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

This document consists of 31 printed pages and 1 blank page. DC (CW/FD) 104348/3 © UCLES 2015 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 8 6 7 9 2 8 0 7 4 4 * CO-ORDINATED SCIENCES 0654/32 Paper 3 (Extended) October/November 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/O/N/15 © UCLES 2015 1 Fig. 1.1 shows a compost bin. Gardeners use these bins to produce compost which is a useful fertiliser for plants. They put weeds, dead leaves and other garden waste into the bin. Over time, these break down to produce the fertiliser. removable lid garden waste placed in here compost bin fertiliser is removed here Fig. 1.1 (a) (i) Name the type of organism that breaks down the garden waste into fertiliser for plants. …[1] (ii) Name two substances in the fertiliser that plants can use. 1 … 2 …[2]

3 0654/32/O/N/15 © UCLES 2015 [Turn over (b) The organisms that break down the garden waste are respiring aerobically and anaerobically. (i) Name two substances that they might produce in anaerobic respiration. 1 … 2 …[2] (ii) Suggest two things that a gardener could do to help the organisms in the compost bin to respire quickly and aerobically. 1 … 2 …[2] (c) On farms, crop plants must be given fertiliser if the crop is to grow well year after year. However, plants in natural ecosystems can grow each year without the need for any fertiliser. Explain why natural ecosystems do not need fertiliser. … …[1]

4 0654/32/O/N/15 © UCLES 2015 2 The reactivity series shows metallic elements in order of their reactivities. This series also contains hydrogen because it has some chemical properties similar to metals. (a) Fig. 2.1 shows apparatus and materials a student uses to investigate the reactivity of an unknown metal J. $ % & ' metal - copper sulfate solution dilute hydrochloric acid magnesium sulfate solution zinc sulfate solution metal - Fig. 2.1 She places a small piece of metal J into each of four test-tubes A, B, C and D. Table 2.1 shows her observations. Table 2.1 test-tube test-tube contents observation with metal J A copper sulfate solution orange-brown solid forms on metal J B dilute hydrochloric acid gas given off slowly C magnesium sulfate solution no reaction D zinc sulfate solution no reaction (i) Use the results in Table 2.1 and your knowledge of the reactivity series to place the five elements, copper, hydrogen, J, magnesium and zinc into order of reactivity. 1 … (most reactive element) 2 … 3 … 4 … 5 … (least reactive element) [2]

5 0654/32/O/N/15 © UCLES 2015 [Turn over (ii) Reduction and oxidation (redox) are terms used to describe chemical reactions that involve the transfer of electrons between particles. Using the ideas of electron transfer, atoms and ions, deduce which particles are reduced during the reaction in test-tube A as shown in Table 2.1. particles that are reduced … explanation … … … …[3] (b) Fig. 2.2 shows a diamond set into a ring made of an alloy of gold. diamond ring made of an alloy of gold Fig. 2.2 (i) The alloy of gold contains many gold atoms with fewer atoms of a different metal. In the box below, draw a sketch to show the arrangement of the atoms in this alloy. Your diagram should include at least fifteen gold atoms. key atom of gold atom of a different metal [2]

6 0654/32/O/N/15 © UCLES 2015 (ii) Diamond is made up of carbon atoms. The mass of a diamond can be measured in units known as carats. A diamond of one carat has a mass of 0.2 grams. Calculate the number of moles of carbon that are contained in a diamond of 186 carats. Show your working. number of moles … [2]

7 0654/32/O/N/15 © UCLES 2015 [Turn over 3 (a) Fig. 3.1 shows a speed / time graph for a train. 0 0 5 10 15 20 25 30 50 100 150 time / s speed m / s 200 250 300 Fig. 3.1 (i) Calculate the distance travelled by the train between 0 s and 250 s. State the unit. Show your working. distance = … unit … [3] (ii) The mass of the train is 500 000 kg. Calculate the kinetic energy of the train in kilojoules, when it is travelling at 20 m / s. State the formula that you use and show your working. formula working kinetic energy = … kJ [2]

8 0654/32/O/N/15 © UCLES 2015 (b) The track for the train is composed of steel rails. Steel has a density of 7.80 g / cm3 at 20 °C. (i) State how the density of steel changes when the temperature rises to 35 °C. Explain why this happens in terms of particles. … … … … …[3] (ii) The steel rails are made from steel blocks. Each block is a cube with sides of 50 cm. Calculate the mass of one of these steel blocks in kilograms when the temperature is 20 °C. Show your working. mass = … kg [3]

9 0654/32/O/N/15 © UCLES 2015 [Turn over 4 Fig . 4.1 shows a liquid fossil fuel being extracted from rock layers beneath the sea bed. layers of rock liquid fossil fuel drilling rig sea bed Fig. 4.1 (a) Name the fossil fuel being extracted. …[1]

10 0654/32/O/N/15 © UCLES 2015 (b) The material extracted from the rock is a mixture of hydrocarbons. Fractional distillation is the process used to separate simpler, more useful mixtures from the fossil fuel. Fig. 4.2 shows a simplified diagram of industrial fractional distillation. 400 °C 40 °C 3 4 5 tower used for fractional distillation fraction hot fossil fuel Fig. 4.2 Fig. 4.2 shows three fractions, P, Q and R, collecting at different heights in the tower. Explain in terms of boiling temperatures and sizes of molecules why different fractions collect at different heights in the tower. … … … … … [3]

11 0654/32/O/N/15 © UCLES 2015 [Turn over (c) Fig. 4.3 shows a simplified diagram of another industrial process involving hydrocarbons. mixture of large alkane molecules heat catalyst mixture of small alkane and alkene molecules Fig. 4.3 (i) Name the process shown in Fig. 4.3. …[1] (ii) Describe a chemical test for an unsaturated hydrocarbon. State the result. test … … result … …[2] (iii) Suggest how the test you have described in (c) (ii) could be used to show that the process shown in Fig. 4.3 produces alkenes. … … …[2]

12 0654/32/O/N/15 © UCLES 2015 5 (a) Define the term nutrition. … … …[2] (b) (i) State what is meant by malnutrition. … …[1] (ii) Describe how malnutrition may result in obesity. … …[1] (c) Fig. 5.1 shows how the percentage of overweight children in a European country changed between 1950 and 2010. 1950 0 10 20 30 percentage overweight children / % 1960 1970 1980 1990 2000 year 2010 Fig. 5.1 (i) Describe how the percentage of overweight children changed between 1950 and 2010. … … … …[2]

13 0654/32/O/N/15 © UCLES 2015 [Turn over (ii) Suggest a reason for this change. … …[1] (iii) State two health problems that may occur in later life if a person is overweight. 1 … 2 …[2] (d) A person’s health will suffer if they do not get enough essential vitamins in their diet, such as vitamin D. (i) State the function of vitamin D in the body. … …[1] (ii) Name one food that is a good source of vitamin D. …[1] (iii) Describe the effects on the body of a shortage of vitamin D. … … …[2]

14 0654/32/O/N/15 © UCLES 2015 6 (a) Fig. 6.1 shows a cyclist approaching a corner. The cyclist is unable to see car C approaching from around the corner unless he uses the mirror positioned at X. mirror cyclist car C X Fig. 6.1 Fig. 6.2 shows the same situation viewed from above. wall cyclist X car C Fig. 6.2 A ray of light is drawn from the car to the cyclist reflecting at point X. On Fig. 6.2 draw the mirror at X at the correct angle. [1]

15 0654/32/O/N/15 © UCLES 2015 [Turn over (b) A reflector on the back of the bicycle is made from many small glass prisms, one of which is shown in Fig. 6.3. 45° P glass prism Fig. 6.3 A ray of light is incident on the back surface of the prism at point P at an angle of 45°. The critical angle for glass is 42°. Explain why light does not leave the prism at point P. … …[1] (c) Bicycle wheels can be made from steel or an aluminium alloy. Suggest a simple way of testing whether a wheel is made from steel or aluminium alloy. … …[1]

16 0654/32/O/N/15 © UCLES 2015 (d) The cyclist has a puncture which he repairs. He pumps up the flat tyre. Each pump stroke takes 90 cm3 of air at a pressure of 1 × 105 Pa and pushes it into the tyre. When fully inflated, the tyre contains 1600 cm3 of air at room temperature and at a pressure of 2 × 105 Pa. Assume that the temperature of the air does not change. (i) Show that the volume of air from the pump required to inflate the tyre fully is 3200 cm3. State the formula that you use and show your working. formula working [2] (ii) Calculate the number of pump strokes needed to pump in 3200 cm3 of air. Show your working. number of pump strokes = … [1]

17 0654/32/O/N/15 © UCLES 2015 [Turn over 7 Fig. 7.1 shows a sperm cell. Sperm cells are male gametes. Fig. 7.1 (a) On Fig. 7.1, label the nucleus and the cell membrane of the sperm cell. [2] (b) Male gametes are mobile but female gametes are not. State two other differences between male and female gametes. 1 … 2 …[2] (c) Fig. 7.2 shows how the mobility of sperm cells varies with temperature. 10 0 50 75 100 15 20 temperature / °C percentage of maximum mobility / % 25 30 Fig. 7.2 (i) State the temperature at which the sperm cells are most mobile. …[1] (ii) Energy for the movement of the sperm comes from respiration. Suggest why the sperm cells are less mobile at 10 °C than at 15 °C. … …[1] (iii) Use the information in Fig. 7.2 to predict the mobility of the sperm cells at 5 °C. …[1]

18 0654/32/O/N/15 © UCLES 2015 (d) Human core body temperature is 37 °C. Use this information and the information in Fig. 7.2 to explain (i) what would be the effect on sperm mobility if the testes were located inside the main body cavity, … …[1] (ii) the advantage of the testes being located in the scrotum, … …[1] (iii) what would be the effect of increased sperm temperature on a man’s fertility. … …[1]

19 0654/32/O/N/15 © UCLES 2015 [Turn over 8 (a) Two cars A and B are left in the hot sun during the day. Car A is painted black and car B is painted white. car A painted black car B painted white Fig. 8.1 Energy from the sun heats both cars. (i) State the method of energy transfer between the Sun and the Earth. …[1] (ii) Suggest which car will have the greater temperature change. Explain your answer. … …[1] (b) Car A has two headlights. The lamp inside each headlight is connected in parallel with the other across a 12 V battery. (i) The current passing through each of the lamps is 4.8 A. Show that the resistance of each lamp is 2.5 Ω. State the formula that you use and show your working. formula working [2] (ii) Calculate the combined resistance of the two lamps, each of resistance 2.5 Ω connected in parallel. State the formula that you use and show your working. formula working resistance = … Ω [2]

20 0654/32/O/N/15 © UCLES 2015 (c) Some cars are fitted with proximity detectors to warn the driver when the car is too close to other objects. These detectors use ultrasound. Fig. 8.2 shows a car fitted with an ultrasound proximity detector. car Fig. 8.2 (i) The ultrasound waves used have a frequency of 40 000 Hz. This means that they are usually outside the audible range of a human. Write down the normal audible human range. … Hz to … Hz [1] (ii) An ultrasound wave is emitted from the sensor in the car and the wave, reflected from a nearby object, is received 0.002 s later. The speed of ultrasound waves in air is 34 000 cm / s. Calculate the distance of the car from the nearby object. State the formula that you use and show your working. formula working distance = … cm [2]

21 0654/32/O/N/15 © UCLES 2015 [Turn over (iii) Use information from (c) (i) and (ii) to calculate the wavelength of the ultrasound waves in metres. State the formula that you use and show your working. formula working wavelength = … m [2] (iv) The ultrasound waves pass through the air as a series of compressions (C) and rarefactions (R). Fig. 8.3 shows the positions of the compressions and rarefactions as the ultrasound wave passes through the air. C C C C C C R R R R R Fig. 8.3 Suggest how and explain why the positions of the compressions and rarefactions change when the frequency of the ultrasound decreases. … … …[2]

22 0654/32/O/N/15 © UCLES 2015 9 Nitrogen is an element in Group V of the Periodic Table. (a) (i) State the electron configuration of a nitrogen atom. …[1] (ii) Explain why the nitride ion, N3–, has an electrical charge of 3–. … … …[2] (iii) Magnesium nitride is an ionic compound that forms when magnesium burns in air. The symbol and charge of a magnesium ion is Mg2+. Deduce the chemical formula of magnesium nitride. Show your working. chemical formula = … [2]

23 0654/32/O/N/15 © UCLES 2015 [Turn over (b) Fig. 9.1 shows apparatus which can be used to make ammonia, NH3. The piston of gas syringe A is pushed in slowly, and the mixture of nitrogen, N2, and hydrogen, H2, moves through the small pieces of heated iron into gas syringe B. gas syringes iron heat mixture of nitrogen and hydrogen mixture containing ammonia piston heat A A B B Fig. 9.1 Some nitrogen reacts with hydrogen on the surface of the heated iron. (i) Construct a balanced equation for the reaction between nitrogen and hydrogen. …[1] (ii) Describe a chemical test used to show that ammonia is produced. State the result of this test. test … result … …[2] (iii) The iron in this reaction acts as a catalyst. Suggest in terms of molecular collisions why the iron is in the form of many small pieces. … … … …[2]

24 0654/32/O/N/15 © UCLES 2015 10 (a) (i) A nuclear power station generates 800 MW of power from a power input of 2400 MW. Calculate the efficiency of the power station. State the formula that you use and show your working. formula working efficiency = … % [2] (ii) In a nuclear power station, fission of uranium-235 nuclei takes place to release energy. A different nuclear process takes place in the Sun to release energy from hydrogen nuclei. Describe what happens to the hydrogen nuclei in the process that takes place in the Sun. … …[1] (b) In a nuclear power station, technicians work close to radioactive sources. These sources emit α-radiation, β-radiation and γ-radiation. (i) State which of these radiations is part of the electromagnetic spectrum. …[1] (ii) State which of these radiations is not deflected by an electric field. Explain your answer. radiation … explanation … …[1]

25 0654/32/O/N/15 © UCLES 2015 [Turn over (c) Large generators are used in power stations to produce electricity. The voltage needs to be increased before transmission. This is done using a transformer, which increases the voltage from 25 000 V to 400 000 V. (i) Explain why high voltages are used for the transmission of electric power. … … …[2] (ii) Fig. 10.1 shows the simplified structure of a transformer. primary coil secondary coil output 400 000 V 25 000 V input iron core Fig. 10.1 Describe how the transformer works to change the voltage. … … … … … …[3]

26 0654/32/O/N/15 © UCLES 2015 11 Fig. 11.1 shows parts of the gas exchange surfaces of a leaf and a lung. blood capillary mesophyll cells moisture nucleus chloroplast cell wall moisture from a lung from a leaf alveolus nucleus Fig. 11.1 (a) (i) Using the information in Fig. 11.1, state two ways in which both of these surfaces are adapted for efficient gas exchange. 1 … 2 …[2] (ii) Using the information in Fig. 11.1, state one feature of the gas exchange surface of the alveolus which is not found in the leaf. … …[1] (b) For the leaf, (i) name the gas that is entering the cells from the air during a period of bright sunlight, …[1] (ii) name the process by which this gas moves into the cells. …[1]

27 0654/32/O/N/15 © UCLES 2015 [Turn over (c) Emphysema is a disease caused by smoking. Fig. 11.2 shows how the alveoli of the lungs change in emphysema. normal alveolus alveolus in emphysema Fig. 11.2 (i) Describe and explain the effect of this change on the functioning of the lungs. … … …[2] (ii) State two other harmful effects of smoking on the gas exchange system. 1 … 2 …[2]

28 0654/32/O/N/15 © UCLES 2015 12 (a) Fig. 12.1 shows a small piece of potassium being added to water containing full-range indicator solution (Universal Indicator). beaker water containing full-range indicator potassium Fig. 12.1 (i) The balanced chemical equation for the reaction between potassium and water is shown below. 2K(s) + 2H2O(l) 2KOH(aq) + H2(g) From the four substances shown in the equation select one example of an element and one example of a compound. Explain your answers. element … explanation … … compound … explanation … … [2] (ii) Explain why the equation in (a) (i) is described as balanced. … …[1]

29 0654/32/O/N/15 © UCLES 2015 [Turn over (iii) State the meaning of the state symbols (l) and (aq). state symbol (l) … … state symbol (aq) … …[2] (iv) When potassium reacts with water, the colour of the full range indicator changes. Describe and explain this change. … … …[2] (v) During the reaction between potassium and water, the piece of potassium melts and a lilac-coloured flame appears. Explain these two observations. … … … …[2]

30 0654/32/O/N/15 © UCLES 2015 (b) Chloramine, NH2Cl, is a compound that is added to water to kill harmful microorganisms. Fig. 12.2 shows the outer shell electrons in one molecule of chloramine. + 1 + &l electron key Fig. 12.2 (i) On Fig. 12.2, draw a label line to a single covalent bond. Label the bond using the letter S. [1] (ii) Explain the arrangement of electrons shown in Fig. 12.2. … … …[2]

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32 0654/32/O/N/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 October/November 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 October/November 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 – October/November 2015 0654 32 © Cambridge International Examinations 2015 1 (a) (i) (named) decomposer ; [1] (ii) nitrate ; phosphate ; potassium ; magnesium ; other named essential mineral ion ; [max 2] (b) (i) carbon dioxide ; ethanol ; [max 2] (ii) keep the compost bin warm ; mix / aerate the compost ; break up compost into smaller pieces ; [max 2] (c) dead matter recycled / (nutrients in) crop not being removed ; [1] [Total: 8] 2 (a) (i) magnesium zinc J hydrogen copper ;; [2] (ii) copper ions ; brown deposit made of copper atoms ; copper ions gain electrons ; gain of electrons is reduction ; [max 3] (b) (i) regular arrangement of gold atoms ; interspersed with fewer of the different atom ; [2] (ii) mass of diamond in grams = 186 × 0.2 = 37.2 g ; moles C = 12 37.2 = 3.1 (moles) ; [2] [Total: 9] 3 (a) (i) distance = area under graph (or working on graph) ; = 25 × 100 + ½ × 150 × 25 = 4375 ; m ; [3] (ii) (KE =) ½ mv2 ; = ½ x 500 000 × 20 × 20 = 100 000 000 (J) = 100 000 (kJ) ; [2]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 32 © Cambridge International Examinations 2015 (b) (i) density decreases ; mass does not change ; kinetic energy of particles increases / speed of particles increases ; particles move further apart ; [max 3] (ii) volume = 125 000 cm3 ; mass = 7.8 × 125 000 = 975 000 g ; = 975 (kg) ; [3] [Total: 11] 4 (a) petroleum / crude oil ; [1] (b) reference to fractions having different boiling ranges / points ; reference to smaller molecules in materials with lower boiling points ; reference to the temperature gradient in the tower ; reference to collection of fraction at heights corresponding to boiling point ; [max 3] (c) (i) cracking ; [1] (ii) (react with) bromine (solution / liquid) ; decolourised if hydrocarbon is unsaturated ; [2] (iii) the idea of applying the test before and after the cracking ; the result that decolourisation only occurs following the cracking process ; [2] [Total: 9] 5 (a) taking in nutrients / organic substances / mineral ions ; containing raw materials / energy ; absorbing / assimilating them ; [max 2] (b) (i) unbalanced diet / wrong amount of some part of the diet ; [1] (ii) too much energy / too much fatty food / too much carbohydrate / sugar so (human) body (makes /) stores as fat ; [1] (c) (i) increases ; after 1970 / no increase before 1970 ; from 5% to 21–22% / by 16–17% ; [max 2] (ii) more available / fast food ; people take less exercise ; [max 1] (iii) diabetes ; arthritis ; (coronary) heart disease ; high blood pressure / cholesterol ; reduced fertility ; cancer ; [max 2]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 32 © Cambridge International Examinations 2015 (d) (i) making / maintaining bones ; absorbing / using calcium ; [max 1] (ii) egg / liver / (oily) fish / milk / other milk products ; [1] (iii) rickets ; soft / brittle bones / ‘bending’ of legs ; [2] [Total: 13] 6 (a) mirror drawn at suitable angle ; [1] (b) total internal reflection / angle of incidence greater than critical angle; [1] (c) steel will be attracted to magnet / aluminium alloy will not be attracted; [1] (d) (i) P1V1 = P2V2 ; V1 = 1 2 2 P V P = 2 × 105 × 1 1600 × 105 (= 3200 cm3) ; [2] (ii) number of strokes = 90 3200 = 35.55 so 36 ; [1] [Total: 6] 7 (a) [2] (b) male gametes smaller / ORA ; male gametes produced in larger numbers / ORA ; male gametes elongated shape / ORA ; [max 3] (c) (i) 20 °C ; [1] (ii) lower rate of respiration / enzymes less active / less kinetic energy for enzymes ; [1] (iii) any suggestion below 62.5% ; [1] cell membrane ; nucleus ;

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 32 © Cambridge International Examinations 2015 (d) (i) less mobile, because too warm ; [1] (ii) sperms are more mobile as they are outside the body cavity and therefore cooler / owtte ; [1] (iii) reduced, because sperm mobility reduced ; [1] [Total: 10] 8 (a) (i) radiation ; [1] (ii) car A / black car – black surfaces absorb heat more ; [1] (b) (i) (R) = I V ; = 4.8 12 = (2.5 (Ω)) ; [2] (ii) 2 1 T R 1 R 1 R 1 + = ; resistance (RT) = 1.25 (Ω) ; [2] (c) (i) 20 (Hz) to 20 000 (Hz) ; [1] (both needed for mark) (ii) (distance =) speed × time ; = 34 000 × 2 0.002 = 34 (cm); [2] (iii) v = f × λ ; wavelength = 000 40 340 = 0.0085 (m) ; [2] (iv) compressions further apart ; larger wavelength ; [2] [Total: 13] 9 (a) (i) 2,5 ; [1] (ii) reference to completion of outer shell ; so now 3 more electrons than protons / ion has 3 more negative electrons compared to the neutral atom ; [2] (iii) Mg3N2 ; reference to charge balance ; [2]

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 32 © Cambridge International Examinations 2015 (b) (i) N2 + 3H2 → 2NH3 ; [1] (ii) use of damp, red litmus paper / universal indicator paper ; colour change to blue / purple ; OR use of hydrogen chloride gas ; white smoke / ammonium chloride ; [max 2] (iii) increases the surface area (of the catalyst) ; increases the frequency that gas molecules collide with the catalyst ; [2] [Total: 10] 10 (a) (i) (efficiency =) in (power) energy useful out (power) energy useful ; = 2400 800 = 0.33 × 100 = 33(%) ; [2] (ii) nuclear fusion / nuclei join together (to release energy) ; [1] (b) (i) γ-radiation ; [1] (ii) (γ-radiation / gamma – no mark if no explanation given) not charged particles so not affected by electric field ; [1] (c) (i) to reduce energy / power losses ; high voltage means low current ; [2] (ii) number of primary coils less than number of secondary ; reference to a.c. / alternating current ; changing magnetic field induces secondary voltage; reference to changing current leading to change in magnetic field ; [max 3] [Total: 10] 11 (a) (i) folded / large surface area ; thin / permeable ; moist ; [max 2] (ii) has blood vessels / (blood) capillaries ; [1] (b) (i) carbon dioxide ; [1] (ii) diffusion ; [1]

Page 7 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 32 © Cambridge International Examinations 2015 (c) (i) slower gas exchange / oxygen uptake ; (because) less surface area ; [2] (ii) cancer ; bronchitis ; asthma ; coughing / excess mucus ; increased risk of colds / sore throat / etc. ; AVP ; (do not accept references to CHD etc.) [max 2] [Total: 9] 12 (a) (i) (element: K or H) cannot be simplified / contains atoms with same proton number / contains only one type of atom ; (compound potassium hydroxide or water) made of different types of atom bonded together / can be simplified / broken into elements ; [2] (ii) same numbers of each type of atom on both sides ; [1] (iii) state symbol: (l) refers to a (single) liquid substance / (liquid containing only one type of molecule) ; state symbol: (aq) refers to a solution of a substance in water ; [2] (iv) green to purple / blue ; potassium hydroxide is an alkali / solution becomes alkaline / pH increases ; [2] (v) reaction is exothermic / heat given off ; hydrogen gas ignites ; [2] (b) (i) line clearly drawn to any shared pair and labelled with an S ; [1] (ii) each atom becomes stable if it can gain complete valence shell / owtte ; complete shells achieved by sharing electrons in pairs ; other detail e.g. H full shell has two electrons the other elements have eight ; [max 2] [Total: 12]