Cambridge IGCSE Science - Combined 0653 — 2012 May/June Paper 3 · Variant 2

This document consists of 19 printed pages and 1 blank page. IB12 06_0653_32/5RP © UCLES 2012 [Turn over *0352851970* For Examiner's Use 1 2 3 4 5 6 7 8 9 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMBINED SCIENCE 0653/32 Paper 3 (Extended) May/June 2012 1 hour 15 minutes 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 soft pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. A copy of the Periodic Table is printed on page 20. 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. www.XtremePapers.com

2 © UCLES 2012 0653/32/M/J/12 For Examiner's Use 1 (a) Most atoms of metallic elements found in the Earth’s crust exist in compounds called ores which are contained in rocks. The chemical formulae of some metal compounds found in ores together with the names of the ores are shown below. argentite Ag2S chromite FeCr2O4 galena PbS scheelite CaWO4 (i) A binary compound is one that contains only two different elements. State which of the compounds in the list above are binary compounds. [1] (ii) State the ore from which the metallic element tungsten could be extracted. [1] (b) Fig. 1.1 shows an incomplete diagram of an atom of an element Q in which only the outer shell electrons are shown. Fig. 1.1 (i) Name element Q and explain your answer. name explanation [3]

3 © UCLES 2012 0653/32/M/J/12 [Turn over For Examiner's Use (ii) Element Q combines with hydrogen to form covalent molecules which have the formula QH4. Complete the bonding diagram below to show how the bonding electrons are arranged. [2] (iii) Element Q may be extracted from its oxide, QO2, in a reaction with carbon, C. In this reaction, the compound carbon monoxide, CO, is formed in addition to the free element Q. Suggest a balanced symbol equation for this reaction. [2]

4 © UCLES 2012 0653/32/M/J/12 For Examiner's Use 2 An athlete warms up by running along a race track. (a) He accelerates from rest and after 10 seconds reaches a maximum speed of 7 m / s. He continues at this speed for another 10 seconds. During the next 5 seconds, he steadily slows down and stops. Draw a speed-time graph to show the motion of the athlete. [3] (b) He then competes in a 200 m running race. (i) He completes the race in 25 seconds. Calculate his average speed. State the formula that you use and show your working. formula used working [2]

5 © UCLES 2012 0653/32/M/J/12 [Turn over For Examiner's Use (ii) The mass of the athlete is 70 kg. Calculate the kinetic energy of the athlete when he is travelling at 6 m / s. State the formula that you use and show your working. formula used working [2] (c) During a race the athlete cools down by sweating. (i) Describe and explain, in terms of the movement of water molecules, how evaporation cools down the athlete. [3] (ii) State two factors which would increase the rate of evaporation. and [1]

6 © UCLES 2012 0653/32/M/J/12 For Examiner's Use 3 (a) Define the term respiration. [2] (b) State the balanced symbolic equation for aerobic respiration. [2] (c) Outline how oxygen is transported to a respiring cell in a muscle. [2]

7 © UCLES 2012 0653/32/M/J/12 [Turn over For Examiner's Use 4 (a) Radio waves are electromagnetic waves. Sound waves are not. State two other ways in which radio waves differ from sound waves. 1 2 [2] (b) Draw lines to connect each type of radiation to its use. radiation gamma microwave infra-red X-rays use examining bones and teeth remote controls for television sets satellite communications sterilising surgical instruments [2] (c) Visible light is another type of electromagnetic wave. The frequency of green light is 5 x 1014 Hz. The wavelength of green light is 6 x 10-7 m. Calculate the speed of green light. State the formula that you use and show your working. formula used working [2]

8 © UCLES 2012 0653/32/M/J/12 For Examiner's Use (d) Describe how to find the density of a small irregular object such as a tooth. [3]

9 © UCLES 2012 0653/32/M/J/12 [Turn over For Examiner's Use 5 Water supplies are often impure and have to be purified to make them safe for humans to drink. (a) State one way that harmful bacteria may be removed from water during purification. [1] (b) Water is a compound which contains the elements hydrogen and oxygen. Describe one difference, other than physical state, between the compound water and a mixture of the elements hydrogen and oxygen. [2] (c) Table 5.1 shows information about water and three compounds that can form mixtures with water. Table 5.1 compound melting point / °C boiling point / °C solubility in water water 0 100 – sodium chloride 801 1413 soluble silicon dioxide 1650 2230 insoluble hexane –95 69 insoluble (i) State which compound in Table 5.1 could be separated from a mixture with water by filtration. [1] (ii) Explain why the other two compounds cannot be separated from a mixture with water by filtration. [2]

10 © UCLES 2012 0653/32/M/J/12 For Examiner's Use (d) (i) A student was asked to use the reaction between the insoluble compound zinc carbonate and dilute sulfuric acid to make a solution that contained only the salt zinc sulfate. Describe the main steps of a method the student should use to carry out this task. You may draw labelled diagrams if it helps you to answer this question. [3] (ii) Suggest the word chemical equation for the reaction between zinc carbonate and dilute sulfuric acid. [2]

11 © UCLES 2012 0653/32/M/J/12 [Turn over For Examiner's Use 6 (a) A car tyre is inflated with air using a footpump. The mechanic using the footpump notices that the pump gets hot. The air going into the tyre is warmed up by the pumping. Describe what happens to the motion of the air molecules as the air warms up. [1] (b) Many forces act on a car tyre during a car journey. State three effects that forces can have on an object. 1 2 3 [2] (c) Car brake lights (stop lights) light up when the driver presses on the footbrake pedal. The pedal acts as a switch. Draw a circuit diagram including a battery to show how this works. Design your circuit so that, if one brake light fails, the other still lights up. [4]

12 © UCLES 2012 0653/32/M/J/12 For Examiner's Use 7 Hawksbill turtles are an endangered species. Adults spend most of their lives at sea, but the females come ashore to lay their eggs. They bury their eggs in nests in the sand, either on a beach or in the vegetation that grows just behind the beach. sand sea The sex of hawksbill turtles is determined by the temperature of the sand in which the eggs develop. • At 29 °C, equal numbers of males and females develop. • Higher temperatures produce more females. • Lower temperatures produce more males. There is concern that in recent years too many female turtles have been produced, and not enough males. (a) Researchers measured the temperature, at a depth of 30 cm, in four different parts of a beach, on Antigua, where hawksbill turtles lay their eggs. The results are shown in Fig. 7.1. The tops of the bars represent the mean temperature. 30.0 29.0 28.0 27.0 open sand low vegetation part of beach edge of forest forest mean temperature / °C Fig. 7.1

13 © UCLES 2012 0653/32/M/J/12 [Turn over For Examiner's Use With reference to Fig. 7.1, describe the effect of the presence of trees on the temperature of the sand. [2] (b) The researchers counted the proportion of male and female turtles hatching from nests in the four different parts of the beach. The results are shown in Table 7.1. Table 7.1 part of beach nests producing more males than females nests producing more females than males nests producing equal numbers of females and males open sand 0 16 0 low vegetation 31 24 6 edge of forest 61 0 11 in forest 36 0 0 (i) State the part of the beach in which most female hawksbill turtles chose to lay their eggs. [1] (ii) Use the information in Fig. 7.1 to explain the results for nests in open sand and in forest, shown in Table 7.1. [2] (c) Tourism is an important industry in Antigua. The vegetation on many beaches has been cut down to make the beaches more attractive to tourists. With reference to the results of this research, suggest how deforestation of beaches could affect hawksbill turtle populations. [2]

14 © UCLES 2012 0653/32/M/J/12 For Examiner's Use (d) Describe two harmful effects to the environment, other than extinction of species, that may result from deforestation. 1 2 [4]

15 © UCLES 2012 0653/32/M/J/12 [Turn over BLANK PAGE Please turn over for Question 8.

16 © UCLES 2012 0653/32/M/J/12 For Examiner's Use 8 Fig. 8.1 shows apparatus a student used to investigate temperature changes that occurred during chemical reactions. insulated beaker thermometer reaction mixture Fig. 8.1 The student added reactants to the insulated beaker and stirred the mixture. She recorded the final temperature of each mixture. At the start of each experiment, the temperature of the reactants was 22 °C. Table 8.1 contains the results the student obtained. Table 8.1 experiment reactant A reactant B final temperature / °C 1 dilute hydrochloric acid sodium hydrogencarbonate 16 2 dilute hydrochloric acid potassium hydroxide solution 26 3 magnesium copper sulfate solution 43 4 copper magnesium sulfate solution 22 (a) Explain which experiment, 1, 2, 3 or 4, was a neutralisation reaction between an acid and an alkali. experiment explanation [1]

17 © UCLES 2012 0653/32/M/J/12 [Turn over For Examiner's Use (b) State and explain which experiment, 1, 2, 3 or 4, was an endothermic reaction. experiment explanation [1] (c) Apart from the change in temperature, state one other observation the student could make when she carried out experiment 3. [1] (d) Explain, in terms of reactivity, why a reaction occurred in experiment 3. [1] (e) Suggest and explain a reason for the result obtained in experiment 4. [2]

18 © UCLES 2012 0653/32/M/J/12 For Examiner's Use 9 (a) Fig. 9.1 shows the effect of pH on the activity of an enzyme. rate of reaction 1 2 3 4 5 pH 6 7 8 9 10 11 12 0 Fig. 9.1 (i) Describe the effect of pH on the activity of this enzyme. [2] (ii) Explain why pH affects the enzyme in this way. [2] (iii) An enzyme digests food in the human stomach, where hydrochloric acid is secreted. This enzyme is adapted to work best in these conditions. On Fig. 9.1, sketch a curve to show how pH affects the activity of this stomach enzyme. [1] (iv) After the food has been in the stomach for a while, it passes into the duodenum. Pancreatic juice, which contains sodium hydrogencarbonate, is mixed with the food in the duodenum. Explain why this stomach enzyme stops working when it enters the duodenum. [2]

19 © UCLES 2012 0653/32/M/J/12 For Examiner's Use (b) Explain how chemical digestion enables body cells to obtain nutrients. [3]

20 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 © UCLES 2012 0653/32/M/J/12 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

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2012 question paper for the guidance of teachers 0653 COMBINED SCIENCE 0653/32 Paper 3 (Extended Theory), maximum raw mark 80 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 must be read in conjunction with the question papers and the report on the examination. • Cambridge will not enter into discussions or correspondence in connection with these mark schemes. Cambridge is publishing the mark schemes for the May/June 2012 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses. www.XtremePapers.com

Page 2 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 32 © University of Cambridge International Examinations 2012 1 (a) (i) argentite and galena (or formulae) ; [1] (ii) scheelite (or formula) ; [1] (b) (i) silicon ; four outer electrons so in Group IV ; three shells so in third period ; OR silicon ; electron configuration is 2,8,4 / inner shells must be full / silicon has 14 electrons ; so proton / atomic number is 14 ; [max 3] (ii) Q H H H H (does not have to be dots and crosses) at least one shared pair of electrons ; four shared pairs ; (max 1 if extraneous electrons) [2] (iii) QO2 + 2C → Q + 2CO ;; [2] (formulae and balanced marked separately) [Total: 9]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 32 © University of Cambridge International Examinations 2012 2 (a) units of m / s and s ; axes right way round and suitable scale labelled speed and time ; accurate line drawn on graph ; [3] (b) (i) average speed = distance / time ; = 200 / 25 = 8 m / s ; [2] (ii) KE = ½ mv2 ; = ½ × 70 × 6 × 6 = 1260 J ; [2] (c) (i) heat transferred from body to sweat / heat absorbed by sweat from athlete’s body ; kinetic energy of water molecules increases / some molecules move faster than others ; faster moving / more energetic (water) molecules escape / leave the surface / break bonds / break forces of attraction ; (KE) / energy of (remaining) water molecules (in sweat) decreases ; [3] (ii) any two from: increased temperature / reduced humidity / increased windspeed / increased surface area ; [max 1] [Total: 11] 3 (a) (chemical reactions that) break down / glucose (molecules) ; to release energy ; [2] (b) C6H12O6 + 6O2 → 6CO2 + 6H2O ;; [2] (formulae and balanced) (c) in red blood cells ; attached to / combined with, haemoglobin ; [2] [Total: 6]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 32 © University of Cambridge International Examinations 2012 radiation gamma microwave infra-red x-rays uses examining bones and teeth remote controls for television sets satellite communications sterilising surgical instruments 4 (a) radio waves are transverse and sound waves are longitudinal ; radio waves have a higher frequency (than sound waves) ; radio waves move at a faster speed (than sound waves) ; sound waves need a medium, radio waves do not ; radio waves can travel further (than sound waves) ; radio waves have a larger range of frequencies (than sound waves) ; [max 2] (b) (all correct gains 2 marks, 3 or 2 correct gains 1 mark) [2] (c) v = f × λ / speed = frequency × wavelength = 6 × 10-7 × 5 × 1014 = 3 × 108 m / s ; [2] (d) measure mass using a balance ; measure volume using displacement can or increase in volume of water in a measuring cylinder ; density = mass / volume ; [3] [Total: 9]

Page 5 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 32 © University of Cambridge International Examinations 2012 5 (a) use of chlorine / ozone / ultrafiltration / boiling / distillation ; [1] (b) in water (molecules) hydrogen (atoms) are bonded to oxygen (atoms) ; in the mixture they are not ; in water the H:O ratio is 2:1 ; in the mixture no fixed ratio ; water unreactive / puts out flame ; mixture burns / will react ; a mixture can be separated by physical means ; a compound cannot / can only be separated by chemical means ; a compound contains different elements that are chemically bonded ; a mixture means two different substances which are not combined ; the compound water is formed by chemical reaction ; the mixture of elements hydrogen and oxygen is not formed by chemical reaction ; (any one pair for 2 marks) [max 2] (c) (i) silicon dioxide ; [1] (ii) sodium chloride forms a solution / is soluble (so all passes through the filter) ; hexane is (also) a liquid (at room temperature) (and so also passes through filter) ; [2] (d) (i) add carbonate to acid ; keep adding carbonate until no more dissolves / reacts ; filter (and keep filtrate) ; [3] (ii) zinc + sulfuric → zinc + carbon + water carbonate acid sulfate dioxide [2] left-hand side correct 1 mark ; right-hand side correct 1 mark ; [Total: 11]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 32 © University of Cambridge International Examinations 2012 6 (a) air molecules will move faster ; [1] (b) change shape ; change speed / start object moving / stop object moving / acceleration etc ; change direction of motion of object ; (3 correct gains 2 marks, 1 or 2 correct gains 1 mark) [max 2] (c) symbols all correct ; complete / full circuit ; lamps in parallel ; (and if lamps in parallel) then switch operates both lamps ; [4] [Total: 7]

Page 7 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 32 © University of Cambridge International Examinations 2012 7 (a) trees reduce the temperature ; reference to figures from the graph / quantitative comparison ; [2] (b) (i) edge of forest ; [1] (ii) open sand is hotter so produced more females / in forest cooler so produced more males ; reference to above 29 °C for producing females / below 29 °C for producing males ; [2] (c) deforestation will result in hotter / open / more open sand / result in a higher temperature ; so more female turtles produced / fewer males ; which might make breeding difficult / might reduce number of young born or increase the number of eggs laid ; [max 2] (d) more carbon dioxide in the atmosphere ; reference to global warming / effects of global warming ; less oxygen in the atmosphere ; reference to possible harmful effects relating to respiration ; fewer roots to hold soil in place / fewer leaves to protect from rain ; more erosion ; fewer trees to absorb rain water ; more flooding ; (any two pairs for max 2 marks each pair) [max 4] [Total: 11] 8 (a) (expt. 2) potassium hydroxide is an alkali / contains hydroxide ions ; [1] (b) (expt. 1) temperature decreased ; [1] (c) orange solid formed / solution becomes paler blue / colourless ; [1] (allow effervescence) (d) magnesium more reactive than copper ; [1] (e) no reaction occurred ; so there was no change in temperature / no energy was transferred ; copper is less reactive than magnesium ; [max 2] [Total: 6]

Page 8 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 32 © University of Cambridge International Examinations 2012 9 (a) (i) greatest activity at pH 6.5 / between 6 and 7 ; no activity at / below pH 4 and at / above pH 9 ; [2] (ii) pH changes the shape of the enzyme (molecule) ; changes shape of active site ; so substrate can no longer fit into it ; [max 2] (iii) curve of similar shape with peak at pH 4 or below ; [1] (iv) sodium hydrogencarbonate neutralises the acid ; so pH rises (above optimum for enzyme) ; [2] (b) break down / digest, large molecules ; to small molecules ; (small) molecules can be absorbed / can be taken into the blood / can pass through the wall of the gut / can diffuse into cells ; [3] [Total: 10]