GCSE Biology June 2003 Answer Key

Mark scheme June 2003 GCSE Biology (Modular) 3413 Foundation Copyright © 2003 AQA and its licensors. All rights reserved. The Assessment and Qualifications Alliance (AQA) is a company limited by guarantee registered in England and Wales 3644723 and a registered charity number 1073334 Registered address: Addleshaw Booth & Co., Sovereign House, PO Box 8, Sovereign Street, Leeds LS1 1HQ Kathleen Tattersall: Director GeneralMark Scheme Biology (Modular) -GCSE 1 ADDITIONAL INFORMATION FOR EXAMINERS Mark Scheme 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 /; e.g. allow smooth /free movement.) 3. Marking points 3.1 Marking of Quality of Written Communication Examiners are reminded of the need to assess QoWC by the following statement appearing in the appropriate parts of the mark scheme: The answer to this question requires ideas in good English in a sensible order with correct use of scientific terms. Quality of written communication should be considered in crediting points in the mark scheme. The maximum marks available to a candidate whose answer is not well expressed will be (the number of marks available –1).Biology (Modular) -GCSE Mark Scheme 2 3.2 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. 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 3.3 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. 3.4 The marking of quantitative relationships Full credit can be given for a correct quantitative relationship expressed in: • named units; • physical quantities; • standard symbols; • a combination of physical quantities and units. No credit can be given for any quantitative relationship expressed in terms of: • a combination of physical quantities, units and symbols; • a diagram, e.g. the ohm’s law triangle, unless the rest of the answer shows clearly that the candidate understands the relationships involved. 3.5 Marking procedure for calculations 3.5.1 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.Mark Scheme GCSE -Biology (Modular) 3 3.5.2 Where calculations are based on incorrectly recalled relationships, neither the incorrectly recalled relationship, nor the resulting calculation based on the incorrect relationship, will be credited. 3.6 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. 3.7 Errors carried forward There should be no error carried forward from a previous answer which has been based on wrong science. Any error in the answers to a structured question should be penalised once only. Examples (a) A candidate who calculates average speed using speed = time/distance and then proceeds to use this incorrect answer to calculate an acceleration based on the correct quantitative relationship should be given credit for the use of the correct acceleration relationship but none for either numerical answer. (b) A candidate who incorrectly calculates average speed using speed = distance/time and then proceeds to use this incorrect value to calculate an acceleration based on the correct quantitative relationship, should be given credit for the use of both correct quantitative relationships and for the correct substitution and use of the incorrect value in the calculation of the rate of acceleration. 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. 3.8 Phonetic spelling The phonetic spelling of correct scientific terminology should be credited unless there is a possible confusion with another technical term. 3.9 Brackets (…..) is 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. 3.10 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. ✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛✛Biology (Modular) -GCSE Mark Scheme 4GCSE BIOLOGY (MODULAR) 3413F MARK SCHEME – FOUNDATION TIER (TERMINAL PAPER) SUMMER 2003 Question 1 answers extra information mark (a) • nucleus • gene 2 (b) • sex chromosomes different /(X and) Y chromosome present 1 (c) • half the number of chromosomes present accept only 23 chromosomes accept only 1 sex chromosome accept 1 set of chromosomes 1 total 4Mark Scheme GCSE -Biology (Modular) 5 Question 2 answers extra information mark (a) • rock • hard • soft • water • oxygen 5 (b)(i) • 400 1 (ii) • 200 1 (iii) • fish and amphibians both must be given, in either order 1 (c) any two from • change in environment • new predators • new disease • new competitors allow 2 examples e.g. less food and water = 2 marks 2 total 10 either orderBiology (Modular) -GCSE Mark Scheme 6Question 3 answers extra information mark (a) (i) any one from • heron • fish • diving beetle • frog 1 (ii) answer dependent on (a) (i) (heron) -fish (fish) -fly larvae or water fly (diving beetle) -water flea (frog) -waterboatmen accept fly/larvae/flea accept flea 1 (b) • frog 1 (c) (i) • more are eaten 1 (ii) • more waterfleas/food 1 (d) biomass decreasing at each tropic level AND all labels correct both points needed 1 (e) • light/sunlight allow the sun 1 total 7Mark Scheme GCSE -Biology (Modular) 7 Question 4 answers extra information mark (a) • 70 1 (b) • combustion/burning • of fossil fuels accept named example 2 (c) any two from • SO2 dissolves to form an acid • damage to trees • organisms cannot survive in acidic water do not credit makes acid rain do not credit effects on limestone 2 total 5Biology (Modular) -GCSE Mark Scheme 8Question 5 answers extra information mark (a) each line should be completely correct for one mark 3 (b) (i) • yeast do not allow mould 1 (ii) Quality of written communication The answer to this question requires ideas in good English in a sensible order with correct use of scientific terms. Quality of written communications should be considered in crediting points in the mark scheme any four from • carbon dioxide (produced) • in respiration • gas trapped in dough • gas expands • when bread is cooked/on heating maximum of 3 if ideas not well expressed 4 total 8 Type of Microbe Cell Wall Protein Coat Cytoplasm Nucleus Yeast (√) √ √ Virus √ Bacteria (√) √Mark Scheme GCSE -Biology (Modular) 9 Question 6 answers extra information mark (a) • source of energy allow for respiration food neutral 1 (b) (i) • microbes enter (from the air) • microbes present in broth • microbes reproduce 3 (ii) any two from • boiling the broth kills microbes • microbes cannot enter (from the air) • sterile air has no microbes 2 total 6Biology (Modular) -GCSE Mark Scheme 10 Question 7 answers extra information mark (a) • large/insoluble • so can pass into blood accept so can leave (small) intestine/be absorbed 2 (b) • E • F 2 total 4Mark Scheme GCSE -Biology (Modular) 11 Question 8 answers extra information mark (a) (i) A 1 (ii) D 1 (b) • glucose • oxygen accept sugar answers in either order 2 total 4Biology (Modular) -GCSE Mark Scheme 12 Question 9 answers extra information mark (a) (i) • change in a gene/genetic information/DNA allow change in base sequence allow change in chromosome number allow a change in a chromosome 1 (ii) • U/V light/x-rays allow ‘certain chemicals’ not just radiation 1 (b) • cut out gene • using enzyme • transfer gene to bacterial cell • then culture bacteria allow then bacteria reproduce/multiply 4 total 6Mark Scheme GCSE -Biology (Modular) 13 Question 10 answers extra information mark (a) • ovary • pituitary answers in either order 2 (b) (i) • prevent egg release/production/maturation allow inhibit FSH 1 (b) (ii) • side effects or example or STDs can still be transmitted e.g. weight gain, circulatory problems, headaches 1 total 4Biology (Modular) -GCSE Mark Scheme 14 Question 11 answers extra information mark (a) Quality of written communication The answer to this question requires ideas in good English in a sensible order with correct use of scientific terms. Quality of written communications should be considered in crediting points in the mark scheme • large size • small surface area to volume ratio • thick layer of body fat • feathers trap air maximum of 3 if ideas not well expressed do not credit has body fat accept insulating coat not fur 4 total 4Mark Scheme GCSE -Biology (Modular) 15 Question 12 answers extra information mark (a) • 2350 allow 2340-2360 1 (b) any one from • abundant food • little competition for food 1 (c) • shortage of food • disease accept correct reference to inbreeding accept new predators not just increased competition 2 total 4Biology (Modular) -GCSE Mark Scheme 16 Question 13 answers extra information mark (a) • starch 1 (b) • enzymes work well/optimum temperature for enzymes 1 (c) • for flavour/taste 1 (d) • ethanol/alcohol • carbon dioxide in either order 2 total 5Mark Scheme GCSE -Biology (Modular) 17 Question 14 answers extra information mark (a) • vaccination results in antibody production • (antibody production) takes time/is slow • virus replicates/causes symptoms before antibody can be produced 3 (b) (i) • antibodies 1 (ii) • antibody reacts with/binds to virus • prevents viral replication/virus destroyed 2 total 6Biology (Modular) -GCSE Mark Scheme 18 Question 15 answers extra information mark (a) (i) incisor tooth correctly labelled 1 (ii) canine tooth correctly labelled 1 (b) • canine teeth pointed/sharp • to pierce/kill/hold/tear prey • molars ridged/large surface area • to crush prey do not credit large must link tooth to function 1111 total 6Mark Scheme GCSE -Biology (Modular) 19 Question 16 answers extra information mark (a) • 3 bars correctly plotted • all bars plotted correctly mark bars for height only 11 (b) • 500/2500 x 100 • 20 award 2 marks for correct answer with no working 2 (c) • more sweating • to cool body 2 (d) • Urea/salts 1 total 7