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Cex0bio Ar 2000

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  SOUTH AUSTRALIAN CERTIFICATE OF EDUCATION SSABSA  SENIORSECONDARYASSESSMENTBOARDOFSOUTHAUSTRALIA  B IOLOGY  2000 ASSESSMENT REPORT Science Learning Area  BIOLOGY2000 ASSESSMENT REPORT The 2000 examination was the first examination on the new syllabus. The mean score for theexamination was 53.7%, which compares with previous means of 59.6% (1999), 54.1% (1998), 57.0%(1997), and 58.2% (1996). The mean mark or higher was obtained by 51.5% of the candidates and therange of examination marks was from 9 to 192 out of 200. The slightly lower than normal mean couldbe attributed to a number of factors such as: ã   the level of difficulty of the examination; ã   the degree of familiarity with the syllabus; ã   changes made to both the structure and the marking of Section D.The mean marks for Sections A, B, C, and D were 57.6% (Section A), 53.1% (Section B), 62.8%(Section C), and 46.7% (Section D). SECTION A: MULTIPLE-CHOICE QUESTIONS Six candidates scored full marks in Section A. The facility for a question is the percentage of candidates who gave the correct response. The mean facility for the multiple-choice questions was57.9%. The mean of facilities and range of facilities for each of the last five years are shown in thetable below: YearMeanFacility(%) Range(%) 200057.924 to 95199958.733 to 88199868.323 to 90199756.819 to 87199656.820 to 84It was the intention of the setters to include a variety of questions, from the simple recall of definitions(e.g. Question 21) through to problem-solving questions in which candidates were required to applytheir biological knowledge to solve an unfamiliar situation (e.g. Questions 5 and 11). Most questionswere intentionally discriminating so that the poorer candidates would be likely to choose the fourresponses with equal frequency, whereas the more capable candidates would show a distinct preferencefor the correct response. A very pleasing aspect of Section A in 2000 was that the top 10% of thecandidates chose the correct response to every question and the top 60% or more of the candidateschose the correct response to nearly all the questions.The table on page 2 indicates the correct response to each of the questions in Section A and thepercentage of responses to each alternative in each question. COMMENTS ON SELECTED MULTIPLE-CHOICE QUESTIONSQuestion 5 The strong support for response L indicated that many candidates either did not read the definition of the term ‘marker’ given under the diagram or were unable to interpret the information provided in thediagram.   Biology 2000 Assessment Report  2 Question 6 The difference between the terms ‘ accuracy ’  and ‘ precision ’  seemed to be well understood, asrelatively few candidates selected response J. However, the significance of the intended studentoutcome ‘ Record data from an experiment to an appropriate degree of precision ’  seemed to be wellunderstood only by the very best candidates. Question 11 This proved to be a good discriminating question: the top 50% of the candidates correctly choseresponse K, whereas the bottom 50% preferred either J or M. Candidates are expected to recognise thechemical formulae that appear in the syllabus. Question 12 Did the relatively high percentage of candidates who incorrectly chose response L ignore the boldedand italicised ‘ incorrect ’  in the stem of the question, or did they simply not know that ‘ specific geneproducts inside cells regulate the onset of division ’ ? Question 18 This question was tackled surprisingly well, with only the bottom 10% of candidates preferring aresponse other than K. The terms ‘ mitosis ’ , ‘ meiosis ’ , ‘ fertilisation ’ , ‘ crossing over ’ , and ‘ independentassortment ’  have been confused by many candidates in previous years. Question 20 The principles that underlie natural selection continue to elude the poorer candidates, with the bottom30% having a preference for response K. Multiple-Choice Analysis QuestionCorrectPercentage of Responses for Each Alternative AnswerJKLM  1L11196542L2257033K26586104M122611515J2466196K12363507M221958L4187269L913661210K1147142811K2335162612J3619331313L1317511914J9141415L81173816L1416472417M152056018K137231319M2716213520M62795821J551627222M82176423K770101324J585201725K1058428   Biology 2000 Assessment Report  3 SECTION B: SHORT-ANSWER QUESTIONS In general in this section 2 marks are allocated for one well-expressed piece of information. Questionsthat require an explanation are worth 4 marks and therefore, in order to obtain full marks, candidatesmust supply two relevant and connected pieces of information.Questions that require candidates to state the name of a syllabus term often have a communicationmark associated with them. A candidate who provides a correct answer but misspells a syllabus term ispenalised by the loss of 1 mark.The mean marks for the questions in Section B are shown in the table below: QuestionMean Mark / Maximum MarkMean Mark (%) 266.62/1066.2274.83/860.4283.33/841.6292.16/453.9302.94/649.0313.18/1031.8322.78/834.8333.53/658.8343.33/655.5355.35/1244.6364.45/674.2375.34/866.7385.30/866.2Total53.14/10053.1 Question 26 Most students knew the structure of DNA, and understood DNA replication and the structure of a gene.Common errors included matching the A with a U or omitting the sugar-phosphate spine in thecomplementary DNA strand. Many candidates had only vague notions about the function of a gene. Question 27 This question was generally answered well, with most students showing some understanding of molecular biology.Answers to part (a) were spelt accurately.There were some excellent descriptions of membrane receptors in answers to part (b).Candidates ’  expression tended to be poor in answers to part (c), but they understood the concept. Question 28 The induced-fit model of enzyme-substrate binding was not well understood. Most candidatesdescribed how the binding occurs at the active site of the enzyme but were unable to proceed further.Only the better candidates were able to use the induced-fit model of enzyme-substrate binding to statehow enzymes lower the activation energy required for a reaction. Question 29 It was not clear from many of the responses whether or not candidates understood that cancer isuncontrolled cell growth. Only the better candidates linked the study of cell death to cancer. Question 30 Most candidates knew the equation for photosynthesis but fewer were able to demonstrateunderstanding of the conversion of light energy into chemical energy.
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