) During prophase the chromosomes condense ✓ and centriolesappear. ✗ q b) When placed in thedrug,DNAdoes not decrease, ✗ so celldivision has not happened. ✗ w Examiner commentary q Reference to centriolesappearing is incorrect as they areabsent inhigherplants. w Reference toDNAdecreasing is toovague.The questionaskshow the results show that the newdrug inhibitsmitosis: references to cell divisionnotoccurring isalso toovague,when information in thequestiondetails that thenew drugprevents spindle formation.Ceri should link this toanaphasenotoccurring,and that subsequently cytokinesiswillnotoccur. Ceriachieves1/6marks Q & A5 133 Questions and answers Thediagramon the right shows the relative lengthsof the cell cycle inactivelydividing cells taken from the root tipofagarlicplant. (a) Describe thechanges thatoccur to thenucleus of aplantcellduringprophase. [3] (b) Anewdrughasbeendeveloped that inhibitsmitosis bypreventing the formationof the spindlefibres. Garlicbulbsweregrown ina solutionof thenew drugand thequantityofDNApresent inacell from the root tipwasmeasuredover the24-hour lengthof thecellcycle.The resultsare shownbelow together with the results fromgarlicbulbsgrown inwater. Usingyourknowledgeof thecellcycle,explainhow the resultsof this experiment show that thenewdrug inhibitsmitosis. [3] Prophase Metaphase Anaphase Telophase Cytokinesis 0 0 2 4 6 4 8 Time /hrs Time /hrs Garlicgrown innewdrug solution Garlicgrown inwater Qualityof DNApercell / arbitraryunits Qualityof DNApercell / arbitraryunits 12 16 20 24 0 0 2 4 6 4 8 12 16 20 24 5 How to use this book: