Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2013 Oct/Nov Paper 2 · Variant 1

This document consists of 31 printed pages and 1 blank page. IB13 11_0654_21/5RP © UCLES 2013 [Turn over *3583153480* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/21 Paper 2 (Core) October/November 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 0654/21/O/N/13 For Examiner's Use 1 Sodium chloride is obtained from underground deposits in the Earth’s crust or from solutions such as sea water. (a) (i) Explain why the Earth’s crust contains the compound sodium chloride and not the uncombined elements sodium and chlorine. [1] (ii) State one difference between a compound and an element. [1] (iii) Describe how crystals of sodium chloride could be obtained from a salt solution. [2] (b) (i) Explain the following statements in terms of protons and electrons. Atoms do not have an overall electrical charge. A potassium ion, K+, has a single positive electrical charge. [2] (ii) The chemical formula of the compound calcium nitride is Ca3N2. Explain the meaning of the numbers in this formula. [1]

3 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (c) Fig. 1.1 shows apparatus used to separate the element lead from the compound lead bromide. low voltage d.c. supply + – molten lead bromide Fig. 1.1 (i) Name the process shown in Fig. 1.1. [1] (ii) Explain why an orange-coloured gas is observed rising from the molten lead bromide during the process. [2]

4 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 2 Fig. 2.1 shows the inside of a refrigerator. The temperature inside the freezing compartment is -20 °C and the temperature in the rest of the refrigerator is +5 °C. freezing compartment Fig. 2.1 (a) The air in the refrigerator is cooled by convection. Draw one arrow on Fig. 2.1 to show the movement of the air cooled by the freezing compartment. [1] (b) The volume of air in the refrigerator is 0.15 m3. The density of air is 1.26 kg / m3. Calculate the mass of air in the refrigerator. State the formula that you use and show your working. formula working kg [2]

5 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (c) (i) Complete the diagrams to show the arrangement of water molecules in solid ice and in liquid water. One molecule has been drawn for you in each box. Each diagram should contain at least twelve water molecules. solid ice liquid water [2] (ii) Each sentence describes either a solid, a liquid or a gas. In the right hand column write the letter S for solid, L for liquid or G for gas to match the description. description S, L or G It cannot flow. It cannot transfer heat by convection. It contains particles which are widely separated. It expands the most when heated. It fills a closed container. It has a fixed volume but not a fixed shape. [3]

6 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 3 The concentration of glucose in the blood does not normally vary much. The hormone adrenaline causes blood glucose concentration to increase. (a) (i) Define the term hormone. [2] (ii) State one effect of adrenaline on the body, other than increasing the concentration of glucose in the blood. [1] (b) Researchers investigated how adding fibre to foods affected the concentration of glucose in the blood after eating. Fig. 3.1 shows the results that they obtained for two different types of cornflakes. Cornflakes contain a lot of starch. 8 6 4 2 0 0 20 40 60 time / minutes 80 100 120 blood glucose concentration / arbitrary units cornflakes with cornflakes with no added fibre no added fibre cornflakes with cornflakes with added fibre added fibre cornflakes with no added fibre cornflakes with added fibre cornflakes eaten Fig. 3.1

7 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use Use the information in Fig. 3.1 to help you to answer the following questions. (i) Describe how the blood glucose concentration changed after eating cornflakes with no added fibre. [3] (ii) Suggest explanations for the changes in blood glucose concentration. [3] (iii) Describe how adding fibre to the cornflakes affected the changes in blood glucose concentration after eating. [3] (c) Outline one other way in which fibre in the diet affects health. [1]

8 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 4 Fig. 4.1 shows a period in the Periodic Table. Four elements are represented by letters which are not their usual chemical symbols. W 1 group number X 2 3 4 5 6 Y 7 Z 0 Fig. 4.1 (a) (i) State and explain which of the elements W, X, Y and Z are poor conductors of electricity. element(s) explanation [2] (ii) One of the elements shown in Fig. 4.1 is not expected to form a compound with any of the others. State and explain which one of the elements this is. element explanation [2]

9 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (b) Fig. 4.2 shows the melting points of four metallic elements from the same group of the Periodic Table. 200 100 0 0 10 20 30 40 50 60 70 proton number melting point / °C Fig. 4.2 (i) State the number of the group that contains the elements whose melting points are shown in Fig. 4.2. Explain your answer briefly. group number explanation [2] (ii) Use the Periodic Table on page 32 to name the element in Fig. 4.2 that has the lowest melting point. [1]

10 © UCLES 2013 0654/21/O/N/13 For Examiner's Use (c) Many elements combine with oxygen to form oxides. (i) A student is given a soluble white solid which she knows is either an oxide of a metal or an oxide of a non-metal. Describe how the student can use the apparatus and materials shown in Fig. 4.3 to find out whether the solid is a metal oxide or a non-metal oxide. water full range indicator white solid Fig. 4.3 [2] (ii) Copper oxide is a black solid which is insoluble in water. The student added excess dilute sulfuric acid to some copper oxide, and warmed the mixture. The copper oxide disappeared and a clear blue solution remained. State one observation which shows that a chemical change has occurred. [1] (iii) Complete the word chemical equation for the reaction between copper oxide and dilute sulfuric acid. copper oxide + sulfuric acid + [2]

11 © UCLES 2013 0654/21/O/N/13 [Turn over Please turn over for Question 5.

12 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 5 Fig. 5.1 shows a solar-powered vehicle which travelled 3000 km in 30 hours. Fig. 5.1 (a) Calculate the average speed of the vehicle in km / hr. State any formula that you use and show your working. formula working km / hr [2] (b) Fig. 5.2 shows a speed / time graph for part of the journey. 0 0.5 1.0 time / hours 1.5 2.0 160 140 120 100 80 60 40 20 0 speed / km per hour A B A C Fig. 5.2

13 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (i) Describe the movement of the vehicle between A and B. [1] (ii) Calculate the distance travelled between B and C. State the formula that you use and show your working. formula working km [2] (c) Fig. 5.3 shows the energy flow diagram for the solar-powered vehicle. solar energy solar cell 90% reflected off solar cell 30% lost to environment electric motor 10% transferred to motor 70% transferred to kinetic energy of vehicle Fig. 5.3 (i) During part of the journey, the solar cell receives 1 000 000 joules of solar energy. Calculate the number of joules transferred as kinetic energy to the vehicle. Show your working. J [2] (ii) Write down the useful energy change which occurs in an electric motor. energy to energy [1]

14 © UCLES 2013 0654/21/O/N/13 For Examiner's Use (d) Solar energy is a renewable energy source. (i) Name one other renewable energy source. [1] (ii) Describe one advantage to the environment of using solar energy as a renewable energy source. [1] (e) The vehicle has mirrors to help the driver see behind him. The driver sees a car in his mirror as shown on Fig. 5.4. Use Fig. 5.4 to describe two characteristics of an image seen in this mirror that are similar to the characteristics of an image seen in a plane mirror. POLICE Fig. 5.4 1 2 [2]

15 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (f) Sunlight can be focused onto smaller areas of a solar panel to improve its efficiency. Fig. 5.5 shows two parallel rays of sunlight being focused by a lens. The lens has a focal length of 5 cm. Complete the diagram to show the rays of sunlight being focused by the lens. 0 1 2 cm cm cm 0 1 2 Fig. 5.5 [2]

16 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 6 Fig. 6.1 shows a section through the heart. pulmonary artery pulmonary vein thick muscle wall on the left side of the heart A B Fig. 6.1 (a) (i) Name the parts labelled A and B. A B [2] (ii) The walls of the heart are made of muscle. Explain how this muscle pushes blood out of the heart. [2] (iii) Explain why the muscle wall on the left side of the heart, labelled on Fig. 6.1, is thicker than on the right side. [2]

17 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (b) (i) Describe two differences between the contents of a pulmonary artery and a pulmonary vein. 1 2 [2] (ii) Describe two differences between the structure of the wall of a pulmonary artery and the wall of a pulmonary vein. 1 2 [2]

18 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 7 Zirconium is a metallic element found in Period 5 of the Periodic Table. (a) Zirconium metal is made into several different types of alloy. State the meaning of the term alloy. [1] (b) A large piece of zirconium does not burn in air but zirconium powder burns rapidly, forming zirconium oxide. (i) Suggest the word chemical equation for the reaction that occurs when zirconium burns in air. [1] (ii) The mass of zirconium oxide formed is greater than the mass of zirconium burned. Explain this in terms of atoms. [2] (iii) Suggest why zirconium powder burns rapidly but a large piece of zirconium does not. [2]

19 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (c) Fig. 7.1 shows information about five different types of zirconium atoms. 90 91 92 93 nucleon number 94 95 96 percentage of each type of zirconium atom Fig. 7.1 (i) Use the Periodic Table on page 32 to find the proton number of zirconium. proton number of zirconium = [1] (ii) Complete Table 7.1 showing the numbers of protons and neutrons in two of the zirconium atoms in Fig. 7.1. Table 7.1 atom number of protons number of neutrons Zr-90 Zr-96 [2] (iii) State the scientific word that is used to refer to atoms of the same element that have different numbers of neutrons. [1]

20 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 8 (a) Complete Table 8.1 below by drawing the circuit symbol for each electrical component. Table 8.1 name of component circuit symbol open switch resistor voltmeter fuse [2] (b) Fig. 8.1 shows an electrical hazard. outer insulation inner insulation copper wire Fig. 8.1 State the hazard. Explain why this situation is dangerous. [2]

21 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (c) In the circuit shown in Fig. 8.2 the reading on ammeter A3 is 0.5 A. (i) State the current readings on ammeters A1 and A2. A3 A A A A1 A2 Fig. 8.2 A1 A A2 A [1] (ii) Each lamp in the circuit has a resistance of 5 Ω. Calculate the combined resistance of the two lamps in the circuit. State the formula that you use and show your working. formula working Ω [2]

22 © UCLES 2013 0654/21/O/N/13 For Examiner's Use (d) Fig. 8.3 shows how the resistance of an electrical component in a circuit changes with temperature. 0 10 20 30 40 50 temperature / °C 2500 2000 1500 1000 500 0 resistance / Ω Fig. 8.3 (i) Write down the equation that shows how resistance is related to potential difference and current. [1] (ii) State the resistance of the component at 30 °C. Ω [1] (iii) Calculate the current that passes through the component at 30 °C when it is connected to a 12 V power supply. Show your working. A [2]

23 © UCLES 2013 0654/21/O/N/13 [Turn over Please turn over for Question 9.

24 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 9 Chinchillas are mammals with thick grey fur. Chinchillas are often kept as pets. People try to breed chinchillas with unusual fur. (a) A rare allele of the gene that determines fur colour, A, is dominant to the normal allele, a. Table 9.1 shows the possible fur colours arising from these two alleles. Table 9.1 genotype colour AA zygote does not develop Aa white aa normal grey (i) State the biological term for the observed effect produced by the genotype. [1]

25 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use (ii) A breeder has two white chinchillas. Complete the genetic diagram to show the genotypes of the offspring that would be produced when these two chinchillas are bred together. genotype of parents gametes … and … and and gametes from female chinchilla gametes from male chinchilla [3] (iii) State the ratio of fur colour that you would expect in the offspring resulting from this cross. Explain your answer. ratio of normal grey fur : white fur = : explanation [2]

26 © UCLES 2013 0654/21/O/N/13 For Examiner's Use (b) Wild chinchillas live in rocky places in the Andes mountains, where it gets cold at night. (i) Suggest how the chinchilla's fur can help it to maintain a constant body temperature. [2] (ii) Suggest why almost all the chinchillas found in the wild have normal grey fur colour rather than white fur. [2]

27 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use 10 Ethene, C2H4, is a gaseous, unsaturated hydrocarbon. (a) Explain the meanings of both words in the term unsaturated hydrocarbon. [2] (b) A sample of ethene was bubbled through bromine solution. ethene bromine solution Fig. 10.1 Describe the colour change that is observed when ethene reacts with bromine. from to [1]

28 © UCLES 2013 0654/21/O/N/13 For Examiner's Use (c) Propane, C3H8, is a gaseous hydrocarbon used as a fuel. Fig. 10.2 shows a cross-section through a small furnace (kiln) in which items of pottery are being heated by a propane burner. The temperature inside the kiln is 950 °C. waste gas mixture 950 °C propane C3H8 kiln walls made from insulating material air Fig. 10.2 (i) State which information from Fig. 10.2 shows that the combustion of propane is exothermic. Explain your answer. [2] (ii) Explain why the waste gas mixture contains high concentrations of carbon dioxide and water vapour. [1] (iii) The waste gases may also contain some carbon monoxide. Suggest a reason for this. [1] (iv) Explain why it is much safer to use a kiln like the one in Fig. 10.2 outside in the open air. [1]

29 © UCLES 2013 0654/21/O/N/13 [Turn over For Examiner's Use 11 X-rays and γ(gamma)–rays are both forms of electromagnetic radiation. They are also both forms of ionising radiation and are used in the treatment of cancer. (a) State the meaning of the term ionising radiation. [1] (b) Name the radiation that comes between X-rays and visible light in the electromagnetic spectrum. Give one use for this radiation. radiation use [2] (c) (i) Electromagnetic waves are transverse waves. Water waves are also transverse. Draw a diagram of a transverse wave on the axes below. Label the amplitude and wavelength on your diagram. [3] (ii) Sound waves are not transverse waves. State the type of wave motion demonstrated by sound waves. [1]

30 © UCLES 2013 0654/21/O/N/13 For Examiner's Use 12 (a) Fig. 12.1 shows a plant cell. chloroplast vacuole membrane cellulose cell wall large permanent vacuole nucleus cell membrane cytoplasm Fig. 12.1 (i) Name the tissue in the leaf in which this type of cell is found. [1] (ii) Describe how photosynthesis is carried out in this cell. [3] (b) About one tenth of the Earth's surface is covered by forests in which much photosynthesis takes place. Explain how extensive deforestation could harm the environment. [3]

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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 0654/21/O/N/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 October/November 2013 series 0654 CO-ORDINATED SCIENCES 0654/21 Paper 2 (Core 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 October/November 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 – October/November 2013 0654 21 © Cambridge International Examinations 2013 1 (a) (i) reference to reactivity of elements / compound is more stable ; [1] (ii) element cannot be simplified / decomposed chemically ; element contains just one type of atom ; element is found in Periodic Table ; [max 1] (iii) heat/boil solution ; leave to evaporate / water evaporates leaving sodium chloride ; [2] (b) (i) number of protons = number of electrons / charges in atoms are balanced ; reference to number of protons – number of electrons = 1 ; [2] (ii) idea that formula shows the ratio Ca:N particles is 3:2 ; [1] (c) (i) electrolysis ; [1] (ii) bromine is formed ; bromine (vapour) is orange ; bromine evaporates / boils off ; [max 2] [Total: 10] 2 (a) arrow going downwards ; [1] (b) (mass) = density × volume ; = 1.26 × 0.15 = 0.19 kg ; [2] (c) (i) solid – all particles touching, regular arrangement particles similar size ; liquid – most particles touching, irregular arrangement particles similar size ; [2] (ii) description S, L or G It cannot flow S It cannot transfer heat by convection S It contains particles which are widely separated G It expands the most when heated G It fills a closed container G It has a fixed volume but not a fixed shape L (2 correct = 1 mark, 4 correct = 2 marks, 6 correct = 3 marks) ;;; [3] [Total: 8]

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0654 21 © Cambridge International Examinations 2013 3 (a) (i) substance produced by a gland ; carried in blood ; affects activity of target organs ; [max 2] (ii) increases heart rate / pulse rate / blood pressure ; increases breathing rate / depth of breathing / width of airways ; increases rate of respiration ; heightens sensitivity / faster reactions ; [1] (b) (i) increased then decreased ; increased more rapidly than it decreased ; maximum 6.6 units / peak reached after 40 minutes ; returned to normal by 100 minutes ; [max 3] (ii) starch digested to, sugar / glucose ; by enzymes / amylase ; sugar / glucose, absorbed into the blood (causing increase) ; (absorbed) from the small intestine ; sugar / glucose, used in respiration (causing decrease) ; [max 3] (iii) (blood glucose concentration) did not rise as high ; maximum 4 units rather than 6.6 units ; rose more slowly ; fell more slowly ; took longer to return to normal / does not return to normal / at end is 0.2 higher ; [max 3] (c) reduces, constipation / bowel cancer / risk of diabetes ; [1] [Total: 13] 4 (a) (i) Y and Z ; non-metals ; [2] (ii) Z ; it is a noble / inert gas / reference to filled shells in atoms ; [2] (b) (i) Group 1 ; reference to at least one of the proton numbers plotted on graph ; [2] (ii) rubidium ; [1] (c) (i) make a solution of the oxide and add indicator ; blue / alkali shows metal oxide or red / acid shows non-metal oxide ; [2] (ii) insoluble substance dissolved / disappeared ; colour change / coloured substance produced ; [max 1] (iii) (reactants→) copper sulfate ; + water ; [2] [Total: 12]

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0654 21 © Cambridge International Examinations 2013 5 (a) (speed) = distance ÷ time ; 30 3000 = = 100 km / hour ; [2] (b) (i) accelerating ; [1] (ii) (distance) = speed × time ; = 180 km ; [2] (c) (i) 1 000 000 × 0.10 × 0.70 ; = 70 000J ; [2] (ii) electrical to kinetic ; [1] (d) (i) geothermal / tides / hydroelectric / waves / wind / biomass ; [1] (ii) fossil fuels not wasted ; no CO2 produced ; [max 1] (e) lateral inversion ; upright ; virtual ; [max 2] (f) parallel rays of light brought to a focus ; at 5 cm ; [2] [Total: 14] 6 (a) (i) A (right) atrium ; B (right) ventricle ; [2] (ii) contracts ; reduces volume of ventricle ; increases pressure ; [max 2] (iii) needs to produce more force ; to push blood all round the body ; not only to the lungs ; [max 2] (b) (i) blood in artery is at higher pressure ; blood in artery is pulsing ; blood in artery is deoxygenated ; blood contains more carbon dioxide ; [max 2] (ii) artery has a thicker wall ; artery has more elastic tissue ; artery does not have valves ; [max 2] [Total: 10]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0654 21 © Cambridge International Examinations 2013 7 (a) mixture of metals / mixture of solid elements most of which are metals ; [1] (b) (i) zirconium + oxygen → zirconium oxide ; [1] (ii) the idea that zirconium and oxygen atoms are now bonded ; and that oxygen atoms have mass ; [2] (iii) powder has higher surface area ; which increase reaction rate / particle collision frequency / allows efficient contact between oxygen and metal ; [2] (c) (i) 40 ; [1] (ii) isotope protons neutrons Zr – 90 40 50 Zr – 96 40 56 (any 2 correct – 1 mark, all 4 correct – 2 marks) ;; [2] (iii) isotopes ; [1] [Total: 10] 8 (a) 2 correct symbols for 1 mark ;; [2] (b) damaged insulation / bare wires ; danger of electrocution ; [2] (c) (i) A1 = 0.5 A and A2 = 0.5 A ; [1] (ii) RT = R1 + R2 ; = 10 Ω ; [2] V open switch resistor voltmeter fuse

Page 6 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0654 21 © Cambridge International Examinations 2013 (d) (i) V = I × R ; [1] (ii) 1300 ohms ; [1] (iii) 12/1300 ; = 0.009 A ; [2] [Total: 11] 9 (a) (i) phenotype ; [1] (ii) (parents’ genotypes) Aa and Aa ; gametes A and a from both parents ; offspring genotypes AA, Aa, Aa and aa ; [3] (iii) 1 : 2 ; none of the AA zygotes develop ; [2] (b) (i) fur traps air ; fur / air, acts as an insulator ; reduces heat loss by, convection / radiation ; [max 2] (ii) white animals less camouflaged ; more easily seen by predators ; reference natural selection ; [max 2] [Total: 10] 10 (a) unsaturated: contains double bonds / not the maximum possible number of H atoms ; hydrocarbon: compound of hydrogen and carbon only ; [2] (b) orange / yellow to colourless ; [1] (c) (i) the temperature (inside kiln) is high / is 950 °C ; exothermic means the reaction releases heat (energy) ; [2] (ii) produced by complete combustion of propane / hydrocarbons ; [1] (iii) produced by incomplete combustion of hydrocarbons ; [1] (iv) carbon monoxide is poisonous (to humans) / risk of suffocation/poisoning if waste gases cannot disperse ; [1] [Total: 8]

Page 7 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0654 21 © Cambridge International Examinations 2013 11 (a) removes electrons from atom / produces a charged particle ; [1] (b) ultraviolet ; fluorescent tubes / security marking / tanning / sterilising ; [2] (c) (i) sine wave ; amplitude correctly labelled ; wavelength correctly labelled ; [3] (ii) longitudinal ; [1] [Total: 7] 12 (a) (i) palisade (mesophyll) ; [1] (ii) takes place in chloroplasts ; chlorophyll absorbs, sunlight / energy from sunlight ; water combines with carbon dioxide ; produces oxygen and glucose / sugar ; [max 3] (b) reduction of habitat ; area too small to support populations / reduction in biodiversity / extinction / species become endangered / lack of opportunity to find new medicines ; flooding / leaching of minerals due to rain falling directly on soil / lack of protection of tree canopy / increased runoff ; soil erosion ; due to lack of tree roots ; drought ; due to lack of transpiration by trees to form rain leading to desertification ; fewer trees to photosynthesise/less photosynthesis ; to remove carbon dioxide ; burning trees produce CO2 ; rotting trees produce CO2 ; by respiration of microbes ; carbon dioxide traps long-wave radiation / infra-red / heat / thermal energy / is a greenhouse gas ; reduces rate of loss of heat from the Earth’s surface ; [max 3] [Total: 7]