Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2015 May/June Paper 3 · Variant 2

This document consists of 30 printed pages and 2 blank pages. DC (AC/SW) 97595/4 © UCLES 2015 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 6 9 4 3 5 9 2 7 7 8 * CO-ORDINATED SCIENCES 0654/32 Paper 3 (Extended) May/June 2015 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. A copy of the Periodic Table is printed on page 32. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

2 0654/32/M/J/15 © UCLES 2015 1 (a) Fig. 1.1 shows a passenger at an airport pulling a suitcase towards the check-in desk. Fig. 1.1 The suitcase has a mass of 18.4 kg and a weight of 180 N. (i) Explain the difference between the terms mass and weight. … … … [2] (ii) Calculate the Earth’s gravitational field strength g in N / kg. g = … N / kg [1] (iii) The suitcase is pulled for a distance of 30 metres using a force of 20 N. Calculate the work done in pulling the suitcase. State the formula that you use and show your working. formula working work done = … J [2]

3 0654/32/M/J/15 © UCLES 2015 [Turn over (iv) Fig. 1.2 shows the suitcase being loaded onto an aircraft using a conveyor belt. The suitcase of mass 18.4 kg is lifted 3.0 m from the ground into the aeroplane. ground aircraft suitcase conveyor belt 3.0 m 10 m Fig. 1.2 Use your answer to (ii) to calculate the increase in the gravitational potential energy of the suitcase. State the formula that you use and show your working. formula working … J [2] (b) An aircraft has a mass of 350 000 kg. It has four engines each of which produces a maximum force of 250 000 N. Calculate the maximum acceleration of the aircraft. State the formula that you use, show your working, and state the unit of your answer. formula working maximum acceleration = … unit … [3]

4 0654/32/M/J/15 © UCLES 2015 2 Sulfur is a yellow crystalline, non-metallic element. Sulfur combines with other elements to form compounds that include magnesium sulfate, MgSO4 hydrogen sulfide, H2S sodium sulfide, Na2S. (a) (i) Suggest reactants that could be used to produce an aqueous solution of the salt, magnesium sulfate. … … [2] (ii) State the names of any other products that are formed in the reaction you have described in (i). … [1]

5 0654/32/M/J/15 © UCLES 2015 [Turn over (b) Hydrogen sulfide is a gaseous compound and sodium sulfide is a solid at room temperature. One of these compounds contains covalent chemical bonds and the other contains ions. Fig. 2.1 shows diagrams of atoms of hydrogen, sodium and sulfur. X X X X X X X X X X X X X X X X X X X X X X X X X X X X hydrogen sodium sulfur Fig. 2.1 Draw bonding diagrams to show how the outer electrons of these atoms are arranged in hydrogen sulfide and sodium sulfide. Your diagrams should show chemical symbols of the elements and ionic charges where appropriate. hydrogen sulfide sodium sulfide [6]

6 0654/32/M/J/15 © UCLES 2015 (c) Petroleum (crude oil) contains dissolved hydrogen sulfide which has to be removed. The symbol equation below shows a reaction that is involved in the removal process. 2 H2S (g) + SO2 (g) 3S (g) + 2 H2O (g) (i) State the total number of hydrogen and sulfur atoms shown on the left hand side (the reactants) of the equation above. hydrogen … sulfur … [1] (ii) Explain why the physical state symbols, (g), show that this reaction occurs at a high temperature. … … … [2]

7 0654/32/M/J/15 © UCLES 2015 [Turn over Please turn over for Question 3.

8 0654/32/M/J/15 © UCLES 2015 3 Fig. 3.1 shows part of the carbon cycle. fossil fuels dead and decaying matter fossilisation decay death death carbon dioxide plants animals Fig. 3.1 (a) Fill in the empty boxes in Fig. 3.1, naming the processes involved in the carbon cycle. Choose words from this list. You may use each word once, more than once, or not at all. breathing combustion decomposition photosynthesis respiration transpiration [4] (b) Add an arrow to Fig. 3.1 to show how animals obtain their carbon. [1]

9 0654/32/M/J/15 © UCLES 2015 [Turn over (c) Explain why an ecosystem needs an external supply of energy from sunlight, but does not need an external supply of carbon atoms. … … … [1] (d) Use the idea of the carbon cycle to suggest an explanation for each of the following. (i) In a deciduous (temperate) forest, the carbon dioxide concentration in the atmosphere falls slightly in spring and summer, and then rises again in the autumn. … … … … [2] (ii) Cutting down rainforests might lead to an increase in the carbon dioxide concentration in the Earth’s atmosphere. … … … [2] (iii) Combustion of fossil fuels is more harmful to the environment than combustion of wood. … … … [2]

10 0654/32/M/J/15 © UCLES 2015 4 (a) Fig. 4.1 shows the chemical symbols of some elements in the first four periods of the Periodic Table. Li K Cu Fe Ne F Br Fig. 4.1 Using only those symbols shown in Fig. 4.1, complete Table 4.1 with the element or elements that match the descriptions in the column on the left. Each symbol may be used once, more than once or not at all. Table 4.1 description element symbol(s) it is a halogen that is more reactive than chlorine it may be used as a catalyst in the Haber Process its atoms have all electron shells filled their atoms have four electron shells they are good electrical conductors they are transition elements [6]

11 0654/32/M/J/15 © UCLES 2015 [Turn over (b) (i) Calculate the mass of 0.2 moles of zinc. The proton number of zinc is 30 and its relative atomic mass may be found in the Periodic Table on page 32. Show your working and state the unit of your answer. … unit … [2] (ii) State what 0.2 moles of zinc has in common with 0.2 moles of any other element. … … [1]

12 0654/32/M/J/15 © UCLES 2015 5 A student measures the heights of all the pupils in her class, and records them to the nearest centimetre. Fig. 5.1 shows her results. 146–150 0 1 2 3 4 5 number of pupils 6 7 8 9 151–155 156–160 161–165 height range / cm 166–170 171–175 176–180 Fig. 5.1 (a) (i) State the most common height range recorded for this group of pupils. … [1] (ii) Calculate the total number of pupils in the class. number of pupils … [1] (b) Name the type of variation shown in Fig. 5.1. … [1]

13 0654/32/M/J/15 © UCLES 2015 [Turn over (c) Two of the pupils in the class are identical twins. This means they developed from the same fertilised egg. Despite this, they are of slightly different heights. (i) Suggest what may have caused them to be of different heights. … … [1] (ii) Explain why these twins, although of slightly different heights, will almost certainly be of very similar heights. … … [1] (d) State two ways in which variation in blood groups in humans is different from variation in height. 1 … 2 … [2]

14 0654/32/M/J/15 © UCLES 2015 6 (a) During car journeys, a car becomes electrostatically charged. This is more obvious on a dry day than on a damp, humid day. On a warm dry day, the potential difference between the driver and the car increases to 10 000 V. (i) Explain what happens to cause the car to become charged. … … … [2] (ii) As the driver touches the car door on a warm and dry day, he gets an electric shock and 24 millijoules (0.024 J) is transferred between the driver and the car. If the discharge lasts for 0.030 milliseconds, calculate the power associated with the discharge. State the formula that you use and show your working. formula working power = … W [2] (iii) Using your answer to (ii) calculate the current which passes through the driver during the discharge. State the formula that you use and show your working. formula working current = … A [2]

15 0654/32/M/J/15 © UCLES 2015 [Turn over (b) A car has two headlamps connected in parallel with each other across a 12 V battery. Each headlamp has a resistance of 3 Ω. Calculate the combined resistance of the two lamps connected in parallel. State the formula that you use and show your working. formula working combined resistance = … Ω [2] (c) A police car uses a blue light and a loud sound from a siren to alert people. (i) State how the sound from the siren changes when the amplitude of the sound waves emitted decreases. … [1] (ii) Sound waves are longitudinal waves but light waves are transverse waves. Describe the difference between a transverse wave and a longitudinal wave. You may draw diagrams if it helps your answer. … … … [2]

16 0654/32/M/J/15 © UCLES 2015 (d) The alternator in the car is an a.c. generator. Fig. 6.1 shows a simple a.c. generator. coil N S a.c. output Fig. 6.1 Describe how the rotation of the coil in the magnetic field and the use of slip rings produce an alternating current. … … … … … [3]

17 0654/32/M/J/15 © UCLES 2015 [Turn over 7 Fig. 7.1 shows four pea seeds inside a pod. The pod is the fruit of the pea plant. One of the pea seeds inside it is shown in section. D E F G A B C seeds Fig. 7.1 Identify which letter in Fig. 7.1 labels a cotyledon, … the fruit wall, … the radicle, … the testa. … [4]

18 0654/32/M/J/15 © UCLES 2015 8 The percentages of chemical elements found in the Earth’s crust and in the Earth’s atmosphere are shown in Fig. 8.1. oxygen silicon 27.7% % of element LQ(DUWK·VFUXVW DOXPLQLXP 8.1% iron 5.0% other elements 12.6% nitrogen oxygen other gases % of element LQWKH(DUWK·V atmosphere Fig. 8.1 (a) Deduce whether the Earth’s crust or atmosphere contains the greater percentage of oxygen. … … [2]

19 0654/32/M/J/15 © UCLES 2015 [Turn over (b) Fig. 8.2 shows the chemical structures of two substances, R and S, that contain oxygen atoms. R S Fig. 8.2 State and explain which structure, R or S, shows a substance that is found in the Earth’s crust and not in the atmosphere. structure … explanation … … … [2] (c) Aluminium and iron are obtained from their oxides. (i) Write a word equation for a reaction in the blast furnace that produces iron from iron oxide. + + [2]

20 0654/32/M/J/15 © UCLES 2015 (ii) Fig. 8.3 shows a simplified diagram of the industrial apparatus that is used to obtain aluminium. – + electrical power supply electrolyte aluminium gas bubbles carbon electrodes Fig. 8.3 Describe how aluminium ions, Al 3+, are changed when they come into contact with the surface of the cathode. … … … [2]

21 0654/32/M/J/15 © UCLES 2015 [Turn over 9 (a) Dolphins communicate with each other under water using sound waves. (i) Sound waves travel through water as a series of compressions and rarefactions. Describe the difference between a compression and a rarefaction. … … [1] (ii) The speed of sound in air is 330 m / s. In water the speed of sound is about 1500 m / s. Suggest why the speed of sound is greater in water than in air. Use ideas about the distances between molecules and the movement of molecules in your answer. … … … … [2] (b) The water in the sea is heated by the Sun. Some molecules of the water evaporate. The water does not boil. State two ways in which boiling differs from evaporation. 1 … … 2 … … [2]

22 0654/32/M/J/15 © UCLES 2015 (c) Fig. 9.1 shows three different ways in which particles may be arranged in substances. A B C Fig. 9.1 Water in the sea is a liquid and water in the air is a gas. (i) State which diagram best represents the way particles are arranged in liquid water. Explain your answer. diagram … explanation … … [1] (ii) State which diagram best represents the way particles are arranged in gaseous air. Explain your answer. diagram … explanation … … [1]

23 0654/32/M/J/15 © UCLES 2015 [Turn over 10 Fig. 10.1 shows a root hair cell from a plant. Fig. 10.1 (a) Name and describe the process by which the root hair cell absorbs water from the soil. name … description … … … [3] (b) State one other function of the root hair cell. … [1] (c) Describe how the shape of a root hair cell helps it to absorb water from the soil. … … [1] (d) Most of the water absorbed by the root hair cell later evaporates from the plant. State where most of this evaporation occurs. … [1] (e) Not all of the water absorbed by a plant is lost by evaporation. Suggest two ways in which a plant might make use of the absorbed water. 1 … 2 … [2] (f) Many plant cells contain chloroplasts. Explain why root hair cells do not contain chloroplasts. … … [1]

24 0654/32/M/J/15 © UCLES 2015 11 Hydrocarbons are described in terms of the homologous series to which they belong. Two homologous series are alkanes and alkenes. Alkanes are found in petroleum (crude oil). Alkenes are produced in the chemical industry. (a) Fig. 11.1 shows the structure of one molecule of a hydrocarbon. H C H C H H C H H C H H Fig. 11.1 (i) State and explain whether this hydrocarbon is an alkane or an alkene. this hydrocarbon is an … explanation … … [1] (ii) Describe what would be observed when this hydrocarbon is shaken with a solution of bromine. … … [1] (b) Describe the process by which alkenes are manufactured in the chemical industry. name of process … description … … … … [4]

25 0654/32/M/J/15 © UCLES 2015 [Turn over (c) When gaseous ethene, C2H4, at a high pressure is heated with a catalyst, it reacts to produce a white solid. The relative molecular masses of ethene and the white solid are shown below. ethene white solid relative molecular mass 28 200 000 (an average value) (i) Show that the relative molecular mass of ethene is 28. [1] (ii) Explain why the white solid has a much higher relative molecular mass than ethene. You may draw a diagram to show what happens in the reaction if it will help you to answer this question. … … … [2] (iii) Suggest why only an average value rather than an exact value for the relative molecular mass of the white solid can be stated. … … … [2]

26 0654/32/M/J/15 © UCLES 2015 12 Table 12.1 shows the death rates from coronary heart disease in two different countries between 2010 and 2013. Table 12.1 year deaths per 100 000 people country A country B 2010 125 144 2011 114 146 2012 120 137 2013 98 145 (a) State two ways in which the death rate from coronary heart disease in country B differs from that in country A. 1 … 2 … [2] (b) In country B, the average age of the population is greater. Explain why this would affect the death rate from coronary heart disease. … … … [1] (c) State two ways in which a person’s diet could increase their chance of suffering from coronary heart disease. 1 … 2 … [2] (d) Suggest two other possible reasons (apart from differences of age or diet) for the difference in the rates of coronary heart disease in these two countries. 1 … 2 … [2] (e) Explain why, when comparing the two countries, it is important to express the death rates per 100 000 people, instead of just giving the total number of deaths in each country. … … [1]

27 0654/32/M/J/15 © UCLES 2015 [Turn over 13 (a) A doctor uses both X-rays and γ-(gamma) rays in a hospital. (i) X-rays and γ-rays are both part of the electromagnetic spectrum. Write each one in its correct box on the incomplete electromagnetic spectrum below. radio waves infra-red ultraviolet increasing frequency [2] (ii) State the speed of all electromagnetic waves in km / s. … km / s [1] (b) To study the blood flow in a patient’s lungs, the patient is injected with a radioactive isotope, technetium-99. The γ-radiation given out by the technetium-99 is detected using a gamma camera outside the patient’s body. (i) Identify all of the statements that explain why γ-radiation is used for this investigation. Place a tick in the correct box or boxes. It can pass through the human body. It destroys cancer cells. It is safer than α- or β-radiation. [1]

28 0654/32/M/J/15 © UCLES 2015 (ii) The label shown in Fig. 13.1 gives some information about the radioactive isotope technetium-99. type of radiation emitted – gamma half life – 6 hours use as a medical tracer Fig. 13.1 The graph in Fig. 13.2 is incomplete. It should show the count rate from a sample of technetium-99 changing with time. At the start, the count rate is 400 counts per minute. This point is plotted on the graph. Plot points to show the count rate after one half-life, after two half-lives and after three half-lives and then draw a smooth curve linking the plotted points. time / hours count rate counts / min 0 0 50 100 150 200 250 300 350 400 450 2 4 6 8 10 12 14 16 18 20 Fig. 13.2 [3]

29 0654/32/M/J/15 © UCLES 2015 (c) Optical fibres are used to see inside the human stomach. Light is sent along a bundle of fibres to enable the doctor to see what is in the stomach. Fig. 13.3 shows an endoscope being used by the doctor to see inside a patient’s stomach. It contains a bundle of optical fibres. optical fibres light in eyepiece lens GRFWRU·VH\H stomach Fig. 13.3 The sentences in Table 13.1 describe how an endoscope allows the doctor to see inside a patient’s stomach. These sentences are in the wrong order. Write the numbers 2, 3, 4 and 5 in the right hand column to indicate the correct order of the sentences. The sentence for the first stage has been identified for you. Table 13.1 A bundle of optical fibres takes the light to an eyepiece lens. Light passes through a bundle of optical fibres into the patient’s stomach. 1 The doctor looks through the eyepiece lens to see the inside of the patient’s stomach. The inside of the stomach reflects some of the light. The reflected light passes into a bundle of optical fibres. [2]

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32 0654/32/M/J/15 © UCLES 2015 Group The Periodic Table of the Elements 140 Ce Cerium 58 141 Pr Praseodymium 59 144 Nd Neodymium 60 Pm Promethium 61 150 Sm Samarium 62 152 Eu Europium 63 157 Gd Gadolinium 64 159 Tb Terbium 65 162 Dy Dysprosium 66 165 Ho Holmium 67 167 Er Erbium 68 169 Tm Thulium 69 173 Yb Ytterbium 70 175 Lu Lutetium 71 232 Th Thorium 90 Pa Protactinium 91 238 231 147 237 244 243 247 247 251 252 257 258 259 260 U Uranium 92 Np Neptunium 93 Pu Plutonium 94 Am Americium 95 Cm Curium 96 Bk Berkelium 97 Cf Californium 98 Es Einsteinium 99 Fm Fermium 100 Md Mendelevium 101 No Nobelium 102 Lr Lawrencium 103 1 H Hydrogen 1 7 Li Lithium 3 23 Na Sodium 11 24 Mg Magnesium 12 40 Ca Calcium 20 45 Sc Scandium 21 48 Ti Titanium 22 51 V Vanadium 23 52 Cr Chromium 24 55 Mn Manganese 25 56 Fe Iron 26 59 Co Cobalt 27 59 Ni Nickel 28 64 Cu Copper 29 65 Zn Zinc 30 70 Ga Gallium 31 27 Al Aluminium 13 11 B Boron 5 12 C Carbon 6 14 N Nitrogen 7 16 O Oxygen 8 19 F Fluorine 9 28 Si Silicon 14 31 P Phosphorus 15 32 S Sulfur 16 35.5 Cl Chlorine 17 40 Ar Argon 18 20 Ne Neon 10 4 He Helium 2 73 Ge Germanium 32 75 As Arsenic 33 79 Se Selenium 34 80 Br Bromine 35 84 Kr Krypton 36 39 K Potassium 19 88 Sr Strontium 38 89 Y Yttrium 39 91 Zr Zirconium 40 93 Nb Niobium 41 96 Mo Molybdenum 42 Tc Technetium 43 101 Ru Ruthenium 44 103 Rh Rhodium 45 106 Pd Palladium 46 108 Ag Silver 47 112 Cd Cadmium 48 115 In Indium 49 119 Sn Tin 50 122 Sb Antimony 51 128 Te Tellurium 52 127 I Iodine 53 131 Xe Xenon 54 137 Ba Barium 56 139 La Lanthanum 57 * 178 Hf Hafnium 72 181 Ta Tantalum 73 184 W Tungsten 74 186 Re Rhenium 75 190 Os Osmium 76 192 Ir Iridium 77 195 Pt Platinum 78 197 Au Gold 79 201 Hg Mercury 80 204 Tl Thallium 81 207 Pb Lead 82 209 209 210 222 Bi Bismuth 83 Po Polonium 84 At Astatine 85 Rn Radon 86 Fr Francium 87 227 Ac Actinium 89 † 9 Be Beryllium 4 I II III IV V VI VII 0 85 Rb Rubidium 37 133 Cs Caesium 55 226 223 Ra Radium 88 a X b a = relative atomic mass X = atomic symbol b = atomic (proton) number Key DATA SHEET * 58–71 Lanthanoid series † 90–103 Actinoid series The volume of one mole of any gas is 24dm3 at room temperature and pressure (r.t.p.). To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series.

® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the May/June 2015 series 0654 CO-ORDINATED SCIENCES 0654/32 Paper 3 (Extended Theory), maximum raw mark 120 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 1 (a) (i) mass is a measure of amount of matter in an object; [max 2] weight is the gravitational force pulling on the object; mass will be the same throughout the universe but weight will depend on gravitational field strength; (ii) 180/18.4 =9.78 (N/kg); [1] (iii) (work =) force x distance ; = 20x 30 = 600 (J); [2] (iv) (potential energy =) mgh; = 18.4 x 9.78 x 3.0 = 539.9 (J); [2] (allow ecf from (ii)) (b) force = mass x acceleration; [3] acceleration = 4 x 250 000 = 2.86; 350 000 m/s2; [Total: 10] 2 (a) (i) (dilute) sulfuric acid ; [2] magnesium / magnesium oxide / magnesium carbonate / magnesium hydrogen carbonate / magnesium hydroxide; (ii) if Mg then hydrogen / H2 (reject H) [1] if MgO / Mg(OH)2 then water / H2O if MgCO3 then carbon dioxide and water / CO2 and H2O if Mg(HCO3)2 then carbon dioxide and water / CO2 and H2O;

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 (b) hydrogen sulfide [3] (H2S) 2 shared pairs; 2 lone pairs; full outer shell for atoms shown and correct symbols; sodium sulfide [3] (Na2S) correct ionic charges; correct ratio of ions; correct number of electrons in each outer shell; (c) (i) hydrogen 4 [1] sulphur 3 both required: (ii) state symbol (g) indicates gaseous state; [2] both sulfur / water are only gases at high temperature / owtte; [Total: 12]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 3 (a) (labels, from top left) [4] photosynthesis; respiration; respiration; combustion; (b) arrow from plants to animals; [1] (c) energy, is not recycled / does not circulate / has linear flow / ORA; [1] (d) (i) more photosynthesis (than respiration and decay) in spring/summer; [2] more decay/respiration (than photosynthesis) in autumn; (ii) less photosynthesis ; [2] which removes CO2 (from atmosphere); (iii) combustion of fossil fuels increases atmospheric CO2; [max 2] combustion of wood balanced by (recent) photosynthesis; combustion of fossil fuels produces SO2 / acid rain; [Total: 12 marks]

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 4 (a) [6] description element symbol(s) it is a halogen that is more reactive than chlorine F it may be used as a catalyst in the Haber Process Fe its atoms have all electron shells filled Ne their atoms have four electron shells K Fe Cu Br they are good electrical conductors Li K Fe Cu they are transition elements Fe Cu 1 mark for each completely correct box; ; ; ; ; ; (b) (i) Ar Zn = 65 ; [2] 65 x 0.2 = 13 g ; (unit required) (ii) the same number of particles / atoms / molecules ; [1] [Total: 9]

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 5 (a) (i) 156–160 (cm) ; [1] (ii) 30 ; [1] (b) continuous; [1] (c) (i) different environments qualified / different diets / mutation / AVP ; [1] (ii) they have the same genotype / height depends (partly) on genes / genotype ; [1] (d) shows discontinuous variation / distinct categories ; [max 2] entirely genetic / not affected by environment ; limited number of phenotypes ; [Total: 7 marks]

Page 7 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 6 (a) (i) friction; [2] transfer of electrons / charges; (ii) (power =) energy / time; [2] = 24 x 10-3 / 3 x 10-5 = 800 (W); (iii) power = voltage x current; [2] current = 800 / 10 000 = 0.08 (A); (e.c.f. from (a)(ii)) (b) 1/RT = 1/R1 + 1/R2 or (RT =) R1R2/R1 + R2; [2] RT = 1.5 (Ω); (c) (i) quieter; [1] (ii) transverse wave, oscillate / vibrate, at right angles to direction of movement of, [2] wave energy transfer; longitudinal wave, oscillate / vibrate, parallel to direction of movement of, wave / energy transfer; longitudinal waves have compressions and rarefactions / longitudinal waves need a medium; (d) (rotating) coil cuts magnetic field / experiences a changing magnetic field; [max 3] induces emf; slip rings conduct current / slip rings avoid wires tangling; emf / current, reverses every half turn; [Total: 14] 7 G; B; E; C; [Total: 4 marks]

Page 8 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 8 (a) (% O in Earths crust is bigger) [max 2] % O in air is 21% ; % O in crust is 100 – (27.7 + 8.1 + 5.0 + 12.6) = 46.6% ; use of bar chart ; (b) (R) [max 2] R (probably) is a solid ; S is a gas ; R is a giant structure ; (c) (i) iron oxide + carbon monoxide → iron + carbon dioxide ; ; [2] (ii) (each ion) gains electrons ; [max 2] (each gains) three electrons ; converted from ions into atoms / ions are discharged ; Al3+ + 3e- → Al ; ; [Total: 8] 9 (a) (i) compression – region of high pressure / particles are closer together / particles are [1] more dense ; OR rarefaction – region of low pressure / particles more spread out / particles less dense ; (ii) particles closer together ; particles, pass on vibrations / collide, more quickly / time between collisions shorter ; [2] (b) evaporation can occur at any temperature / boiling only happens at the boiling point ; [max 2] evaporation happens only at the surface / boiling happens throughout the liquid ; boiling takes energy in (endothermic) to occur / evaporation lets only the molecules with the highest kinetic energy out ; evaporation can occur using the internal energy of the system / while boiling requires an (external) source of heat ; evaporation produces cooling / boiling does not produce cooling ; evaporation is a slow process / boiling is a rapid process ; (c) (i) B because most particles are touching / closely packed and randomly arranged ; [1] (ii) C because particles are widely spaced and randomly arranged ; [1] [Total: 7]

Page 9 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 10 (a) osmosis (allow: diffusion) ; [3] through partially permeable (cell) membrane ; down water potential gradient; (b) absorbs / intake of mineral ions / nitrate (ions) / magnesium (ions) / [1] other named mineral ion ; (c) creates large surface area ; [1] (d) leaves / stomata ; [1] (e) for photosynthesis ; [max 2] as part of cytoplasm / for growth ; support / turgor ; for transport (of ions / sugars) ; (f) because underground / no light ; [1] [Total: 9 marks]

Page 10 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 11 (a) (i) (alkene) [1] reference to the double bond / has the general formula CnH2n; (ii) bromine is decolourised / orange to colourless ; [1] (b) (thermal / catalytic) cracking ; [4] (feedstock is) alkanes ; (alkanes) are heated / vaporised ; in presence of a catalyst / at high pressure ; (c) (i) Mr ethene = (2 x 12) + (4 x 1) ; [1] (ii) (addition) polymerisation occurs ; ethene molecules join to form (long) chains ; OR [2] correct symbol representation e.g. n C2H4 → –(C2H4)n– scores both marks (iii) many chains / polymer molecules are formed ; chains vary in length ; [2] [Total: 11]

Page 11 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 12 (a) higher rate ; [2] not decreasing ; (b) people more likely to suffer CHD as they get older ; [max 1] younger people more likely to die of other causes ; (c) too much food / energy, leading to obesity ; [max 2] too much (saturated) fat ; too much salt ; (d) differences in smoking rates ; [max 2] differences in stress ; different amounts of exercise ; genetic differences ; more / fewer deaths from other causes / differences in health care ; ref to differences in education ; (e) different population sizes ; [max 1] [Total: 8 marks]

Page 12 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 32 13 (a) (i) [2] ; ; (ii) 3 x 105 (km/s) ; [1] (b) (i) both statements ticked ; [1] It can pass through the human body. It is safer than α or β radiation. (ii) first point plotted ; [3] 2nd and third points plotted ; smooth curve not reaching axis ; (c) [2] ; ; [Total: 9] A bundle of optical fibres takes the light to an eyepiece lens 4 Light passes through a bundle of optical fibres into the patient’s stomach 1 The doctor looks through the eye-piece lens to see the inside of the patient’s stomach 5 The inside of the stomach reflects some of the light 2 The reflected light passes into a bundle of optical fibres 3