GCSE Biology May 2008 Answer Key

Version 1.0: 0608 abc General Certificate of Secondary Education Biology 4411 BLY3F Unit 3 Biology Mark Scheme 2008 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 candidatesresponses 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 candidatesscripts: 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 candidatesreactions to a particular paper. Assumptions about future mark schemes on the basis of one years 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 © 2008 AQA and its licensors. All rights reserved. COPYRIGHT AQA retains the copyright on all its publications. However, registered centres for AQA are permitted to copy material from this booklet for their own internal use, with the following important exception: AQA cannot give permission to centres to photocopy any material that is acknowledged to a third party even for internal use within the centre. Set and published by the Assessment and Qualifications Alliance. 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 GeneralBiology BLY3F AQA GCSE Mark Scheme 2008 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 fromis 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. Biology BLY3F AQA GCSE Mark Scheme 2008 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 informationcolumn; 3.4 Interpretation of itAnswers using the word itshould be given credit only if it is clear that the itrefers 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. Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 5 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 1(a) A = nucleus B = cell wall 1 1 1(b)(i) carbon dioxide 1 1(b)(ii) respiration 1 1(c)(i) amount of flour /yeast /water /dough or type of flour /yeast /dough 1 1(c)(ii) 35 1 Total 6 Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 6 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 2(a) glucose ! urea ! water ! sodium ions ! protein all 3 correct = 2 marks 2 correct = 1 mark 0 or 1 correct = 0 marks max 2 2(b)(i) protein cannot pass through filter or protein (too) large or protein stays in the blood 1 2(b)(ii) reabsorbed 1 2(c)(i) less 1 2(c)(ii) more 1 Total 6 Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 7 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 3(a) methane 1 3(b) (insulation maintains) higher temperature /warm(er) /keeps heat in /prevents heat loss /optimum temperature /heat increases rate of reaction do not allow hot(ter) /high temperature ignore same /constant temperature 1 3(c)(i) ($)25 000 ignore units ignore working or lack of working add 3 figures and subtract 10 000 or use of 35 000 and 10 000 but wrong answer for 1 mark 2 3(c) (ii) 8 years = 2 marks or correct answer from (c)(i) = 2 marks ignore working or lack of working 200 000 but wrong answer = 1 mark (c)(i) 2 Total 6 Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 8 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 4(a)(i) red cell 1 4(a) (ii) diffusion 1 4(a) (iii) haemoglobin 1 4(a) (iv) a nucleus 1 4(b) (on diagram) arrow from any part of blood to air 1 Total 5 Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 9 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 5(a) heat at 120oC for 30 minutes 1 5(b) no bacteria near the mould or nothing grows near Penicillium or gap between bacteria and Penicillium or bacteria gone /killed /destroyed near Penicillium 1 5(c)(i) valid /reliable /representative not accurateignore fair1 5(c) (ii) 6 1 5(c) (iii) 2 1 5(c) (iv) 48 to 60 1 5(d) any two from: • temperature /heat /suitable temperature range eg 2540°C • pressure • (concentration of) oxygen • food /nutrients • ions /correct eg /NH3 /NH4+ /nutrients • wastes /named wastes eg. carbon dioxide /lactic acid do not allow keep cool ignore water /nutrient agar allow nutrients only once 2 Total 8 Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 10 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 6(a) any two from: • large surface /area or many villi or have microvilli • thin surface or thin wall or surface 1-cell thick or capillaries near surface or permeable or partially permeable • many blood vessels or many capillaries or capillary network or good blood supply • have enzymes accept big surface /area accept they are thin do not allow thin cell wall ignore constant blood flowowtte ignore extras eg moist or reference to gases ignore release enzymes • accept reference to lacteal as 5th point • allow reference to having mitochondria 2 6(b)(i) small(er) (surface area) /flat(ter) /short(er) or not as folded or fewer capillaries owtte allow small(er) lacteal ignore references to wide /thick /spread out etc 1 6(b)(ii) less absorption (of digested food) /less digestion /diffusion accept slower for less accept description of less digestion accept less food can get in do not allow zero absorption do not allow collectionof nutrients 1 Total 4 Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 11 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 7(a) B (B has) low(est) number of stomata or no stomata on upper surface or only 800 (on lower surface) less transpiration /evaporation /water loss owtte or water (vapour) is lost via stomata only allow zero water loss if linked to no stomata on upper surface /linked to leaf B upper surface ignore references to leaf surface area 1 1 1 7(b) reduce loss /amount of water (vapour) or reduced transpiration (from upper surface) warmer above leaf or wilted leaf folds over lower surface or lower leaf in shade or less light /heat /sun on lower side accept converse do not allow no water is lost accept converse ignore reference to dust 1 1 Total 5 Biology BLY3F AQA GCSE Mark Scheme 2008 June Series 12 COMPONENT NUMBER: BLY3F COMPONENT NAME: Biology STATUS: Final DATE: June 2008 question answers extra information mark 8(a) increased speed or harder exercise /running →increased need /use /loss of energy increased mass /bigger → increased use of energy allow further you run /walk the more energy you need 1 1 8(b) any three from: • supply /using (more /enough) oxygen or get (more) oxygen in blood • remove (more) CO2 • doing (more) work or using (more) energy allow produce energy • for respiration • prevent build up of lactic acid or prevent oxygen debt or prevent anaerobic (respiration) or allow aerobic (respiration) need reference to moreONCE only for full marks 3 Total 5