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Mark Schemes March 2008
GCSE 360Science
GCSE
GCSE Additional Science (2103) GCSE Biology (2105) GCSE Chemistry (2107) GCSE Physics (2109)
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March 2008
Publications Code UG ??????
All the material in this publication is copyright © Edexcel Ltd 2008
Contents Multiple choice papers
Unit 5015/5027 1
Unit 5017/5037 2
Unit 5019/5047 3
Structured papers
Using the Mark Scheme 4
Unit 5016F/5028F 5
Unit 5016H/5028H 8
Unit 5018F/5038F 11
Unit 5018H/5038H 14
Unit 5020F/5048F 17
Unit 5020H/5048H 21
1
Multiple Choice Papers – March 2008 Unit B2 – 5015 Unit B2 – 5015 Unit B2 – 5015
Topics 1, 2, 3 & 4
Topics 1, 2, 3 & 4
Topics 1, 2, 3 & 4
1 B 17 B 25 B 2 C 18 B 26 D 3 B 19 D 27 A 4 D 20 A 28 C 5 A 21 A 29 C 6 C 22 C 30 D 7 C 23 C 31 A 8 C 24 B 32 B 9 A 33 C 10 C 34 C 11 B 35 D 12 D 36 B 13 A 37 B 14 D 38 C 15 D 39 D 16 C 40 D
2
Unit C2 – 5017/5037 Unit C2 – 5017/5037 Unit C2 – 5017/5037 Topics 5, 6, 7 & 8
Topics 5, 6, 7 & 8
Topics 5, 6, 7 & 8
1 C 17 C 25 A 2 D 18 C 26 C 3 B 19 A 27 A 4 C 20 A 28 C 5 B 21 D 29 B 6 A 22 C 30 C 7 B 23 B 31 A 8 D 24 B 32 C 9 A 33 C 10 B 34 D 11 B 35 A 12 C 36 D 13 C 37 D 14 D 38 A 15 C 39 C 16 A 40 C
3
Unit P2 – 5019/5047 Unit P2 – 5019/5047 Unit P2 – 5019/5047
Topics 9, 10, 11 & 12
Topics 9, 10, 11 & 12
Topics 9, 10, 11 & 12
1 C 17 C 25 B 2 D 18 C 26 A 3 C 19 B 27 D 4 B 20 C 28 A 5 D 21 A 29 A 6 B 22 D 30 C 7 B 23 A 31 D 8 B 24 D 32 B 9 A 33 D 10 D 34 B 11 A 35 C 12 A 36 C 13 A 37 A 14 D 38 B 15 D 39 C 16 B 40 D
4
Structured Papers – March 2008 Using the Mark Scheme 1. This mark scheme gives you; * an idea of the type of response expected * how individual marks are to be awarded * the total mark for each question * examples of responses that should not receive credit. 2. ; separates points for the award of each mark. 3. / means that the responses are alternatives and either answer should receive full credit. 4. ( ) means that a phrase/word is not essential for the award of the mark but helps the examiner to get the sense of the expected answer. 5. Phrases/words in bold indicate that the meaning of the phrase/word is essential to the answer. 6. OWTTE (or words to that effect) and eq (equivalent) indicate that valid alternative answers (which have not been specified) are acceptable. 7. ‘Ignore’ means that this answer is not worth a mark but does not negate an additional correct response. 8. ‘Reject’ means that the answer is wrong and negates any additional correct response for that specific mark. 9. ORA (or reverse argument) indicates that the complete reverse is also valid for the award of marks. 10. ecf (error carried forward) means that a wrong answer given in an earlier part of a question is used correctly in answer to a later part of the same question. Marking 1. You must give a tick (in red) for every mark awarded. The tick must be placed on the script close to the answer. The total mark awarded for a question should be written in the box at the end of the question. 2. The total marks for a question should then transferred to the front of the script. 3. Suggestion/explanation questions should be marked correct even when the suggestion is contained within the explanation. 4. Do not award marks for repetition of the stem of the question. 5. Make sure that the answer makes sense. Do not give credit for correct words/phrases which are put together in a meaningless manner. Answers must be in the correct scientific context. Amplification 1. In calculations, full credit must be given for a bald, correct answer. If a numerical answer is incorrect, look at the working and award marks according to the mark scheme. 2. Consequential marking should be used in calculations. This is where a candidate's working is correct but is based upon a previous error. When consequential marks have been awarded write "ecf" next to the ticks. 3. If candidates use the mole in calculations they must be awarded full marks for a correct answer even though the term may not be on the syllabus at their level.
4. If candidates use chemical formulae instead of chemical names, credit can only be given if the formulae are correct.
5
Additional Science 5016F Biology 5028F
Question Number
Answer Mark
1 glucose; oxygen; (may be reversed) carbon dioxide; water; (may be reversed)
(4)
Question Number
Answer Mark
2 (a) (i) 122 – 124; (1) Question Number
Answer Mark
2 (a) (ii) 11.5 – 13.5; (1) Question Number
Answer Mark
2 (a) (iii) 55 -58; (1) Question Number
Answer Mark
2 (b) (i) increased height / larger / get bigger / taller / weight / mass / number of cells;
(1)
Question Number
Answer Mark
2 (b) (ii) number of cells / mass / weight / bigger; [Ignore dry mass]
(1)
Question Number
Answer Mark
3 (a) 27 or 28; (1)
Question Number
Answer Mark
3 (b) only Jean’s point would also explain why air pollution has increased; first box
(1)
6
Question Number
Answer Mark
3 (c) Any three from: 1. more people; 2. more factories; 3. less trees in urban areas / OWTTE; 4. more power stations; 5. bigger, more polluting cars; 6. need for more energy (power stations); 7. deforestation; 8. forest fires; 9. more CFC’s / more fridge disposal / more aerosols; Accept other correct responses that would cause an increase in air pollution
(3)
Question Number
Answer Mark
4 (a) Any two from: 1. tree/trunk cut off; 2. just above ground level; 3. repeated every few years;
(2)
Question Number
Answer Mark
4 (b) Any two from: 1. stems harvested for use / supply / demand; 2. not all trees are at desired size; 3. provides annual crop / income; 4. correct reference to maintaining biodiversity;
(2)
Question Number
Answer Mark
4 (c) Any two from: 1. lets in more light / increased temperature / more rain / dryer; 2. increased variety of plants can grow; 3. increased habitats for animals;
(2)
Question Number
Answer Mark
5 (a) mitosis; (1) Question Number
Answer Mark
5 (b) Any two from: 1. wound sealed / healed / scab formed; 2. mass / ball of cells; 3. (which are) undifferentiated;
7
4. stem cells / no Hayflick limit; 5. cells grow / regenerate / mitosis / divide; 6. differentiate / examples; [Ignore cells grow larger]
(2)
Question Number
Answer Mark
5 (c) re-grow human limbs / cheaper compared to prosthetics/ better chance of survival if injured/ produce stem cells / must relate newt gene to GM;
(1)
Question Number
Answer Mark
6 (a) photosynthesis; [Reject respiration]
(1)
Question Number
Answer Mark
6 (b) Any two from: 1. idea that percentage of carbon dioxide is not affected (significantly) by a nearby plant/ a tree / enough carbon dioxide to go around; [Ignore lots of carbon dioxide] 2. air movement/ wind means air constantly changing; 3. replaced by respiration / trees make carbon dioxide / decomposition / combustion;
(2)
Question Number
Answer Mark
6 (c) (i) Any two from: 1. sample the soil (under the tree); 2. test nitrate concentrations / levels; 3. link range to test; 4. research what typical nitrate levels are in soil (using books / internet);
(2)
Question Number
Answer Mark
6 (c) (ii) temperature / carbon dioxide levels / water levels / light intensity / other mineral levels / pH / colour or green-ness of plant / density of grass plants in the pots / length or surface area of roots; [Ignore width of stem / dry mass / wet mass]
(1)
TOTAL FOR PAPER: 30 MARKS
8
Additional Science 5016H Biology 5028H
Question Number
Answer Mark
1 (a) mitosis; (1) Question Number
Answer Mark
1 (b) Any two from: 1. wound sealed / healed / scab formed; 2. mass / ball of cells; 3. (which are) undifferentiated; 4. stem cells / no Hayflick limit; 5. cells grow / regenerate / mitosis / divide; 6. differentiate / examples; [Ignore cells grow larger]
(2)
Question Number
Answer Mark
1 (c) re-grow human limbs / cheaper compared to prosthetics/ better chance of survival if injured/ produce stem cells / must relate newt gene to GM;
(1)
Question Number
Answer Mark
2 (a) photosynthesis; [Reject respiration]
(1)
Question Number
Answer Mark
2 (b) Any two from: 1. idea that percentage of carbon dioxide is not affected (significantly) by a nearby plant/ a tree / enough carbon dioxide to go around; [Ignore lots of carbon dioxide] 2. air movement/ wind means air constantly changing; 3. replaced by respiration / trees make carbon dioxide / decomposition / combustion;
(2)
Question Number
Answer Mark
2 (c) (i) Any two from: 1. sample the soil (under the tree); 2. test nitrate concentrations / levels; 3. link range to test; 4. research what typical nitrate levels are in soil (using books / internet);
(2)
9
Question Number
Answer Mark
2 (c) (ii) temperature / carbon dioxide levels / water levels / light intensity / other mineral levels / pH / colour or green-ness of plant / density of grass plants in the pots / length or surface area of roots; [Ignore width of stem / dry mass / wet mass]
(1)
Question Number
Answer Mark
3 (a) all points plotted correctly +/- half a small square; deduct one mark for each incorrectly plotted point; suitable line of best fit;
(2) (1)
Question Number
Answer Mark
3 (b) Any two from: 1. at the top of the fermenter the pH remains steady / at the bottom the pH is more varied; 2. at the bottom of the fermenter as the speed increases the pH falls; 3. credit accurate or detailed description of pupil line e.g. levels off after 40; 4. pH at bottom never falls as low as pH at the top of the fermenter; 5. credit correct manipulation of figures;
(2)
Question Number
Answer Mark
3 (c) to ensure optimum conditions throughout the whole of the fermenter (for the micro organisms) / stops settling / reduces settling / stops or reduce areas where cells die;
(1)
Question Number
Answer Mark
4 (a) less (fossil) fuels/ containing sulphur being burnt / smokeless zones / idea of more efficient scrubbing / cleaning of sulphur dioxide / switching to renewable energy;
(1)
Question Number
Answer Mark
4 (b) lichen diversity increases / it increases / more types of lichen;
(1)
10
Question Number
Answer Mark
5 (a) 50 X 19; 950(m3);
(1) (1)
Question Number
Answer Mark
5 (b) Any two from: 1. light intensity lower (on mars); 2. colder (for algae); 3. leakage of oxygen from biosphere; 4. other organisms may get in;
(2)
Question Number
Answer Mark
5 (c) Any two from: 1. not seasonal; 2. rapid population growth / wheat grows slowly; 3. easily manipulated; 4. uses up waste, e.g. nitrates more effectively; 5. no need for soil/eq; 6. less waste (e.g. straw) after harvesting / less space used / ORA;
(2)
Question Number
Answer Mark
5 (d) (solar panels generate electricity) for heat / warmth / increased light levels for more photosynthesis / enzymes working faster; OR provide light at night so photosynthesis goes on for longer;
(1)
Question Number
Answer Mark
6 Any five from: 1. DNA splits (along a small length) / unwinds / unzips; [Ignore A-T] 2. complimentary base pairs match up; 3. (m)RNA made; 4. (m)RNA leaves nucleus; 5. (m)RNA lies on/attaches to ribosomes; 6. triplets/codons; 7. anticodons pair up; 8. (t)RNA specific to amino acids; [Reject wrong RNA] 9. amino acids joined together; 10. by enzyme (e.g. protein synthetase); [Credit transcription or/and translation if used correctly]
(5)
TOTAL FOR PAPER: 30 MARKS
11
Additional Science 5018F Chemistry 5038F
Question Number
Answer Mark
1(a) alloys; (1) Question Number
Answer Mark
1 (b) electrons; (1) Question Number
Answer Mark
1 (c) malleable; (1) Question Number
Answer Mark
2 (a) exothermic / combustion / oxidation / burning; (1) Question Number
Answer Mark
2 (b) ethane; [Reject ethene]
(1)
3; (1)
C C C CH
H
H H
H
H
HHH
H ; [Allow CH3 CH2 CH2 CH3]
(1)
Question Number
Answer Mark
2 (c) covalent; (1) Question Number
Answer Mark
2 (d) C C/ double bond / / ‘equals sign’; (1) Question Number
Answer Mark
2 (e) polymer; (1) Question Number
Answer Mark
3 (a) electrolysis / (electro)plating / silver plating / reduction / oxidation / redox;
(1)
12
Question Number
Answer Mark
3 (b) (i) atom (or group of atoms) with a (positive or negative) charge / charged particle / atom that has gained or lost electrons;
(1)
Question Number
Answer Mark
3 (b) (ii) AgNO3; [Allow Ag+NO3
− / AgNO3] (1)
Question Number
Answer Mark
3 (b) (iii) positive (ions attracted to negative electrode) / they are cations /opposite charges attract;
(1)
Question Number
Answer Mark
4 (a) reversible; (1) Question Number
Answer Mark
4 (b) 17 / 14 + 1 + 1 + 1 / 14 + (3 x 1); (1) Question Number
Answer Mark
4 (c) increases rate of reaction / speeds up reaction/ can use a lower temperature for the reaction / get ammonia faster / more profit / less energy used;
(1)
Question Number
Answer Mark
4(d) (i) greater yield / faster growth / better growth / more crop / bigger plants / more profit / adds nutrients etc;
(1)
Question Number
Answer Mark
4 (d) (ii) Any two from: 1. (excess) fertiliser washes off land / leaching; 2. pollutes rivers; 3. causes eutrophication; 4. kills wildlife / fish; 5. causes algae to grow in rivers; …. 6. …. which reduces oxygen content of water; 7. pollutes drinking water; 8. Blue baby syndrome;
(2)
13
Question Number
Answer Mark
5 (a) Any two from: 1. non-biodegradable; 2. does not rot; 3. therefore persists; 4. uses up space; 5. toxic decomposition products; 6. toxic substances leached out; 7. animals can be stuck in plastic; 8. any other relevant point;
(2)
Question Number
Answer Mark
5 (b) Any two from: 1. harder to make / shortage of any crude oil product; 2. need new source of crude oil product; 3. prices rise; 4. any other suitable point;
(2)
Question Number
Answer Mark
6 (a) (i) 2,8,7; (1) Question Number
Answer Mark
6 (a) (ii) both same no/seven outer electrons / each short of one outer electron;
(1)
Question Number
Answer Mark
6 (b) Any two from: 1. full outer shell/8 electrons in outer shell; 2. much energy needed to use electrons to form bonds; 3. does not gain/ lose electrons;
(2)
Question Number
Answer Mark
6 (c) (i) 52 / 28 + 24; (1) Question Number
Answer Mark
6 (c) (ii) chromium/ Cr; (1) TOTAL FOR PAPER: 30 MARKS
14
Additional Science 5018H Chemistry 5038H
Question Number
Answer Mark
1 (a) Any two from: 1. non-biodegradable; 2. does not rot; 3. therefore persists; 4. uses up space; 5. toxic decomposition products; 6. toxic substances leached out; 7. animals can be stuck in plastic; 8. any other relevant point;
(2)
Question Number
Answer Mark
1 (b) Any two from: 1. harder to make / shortage of any crude oil product; 2. need new source of crude oil product; 3. prices rise; 4. any other suitable point;
(2)
Question Number
Answer Mark
2 (a) (i) 2,8,7; (1) Question Number
Answer Mark
2 (a) (ii) both same no/seven outer electrons / each short of one outer electron;
(1)
Question Number
Answer Mark
2 (b) Any two from: 1. full outer shell/8 electrons in outer shell; 2. much energy needed to use electrons to form bonds; 3. does not gain/ lose electrons;
(2)
Question Number
Answer Mark
2 (c) (i) 52 / 28 + 24; (1) Question Number
Answer Mark
2 (c) (ii) chromium/ Cr; (1)
15
Question Number
Answer Mark
3 (a) 2 HCl; s, aq, g, l [Allow 1 error]; [Allow S, AQ, G, L]
(2)
Question Number
Answer Mark
3 (b) Any three from: 1. particles gain energy; 2. move faster / more; 3. more collisions; 4. have more (activation) energy; 5. which is energy required for reaction; 6. greater proportion of collisions successful;
(3)
Question Number
Answer Mark
3 (c) measure loss in mass/ volume gas produced / use a datalogger / use balance / use gas syringe / use upward measuring cylinder / time reaction /
use stopwatch / time
quantity;
(1)
Question Number
Answer Mark
4 (a) 1 correct shared pair; rest of molecule correct (with or without inner electrons);
(2)
Question Number
Answer Mark
4 (b) in diamond strong / covalent bonds must be broken; in water only weak IMF / molecules easy to separate;
(2)
Question Number
Answer Mark
4 (c) (H2 = 2 and) H2O = 18; (or 2H2O = 36) ratio 1:1; 20 g 180 g; Or 4 g 36 g;;
20 g 36 x 4
20 = 180 g;
(3)
16
Question Number
Answer Mark
5 (a) all three gases / N2, H2 and NH3 / everything; reaction goes both ways/ reaches equilibrium/ reversible/ does not go to completion;
(2)
Question Number
Answer Mark
5 (b) (i) increases / more (ammonia); (1) Question Number
Answer Mark
5 (b (ii) fewer molecules on RHS / equilibrium moves to RHS; (1) Question Number
Answer Mark
5 (c) Any three from: 1. higher temperature gives lower yield; 2. higher temperature more expensive; 3. lower temperature slower; 4. 400 °C optimum; 5. 400 °C gives good yield; 6. 400 °C gives yield in reasonable time; 7. maximum output under these conditions;
(3)
TOTAL FOR PAPER: 30 MARKS
17
Additional Science 5020F Physics 5048F
Q no. answer allow ignore reject mark 1a Any two from
• low friction (between road surface and tyres)/ slippery;
• unable to produce turning force/OWTTE;
• (tyres) can’t grip the road; • stopping distance increased;
can’t control the car 2
1b
Any two sensible;; e.g. airbag/air cushion crumple zone seat belt
side impact bar a.b.s.
reference to speed 2
electrons; recognisable spellings 1 positive; recognisable spellings 1
repelled; recognisable spellings 1
like OR positive; recognisable spellings (the) same (type of)
1
2a
forces; recognisable spellings 1 2bi Any two from:
• static /charge; • caused by friction; • Phillip is earthed/ORA; • car is charged; • discharged through Phillip;
2
18
2bii Any one from:
• charges ‘leak’ in damp weather/ORA;
• more charge when warm and dry;
• less charge when raining;
1
3ai
Any two from: • n hits U (nucleus); • U (nucleus) becomes unstable; • U (nucleus) splits; • 2 daughter products; • extra n released; • energy released;
high speed of particles
fission fragments 2
3aii kinetic (energy); movement (energy) recognisable spellings
thermal /(heat) 1
3b
fuel rods remain radioactive for a long time after use; fuel rods could be used to help make nuclear weapons; 1 correct tick = 1mark 2 correct ticks = 2marks 1 correct and 1 incorrect =1 mark 2 correct and 1 incorrect = 1 mark 2 or 3 incorrect = 0 marks
2
19
4ai (gravitational) potential energy reduced/transferred/changed; kinetic energy;
stored for potential movement energy for kinetic
2
4aii any two from: requirement for energy to gain ht; idea of energy loss; where energy is lost;
2
4b work done equals electrical energy
spent / V I t; 600 x 25 x 180 OR 2 700 000 /2.7MJ / 2 700 KJ; mark from bottom up
bald correct ans = 2 marks
2
5a more than one tick per horizontal
row negates that row most penetrating – gamma least penetrating – alpha most ionising – alpha least ionising – gamma Any one correct row; (1 mark) All 4 rows correct;;
2
5b gamma most penetrating/greatest range;
least ionising so safer
1
5c protons =27 electrons = 27 neutrons = 33 Any one correct; (1 mark) All 3 correct;;
2
20
5d (performance) cobalt penetration OR time to scan;
x-rays 1
5d (safety) cobalt faster;
X ray lower energy references to penetration
1
TOTAL FOR PAPER: 30 MARKS
21
Additional Science 5020H Physics 5048H
Q no. answer allow ignore reject mark 1a more than one tick per horizontal
row negates that row most penetrating – gamma least penetrating – alpha most ionising – alpha least ionising – gamma Any one correct row; (1 mark) All 4 rows correct;;
2
1b gamma most penetrating/greatest range;
least ionising so safer
1
1c protons =27 electrons = 27 neutrons = 33 Any one correct; (1 mark) All 3 correct;;
2
1d (performance–) cobalt penetration OR time to scan;
X-rays 1
1d (safety –) cobalt faster;
X ray lower energy
references to penetration
1
2ai no mark for f=ma
substitution/ 7.92X0.93; 7.37 (N)/7.4(N);
ecf from incorrect mass (5) 39.6 (40) for 1 mark (5.93) 46.96 (47) for 1 mark
2
2aii backwards /to oppose movement/ to left;
unqualified ‘against the trolley’
1
22
2aiii Any two from: 1. (between) wheels/trolley and bench; 2. friction at the axle(s); 3. (friction at) the pulley; 4. drag/air resistance;
2
2bi mgh no marks substitution / 5 X 10 X 0.6; 30 (J);
ecf from incorrect mass OR incorrect length for 1 mark 35.58/ 5.58/ 3000
2
2bii 30 (J) ecf from 2bi
1
2biii no mark for equation substitution: 30 = 0.5 X 5.93 X v2; 3.18 (m/s)/3.2 (m/s);
ecf from bii or bi 35.58 3.46…….2 marks 5.58 1.372…….2 marks 3000 31.809……2 marks ecf from incorrect mass for 1 mark if 0.93 used 8.032 if 5 used 3.46…CARE Check and allow maximum of 1 error in biii….ecf from bii does not count as an error
2
23
3a 2+ nuclei fuse/join/merge; specific example (H He)
• particles unless qualified by nuclear
• idea of chemical bonding
1
3b Any two from: • high pressure; • high temperature; • high particle density;
high energy levels instead of temperature
suitable/correct temperature suitable/correct pressure
2
4ai (background) radiation/ particles
from the sun or outer space or galaxy; idea of source is needed
very high energy radiation plus consequence (range/penetration)
rays microwave radiation from big bang
1
4aii Any one from • ionises; • produces secondary
particles; • causes mutations/tissue
damage;
• penetration idea • very high energy • mutates DNA • genetic damage • damaging/killing
cells • causes cancer
• confusion with UV, IR etc
• mutates cells
causes skin cancers 1
4bi the greater the altitude the smaller the number of hours flying time/ORA;
inverse relationship (e.g. inversely proportional)
• if dose is not the same
• greater dose at higher altitudes/ ORA
1
4bii idea altitude X flying time ≡ dose; OWTTE credit bii if seen in bi
negative correlation inversely proportional
1
24
4biii atmosphere absorbs radiation/ ORA;
thinner air not closer to space 1
4ci all points; best fit curve;
points not seen decent attempt at curve (some wobble, but must go through at least 4 points)
• “tram” lines • thick lines • definite st lines
2
4cii magnetosphere protects us/ forms ‘barrier’ esp. over equator;
(Earth’s) magnetic field ozone layer 1
4di damage to cells leading to altered growth/ionising babies cells;
birth defects mutation of DNA
cancer mutation of cells
4dii any sensible e.g. transfer to low level flying; transfer to routes over equator; become ground crew;
lead lined clothing fly less frequently
TOTAL FOR PAPER: 30 MARKS
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