Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2013 May/June Paper 3 · Variant 2

This document consists of 30 printed pages and 2 blank pages. IB13 06_0654_32/4RP © UCLES 2013 [Turn over *1788880769* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/32 Paper 3 (Extended) May/June 2013 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 a pencil for any diagrams or graphs. 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 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 1 Most of the elements in the Periodic Table can be classified as either metals or non-metals. Fig. 1.1 shows the elements in Group 4 of the Periodic Table. Si Ge C Sn Pb Fig. 1.1 (a) Use the classification of metal or non-metal to describe how the Group 4 elements differ from both Group 1 (alkali metals) and Group 7 (halogens). [2] (b) Carbon occurs naturally in the Earth’s crust as the uncombined element. Diamond and graphite are different forms of carbon (carbon allotropes) that have very different physical properties. A small section of the structure of one of the carbon allotropes is shown in Fig. 1.2. carbon atoms covalent bonds Fig. 1.2 State and explain one use of the carbon allotrope shown in Fig. 1.2. [2]

3 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (c) Fig. 1.3 shows apparatus used to extract lead from lead oxide, PbO. hydrogen gas heat lead oxide U-tube excess hydrogen being burnt cold water water condensing inside U-tube Fig. 1.3 (i) Construct a balanced symbolic equation for the reaction between hydrogen and lead oxide. [2] (ii) Suggest why the method shown in Fig. 1.3 could not be used to extract calcium from calcium oxide. [2]

4 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 2 (a) An elephant of mass 5000 kg exerts a constant force of 1400 N to push a tree trunk along at a steady speed of 1.5 m / s. (i) Calculate the work done by the elephant when the tree trunk moves 10 m. State the formula that you use and show your working. formula working [2] (ii) Calculate the kinetic energy of the elephant when it is moving at 1.5 m / s. State the formula that you use and show your working. formula working [2]

5 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (b) The elephant has a weight of 50 000 N and stands with all four feet in contact with the ground. Each foot of the elephant has an area of 0.2 m2. Calculate the pressure exerted by the elephant on the ground. State the formula that you use and show your working. formula working [2] (c) The volume of the elephant is 5 m3. Its mass is 5000 kg. Calculate the density of the elephant. State the formula that you use and show your working. formula working [2]

6 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 3 Fig. 3.1 shows an animal cell just before it divides. cell membrane cytoplasm chromosome Fig. 3.1 (a) Define the term chromosome. [2] (b) The cell in Fig. 3.1 is a diploid cell. State the number of chromosomes that there will be in each of the daughter cells if this cell divides by mitosis, meiosis. [2] (c) Describe the roles of mitosis in an animal's body. [2]

7 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (d) Some cattle have horns, but other cattle do not. This is determined by a gene that has two alleles. The recessive allele, h, produces horns. (i) Complete Table 3.1 to show the phenotypes of cattle with each of the possible genotypes for this gene. Table 3.1 genotype phenotype HH Hh hh [2] (ii) A farmer has a bull with no horns. He wants to make sure that the bull does not have the recessive allele, h, for horns. Suggest and explain what the farmer can do to find out whether the bull has the allele h. You should use a genetic diagram as part of your answer. [4]

8 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 4 Fig. 4.1 shows a microwave oven. The energy of microwaves is used to cook food by heating up the water molecules in the food. Fig. 4.1 (a) A student heated some water in a microwave oven for five minutes. Fig. 4.2 shows how the temperature of the water changed. 100 50 0 0 1 2 time / minutes temperature / °C 3 4 5 Fig. 4.2 The temperature of the water stops increasing after two minutes. Explain what happened to the water molecules during the five minutes. [3]

9 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (b) 0.5 kg of water is heated in the microwave from 10 °C to 50 °C. The specific heating capacity of water is 4200 J / kg °C. Calculate the energy needed to heat the water. State the formula that you use and show your working. formula used working [3] (c) The following label is found on a cooker that combines a microwave oven and a grill. voltage 220 V microwave power 0.60 kW grill power 1.20 kW Some meat is cooked using both the microwave oven and the grill. Both are switched on at full power for 30 minutes. Calculate the total energy transferred by the cooker. Show your working. [3]

10 © UCLES 2013 0654/32/M/J/13 For Examiner's Use (d) Fig. 4.3 shows a reed relay being used in the door of a microwave oven. 88:88 magnet in edge of door reed relay in microwave generator circuit Fig. 4.3 Describe how the relay ensures that the oven only operates when the oven door is shut. [2]

11 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use 5 (a) When sodium is burned in air a mixture of solid products, which contains the ionic compound sodium oxide, is produced. Fig. 5.1 shows diagrams of a sodium atom and an oxygen atom as they exist just before sodium oxide starts to form. Na O Fig. 5.1 (i) Describe how sodium and oxygen atoms become bonded together. Your answer should explain why the formula of sodium oxide is Na2O. [3] (ii) Describe two differences in the properties of a typical ionic compound and a typical covalent compound. 1 2 [2]

12 © UCLES 2013 0654/32/M/J/13 For Examiner's Use (b) Fig. 5.2 shows apparatus a student used to investigate the electrolysis of dilute sulfuric acid. gas P hydrogen dilute sulfuric acid A variable resistor d.c. power supply + – Fig. 5.2 The variable resistor was included in the electrolysis circuit so that the student could alter the current. Table 5.1 shows some of the measurements the student made in his investigation. Table 5.1 experiment number current / A time current was passed / seconds volume of hydrogen collected / cm3 1 0.48 400 24 2 0.24 400 12 (i) Name gas P. [1]

13 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (ii) Calculate the rate at which hydrogen was produced in experiment 1. Show your working and state the units. [2] (iii) Calculate the number of moles of hydrogen produced in experiment 2. Assume that the volume of one mole of a gas under the conditions of the experiment is 24 dm3. Show your working. [2] (iv) All dilute solutions of acids contain hydrogen ions, H+. Explain the difference between the results for experiments 1 and 2 in terms of electrons, ions, atoms and electric current. [3]

14 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 6 Fig. 6.1 shows a section through a blood capillary. cell A cell B Fig. 6.1 (a) Describe how cell A transports oxygen. [2] (b) Explain how the structure of the blood capillary helps oxygen to be provided easily to the body tissues. [2] (c) Describe the function of cell B. [2]

15 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use 7 (a) A resistor of 1200 Ω is connected in parallel with another resistor of 2400 Ω. Calculate the combined resistance of these two resistors. State the formula that you use and show your working. formula working [3] (b) Torches (flashlights) are usually powered by electrical cells. They can also be powered by energy from the Sun (solar energy). Solar energy is a renewable energy resource. (i) Write the energy resources below into Table 7.1 to show which are renewable and which are non-renewable. coal geothermal hydroelectric natural gas oil tidal wave wind Table 7.1 renewable resource non-renewable resource [1] (ii) Name the process that releases energy within the Sun. [1]

16 © UCLES 2013 0654/32/M/J/13 For Examiner's Use (iii) Energy is transferred from the Sun to the Earth by radiation. Explain why energy cannot be transferred from the Sun to the Earth by conduction. [1] (c) Fig. 7.1 shows a torch that works without electrical cells. X Y electric storage device powerful magnet large coil of wire Fig. 7.1 To use the torch, it is first shaken for 40 seconds. This moves the magnet backwards and forwards inside the torch. The magnet can move between points X and Y. Explain why shaking the torch produces an electric current. [4]

17 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use 8 (a) The ovary of a flower contains one or more ovules. The ovules contain female gametes. After fertilisation, an ovule becomes a seed containing an embryo plant. Fig. 8.1 shows a pea seed developing inside a pod. pea seed A B C Fig. 8.1 (i) Explain the meaning of each of the following terms. gamete fertilisation [2] (ii) Parts A and B in Fig. 8.1 remain from the flower. State the name and function of each of these parts in the flower. name of part A function name of part B function [4] (iii) Suggest the part of the flower from which structure C developed. [1]

18 © UCLES 2013 0654/32/M/J/13 For Examiner's Use (b) A pea seed was planted in a pot. When the seed had grown into a young plant, the pot was placed on its side in a room where light was coming from all sides. Fig. 8.2 shows the young pea plant three days after the pot had been placed on its side. Fig. 8.2 (i) Name the response shown by the pea plant in Fig. 8.2. [2] (ii) Suggest how this response will help the plant to reproduce sexually when it has grown to maturity. [2]

19 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (iii) On one of the days when the pot was placed on its side, a scientist measured • the increase in length of the upper surface and the lower surface of the stem of the pea plant, • the concentration of auxin in the cells on the upper surface and lower surface of the stem of the pea plant. His results are shown in Fig. 8.3. 8 7 6 5 4 3 2 1 0 0 20 time / minutes 40 60 % change in length 1.5 1.0 0.5 0 upper surface part of plant lower surface concentration of auxin / arbitrary units lower lower surface surface upper upper surface surface lower surface upper surface Fig. 8.3 Use the results in Fig. 8.3 to explain what has caused the stem of the pea plant to grow upwards. [3]

20 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 9 (a) Nylon is a synthetic polymer which can be made by mixing solutions as shown in Fig. 9.1. The simplified diagrams of molecules show the compounds that are contained in the solutions. N H H H N H C O O H H O C O nylon Fig. 9.1 (i) What general name is given to small molecules that link together to form polymers? [1] (ii) Draw a short section of the nylon molecule that forms when the molecules shown in Fig. 9.1 react together. Use the same symbols that are used in Fig. 9.1. [3] (iii) State • the full name of the type of chemical reaction that occurs to form nylon, • the chemical formula of the compound which is produced in addition to nylon (the by-product). [2]

21 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (b) Proteins are polymers that occur in nature. (i) Name the type of compounds that link together to form proteins. [1] (ii) Describe briefly how the polymer chains in proteins may be broken down into small molecules. [2] (iii) Name the type of chemical reaction which occurs in (ii). [1]

22 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 10 (a) X-rays and γ (gamma) rays are both examples of ionising radiation. Explain what is meant by the term ionising radiation. [1] (b) Fig. 10.1 is a graph showing how the count rate of a radioactive isotope decreases with time. 1400 1200 1000 800 600 400 200 0 count rate / counts per minute 0 100 200 300 time / minutes 400 500 600 Fig. 10.1

23 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (i) Calculate the half-life of this isotope. Show your working. [2] (ii) What percentage of the original radioactive nuclei will still be present after 250 minutes? Show your working. % [2]

24 © UCLES 2013 0654/32/M/J/13 For Examiner's Use (c) A teacher demonstrated how the count rate detected by a Geiger-Müller tube depends on the distance between the front of the tube and a radioactive α (alpha) source. Fig. 10.2 shows how the equipment was set up. d cable to counter radioactive α source Geiger-Müller tube d = distance between source and Geiger-Müller tube Fig. 10.2 Fig. 10.3 shows a graph of the results of the experiment. 200 100 0 0 2 4 d / cm count rate / counts per minute 6 8 Fig. 10.3 (i) State the range of the alpha particles. [1] (ii) Describe how you would use the apparatus to obtain these results. [3]

25 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use (iii) Before carrying out the experiment the teacher discussed how to reduce her exposure to radiation. Which idea below would not help reduce the radiation exposure of the teacher during the experiment? Explain your answer. idea 1 Hold the source with long tongs and wear gloves. idea 2 Place a lead shield between the source and the teacher. idea 3 Wear a photographic badge that detects radiation. idea because [2]

26 © UCLES 2013 0654/32/M/J/13 For Examiner's Use 11 Fig. 11.1 shows a food chain. The arrows show how energy flows from one organism to another along the chain. man sheep grass Fig. 11.1 (a) The grass is the producer in this food chain. Explain how plants produce a supply of chemical energy at the start of the food chain. [4] (b) Energy is lost between the trophic levels in a food chain. Describe one way in which energy is lost from this food chain. [2] (c) Outline how the cells in the man's body obtain useful energy from the food that has been digested and absorbed into them. [2]

27 © UCLES 2013 0654/32/M/J/13 [Turn over For Examiner's Use 12 (a) A student added a solution of the same dilute acid to each of the test-tubes P to T shown in Fig. 12.1. P magnesium Q magnesium carbonate R copper carbonate S copper oxide T alkaline solution containing litmus Fig. 12.1 Complete Table 12.1 by matching the test-tubes, P, Q, R, S and T, with the observations which are made when the dilute acid reacts with the contents. Some of the observations apply to more than one of the test-tubes. You may use each letter once, more than once or not at all. Table 12.1 observations test-tube(s) The mixture turns red when excess acid has been added. A colourless gas is given off. A blue solution is formed. A colourless gas which pops when ignited is given off. [4]

28 © UCLES 2013 0654/32/M/J/13 For Examiner's Use (b) The student used the apparatus shown in Fig. 12.2 to investigate neutralisation reactions involving two acids, A and B. sodium hydroxide solution pH sensor acid Fig. 12.2 In each experiment, 25.0 cm3 of the same solution of sodium hydroxide were placed into a beaker. The acid was added at a constant rate until it was in excess. The measurements were displayed on the computer screen as a graph of pH of the reaction mixture against volume of acid that had been added. The results for the two acids are shown in Fig. 12.3. 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 80 pH of reaction mixture 0 10 20 30 40 volume of acid added / cm3 50 60 70 A B Fig.12.3

29 © UCLES 2013 0654/32/M/J/13 For Examiner's Use (i) Describe how the pH of the mixture in the beaker changes as the volume of acid A increases. [2] (ii) The student found that 12.5 cm3 of acid A and 62.5 cm3 of acid B were needed to neutralise the sodium hydroxide in the beaker. Explain how the student obtains these results from the graph shown in Fig. 12.3. [1] (iii) Acids A and B are different concentrations of hydrochloric acid, HCl. Acid B had a concentration of 1.0 mol / dm3. Use the results the student obtained to calculate the concentration of acid A. Explain your answer briefly. [2]

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32 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. © UCLES 2013 0654/32/M/J/13 Group 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 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 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 Ra Radium 88 The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). a X b a = relative atomic mass X = atomic symbol b = proton (atomic) number Key *58-71 Lanthanoid series 90-103 Actinoid series DATA SHEET The Periodic Table of the Elements

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2013 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 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

Page 2 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 32 © Cambridge International Examinations 2013 1 (a) Group 1 elements all metals and Group 7 elements all non-metals ; Group 4 elements non-metals at top and metals at bottom / contain both types of element ; [2] (b) as electrode e.g. in dry cell or electrolysis ; because graphite is an electrical conductor ; OR as a lubricant ; layers of carbon atoms easily slide / move past each other ; [max 2] (c) (i) PbO + H2 Pb + H2O ;; (LHS ; RHS ;) [2] (ii) calcium has a high reactivity / too reactive ; (calcium reactivity) greater than hydrogen / hydrogen cannot displace Ca ; calcium too strongly bonded to oxygen ; [max 2] [Total: 8] 2 (a) (i) (W =) F × D or F × d or F × s ; = 1400 × 10 = 14 000 J ; [2] (ii) (KE =) ½ mv2; = ½ × 5000 × 1.5 × 1.5 = 5625 J ; [2] (b) (pressure =) force / area or F/A ; = 50000 / 0.8 = 62500 N / m2 ; [2] (c) (density =) mass / volume or m/v ; = 5000 / 5 = 1000 kg / m3 ; [2] [Total 8] 3 (a) (thread of) DNA ; (contains) genes ; [2] (b) four / 4 ; two / 2 ; [2] (c) produces (genetically) identical cells ; for growth (not growth of cells) ; for repair (not repair of cells) ; for replacement of cells ; [max 2]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 32 © Cambridge International Examinations 2013 (d) (i) HH = no horns Hh = no horns hh = horns (all three correct 2 marks, one or two correct 1 mark) ;; [2] (ii) breed the bull with a cow with horns ; if any offspring have horns then the bull has the h allele ; possible genotypes of bull shown as HH or Hh ; genotype of cow shown as hh ; possible gametes of heterozygous bull shown as H and h ; possible offspring of heterozygous bull shown as Hh and hh ; [4 max] [Total: 12] 4 (a) energy is input throughout 5 minutes / at constant rate ; up to 100 °C / for first 2 minutes increase in the kinetic energy of the particles (in liquid) ; water boils at 100 °C / after 2 minutes ; energy used to separate water molecules/break forces/bonds between molecules (not for more KE) ; correct reference to Latent Heat ; [max 3] (b) (energy =) mc∆T or msθ or mass × SHC × change in temperature ; ∆T= 40 ; energy = 0.5 × 4200 × 40 = 84000 J ; [3] (c) (total power =) 1.8 (kW) / 1800 (W); energy = power × time / 1800 × 30 × 60 ; = 3 240 000 J ; [3] (d) magnet (in door) turns reed relay on / attracts / pulls / repels relay / reed relay acts as switch ; (which) completes the (microwave generator) circuit ; magnet is only close enough to affect relay when door is closed / owtte ; [max 2] [Total: 11] 5 (a) (i) sodium atom loses an electron / outer shell ; oxygen atom gains two electrons / fills outer shell ; idea that two electrons provided by two sodium atoms ; reference to ions formed ; attraction between positive and negative ions ; (a diagram clearly showing the ‘loss and gain’ of electrons and correct symbols is worth 2 marks) [max 3] (ii) ionic always solid (at room temperature) / covalent can be liquids and gases / ionic higher melting point or boiling point ; ionic (often) soluble in water / covalent (tend to be) insoluble in water ; ionic can form electrolytes / covalent cannot be electrolytes ; [max 2]

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 32 © Cambridge International Examinations 2013 (b) (i) oxygen ; [1] (ii) 24 ÷ 400 / 0.06 ; cm3 per second ; [2] (iii) 12 ÷ 24000 ; 0.0005 / 5 × 10–4 ; [2] (iv) when current less the rate of gas production is less ; (at cathode) hydrogen ions gain electrons / hydrogen is discharged ; current is rate of flow of electrons ; so if electrons arriving at cathode (per second) is halved then H+ discharging (per second) ; is halved / rate of discharge is proportional to current ; [max 3] [Total: 13] 6 (a) reference to haemoglobin ; haemoglobin combines with oxygen ; picks up oxygen in lungs / alveoli and drops it in tissues ; [max 2] (b) very narrow ; so red blood cell always close to, the wall / the body tissues ; so red blood cell takes longer to pass (for better diffusion) ; OR thin / one cell thick walls ; so oxygen can diffuse through quickly ; [max 2] (c) protection against disease / destroys invading microorganisms / bacteria ; phagocytosis / description of process ; [2] [Total: 6] 7 (a) 2 1 R 1 + R 1 R 1 = OR ) R + (R R × R =) (R 2 1 2 1 ; 2400 3 2400 1 1200 1 = + = ; R = 800 Ω ; [3]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 32 © Cambridge International Examinations 2013 (b) (i) renewable resource non-renewable resource geothermal coal tidal oil wave natural gas wind hydroelectric ; [1] (ii) (nuclear) fusion ; [1] (iii) (conduction) requires particles / a medium ; only radiation can pass through a vacuum ; [max 1] (c) magnet moves through coil ; magnetic field (around coil) ; magnetic field changes, lines of magnetic force are cut by coils ; this induces voltage ; [4] [Total: 10] 8 (a) (i) gamete a sex cell ; fertilisation joining of nuclei of, male and female gametes / sex cells ; [2] (ii) (A) sepal ; protects flower when in bud ; (B) anther / stamen ; produces pollen / male gametes ; [4] (iii) ovary (wall) ; [1] (b) (i) tropism ; (negative) geotropism / gravitropism ; [2] (ii) flowers held up ; where insects can reach them ; [2] (iii) lower surface has grown more than upper surface ; use of figures from first graph ; auxin concentrates on lower surface / higher concentration lower surface ; use of figures from second graph / deduction that auxin has moved away from upper surface ; more auxin causes more growth ; [max 3] [Total: 14]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 32 © Cambridge International Examinations 2013 9 (a) (i) monomers [1] (ii) different monomers joined (in some way) ; correctly joined (peptide type linkage) ; bond continuation shown ; (diagram below gains 3 marks) [max 3] (iii) condensation polymerisation ; H2O ; [2] (b) (i) amino acids ; [1] (ii) heat ; aqueous acid / alkali ; OR enzymes / biological catalysts ; at optimum temperature or pH ; [max 2] (iii) (acid / alkaline) hydrolysis ; [1] [Total 10] 10 (a) removes electrons from atoms / turns atoms into ions ; (b) (i) 150 minutes ; working ; [2] (ii) 400 / 1280 ; 31.3(%) ; [2] (c) (i) 5 cm ; [1] (ii) measure separation / distance and record count rate ; measure count for one minute ; repeat reading and take mean ; change separation / distance and repeat ; reference to dealing with background radiation ; [max 3] (iii) wear a photographic film badge / idea 3 ; this only detects radiation / does not provide protection ; [2] [Total: 11]

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 32 © Cambridge International Examinations 2013 11 (a) photosynthesis ; changes light energy to chemical energy ; light energy absorbed by chlorophyll ; water combined with carbon dioxide ; carbohydrates produced ; carbohydrates contain chemical energy ; [max 4] (b) respiration ; energy lost as heat ; OR not all organisms eaten / not all parts of organisms eaten / dies before eaten ; e.g. sheep does not eat grass roots / human does not eat sheep's feet / other relevant example ; idea that this energy goes into decomposer food chain ; OR not all food digested ; so some not absorbed into organism's body / some lost in faeces ; idea that this energy goes into decomposer food chain ; [max 2] (c) respiration ; glucose, oxidised / broken down / energy released from glucose ; [2] [Total: 8] 12 (a) T ; P Q R ; R (S) ; P ; [4] (b) (i) decreases slowly (at start and end) ; followed by rapid decrease / steep fall ; use of data ; [max 2] (ii) these are the volumes at pH 7 / owtte ; [1] (iii) 5 mol / dm3 ; 62.5 ÷ 12.5 = 5 (× the volume of B is required compared to A) ; so acid A is five times more concentrated (allow stronger) ; [max 2] [Total: 9]