GCSE SCIENCE A. SCA1HP Mark scheme June Version: 1.0 Final

Transcription

1 GCS SCINC A SCAHP Mark scheme 4406 June 204 Version:.0 Final

2 Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation events which all associates participate in and is the scheme which was used by them in this examination. The standardisation process ensures that the mark scheme covers the students responses to questions and that every associate understands and applies it in the same crect way. As preparation f standardisation each associate analyses a number of students scripts: alternative answers not already covered by the mark scheme are discussed and legislated f. If, after the standardisation process, associates encounter unusual answers which have not been raised they are required to refer these to the Lead Assessment Writer. It must be stressed that a mark scheme is a wking document, in many cases further developed and expanded on the basis of students 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 from aqa.g.uk Copyright 204 AQA and its licenss. All rights reserved. AQA retains the copyright on all its publications. However, registered schools/colleges f AQA are permitted to copy material from this booklet f their own internal use, with the following imptant exception: AQA cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third party even f internal use within the centre.

3 MARK SCHM GCS Science A - SCAHP June 204. General The mark scheme f each question shows: Infmation to xaminers the marks available f each part of the question the total marks available f the question the typical answer answers which are expected extra infmation to help the xaminer make his her judgement and help to delineate what is acceptable not wthy of credit, in discursive answers, to give an overview of the area in which a mark marks may be awarded the Assessment Objectives and specification content that each question is intended to cover. The extra infmation 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, f example: where consequential marking needs to be considered in a calculation; the answer may be on the diagram 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 straightfward and consistent. 2. mboldening 2. In a list of acceptable answers where me than one mark is available any two from is used, with the number of marks emboldened. ach of the following bullet points 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 f a mark are indicated by the use of. Different terms in the mark scheme are shown by a / ; e.g. allow smooth / free movement. 3. Marking points 3. Marking of lists This applies to questions requiring a set number of responses, but f which candidates have provided extra responses. The general principle to be followed in such a situation is that right + wrong = wrong. ach err / contradiction negates each crect response. So, if the number of err / contradictions equals exceeds the number of marks available f the question, no marks can be awarded. However, responses considered to be neutral (indicated as * in example ) are not penalised. xample : What is the ph of an acidic solution? ( mark) Candidate Response Marks awarded green, red*, 5 3 red*, of 22

4 MARK SCHM GCS Science A - SCAHP June 204 xample 2: Name two planets in the solar system. (2 marks) Candidate Response Marks awarded Neptune, Mars, Moon 2 Neptune, Sun, Mars, Moon Use of chemical symbols / fmulae If a candidate writes a chemical symbol / fmula instead of a required chemical name, full credit can be given if the symbol / fmula is crect and if, in the context of the question, such action is appropriate. 3.3 Marking procedure f calculations Full marks can be given f a crect numerical answer, without any wking shown. However, if the answer is increct, mark(s) can be gained by crect substitution / wking and this is shown in the extra infmation column by each stage of a longer calculation. 3.4 Interpretation of it Answers using the wd it should be given credit only if it is clear that the it refers to the crect subject. 3.5 rrs carried fward Any err 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 errs can be carried fward are kept to a minimum. Allowances f errs carried fward 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 crect scientific terminology should be credited unless there is a possible confusion with another technical term. 3.7 Brackets (..) are used to indicate infmation which is not essential f the mark to be awarded but is included to help the examiner identify the sense of the answer required. 3.8 Igne / Insufficient / Do not allow Igne insufficient is used when the infmation given is irrelevant to the question not enough to gain the marking point. Any further crect amplification could gain the marking point. Do not allow means that this is a wrong answer which, even if the crect answer is given, will still mean that the mark is not awarded. 4 of 22

5 MARK SCHM GCS Science A - SCAHP June 204 Quality of Written Communication and levels marking In Question 9 candidates are required to produce extended written material in nglish, and will be assessed on the quality of their written communication as well as the standard of the scientific response. Candidates will be required to: use good nglish ganise infmation clearly use specialist vocabulary where appropriate. The following general criteria should be used to assign marks to a level: Level : basic Knowledge of basic infmation Simple understanding The answer is poly ganised, with almost no specialist terms and their use demonstrating a general lack of understanding of their meaning, little no detail The spelling, punctuation and grammar are very weak. Level 2: clear Knowledge of accurate infmation Clear understanding The answer has some structure and ganisation, use of specialist terms has been attempted but not always accurately, some detail is given There is reasonable accuracy in spelling, punctuation and grammar, although there may still be some errs. Level 3: detailed Knowledge of accurate infmation appropriately contextualised Detailed understanding, suppted by relevant evidence and examples Answer is coherent and in an ganised, logical sequence, containing a wide range of appropriate relevant specialist terms used accurately. The answer shows almost faultless spelling, punctuation and grammar. 5 of 22

6 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark (a) reduces / controls amount of light entering the eye igne stops light entering the eye A02 B.2.a,d (so) less chance of damage accept protects the retina allow (so) can see better (in bright light) (b) any two from: allow converse statements 2 A0 B.2.d A reflex action is: fast(er) automatic / not thought about involves few(er) neurones involves few(er) synapses does not (always) involve the brain allow nerves do not allow reference to hmones Total 4 6 of 22

7 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 2 iginal use: as a sleeping pill A0 B.3.d me recent uses: to treat leprosy also used: to treat mning sickness (in pregnant women) reason f ban: caused arm / leg / limb abnmalities (in some babies) accept to treat cancers / leukaemia / skin disders / inflammaty diseases / arthritis allow toes / fingers / thumbs / hands / feet / body / body parts / bones Total 4 7 of 22

8 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 3 Marks awarded f this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. xaminers should also refer to the infmation on page 5 and apply a best-fit approach to the marking. 6 A0x4 A02x2 B..a,b,c,e 0 marks Level ( 2 marks) Level 2 (3 4 marks) Level 3 (5 6 marks) No relevant content There is a brief description of either an effect of an unbalanced diet an effect of not enough exercise on the body. There is a description of effect(s) of an unbalanced diet and / effect(s) of not enough exercise on the body. There is a clear description of the effects of an unbalanced diet and of not enough exercise on the body. examples of the points made in the response extra infmation effects of an unbalanced diet: igne malnourishment / no energy overweight underweight deficiency disease (Type 2) diabetes igne anexia allow named deficiency disease accept : arthritis weakened immune system periods stop in women allow: affects cholesterol levels constipation heart disease/ heart problems blood pressure (bowel) cancer Question 3 continues on the next page 8 of 22

9 MARK SCHM GCS Science A - SCAHP June 204 Question 3 continued effects of not enough exercise: less energy (transferred) weight gain slower metabolic rate less muscle mass weaker muscles me body fat allow answers written in terms of the positive effects of exercise igne no energy accept: weaker bones weaker heart po circulation less flexible effects on stress level and mood effects on balance / codination longer reaction time weaker immune system if no relevant content allow an answer referring to balanced diet if qualified f Level 9 of 22

10 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 4(a) 2 neutrons 2 electrons allow / e / e - / a small dot f an electron A0/A02 C.. c,e,g,h do not accept the symbol f a neutron electrons on outer shell and neutrons in nucleus igne number of particles 4(b) stable arrangement of electrons igne references to noble gases allow have a complete / full outer shell (of electrons) allow have a complete outer energy level (of electrons) A0 C..2b 4(c) will run out (soon) igne references to cost allow does not remain in arth s atmosphere only if qualified, eg can t be recovered A03 C..2b me imptant uses allow is a waste (of helium) igne people will inhale it Total 6 0 of 22

11 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 5(a) rare igne figures without qualification A03 C.3.c very small amount in arth s crust 5(b)(i) G electrolysis A0 C.3.d,e 5(b)(ii) (electrolysis) uses me energy igne references to reactivity accept uses a large amount of energy A02 C.3.d,e there are many stages in the process 5(c) 2Fe 2 O 3 + 3C 4Fe + 3CO 2 crect fmulae f mark 2 A02 C.3.d crect balancing of crect fmulae f mark allow multiples accept f 2 marks: Fe 2 O 3 + 3CO 2Fe + 3CO 2 Total 5 of 22

12 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 6(a) contains only one st of atom A0 C..a 6(b) platinum is not a compound / mixture / alloy allow platinum is (an element so) not made of gold and silver A03 C..a,b platinum is an element so should have own (unique) symbol symbol shown represents 2 different sts of atom 6(c) it contains two silver ions and one oxide ion maximum of mark if mention of being mixed together / covalently bonded allow silver atoms f silver ions allow oxygen atom / ion f oxide ion 2 A0/A02 C..b C..3a allow f mark: it is silver oxide it is made of silver and oxygen it is a compound crect ratio of 2: atoms / ions f increct element(s) Total 4 2 of 22

13 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 7(a) any four from: max 3 marks if mention of particles becoming me / less dense 4 A0 P..3a water particles gain (kinetic) energy allow water particles move faster water particles spread out accept (heated) water expands do not accept (water) particles expand (so) water becomes less dense (so) heated water rises do not accept heat rises (and) cooler water falls allow less energetic particles fall 7(b)(i) G reflect A0 P..e 7(b)(ii) any four from: Design A has a bigger area / is 3 m 2 instead of 2 m 2 allow energy / heat f infrared radiation 4 A02/A03 P..3a Design A reflects me / greater percentage of infrared radiation (in total) Design A makes the food get hotter (quicker) Design B always points at the Sun allow benefit related to this point, eg labour saving Design B is (me) easily transpted (because it folds) allow Design B is (me) ptable Total 9 3 of 22

14 MARK SCHM GCS Science A - SCAHP June 204 question Answers extra infmation mark 8(a) A A greater proption of the energy is wasted A0 P.2.b 8(b) any three from: metal is a good conduct allow heat f energy 3 A02 P..c mesh has a big surface area black surfaces are good emitters / radiats (of infrared radiation / energy) allow mesh / holes allows airflow black surfaces are good absbers of infrared radiation / energy from the laptop computer fans increase convection allow fans replace hot air with cooler air allow fans maintain / increases temperature difference / gradient (between laptop and surroundings) 8(c) arrow 4 squares wide labelled wasted (energy) and arrow 6 squares wide labelled useful (energy) i.e. allow f mark: crect width arrows with no labels crect width arrows with numerical labels only arrows plotted crectly but wasted energy arrow in increct position a crectly labelled diagram showing useful energy is greater than wasted energy 2 A02 P.2.a Total 6 4 of 22

15 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 9(a) auxin accept IAA / indoleacetic acid / gibberellins allow phonetic spellings A0 B.2.3b 9(b)(i) View with 9(a) any one from: the tip is needed f growth auxin / hmone is produced at the tip (of the shoot) allow ecf from (a) A03 B.2.3b auxin / hmone still active if tip removed and replaced 9(b)(ii) as a control igne references to hmones A03 B.2.3b to see if jelly on its own affected growth 9(b)(iii) View with 9(a) auxin / hmone stimulates / is needed f growth / cell elongation (of shoots) allow ecf from (a) A03 B.2.3b 9(b)(iv) no light (to affect growth) allow no stimulus (to affect growth) A02 B.2.3a,c even distribution of auxin / hmone Total 5 5 of 22

16 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 0(a) (bacteria and viruses produce) toxins allow poisons allow damage body cells A0 B..2b 0(b) (temperature at which) enzymes wk best A0 B.2.2a 0(c)(i) body mass allow weight allow ethnicity A03 B.3.b igne height / size 0(c)(ii) placebo / fake drug allow sugar pill allow no treatment A0 B.3.b 0(c)(iii) any one from: as a control group A03 B..2g B.3.b f comparison to see if the drugs wked to take account of psychological effect accept placebo effect allow to avoid bias 0(d)(i) G.2 ( C) A02 B..2g 0(d)(ii) G 3 (hours) A02 B..2g Question 0 continues on the next page 6 of 22

17 MARK SCHM GCS Science A - SCAHP June 204 Question 0 cont d question answers extra infmation mark 0(e)(i) (Paracetamol) any two from: 2 A02/A03 B..2g ibuprofen reduces body temperature faster allow wks faster ibuprofen reduces temperature me ibuprofen doesn t need to be taken as often ibuprofen keeps body temperature lower / nmal / 37 ºC f longer 0(e)(ii) (Paracetamol + ibuprofen) any two from: 2 A02 B..2g body temperature decreases at a similar rate ibuprofen maintained body temperature close to nmal / 37 C allow ibuprofen wks (almost) as fast allow ibuprofen maintained nmal body temperature almost as long allow doesn t make temperature drop below nmal as long (better to) take fewer drugs allow less chance of overdose / giving too much allow (better to) take drugs less frequently easier to administer allow less chance of missing doses / taking at the wrong time Total 7 of 22

18 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark (a) (black) copper oxide fmed explanation must be linked to crect observation A0/A03 C.2.c,e loss in mass is due to carbon dioxide / gas production limewater cloudy shows carbon dioxide produced (b)(i) any one from: (bunsen burner flame) not hot enough (to decompose potassium carbonate) igne references to reactivity accept temperature not high enough (to decompose potassium carbonate) A0 C.2.c not all Group carbonates decompose allow potassium is in Group (b)(ii) View with table potassium carbonate: (mass) 3.8 g (limewater) colourless accept no change f colourless igne clear A02 C.2.c,e zinc carbonate: (limewater turns) cloudy Metal carbonate Potassium carbonate Zinc carbonate Mass after heating in g Limewater 3.8 colourless cloudy Total 7 8 of 22

19 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 2(a)(i) solid particles accept soot / carbon / unburnt fuels A0 C.4.3a 2(a)(ii) global dimming allow smog A0 C.4.3a,c 2(a)(iii) any two from: irregular pattern in the graph 2 A03 C.4.3a,c cannot predict future development of industry / technology cannot predict future number of cars cannot predict future efficiency / type of engines might be other sources of particulates in future change in amount of fossil fuels burnt allow change in use to other fuels / energy sources cannot predict future volcanic eruptions 2(b)(i) rate of decay is lower (because) less acid rain (as) sulfur dioxide is a cause of acid rain limestone / calcium carbonate reacts with acid (rain) allow rate of decay is less must refer to idea of less / reduced / not as much acid rain not crodes A0/A03 C.2.f C.4.3a,c 2(b)(ii) any one from: remove (sulfur dioxide) from waste gases use low sulfur fuels accept (sulfur dioxide) reacted with limestone / calcium carbonate / calcium hydroxide / calcium oxide accept flue gas desulfurisation A0 C.4.3d Total 8 9 of 22

20 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 3(a) reason only sces if a crect value f the resolution is given A02/A03 P..4d a value of C less temperatures in investigation are recded to the nearest degree (Celsius) do not allow 0 / zero differences between temperature rises f different materials is greater than C 3(b) any one from: A03 P..4d room temperature / start temperature (of material) type of insulation thickness of insulation allow amount time that cylinder was heated f the power output of the immersion heater 3(c) aluminium reason only sces if aluminium is given A02/A03 P..4d smallest temperature rise allow smaller temperature rise (than the other metals) accept justification by calculation 20 of 22

21 MARK SCHM GCS Science A - SCAHP June 204 3(d) 500(J/kg C) allow temperature increase = 8 C f mark 3 A02 P..4d crect substitution 8000 = 2 x c x 8 gains 2 marks provided no subsequent step crect substitution and rearrangement c = 8000 / (2 x 8) gains 2 marks provided no subsequent step allow 2 marks f 474 (J/kg C) (a SHC calculated using a temperature of 9 C) allow mark f substitution 8000 = 2 x c x 9 provided no subsequent step substitution and rearrangement c = 8000 / (2 x 9) provided no subsequent step allow 2 marks f a SHC calculated using a temperature increase of an increct metal, ie 900 (J/kg C f aluminium) 39 (J/kg C f copper) 450 (J/kg C f iron) 34 (J/kg C f lead) Total 8 2 of 22

22 MARK SCHM GCS Science A - SCAHP June 204 question answers extra infmation mark 4(a) so it is a good insulat igne references to efficiency allow low (rate of) energy / heat transfer do not accept prevents energy transfer A0 P..4a 4(b) air is a(n) (good) insulat (so) air reduces conduction allow air is a po conduct do not allow stops conduction A0 P..3a trapped air / air bubbles reduce(s) / stop(s) convection 4(c) any three from: ice-pack is (much) colder than the cool box contents ice-pack reduces the (overall) temperature of the cool box / air (in the cool box) 3 A0/A02 P..3d P..4d ice pack requires a lot of energy to heat up / increase temperature / change temperature ice-pack requires heating up befe the cool box contents warm up ice-pack cools the air which becomes me dense and sinks allow heat f energy allow heat f energy allow ice-pack takes a long time to heat up / increase temperature / change temperature allow ice-pack cools the air and causes (a) convection (current) accept energy / heat is needed to melt the (contents of the) icepack Total 7 22 of 22