Final Marking Guidelines 2011 examination June series. Biology Unit 6T A2 Investigative Skills Assignment. General Certificate of Education

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1 Genera Certificate of Education Bioogy Unit 6T A Investigative Skis Assignment BIO6T/P11/MG Fina Marking Guideines 011 examination June series WMP/Jun11/BIO6T/P11/MG

2 Bioogy - AQA GCE BIO6T/P11 /Marking Guideines/011 June series Marking Guideines are prepared by the Principa Moderator and considered, together with the reevant questions, by a pane of subject teachers. Copyright 011 AQA and its icensors. A rights reserved. COPYRIGHT AQA retains the copyright on a its pubications. However, registered centres for AQA are permitted to copy materia from this booket for their own interna use, with the foowing important exception: AQA cannot give permission to centres to photocopy any materia that is acknowedged to a third party even for interna use within the centre. Set and pubished by the Assessment and Quaifications Aiance. The Assessment and Quaifications Aiance (AQA) is a company imited by guarantee registered in Engand and Waes (company number ) and a registered charity (registered charity number ). Registered address: AQA, Devas Street, Manchester M15 6EX.

3 Guidance for teachers marking Bioogy ISAs Fina Marking Guideines must be used to mark candidates work Genera principes In genera, you are ooking for evidence that the candidate knows and understands the point required by the Marking Guideines. It is important to mark what the candidate has written, not to assume what may have been intended. It is aso important to make sure that a vaid point is in the correct context. Individua words or phrases where the overa answer does not appy to the question asked shoud not be credited. Conventions The foowing conventions are used in the Marking Guideines. A semicoon (;) separates each marking point An obique stroke (/) separates aternatives within a marking point Underining of a word or phrase means that the term must be used For exampe anaphase, the term must appear For exampe... and..., both items must be present for a mark Brackets are used to indicate contexts for which a marking point is vaid. This context may be impied by a candidate's answer 'Accept' and 'reject' show answers which shoud be aowed or not aowed. Additiona instructions are shown in the fina coumn Max refers to the maximum mark that can be awarded for a particuar question or part question. The Marking Guideines show the minimum acceptabe answer(s) for each marking point. A better, more detaied, or more advanced answer shoud aways be accepted, provided that it covers the same key point. Marking Guideines cannot give every possibe aternative wording - equivaent phrasing of answers shoud be accepted. For exampe the water potentia is higher in the ces is equivaent to the water potentia is ess negative in the ces. It is, however, important to be sure that the minimum requirement of the Marking Guideines is met and that the point is made unambiguousy. Converse answers are normay acceptabe, uness the wording of the question rues this out. For exampe, 'the water potentia is ower in the soution is an acceptabe converse of the water potentia is higher in the ce. Very occasionay, a candidate wi give a bioogicay correct answer that is not covered in the Marking Guideines. If it is equivaent in standard to the Marking Guideine answers, it shoud be credited. In this case, write the word vaid. A marking points are awarded independenty, uness a ink between points is specified in the 3

4 The mechanics of marking Aways mark in red ink. Make sure that some red ink appears on every page on which the candidate has written. For each mark awarded, put a tick cose to the marking point. In a cases, a tick shoud equa one mark and the tota number of ticks shoud match the mark totas in the margins. The tota mark for each part answer shoud be written in the right hand margin. Put a cross against incorrect points. It is hepfu to indicate omissions of key words or incompete answers with a Λ symbo, and to highight irreevancies or contradictions by underining. It is aso hepfu to write brief comments to expain the reason for awarding or withhoding a mark when the answer does not obviousy match the Marking Guideines. When marking answers with many marking points, the points wi be numbered. The points do not have to appear in the candidate s response in the order in the Marking Guideines. The appropriate number must be paced aongside the tick. This heps to carify where a specific point has been awarded and makes moderation much easier. It aso heps to avoid awarding the same point twice. Disquaifiers A correct point shoud be disquaified when the candidate contradicts it in the same answer. Indicate this on the script by 'dq'. If a tick has aready been paced against a vaid point, ensure that it is ceary deeted. Note that there is no penaty for incorrect points which are not contradictory, or for surpus or neutra information. The ist rue When a question asks for a specific number of points, and the candidate gives more, the genera rue is that any wrong answer cances a correct answer. For exampe, if a question asks for two points and three answers are given, two correct and one ceary wrong, the mark awarded is one, whatever the order of the answers. This prevents candidates from gaining fu marks from a ist of right and wrong answers. Name two substances that are produced in photosynthesis. ( marks) Answer Marks Comment Oxygen, gucose Both correct Oxygen, carbon dioxide 1 One correct, one incorrect Carbon dioxide, oxygen, gucose 1 Carbon dioxide is ceary incorrect and cances one of the marks Oxygen, gucose, water Regard water as a neutra point. It is not worth a mark but it is not incorrect Two or more correct points on the same answer ine shoud be credited. 'Neutra' points, i.e. ones which are not creditworthy but not actuay incorrect, shoud not negate a correct answer. Speing Reasonaby cose phonetic speings shoud be credited. However, any misspeing of technica terms which can easiy be confused, such as intermediate between mitosis and meiosis, shoud resut in the reevant marking point being withhed. Terms ike this wi be indicated in the fina coumn in the Marking Guideines to show that misspeings must not be credited. 4

5 Stage (NB no marks are awarded for Stage 1 at A) 1 Cear statement of nu hypothesis; 1 e.g. ammonium hydroxide has no effect on the time taken for coour change (a) Standard error (and 95% confidence imits); 1 (b) Compare two means; 1 Do not credit if wrong test is chosen 3 Test statistic cacuated accuratey; 1 Accept candidate's accurate cacuation even if the test is not appropriate. If working not shown, cacucation must be checked against raw data. 4 1 Correct interpretation of statistica test in terms of Use candidate's vaue from chosen test, even acceptance or rejection of nu hypothesis; if it is incorrect Interpretation invoves appropriate reference to the probabiity of Probabiity and chance must be used in the the resuts being due to chance; correct context Tota 6 The tabe of raw data and the Stage sheet is required for moderation and must be attached to the ISA test. 5

6 ISA test Section A 5 (a) Few/no choropasts present / tough materia so wi not be 1 cut up (by bender); 5 (b) Break open ces / break ce was / aow reease of 1 choropasts; 6 (a) EITHER 3 Do not credit references to 1 Sows/stops enzyme activity; microorganisms/bacteria/decay Enzymes reeased during bending; 3 Choropasts not damaged/sti function/photosynthesis continues; OR: 4 Bending produces friction/reeases heat; Aow answers via one route ony 5 (Heat) changes the tertiary structure (of enzymes) / denatures enzymes; 6 Choropasts not damaged / sti function / photosynthesis continues; 1 Same water potentia (as pant tissue) / no osmosis/no water movement in/no water movement out; Choropasts/organees do not burst / choropasts do not shrive / choropasts are not damaged; 6 (b) Accept no osmosis in or out Accept no water movement in or out Answer to second point must foow from first Reject ces do not burst 7 1 Fiter/centrifuge; 3 At ow speed then high speed / centrifuge again at higher speed / fiter then centrifuge; 3 Coect peet/sediment; Marking principes are: 1. Fitering or centrifuging. Carrying out procedure twice at different speeds 3. Peet is required 6

7 8 Prevent entry of ight/keep in the dark / to sow reease of 1 eectrons from chorophy / because reease of eectrons / photosynthesis ony occurs in the ight /to stop photosynthesis; 9 1 Shows that coour change in x / coour does not change in B; max Accept shows that mitochondria do not affect (Coour change) not due to isoation medium; resut. 3 (Coour change) is due to choropasts / chorophy; 10 Choropast membrane; 1 Accept grana or thyakoids 11 1 Ammonium hydroxide has stopped/sowed transfer of eectrons; Accept equivaent terms for eectron Aong eectron transport chain/to DCPIP; transport chain OR Do not accept from chorophy. This 3 Ammonium hydroxide accepts eectrons; is insufficient 4 Does not pass aong eectron transport chain / to DCPIP; OR 5 Ammonium hydroxide affects ph; 6 ph affects proteins in eectron transport chain; Reject enzymes. 1 (a) 1 Stop/sow ight-dependent reaction; max Stop/ess production of reduced NADP/ATP; 3 Light-independent reaction sowed/stopped / photosynthesis sower/not competed; Must refer to reduced NADP or aternatives for reduced NADP Sows or stops ight-dependent reaction and ight-independent reaction gain marks 1 (b) 1 (Substance in weed kier) absorbed by crop; max 1 Idea of uptake Reduce growth/yied of crop / weed kier not seective; Idea of effect of uptake 3 Toxic effects on other wid ife/when crop eaten; e.g. buids up in food chain and toxic / poisonous/harmfu to other organisms 4 Sows/stops respiration; Tota 0 7

8 Section B 13 Two marks for correct answer, 41.9 / 4 ;; One mark for incorrect answer of 0.4; 14 Increases proportion of crop that is used / 1 greater proportion is grain / reduces proportion of crop that is not used / is not grain; 15 1 Quadrats from different parts of fied; 1 Biotic / abiotic factors / named biotic /abiotic factor different; 16 1 Water (in pants and grain); Varies; 17 1 Greater when treated with herbicide G; Same number but tota biomass arger; Can be shown by figures 18 1 Fewer weeds eft; max Fewer weeds to produce seeds; 3 Less contamination of crop (by weeds); 4 Fewer weeds to separate from crop; 5 Less competition (between crop and weeds); 8

9 19 Advantage 1 Weeds growing fast / photosynthesising fast so effect wi be seen / wi have arge effect; One mark for advantage and one mark for disadvantage Disadvantage No information about winter / other seasons / weeds not growing fast / coud ki (beneficia) insects / crop may be harvested before effects noticeabe; 0 Limitations of investigation 5 max When marking pease number the 1. No contro/untreated fied; marking points. Amount of herbicide may be different; 5 e.g. 3. May be differences between fieds; means a mark award for point 5 3. Eg soi Nutrients/fertiiser added Type of weed Microcimates 4. May be different number of weeds (at start); Limitations of resuts 5. No repicates/one set of data; 6. Fied size may vary/not specified; Scientific Research 7. Scientific research/exampe of scientific research has ed to greater yied; Tota 18 9 Copyright 010 AQA and its icensors. A rights reserved.