Cambridge IGCSE Science - Combined 0653 — 2007 May/June Paper 3 · Variant 1

This document consists of 16 printed pages. IB07 06_0653_03/5RP © UCLES 2007 [Turn over *9505164189* 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 0653/03 Paper 3 (Extended) May/June 2007 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 16. 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 2007 0653/03/M/J/07 For Examiner's Use 1 Fig. 1.1 shows a vertical section through a human heart. aorta pulmonary vein left ventricle Fig. 1.1 (a) On the diagram, use label lines to label these parts of the heart. [3] bicuspid valve pulmonary artery septum (b) Explain why the wall of the left ventricle is thicker than the wall of the right ventricle. [2] (c) Describe two differences between the structure of the aorta and the pulmonary vein. 1. 2. [2] (d) The heart muscle is supplied with blood through the coronary arteries. Explain why a blockage in these arteries can cause a heart attack. [2]

3 © UCLES 2007 0653/03/M/J/07 [Turn over For Examiner's Use 2 (a) Fig. 2.1 shows a simple circuit containing two identical lamps. A2 A1 A3 6V V1 V2 Fig. 2.1 Ammeter A1 reads 0.15 A. Write down the readings on ammeter A2, ammeter A3, voltmeter V1, voltmeter V2. [2] (b) (i) The electrical output from a power station is at 25 000 V. The voltage is stepped up to 400 000 V by a transformer. The number of turns on the primary coil is 20 000. Calculate the number of turns on the secondary coil. State the formula that you use and show your working. formula used working turns [3] (ii) Explain why transformers require an a.c. input. [2]

4 © UCLES 2007 0653/03/M/J/07 For Examiner's Use 3 Fig. 3.1 shows a car in motion. The energy which is needed to make the car move comes from burning a mixture of air and fuel in the engine. mixture of exhaust gases air taken into the engine Fig. 3.1 (a) Air is a mixture of gases. Describe one difference between a mixture of two gases and a compound formed from two gases. [1] (b) Gasoline, a mixture of hydrocarbons, is a fuel used in car engines. When gasoline is burnt most of it undergoes complete combustion, but a small amount is incompletely combusted. (i) Name one gaseous substance and one solid substance which are formed as the result of incomplete combustion. gaseous substance solid substance [2] (ii) Two chemical tests could be carried out on the mixture of exhaust gases to show that much of the gasoline fuel was undergoing complete combustion. Describe these chemical tests. 1. 2. [4]

5 © UCLES 2007 0653/03/M/J/07 [Turn over For Examiner's Use (c) The car battery contains sulphuric acid. (i) State the chemical formula of an alkali which would neutralise sulphuric acid to produce the salt, potassium sulphate. [1] (ii) Write a balanced equation involving ions which shows what happens when any acid is neutralised by any alkali. [2]

6 © UCLES 2007 0653/03/M/J/07 For Examiner's Use 4 In Mexico, some areas of tropical rainforest have been cleared for growing cacao trees. Beans from cacao trees are used for making chocolate. The beans are seeds, and they develop from fertilised flowers. Bats are flying mammals that feed on insects, fruit or nectar. Many different bat species live in tropical rainforests. Table 4.1 shows information about the numbers of plants and bats found in an undisturbed tropical rainforest and in a cacao plantation. Table 4.1 habitat number of different species of plants number of different species of bats number of bat species found only in that habitat in undisturbed rainforest 93 27 14 in cacao plantation 77 21 1 (a) Explain how the data in Table 4.1 show that the rainforest has a higher species diversity than the cacao plantation. [2] (b) Using the data in Table 4.1, suggest one reason, other than species diversity, why leaving some areas of tropical rainforests undisturbed is important for the conservation of bats. [1] (c) Using the information provided, suggest how bats could help to increase the yield of beans from a cacao plantation. [2]

7 © UCLES 2007 0653/03/M/J/07 [Turn over For Examiner's Use (d) Farmers allow other plants to grow underneath the cacao trees. Explain how this could help to reduce soil erosion. [2] (e) Cacao trees are also grown in Africa. A fungus causes a disease called black pod, which can destroy up to 80 % of the crop. Farmers have found that the pesticides they have been using are no longer effective against this fungus. They have tried biological control instead, using a different fungus that attacks the black pod fungus. Fig. 4.1 shows the percentage of pods affected by black pod when no treatment was given and when the trees were treated with the biological control fungus. 0 1 2 3 30 25 20 15 10 5 0 weeks after treatment diseased pods (%) no treatment biological control Fig. 4.1 (i) Describe the effect of the biological control fungus on black pod disease. [2] (ii) Suggest reasons for the changes in the number of diseased pods over the three week period when the biological control fungus was used. [2]

8 © UCLES 2007 0653/03/M/J/07 For Examiner's Use 5 (a) A car is being driven along the road. Fig. 5.1 shows the speed-time graph for the journey. 10 0 20 30 40 50 60 70 30 20 10 0 speed m / s B A C A B C time / s Fig. 5.1 (i) Which section of the graph, A, B, or C, represents a constant speed? Explain your answer. [1] (ii) Calculate the acceleration of the car during the first 20 seconds. Show your working. [2]

9 © UCLES 2007 0653/03/M/J/07 [Turn over For Examiner's Use (iii) The car and driver have a total mass of 1400 kg. Calculate the force that produced the acceleration over the first 20 seconds. State the formula that you use and show your working. formula used working [2] (iv) Calculate the total distance travelled over 60 seconds. Show your working. [2] Question 5 is continued on page 10, overleaf.

10 © UCLES 2007 0653/03/M/J/07 For Examiner's Use (b) The car travels over a long bridge. The bridge is made in sections, with gaps between each section. The gaps are filled with rubber. road road rubber Suggest why (i) these gaps are left, [1] (ii) these gaps are filled with rubber. [1] (c) The heated rear windscreen of the car contains nine wires, connected in parallel, each with a resistance of 10 ohms. Is the combined resistance of all the wires more or less than 10 ohms? Explain your answer. [1]

11 © UCLES 2007 0653/03/M/J/07 [Turn over For Examiner's Use 6 (a) Fig. 6.1 shows a metal reacting in cold water. A gas is produced very quickly during the reaction, and when this gas is tested it burns with a squeaky pop. water metal gas produced Fig. 6.1 Suggest the name of a metal which would react like the one shown in Fig. 6.1. Explain your answer. name of metal explanation [3] (b) A student carried out an experiment into the rusting of steel nails. She used 31.0 g of new nails in her experiment. After some days the nails had become rusty and the student re-weighed them. Her result is shown in Fig. 6.2. balance steel nails Fig. 6.2 (i) State the type of chemical reaction which takes place when steel rusts. [1] (ii) Explain the increase in mass which the student found in her experiment. [2]

12 © UCLES 2007 0653/03/M/J/07 For Examiner's Use 7 All metabolic reactions in animals and plants are catalysed by enzymes. Enzymes from plants usually have a lower optimum temperature than enzymes from humans. Fig. 7.1 shows the rate of activity of a human enzyme at different temperatures. rate of enzyme activity 0 10 20 30 temperature / °C 40 50 60 Fig. 7.1 (a) On Fig. 7.1, sketch a curve to show the rate of activity of a plant enzyme. [1] (b) Explain the reasons for the shape of the curve for the human enzyme. [4] (c) Suggest why it is advantageous to a plant to have enzymes that have a lower optimum temperature than human enzymes. [1]

13 © UCLES 2007 0653/03/M/J/07 [Turn over For Examiner's Use 8 Gamma radiation and visible light are two regions of the electromagnetic spectrum. (a) (i) Name another region of the electromagnetic spectrum that is used for cooking food. [1] (ii) All electromagnetic waves travel at the same speed in a vacuum. State this speed. [1] (iii) State one way in which the waves in different regions of the electromagnetic spectrum differ from each other. [1] (b) Alpha, beta and gamma are three types of radiation emitted during radioactive decay. (i) State the meaning of the term radioactive decay. [1] (ii) Name a suitable detector for these three types of radiation. [1] (iii) State clearly what happens to each of the types of radiation when they pass between metal plates that have opposite electrical charges. alpha beta gamma [3] (iv) Describe how these types of radiation can be dangerous to the human body. [2]

14 © UCLES 2007 0653/03/M/J/07 For Examiner's Use 9 The apparatus in Fig. 9.1 can be used to break down the compound lead bromide into its elements. strong heat lead bromide + – Fig. 9.1 (a) (i) Name the non-metallic element which is produced in this process. [1] (ii) Explain why the lead bromide shown in Fig. 9.1 has to be heated strongly in order for the process to work. [2] (b) Lead bromide has the chemical formula PbBr2. Bromide ions are Br –. (i) Deduce the charge on lead ions in lead bromide. Show how you obtained your answer. [2]

15 © UCLES 2007 0653/03/M/J/07 [Turn over For Examiner's Use (ii) Deduce the total number of electrons in one bromide ion. Explain how you obtained your answer. number of electrons explanation [2] (c) A process similar to that in Fig. 9.1 is used in the chemical industry to produce the important element chlorine. (i) Complete the bonding diagram below to show how the outer electrons are arranged in a chlorine molecule. Cl Cl [2] (ii) Chlorine reacts with the element silicon to form silicon chloride. In silicon chloride molecules, one silicon atom is bonded to four chlorine atoms. Deduce a balanced symbolic equation for the reaction between silicon and chlorine. [2]

16 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 2007 0653/03/M/J/07 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 Sulphur 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 2007 question paper 0653 COMBINED SCIENCE 0653/03 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. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2007 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 Syllabus Paper IGCSE – May/June 2007 0653 03 © UCLES 2007 1 (a) one mark for each correct label ; ; ; bicuspid valve septum pulmonary artery [3] (b) contains more muscle ; to provide, more force / high(er) pressure ; to push blood further round the body ; right ventricle only pushes blood to lungs ; [max 2] (c) aorta wall is thicker ; aorta lumen is smaller ; aorta wall is more elastic ; vein has valves ; [max 2] (d) muscle does not get oxygen ; so cannot respire ; so cannot contract ; [max 2] 2 (a) A2 = 0.015 A A3 = 0.15 A ; V1 = 3 V ; V2 = 3 V ; [2] (b) (i) Vp/Vs = Np/Ns ; (or rearranged) 25 000 / 400 000 = 20 000 / Ns ; (or alternative working method) (Ns) = 320 000 ; [3] (ii) changing current causes changing magnetic field ; changing magnetic field induces voltage in secondary coil ; [2]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0653 03 © UCLES 2007 3 (a) in mixture: (particles / molecules) of the different gases are not bonded / gases have the same (chemical) properties as when not mixed / any proportions are possible / can be separated by physical methods ; [1] (b) (i) carbon monoxide / steam ; carbon / soot ; [2] (ii) shake with limewater ; goes cloudy ; shows carbon dioxide ; test with, cobalt chloride (paper) / anhydrous copper sulfate ; goes from, blue to pink / white to blue ; shows water ; [max 4] (c) (i) KOH ; [1] (ii) H+ + OH- H2O ; ; (left hand side and right hand side) [2] 4 (a) more species in the rainforest ; of plants and bats / figures quoted ; [2] (b) 14 species found only in the rainforest ; [1] (c) bats go to flowers for nectar ; pollination ; (not ‘pollen dispersed’) ref. to fertilisation following pollination ; beans form after, fertilisation / pollination ; [max 2] (d) stops rain hitting the ground directly ; more roots to soak up the water ; less run-off ; roots hold the soil ; [max 2] (e) (i) it reduces the number of pods infected ; compared with, the control / no treatment ; but does not completely eliminate infection / use of figures ; [max 2] (ii) takes time for the b.c. fungus to work ; any other relevant suggestion (related to a particular stage of the curve) ; [2]

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0653 03 © UCLES 2007 5 (a) (i) B because the line is horizontal ; [1] (ii) change of speed = 0 to 28 s / a = (v-u)/ t ; 1.4 m/s2 ; [2] (iii) force = mass x acceleration ; = 1400 x 1.4 = 1960 N ; [2] (iv) working ; 1036 m ; [2] (b) (i) road material expands when hot ; [1] (ii) rubber, can be compressed / is elastic / can stretch ; [1] (c) (less) explanation relating to resistances in parallel ; [1] 6 (a) any group 1 or calcium / strontium / barium ; reference to hydrogen ; (only) these metals produce hydrogen (rapidly) / at room temp / in cold water, when they react with water ; [3] (b) (i) oxidation / redox ; [1] (ii) oxygen / water / substances from the air, have reacted with the, iron / steel ; rust is (hydrated) iron oxide ; ref. to the combined mass of iron and other substances ; [max 2] 7 (a) similar shape with optimum at lower temperature ; [1] (b) as temperature rises (below optimum) movement of molecules increases ; more frequent collisions / more energetic collisions ; between enzyme and substrate ; beyond optimum enzymes denature ; they are proteins ; lose their shape at high temperatures ; [max 4] (c) plant cells at lower temperatures / plant enzymes work better where they live ; [1]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0653 03 © UCLES 2007 8 (a) (i) infra-red / microwaves ; [1] (ii) 300 000 000 m/s ; [1] (iii) frequency / wavelength ; [1] (b) (i) breakdown of an (unstable) nucleus ; [1] (ii) Geiger-Müller tube ; [1] (iii) moves, towards negative plate / away from positive plate ; moves, towards positive plate / away from negative plate ; unaffected by plates ; [3] (iv) ionises ; damages cells or DNA or mutates ; cancer ; skin burns ; radiation sickness ; [max 2] 9 (a) (i) bromine ; [1] (ii) to form an electrolyte / to melt the lead bromide ; enables ions to move ; so that an electric current will flow through it ; [max 2] (b) (i) +2 ; two -1 bromide ions balance the charge on the lead ion ; [2] (ii) (36) because bromine atom has 35 electrons / same number of electrons as proton number ; has gained one electron / has single negative charge so one extra electron ; [2] (c) (i) shared pair ; all other non-bonding electrons shown ; [2] (ii) Si + 2Cl2 SiCl4 ; ; (formula and balanced) [2]