Cambridge IGCSE Science - Combined 0653 — 2007 May/June Paper 2 · Variant 1

This document consists of 18 printed pages and 2 blank pages. IB07 06_0653_02/3RP © UCLES 2007 [Turn over *6080480336* 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 0653/02 Paper 2 (Core) 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 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

3 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use 1 Fig. 1.1 shows a vertical section through a human heart, drawn as though the person is facing you. A B C Fig. 1.1 (a) Name the parts of the heart labelled A, B and C. A B C [3] (b) (i) Use a pencil to lightly shade in the places in Fig. 1.1 where there is oxygenated blood. [1] (ii) Where does the blood become oxygenated? [1] (c) On the diagram, draw two arrows to show how blood travels through the left hand side of the heart. [1] (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]

4 © UCLES 2007 0653/02/M/J/07 For Examiner's Use 2 Fig. 2.1 shows the structure of an atom of an element Q. + + + – – – … … … Fig. 2.1 (a) (i) Label the particles shown in Fig. 2.1. [3] (ii) Use the Periodic Table on page 20 to find the chemical symbol of element Q, and explain your answer. chemical symbol of Q explanation [2] (b) Fig. 2.2 shows calcium metal reacting in water which contains Universal Indicator. The gas produced during the reaction was tested as shown. pop burning splint Fig. 2.2 (i) Name the gas produced in this reaction. [1]

5 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use (ii) State and explain the colour change of the Universal Indicator during the reaction. [2] (c) The piece of iron in Fig. 2.3 will take part in a chemical reaction which involves water. water iron Fig. 2.3 State two ways in which the reaction of iron in Fig. 2.3 is different from the reaction of calcium in Fig. 2.2. 1. 2. [2]

6 © UCLES 2007 0653/02/M/J/07 For Examiner's Use 3 (a) A model car is at rest. A force is applied and it starts to move. (i) Complete the formula for calculating the work done on the model car using some of the words in the list. acceleration distance moved force applied speed time taken work done on model car = X [2] (ii) State one other way in which a force can affect an object. [1] (b) Fig. 3.1 shows the speed-time graph for a car 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. 3.1 (i) Which section of the graph, A, B, or C, represents a constant speed? Explain your answer. [1]

7 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use (ii) Calculate the acceleration of the car during the first 20 seconds. Show your working. m / s2 [2] (c) 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]

8 © UCLES 2007 0653/02/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. Table 4.1 shows information about the numbers of bats found in an undisturbed tropical rainforest and in a cacao plantation. Table 4.1 habitat number of different species of bats number of bat species found only in that habitat number of individual bats undisturbed rainforest 27 14 423 cacao plantation 21 1 644 (a) Which habitat has the higher species diversity of bats? Explain your answer. habitat explanation [1] (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]

9 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use (c) Some bats feed on nectar. (i) How might this explain the results for the numbers of individual bats in the two habitats? [1] (ii) Explain how bats could help to increase the yield of beans from a cacao plantation. [2] (d) Complete these sentences, using some of the words in the list. clones genetically not sexually unhealthy zygotes Cacao trees can reproduce , using flowers and making seeds. The new trees that are produced are different from each other. Farmers can propagate cacao trees asexually. The new trees that are produced are [3] (e) Farmers allow other plants to grow underneath the cacao trees. Explain how this could help to reduce soil erosion. [2]

10 © UCLES 2007 0653/02/M/J/07 For Examiner's Use 5 Lead bromide is a compound. It can be broken down into its elements by using the apparatus shown in Fig. 5.1. strong heat electrode A molten lead bromide + – Fig. 5.1 (a) (i) Name the process shown in Fig. 5.1. [1] (ii) Name the non-metallic element which is produced in this process. [1] (iii) Explain why the lead bromide shown in Fig. 5.1 has to be molten in order for the process to work. [1] (iv) Is electrode A in Fig. 5.1 the anode or the cathode? Explain your answer. [1]

11 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use (b) A process similar to that in Fig. 5.1 is used in the chemical industry to produce the important element chlorine. (i) The formula of the molecules in chlorine gas is Cl2. Explain what is meant by this formula. [2] (ii) Chlorine is used to treat water supplies. Explain this use of chlorine. [1] (iii) Chlorine reacts with aluminium to form aluminium chloride. The symbolic equation for this reaction is shown below. Complete the balancing of this equation. 2 Al + Cl2 2 AlCl3 [1]

12 © UCLES 2007 0653/02/M/J/07 For Examiner's Use 6 (a) Fig. 6.1 shows a simple circuit containing two identical lamps. A2 A1 A3 6V Fig. 6.1 Ammeter A1 reads 0.15 A. Write down the readings on ammeter A2, ammeter A3. [1] (b) Fig. 6.2 shows an electricity generating station. furnace and boiler turbine generator pylon transformer house cooling or condensing towers Fig. 6.2 (i) Name two fossil fuels which could be burned in the furnace to heat water in the boiler. 1. 2. [2]

13 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use (ii) Complete the energy transfer statements below. In the furnace energy is converted into heat energy. In the turbine the energy in the steam is converted into the energy of the turbine. The generator converts kinetic energy into energy. [3] (iii) 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] (iv) Why does the electrical output from this power station have to be a.c.? [1]

14 © UCLES 2007 0653/02/M/J/07 For Examiner's Use 7 Fig. 7.1 shows a car in motion. The energy which is needed to make the car move comes from the burning of a mixture of air and fuel in the engine. mixture of exhaust gases air taken into the engine Fig. 7.1 (a) Air is a mixture of gases. (i) Which gas makes up the greatest percentage of the air? [1] (ii) Describe one difference between a mixture of two gases and a compound formed from two gases. [1] (b) In some modern cars, two fuels are used. One of these is hydrogen gas and the other is gasoline, a mixture of hydrocarbons. Only one fuel is used at a time. (i) Explain why the fuel is said to be oxidised in the engine. [1] (ii) Suggest why, when hydrogen is used, the exhaust gases are not toxic (poisonous), but when gasoline is used the exhaust gases are toxic. [2]

15 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use (iii) Describe a chemical test which could be used to show that the exhaust gases contain carbon dioxide. [2] (c) The car battery contains sulphuric acid. (i) State the chemical formula of sulphuric acid. [1] (ii) Underline one of the following substances to show which could be used to neutralise a spillage of sulphuric acid safely. sodium sodium carbonate sodium chloride sodium sulphate [1]

16 © UCLES 2007 0653/02/M/J/07 For Examiner's Use 8 (a) Explain why sound needs a medium to travel through. [2] (b) Fig. 8.1 shows a student carrying out an experiment to find the speed of sound in air. 300 m cliff girl making loud noise Fig. 8.1 She stood 300 m from the edge of a cliff and made a loud noise. The echo reached her 2.0 s later. Calculate the speed of sound in air using these results. State the formula that you use and show your working. formula used working m / s [2]

17 © UCLES 2007 0653/02/M/J/07 [Turn over For Examiner's Use (c) A sound has a frequency of 500 Hz. (i) Explain the meaning of the term frequency. [1] (ii) State the approximate range of audible frequencies detected by the normal human ear. [1] (d) Fig. 8.2 shows the oscilloscope trace of two different sounds, P and Q. The settings on the oscilloscope are exactly the same for both. sound P sound Q time Fig. 8.2 State two ways in which sound P differs from sound Q. 1. 2. [2]

18 © UCLES 2007 0653/02/M/J/07 For Examiner's Use 9 (a) Cells in all of our tissues need a constant supply of glucose. Glucose is transported around the body in the blood. (i) Name the part of the blood in which glucose is transported. [1] (ii) Explain why cells in the human body need glucose. [2] (b) Plants make glucose in photosynthesis. They can then build the glucose into other substances, including cellulose and proteins. (i) State the function of cellulose in a plant. [1] (ii) Describe how you would test part of a plant to see if it contains proteins. [3] (c) All metabolic reactions in animals and plants are catalysed by enzymes. The temperature at which an enzyme works best is called its optimum temperature. Plant enzymes are denatured at lower temperatures than human enzymes. (i) Explain what is meant by the term denatured. [1] (ii) Explain why it is an advantage to plants that their enzymes have a lower optimum temperature than human enzymes. [1]

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 Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. © UCLES 2007 0653/02/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 0653/02 Paper 2 (Core 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 02 © UCLES 2007 1 (a) A left ventricle; B septum; C valve; [3] (b) (i) space within the left atrium and left ventricle shaded; [1] (ii) lungs / alveoli; [1] (c) arrow from the left atrium to the left ventricle and arrow from the left ventricle into the aorta; [1] (d) (heart) muscle does not get oxygen; so cannot respire; so cannot contract; [max 2] 2 (a) (i) proton(s) neutron(s) electron(s) labelled correctly; [3] (ii) Li; (reject lithium) proton number is 3 / there are 3 protons / nucleon number is 7 / the atom will have a mass of 7 (units) / there is one outer electron and two shells and so Q is in Group1 and Period 2; [2] (reject there are 3 electrons or four neutrons) (b) (i) hydrogen; [1] (ii) (green) changes to blue / purple / mauve; reaction produces an alkali / a hydroxide / causes pH to increase; [2] (c) it is slower / less vigorous / iron is less reactive; very little gas produced; (accept no gas produced) it does not make an alkali; it produces an orange product / rust; it needs oxygen to react; [max 2]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0653 02 © UCLES 2007 3 (a) (i) force applied; distance moved; (in either order) [2] (ii) change direction of motion of object; change shape of object; change the speed of an object / speed up / slow down; [max 1] (b) (i) B [no mark] graph is horizontal; (accept numerical use of the graph) [1] (ii) change of speed = 28 m/s / a = (v-u)/t or equivalent; so acceleration = 28/20 = 1.4 m/s2; [2] (c) (i) road material expands when hot; [1] (ii) rubber strips can be compressed / reference to general idea that rubber accommodates movement of road material / prevent road breaking up; [1] 4 (a) undisturbed rainforest, because there are more different species there; [1] (b) 14 species are found only in the rainforest; [1] (c) (i) more flowers in the cacao plantation than in the rainforest; [1] (ii) pollination; detail – e.g. they go to the flowers to get nectar / they brush pollen from anthers to stigma / seeds or fruits form after pollination; [2] (d) sexually; genetically; clones; [3] (e) stops rain hitting the ground directly; more roots / plants to soak up the water; less run-off; roots / plants hold the soil; [max 2]

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0653 02 © UCLES 2007 5 (a) (i) electrolysis; [1] (ii) bromine; [1] (iii) so that an electric current will flow through it / to make it into an electrolyte / so ions can move through it; [1] (iv) (anode) because it is the positive electrode; [1] (b) (i) two chlorine atoms; are (chemically) bonded (in each molecule); [2] (ii) sterilise / kill harmful microorganisms; to make water safe to drink / owtte; [1] (iii) 2Al + 3 Cl2 → 2 AlCl3 [1] 6 (a) A2 0.15 A A3 0.15 A; (both needed for mark) [1] (b) (i) coal / oil / gas / peat; (reject crude oil) [2] (ii) chemical; kinetic; electrical; [3] (iii) Vp/Vs = Np/Ns; 25000/400000 = 20000/Ns; Ns = 320000; [3] (iv) transformers only work using a.c.; [1]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0653 02 © UCLES 2007 7 (a) (i) nitrogen; [1] (ii) in mixture: particles / atoms / molecules of the different gases are not bonded / owtte / gases have same (chemical) properties as when not mixed / any proportions possible / can be separated by physical methods; [1] (b) (i) fuel is burnt and burning is an oxidation reaction / fuel combines / reacts with oxygen; [1] (ii) burning hydrocarbons produces carbon monoxide / other correct toxin; (reject carbon dioxide) burning hydrogen produces mainly water; [2] (iii) shake with limewater; goes cloudy; [2] (c) (i) H2SO4; [1] (ii) sodium carbonate [1] 8 (a) reference to particles (needing to move); compressions and rarefactions / vibrations; [2] (b) speed = distance / time; = 600/2 = 300 m/s; [2] (c) (i) number of waves / second; [1] (ii) 20 – 25000 Hz; [1] (d) P quieter; P lower pitch; [2]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0653 02 © UCLES 2007 9 (a) (i) plasma; [1] (ii) for respiration; to release energy (from glucose); [2] (b) (i) make cell walls; [1] (ii) chop / crush; add biuret (reagent) / general reference to biuret test; purple indicates protein; [3] (c) (i) destroyed / no longer work / function; (reject killed) [1] (ii) human body temperature higher than plant temperature / plant enzymes work better at, lower temperatures / the temperature in the plant; [1]