GCSE Biology June 2007 Paper Answer Key

Version 1.0: 0707 abc General Certificate of Secondary Education Science B 4462 /Biology 4411 BLY1F Unit Biology 1 Mark Scheme 2007 examination -June series Mark schemes are prepared by the Principal Examiner and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation meeting attended by all examiners and is the scheme which was used by them in this examination. The standardisation meeting ensures that the mark scheme covers the candidates’ responses to questions and that every examiner understands and applies it in the same correct way. As preparation for the standardisation meeting each examiner analyses a number of candidates’ scripts: alternative answers not already covered by the mark scheme are discussed at the meeting and legislated for. If, after this meeting, examiners encounter unusual answers which have not been discussed at the meeting they are required to refer these to the Principal Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of candidates’ reactions to a particular paper. Assumptions about future mark schemes on the basis of one year’s document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper. Further copies of this Mark Scheme are available to download from the AQA Website: www.aqa.org.uk Copyright © 2007 AQA and its licensors. All rights reserved. The Assessment and Qualifications Alliance (AQA) is a company limited by guarantee registered in England and Wales (company number 3644723) and a registered charity (registered charity number 1073334). Registered address: AQA, Devas Street, Manchester M15 6EX. Dr Michael Cresswell, Director General. Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 3 MARK SCHEME Information to Examiners 1. General The mark scheme for each question shows: • the marks available for each part of the question • the total marks available for the question • the typical answer or answers which are expected • extra information to help the Examiner make his or her judgement and help to delineate what is acceptable or not worthy of credit or, in discursive answers, to give an overview of the area in which a mark or marks may be awarded. The extra information is aligned to the appropriate answer in the left-hand part of the mark scheme and should only be applied to that item in the mark scheme. At the beginning of a part of a question a reminder may be given, for example: where consequential marking needs to be considered in a calculation; or the answer may be on the diagram or at a different place on the script. In general the right hand side of the mark scheme is there to provide those extra details which confuse the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and consistent. 2. Emboldening 2.1 In a list of acceptable answers where more than one mark is available ‘any two from’ is used, with the number of marks emboldened. Each of the following lines is a potential mark. 2.2 A bold and is used to indicate that both parts of the answer are required to award the mark. 2.3 Alternative answers acceptable for a mark are indicated by the use of or. (Different terms in the mark scheme are shown by a /; eg allow smooth /free movement.) 3. Marking points 3.1 Marking of lists This applies to questions requiring a set number of responses, but for which candidates have provided extra responses. The general principle to be followed in such a situation is that ‘right + wrong = wrong’. Each error/contradiction negates each correct response. So, if the number of error/contradictions equals or exceeds the number of marks available for the question, no marks can be awarded. However, responses considered to be neutral (indicated as * in example 1) are not penalised. Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 4 Example 1: What is the pH of an acidic solution? (1 mark) Candidate Response Marks awarded 1 4,8 0 2 green, 5 0 3 red*, 5 1 4 red*, 8 0 Example 2: Name two planets in the solar system. (2 marks) Candidate Response Marks awarded 1 Pluto, Mars, Moon 1 2 Pluto, Sun, Mars, Moon 0 3.2 Use of chemical symbols /formulae If a candidate writes a chemical symbol /formula instead of a required chemical name, full credit can be given if the symbol /formula is correct and if, in the context of the question, such action is appropriate. 3.3 Marking procedure for calculations Full marks can be given for a correct numerical answer, as shown in the column ‘answers’, without any working shown. However if the answer is incorrect, mark(s) can be gained by correct substitution /working and this is shown in the ‘extra information’ column; 3.4 Interpretation of ‘it’ Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the correct subject. 3.5 Errors carried forward Any error in the answers to a structured question should be penalised once only. Papers should be constructed in such a way that the number of times errors can be carried forward are kept to a minimum. Allowances for errors carried forward are most likely to be restricted to calculation questions and should be shown by the abbreviation e.c.f. in the marking scheme. 3.6 Phonetic spelling The phonetic spelling of correct scientific terminology should be credited unless there is a possible confusion with another technical term. 3.7 Brackets (…..) are used to indicate information which is not essential for the mark to be awarded but is included to help the examiner identify the sense of the answer required. 3.8 Unexpected Correct Answers not in the Mark Scheme The Examiner should use professional judgement to award credit where a candidate has given an unexpected correct answer which is not covered by the mark scheme. The Examiner should consult with the Team Leader to confirm the judgement. The Team Leader should pass this answer on to the Principal Examiner with a view to informing all examiners. Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 5 BLY1F Question 1 answers extra information mark (a)(i) any two from: • light • water • space • nutrients /ions /minerals /named • carbon dioxide /CO2 list principle ignore oxygen /food /sun 2 (ii) less competition for water or more water /nutrients /minerals available ignore space /light /food 1 (b) camouflage /same shape as leaf /looks like a leaf allow ‘blends in’ ignore colour 1 total 4 Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 6 BLY1F Question 2 answers extra information mark (a) any three from: • water • ions /minerals /salts • temperature • blood sugar • heart rate • blood pressure allow breathing /oxygen /carbon dioxide allow sodium /chloride, other ions neutral allow heat ignore urea 3 (b) contraceptive drug fertility drug 1 1 (c)(i) eg nicotine, alcohol, cocaine, heroin, painkillers, tranquilisers, LSD allow cannabis /weed or other alternative names allow tobacco ignore smoking /ecstasy 1 (ii) alters body chemistry or craving /needing /dependence withdrawal symptoms on stopping allow psychological dependence allow withdrawal described allow ‘feel ill without it’ 1 1 total 8 Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 7 BLY1F Question 3 answers extra information mark joining sexual identical asexual clones 1 1 1 1 1 total 5 BLY1F Question 4 answers extra information mark (a) 7.8 1 (b) 14 /13.6 allow answer 13 without working for 1 mark 7500 ÷ 550 gains 1 mark 2 (c) produces /increases blood cholesterol affects heart or affects blood vessels or affects blood pressure ignore obesity accept clogs blood vessels 1 1 (d) (increases) blood pressure ignore references to heart /blood vessels 1 total 6 Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 8 BLY1F Question 5 answers extra information mark (a) fossils /teeth /bones /skeleton /foot prints allow cave drawings do not accept scientists have seen them 1 (b) only (some) bones remain /soft parts have decayed accept ‘no-one has ever seen one’ allow no photos, no pictures, no drawings 1 (c) any two from: • hunted by human • (new) predator • (new) competitor • (new) disease • environment changed /named environmental change • prey extinct /loss of food supply allow more predators allow natural disaster ignore not enough food 2 total 4 Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 9 BLY1F Question 6 answers extra information mark (a)(i) 56 accept 54 – 58 1 (ii) increased reasonable qualification eg slowly then more quickly or to 174 /176 or by 138 /140 1 1 (b) any two from: • no immunity or antibodies ineffective • no vaccines or humans not immunised • idea of large scale contact or large scale travel accept no resistance do not accept passed on ignore no cure 2 total 5 Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 10 BLY1F Question 7 answers extra information mark (a) scientists figures based on research /calculations /data or scientists sample whole area fishermen based on impression /hearsay /experience or fishermen fish in well-stocked /limited areas ignore reasons based on bias scientists sample a wider area = 2 marks fishermen only fish in well-stocked areas = 2 marks if no marks gained fishermens’ opinion and scientists’ opinion gains 1 mark 1 1 (b) any two from: • economic considerations • political impact • pressure groups or fears of extinction eg fear for jobs, profits, big demand for cod eg allow EU /government decide or laws will be passed 2 total 4 Science B /Biology BLY1F -AQA GCSE Mark Scheme 2007 June series 11 BLY1F Question 8 answers extra information mark (a) any two from: • area of bed sampled • sampling time • size of net • kicking action • net position control variables from information given 2 (b) any two from: • some animals not dislodged • some animals missed /through /escaped net • invertebrates difficult to identify • invertebrates from outside area must be ideas related to a sample ignore reliability etc 2 (c) 10 to 99 or 10 – 99 or 99 to 10 or 99 – 10 1 (d) any two from: • increased /goes up • 0 at sample 4 • to (more than) 100 allow increase implied from all data described 2 (e) mayfly because not found downstream of point where sewage enters stream or only in the unpolluted water 1 1 total 9