Cambridge IGCSE Science - Combined 0653 — 2007 Oct/Nov Paper 3 · Variant 1

This document consists of 21 printed pages and 3 blank pages. IB07 11_0653_03/3RP © UCLES 2007 [Turn over *3454612941* 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) October/November 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 24. 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/O/N/07 For Examiner's Use 1 Hydrogen peroxide, H2O2, is a colourless liquid. Hydrogen peroxide decomposes according to the equation below. hydrogen peroxide → water + oxygen (a) State the total number of atoms which are bonded in one molecule of hydrogen peroxide. [1] (b) Complete the bonding diagram below to show • the chemical symbols of the elements in a molecule of water, • the arrangement of the outer electrons of each atom. [2] (c) Fig. 1.1 shows apparatus which a student used to measure the rate at which hydrogen peroxide decomposes. water measuring cylinder manganese dioxide hydrogen peroxide solution Fig. 1.1 The student measured the time for a known volume of oxygen gas to collect in the measuring cylinder.

3 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use Table 1.1 shows results the student obtained for four experiments, A, B, C and D. Table 1.1 experiment volume of oxygen gas collected /cm3 time taken for oxygen to collect /seconds A 40 35 B 40 15 C 40 10 D 40 25 (i) State and explain in which experiment, A, B, C or D, the reaction rate was the highest. [1] (ii) State and explain, in terms of particles, one variable (factor) which the student could have changed in order to obtain the results shown in Table 1.1. [3]

4 © UCLES 2007 0653/03/O/N/07 For Examiner's Use 2 Fig. 2.1 shows the inside of a refrigerator. freezing compartment Fig. 2.1 (a) (i) Draw arrows on Fig. 2.1 to show what happens to the air cooled by the freezing compartment. [1] (ii) Use the idea of density to explain why this happens. [2] (b) When the refrigerator is used for 60 minutes, 360 000 joules of electrical energy are converted. (i) How many joules of energy are converted per second? joules [1] (ii) What is the power of the refrigerator? [1]

5 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use (c) The refrigerator has two lamps inside. The supply voltage is 240 V and the current passing through each lamp is 0.04 A. (i) Show that the resistance of one lamp is 6000 Ω. State the formula that you use and show your working. formula used working [1] (ii) The lamps are connected together in parallel. Calculate the combined resistance of the two lamps. State the formula that you use and show your working. formula used working [3]

6 © UCLES 2007 0653/03/O/N/07 For Examiner's Use 3 Fig. 3.1 shows a plant, and also a cell from part of the plant. A B C D Fig. 3.1 (a) From which part of the plant, A, B, C or D, does the cell come? [1] (b) On the diagram of the cell in Fig. 3.1, label the following structures. Use label lines and the appropriate letters. P a partially permeable membrane Q the part of the cell that contains DNA R a part of the cell that contains a substance whose molecules contain magnesium [3] (c) When a leaf is tested for starch, it is first boiled in water and then put into hot alcohol. Explain why these steps are necessary. boiling in water putting into hot alcohol [2]

7 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use (d) Part A of the plant in Fig. 3.1 is a flower. (i) Is this an insect-pollinated or a wind-pollinated flower? Explain your answer. type of pollination explanation [1] (ii) Some pollen from one of the flowers on this plant is transferred onto the stigma of another flower on the same plant. The male gamete in the pollen fertilises a female gamete in the flower. Is this asexual reproduction or sexual reproduction? Explain your answer. type of reproduction explanation [1] (iii) Explain why a plant breeder may prefer to use an asexual method of propagation of his plants, rather than a sexual method. [2]

8 © UCLES 2007 0653/03/O/N/07 For Examiner's Use 4 The apparatus in Fig. 4.1 can be used to study the reaction between potassium and oxygen. flask potassium reacting with oxygen reaction products Fig. 4.1 (a) Suggest why the flask becomes warm during the reaction. [1] (b) One of the compounds formed in this reaction is potassium oxide. The electron configurations of a potassium atom and an oxygen atom are shown below. K 2.8.8.1 O 2.6 Use this information to explain the bonding in potassium oxide. In your answer you should describe any changes in the electron configurations of these atoms, and deduce the chemical formula of potassium oxide. [5]

9 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use (c) Another compound formed in the reaction in Fig. 4.1 is potassium peroxide, K2O2. When potassium peroxide is added to water the products are potassium hydroxide and oxygen gas. (i) A student attempted to work out the balanced equation for this reaction. His attempt is shown below. 2K2O2 + 2H2O 2KOH + O2 His teacher said this attempt was incorrect. Explain why this attempt is incorrect, and write down the correct equation. [2] (ii) Describe how the student should test the gas given off to confirm that it is oxygen. [1] (iii) The student found that the pH of the final mixture was 13. Write the formula and charge of the ion present in the mixture which is responsible for this pH value. [1]

10 © UCLES 2007 0653/03/O/N/07 For Examiner's Use 5 A space rocket is launched to the Moon. (a) After launch, the empty fuel tanks are released and fall back to Earth. As a tank falls, two forces act on it as shown in Fig. 5.1. F1 F2 fuel tank Fig. 5.1 (i) Name forces F1 and F2. F1 F2 [2] (ii) As it falls, the tank accelerates because F1 is greater than F2. What will happen to the size of force F2 as the tank goes faster? [1] (iii) Eventually the two forces will balance each other. How will this affect the speed of the falling tank? Explain your answer. [2]

11 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use (b) The rocket travels 400 000 km to the Moon in 80 hours. Calculate the average speed of the rocket. State the formula that you use and show your working. formula used working [2] (c) One of the astronauts on the rocket has a mass of 90 kg. The gravitational field strength of the Moon is about one-sixth that of the Earth. State the differences, if any, between (i) the mass of the astronaut on the Earth and on the Moon, [1] (ii) the weight of the astronaut on the Earth and on the Moon. [1]

12 © UCLES 2007 0653/03/O/N/07 For Examiner's Use 6 Tuberculosis (TB) is an infectious disease caused by a bacterium. HIV/AIDS is caused by a virus. (a) Name the cells in the body that help to destroy harmful bacteria and viruses by (i) producing antibodies, [1] (ii) phagocytosis . [1] (b) Table 6.1 shows the percentage of people with TB and HIV/AIDS in four parts of the world in 2005. Table 6.1 part of the world percentage of people with TB percentage of people with HIV/AIDS sub-Saharan Africa 0.51 7.2 Southeast Asia 0.35 1.1 Americas 0.07 0.7 Europe 0.06 0.5 (i) Describe any pattern that seems to link the percentages of people with TB and with HIV/AIDS. [1] (ii) The virus that causes AIDS infects white blood cells. Explain how this could be responsible for the pattern that you have described in (i). [2]

13 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use (c) In many countries, young people are vaccinated against TB. They are given an injection of weakened TB bacteria. Explain how this vaccination could make a person immune to TB. [2]

14 © UCLES 2007 0653/03/O/N/07 For Examiner's Use 7 Aluminium, iron, sodium and chlorine are important elements produced by the chemical industry. (a) State which of the elements above (i) has atoms which are converted into ions by gaining an electron, [1] (ii) has atoms which contain 3 electrons in their outer shells. [1] (b) When chlorine gas is bubbled into a colourless solution of sodium bromide, the solution turns orange. Explain this observation. [2]

15 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use (c) Fig. 7.1 shows a blast furnace which is used to convert iron(III) oxide into iron. molten iron raw materials including iron(III) oxide and carbon Fe2O3 + 3CO 2Fe + 3CO2 CO2 + C 2CO C + O2 CO2 Fig. 7.1 The balanced equations of the three main chemical reactions in the blast furnace are shown in Fig. 7.1. Each reaction is a redox reaction. (i) State two substances, shown in Fig. 7.1, which are reduced. Explain your answer briefly. [3] (ii) Use the relative atomic masses shown on the Periodic Table to calculate the relative formula mass of iron(III) oxide. Show your working. [1]

16 © UCLES 2007 0653/03/O/N/07 For Examiner's Use 8 A student is having a medical examination. (a) A dentist checks the student’s teeth using a dental mirror. This is shown in Fig. 8.1. dentist’s eye mirror tooth A Fig. 8.1 (i) Draw a ray of light from the back of tooth A to the dentist’s eye to show how the dentist is able to see the back of the tooth. On the ray, draw arrows showing the direction in which light travels. [3] (ii) Describe how the dentist could find the density of an irregular object such as an extracted tooth. [4]

17 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use (b) The doctor wants to use a small torch to look down the student’s throat. When he switches the torch on, it does not work. Fig. 8.2 shows the circuit diagram for the torch. Fig. 8.2 (i) Explain what is wrong with the torch. [1] (ii) Draw the correct circuit diagram. [1]

19 © UCLES 2007 0653/03/O/N/07 [Turn over For Examiner's Use 9 Fig. 9.1 shows part of the carbon cycle. fossil fuels carbon dioxide in atmosphere X Fig. 9.1 (a) Name the process labelled X on Fig. 9.1. [1] (b) Explain how carbon dioxide is returned to the air from the bodies of dead organisms. [2]

20 © UCLES 2007 0653/03/O/N/07 For Examiner's Use (c) Describe how fossil fuels are formed. [2] (d) Fossil fuels are burned in cars, trucks and other vehicles. Fig. 9.2 shows the quantity of sulphur dioxide and nitrogen oxides emitted from vehicles in a European country between 1990 and 2003. Over this period, the country brought in measures to try to decrease the emissions of these gases. The number of vehicles using the roads increased over this time period. 1990 91 92 93 94 95 96 97 98 99 2000 01 02 03 100 90 80 70 60 50 40 30 20 10 0 1000 900 800 700 600 500 400 300 200 100 0 sulphur dioxide emissions / thousand tonnes nitrogen oxide emissions / thousand tonnes year Fig. 9.2

21 © UCLES 2007 0653/03/O/N/07 For Examiner's Use (i) Suggest a reason for the trend in sulphur dioxide emissions between 1990 and 2003. [1] (ii) Catalytic converters were introduced into this country in 1993. They are fitted onto car exhaust systems, and they contain catalysts that cause nitrogen oxide to be reduced to nitrogen. Suggest two reasons why nitrogen oxides had not been completely eliminated from car exhaust gases by 2003. 1. 2. [2] (iii) Explain how emissions of sulphur dioxide and nitrogen oxides can harm living organisms. [3]

24 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/O/N/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 October/November 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 October/November 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 – October/November 2007 0653 03 © UCLES 2007 1 (a) 4; [1] (b) shared pairs shown; symbols correct and two lone pairs shown on oxygen; [2] (c) (i) (C) it took the shortest time / was faster, to collect the (40 cm3 of) gas; [1] (ii) concentration of H2O2 / surface area of catalyst; reference to collision frequency (with catalyst); higher concentration / larger surface area linked to higher rate; or temperature ; reference to collision, frequency / force ; higher temperature linked to higher rate ; [3] 2 (a) (i) arrow(s) going down; [1] (ii) cold air is denser (than warm air); particles closer together ; drops / displaces warm air which moves upwards ; [2 max] (b) (i) 100(J); [1] (ii) 100W or 100 J/s ; [1] (c) (i) R = V/I = 240/0.04 (=6000Ω) ; [1] (ii) 1/R = 1/R1 + 1/R2 ; = 1/6000 + 1/6000 = 1/3000; R = 3000Ω [3]

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2007 0653 03 © UCLES 2007 3 (a) leaf / C ; [1] (b) P to cell membrane / to membrane around vacuole ; Q to nucleus ; R to chloroplast ; [3] (c) break down, tissues / cells / cell walls / cell membrane ; remove chlorophyll / (green) colour ; [2] (d) (i) insect, because it has (large) petals / no stamens hanging out / no anthers hanging out / no stigma hanging out ; [1] (ii) sexual, because gametes / fertilisation are involved ; [1] (iii) new plants are genetically identical / clones ; have the same features as their parents / no variation ; [2] 4 (a) reaction is exothermic / gives out heat (energy) ; [1] (b) potassium atoms lose one / their outer electron / e.c. becomes 2.8.8 ; oxygen atoms gain two electrons / complete their outer shell / e.c. becomes 2.8 ; reference to positive potassium ion / K+ ; reference to negative oxide ion / O2 -; reference to attraction between positive and negative ions/oppositely charged ions ; ionic charge balance / each O accepts an electron from two K atoms / K2O ; [max 5] (c) (i) (not balanced) balanced means the same number of each type of atom on both sides / detail of why this is unbalanced e.g. 4 x K on left 2 x K on right / would need to have 4 KOH on right; 2K2O2 + 2H2O 4KOH + O2 ; [2] (ii) re-lights glowing splint; [1] (iii) OH-; [1]

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2007 0653 03 © UCLES 2007 5 (a) (i) weight / gravity; friction / air resistance; [2] (ii) increase; [1] (iii) travel at constant speed / terminal velocity ; no resultant force / forces cancel out / equal and opposite forces / weight = air resistance ; [2] (b) speed = distance/time ; = 400 000/80= 5000 km/h or 1388.9 m/s or 83.3 km / min ; [2] (c) (i) there is no difference; [1] (ii) weight will be less on the moon; [1] 6 (a) (i) lymphocytes ; [1] (ii) phagocytes ; [1] (b) (i) the more HIV/AIDS, the more TB ; [1] (ii) white cells / immune system / T cells, cannot work properly ; cannot destroy, bacteria / pathogens / antigens, that cause TB ; [2] (c) idea that white cells react to the (weakened) bacteria ; correct ref. to, antibodies / memory cells ; that attack bacteria / pathogens / antigens (immediately) in future ; [max 2] 7 (a) (i) chlorine / Cl; [1] (ii) aluminium / Al; [1] (b) orange substance is bromine / bromine is produced; chlorine is more reactive than bromine; chlorine displaces bromine / chlorine reacts with bromide ; correct reference to redox; [max 2] (c) (i) iron(III) oxide; carbon dioxide; because these substances lose oxygen / reduction is loss of oxygen; oxygen; because carbon is oxidised and so oxygen must be reduced; [max 3] (ii) (56 x 2) + (16 x 3) or 160; [1]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2007 0653 03 © UCLES 2007 8 (a) (i) arrows in right direction; ray of light from tooth to touch mirror and mirror to eye; approx correct angles; [3] (ii) measure mass of object; measure volume of object; by displacement / Eureka can + measure volume of displaced water ; density = mass / volume; [4] (b) (i) one cell is back to front; [1] (ii) circuit diagram as in Fig. 8.2 with one cell reversed ; [1] 9 (a) respiration ; [1] (b) decay organisms / detritivores / decomposers / ref to decomposing ; bacteria / fungi ; respire ; [2 max] (c) dead organisms / plants / animals / bacteria ; do not decay fully ; in airless / anaerobic / waterlogged conditions ; idea that they are, compressed / buried ; ref to long time period ; [max 2] (d) (i) removal of sulphur from fuels / use of low-sulphur fuels ; [1] (ii) idea that not all nitrogen oxides react in catalytic converter ; not all cars fitted with catalytic converters ; not all catalytic converters work; [2] (iii) acid rain ; damages trees ; makes rivers / lakes acidic which; allows heavy metals / aluminium, to leach from soil ; kills fish / kills aquatic organisms / kills named aquatic organism ; [max 3]