Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2016 May/June Paper 3 · Variant 2

This document consists of 31 printed pages and 1 blank page. DC (RW/SW) 110311/4 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 0 1 7 8 1 1 6 3 0 2 * CO-ORDINATED SCIENCES 0654/32 Paper 3 (Extended) May/June 2016 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 an HB 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 0654/32/M/J/16 © UCLES 2016 1 A student adds four liquids to four solids. Fig. 1.1 shows the four experiments A, B, C and D. dilute hydrochloric acid A B C D copper sulfate solution dilute sulfuric acid magnesium sulfate solution zinc sodium hydrogencarbonate magnesium copper Fig. 1.1 (a) (i) Give the letter of the experiment in which a reaction occurs that releases a gaseous compound. Name the gaseous compound. experiment … name of gaseous compound …[2] (ii) Give the letter of the experiment which involves a change of colour. Explain your answer. experiment … explanation … … …[2]

3 0654/32/M/J/16 © UCLES 2016 [Turn over (b) Table 1.1 shows the temperature measurements the student makes during his investigation. Table 1.1 experiment temperature of substances before mixing / °C temperature of the mixture after one minute / °C A 22 22 B 22 45 C 22 15 D 22 22 (i) Give the letter of the experiment in which an exothermic reaction occurs. Explain your answer. reaction … explanation … … [1] (ii) Give the letter of the experiment in which there is a decrease in the speed of the molecules. Explain your answer in terms of the energy conversion that occurs. reaction … explanation … … … [2] (iii) Explain the results for experiment A. … … …[2]

4 0654/32/M/J/16 © UCLES 2016 2 (a) Plants lose water by evaporation. (i) State the term for the loss of water from a plant by evaporation. …[1] (ii) Describe and explain how the rate of this evaporation is affected by the number of stomata in a leaf. … … …[1] (iii) Most leaves have more stomata on their underside than on their upper surface. Suggest why this is an advantage for the plant. … …[2] (b) Fig. 2.1 shows the rate of water loss and the rate of water uptake for a plant over a period of one day. 00:00 0 10 20 30 40 04:00 08:00 12:00 16:00 20:00 time / hours water / g per hour 24:00 water loss water uptake Fig. 2.1

5 0654/32/M/J/16 © UCLES 2016 [Turn over (i) For this day, state the time at which the rate of water loss is greatest, … a time when the rate of water loss is the same as the rate of water uptake. … [2] (ii) Describe the relationship between water loss and water uptake that is shown in Fig. 2.1. … … …[2] (c) State two ways in which the structure of a root hair helps a plant to absorb water. 1 … 2 … [2]

6 0654/32/M/J/16 © UCLES 2016 3 Fig. 3.1 shows an aircraft of mass 3.6 × 105 kg moving with constant acceleration from rest along an airport runway. Fig. 3.1 (a) After 30 seconds the aircraft reaches a speed of 60 m / s. (i) Calculate the kinetic energy of the aircraft, when travelling at 60 m / s. State the formula you use and show your working. formula working kinetic energy = … J [2] (ii) Calculate the acceleration of the aircraft during the first 30 seconds. Show your working. acceleration = … m / s2 [2]

7 0654/32/M/J/16 © UCLES 2016 [Turn over (b) Just after taking off, the aircraft continues to accelerate as it gains height. State two forms of energy gained by the aircraft during this time. 1 … 2 … [1] (c) State the difference between the terms speed and velocity. … …[1] (d) The aircraft has 20 tyres. Each tyre has an area of 0.06 m2 in contact with the ground when the aircraft is on the runway. The weight of the aircraft is 3 600 000 N. Calculate the pressure exerted by the aircraft on the runway. State the formula you use and show your working. formula working pressure = … N / m2 [3] (e) It has been raining and there is a large puddle of water on the runway. State two factors that would increase the rate at which the water evaporates from the puddle. 1 … 2 … [2]

8 0654/32/M/J/16 © UCLES 2016 (f) Fig. 3.2 shows an aircraft being refuelled through a rubber pipe. aircraft rubber pipe tanker Fig. 3.2 As the fuel flows through the rubber pipe, it becomes positively charged. Suggest, in terms of electrons, why the fuel becomes positively charged. … … …[2]

9 0654/32/M/J/16 © UCLES 2016 [Turn over 4 Fig. 4.1 shows a hot-air balloon with a propane gas burner and a helium-filled airship. propane gas burner hot-air balloon helium-filled airship Fig. 4.1 (a) Both helium and hydrogen could be used to fill airships. Explain why helium is preferred to hydrogen for filling airships designed to transport people. … … …[2] (b) Propane is an alkane. A molecule of propane contains three carbon atoms. Complete the diagram to show one molecule of propane. C [2]

10 0654/32/M/J/16 © UCLES 2016 (c) Explain, in terms of the properties of molecules, why propane has a higher boiling point than helium. … … … …[2]

11 0654/32/M/J/16 © UCLES 2016 [Turn over 5 (a) Fig. 5.1 shows part of a food web from a rainforest. The food web is a network of interconnecting food chains. anaconda snake jaguar tree frog insects tamarin monkey sloth howler monkey plants Fig. 5.1 (i) State the number of trophic levels in the longest food chain in Fig. 5.1. …[1] (ii) Name an organism in Fig. 5.1 that is at the second trophic level. …[1] (iii) Explain why food webs rarely have more than five trophic levels. … … …[2] (iv) Name a type of organism that might feed on all of the organisms shown in Fig. 5.1. …[1]

12 0654/32/M/J/16 © UCLES 2016 (b) In the last 50 years, large areas of rainforest have been cut down for timber. Some of the timber has been used as building material and some has been used as fuel. (i) Many people believe that cutting down trees increases the amount of carbon dioxide in the Earth’s atmosphere. Explain why cutting down trees could cause this increase. … … … …[2] (ii) Explain why using timber as a fuel will have more effect on the Earth’s atmosphere than using timber as a building material. … …[1]

13 0654/32/M/J/16 © UCLES 2016 [Turn over 6 (a) Fig. 6.1 shows an incomplete diagram of the electromagnetic spectrum. radio waves ultraviolet gamma radiation Fig. 6.1 Visible light is part of the electromagnetic spectrum. On Fig. 6.1 write visible light in the correct position. [1] (b) Gamma radiation is emitted from some unstable nuclei. Gamma radiation is ionising. (i) State one risk to humans of exposure to ionising radiation. … …[1] (ii) Alpha radiation is also emitted from some unstable nuclei. State one difference between gamma radiation and alpha radiation. … …[1]

14 0654/32/M/J/16 © UCLES 2016 (c) Visible light is able to pass through an optical fibre by total internal reflection. Fig. 6.2 shows a student’s diagram of total internal reflection along the optical fibre. The diagram contains some errors. Fig. 6.2 On Fig. 6.2, circle two errors the student has made in their diagram. Describe the errors you have identified. error 1 … … … error 2 … … … [3]

15 0654/32/M/J/16 © UCLES 2016 [Turn over (d) The frequency of red light is 4 × 1014 Hz. Red light travels at a speed of 3 × 108 m / s in a vacuum. (i) Calculate the wavelength of red light. State the formula you use and show your working. formula working wavelength = … m [2] (ii) The frequency of blue light is 6.5 × 1014 Hz. Write down the speed of blue light in a vacuum. Explain your answer. speed = … m / s explanation … … [1]

16 0654/32/M/J/16 © UCLES 2016 7 (a) Homeostasis depends on negative feedback. Explain what is meant by the term negative feedback. … … … …[2] (b) Fig. 7.1 shows part of the alimentary canal and some associated organs. Fig. 7.1 (i) On Fig. 7.1, label the pancreas. [1] (ii) The pancreas helps to maintain a constant concentration of glucose in the blood. Use the words in the list to complete the sentences about the pancreas. Each word may be used once, more than once, or not at all. adrenaline amylase glucagon glycogen insulin kidneys liver starch When the blood glucose concentration is too high, the pancreas secretes … into the blood. This causes the … to convert glucose to … . If the blood glucose is too low, the pancreas secretes … . [4]

17 0654/32/M/J/16 © UCLES 2016 [Turn over 8 Fig. 8.1 shows two cars. One car is painted black. The other car is painted white. Fig. 8.1 (a) The cars are left outside on a hot, sunny day. (i) State the method of energy transfer by which energy travels from the Sun to the Earth. …[1] (ii) State the process by which energy is released in the Sun. …[1] (iii) The black car gets much hotter than the white car. Suggest why the black car gets hotter than the white car. … …[1]

18 0654/32/M/J/16 © UCLES 2016 (b) Each of the cars has its own electrical generator to generate electricity for the car. Fig. 8.2 shows a simple a.c. generator. a.c. output S N coil Fig. 8.2 Explain how the rotation of the coil in the magnetic field and the use of slip rings produce an alternating current. … … … … …[3]

19 0654/32/M/J/16 © UCLES 2016 [Turn over (c) The engine in a car is noisy. It emits a sound with a frequency of 5000 Hz. (i) State what is meant by the term frequency. … …[1] (ii) While he was driving, the driver notices that the noise from the engine becomes quieter and the frequency of the sound waves decreases. State whether the sound waves have a larger or smaller amplitude than the original sound waves, … a higher or lower pitch than the original sound waves. … [1] (iii) The sound waves produced travel through the air by compressions and rarefactions. Describe the difference between a compression and a rarefaction. … …[1]

20 0654/32/M/J/16 © UCLES 2016 9 (a) (i) Use data from the Periodic Table on page 32 to describe how the electrons are arranged in an atom of sodium. You may draw a diagram if it helps your answer. … …[2] (ii) Rubidium, Rb, is an element in the same group of the Periodic Table as sodium, Na. State how the arrangements of the electrons in these two elements cause them to have very similar chemical properties. … …[1] (b) Sodium is obtained by electrolysis of molten sodium chloride, NaCl. Describe, in terms of the particles involved, what happens at the cathode during this electrolysis. … … …[2]

21 0654/32/M/J/16 © UCLES 2016 [Turn over (c) Fig. 9.1 shows the apparatus and materials used to investigate the reaction between sodium and water. pH meter pH sodium hydrogen gas given off water sodium hydroxide dissolves Fig. 9.1 The reaction between sodium and water produces hydrogen gas and a solution of sodium hydroxide, NaOH. (i) Suggest and explain the reading of the pH meter at the end of the reaction. pH reading … explanation … … [2] (ii) Write the balanced symbol equation for the reaction between sodium and water. …[2]

22 0654/32/M/J/16 © UCLES 2016 (d) Lithium hydroxide is used in space vehicles to remove the carbon dioxide produced by the astronauts. The balanced equation for this reaction is shown. 2LiOH + CO2 Li2CO3 + H2O It is estimated that during a particular mission, the astronauts will produce a total of 1000 moles of carbon dioxide. Calculate the minimum mass of lithium hydroxide needed to react with 1000 moles of carbon dioxide. Show your working and state the unit of your answer. Relative atomic masses may be found in the Periodic Table on page 32. mass = … unit = … [3]

23 0654/32/M/J/16 © UCLES 2016 [Turn over 10 Cystic fibrosis (CF) is a genetic disorder that can be caused by a mutation. (a) State what is meant by the term mutation. … … …[2] (b) Fig. 10.1 shows the inheritance of cystic fibrosis in a family. = normal male NH\ 3 JUDQGSDUHQWV SDUHQWV RIIVSULQJ 5 4 = male with CF = normal female = female with CF Fig. 10.1 (i) Using the symbols N (allele for normal) and n (allele for CF), state all the possible genotypes of the people labelled P and Q. P … Q … [3] (ii) With reference to Fig. 10.1, explain why this family tree shows that the allele for cystic fibrosis must be recessive. … … …[2]

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25 0654/32/M/J/16 © UCLES 2016 [Turn over 11 Sulfur is a yellow crystalline solid that occurs naturally in the Earth’s crust. (a) Fig. 11.1 shows a diagram of a molecule of sulfur. sulfur atom covalent bond key Fig. 11.1 (i) State the chemical formula of the molecule shown in Fig. 11.1. …[1] (ii) Explain why Fig. 11.1 shows that sulfur is an element and not a compound. … …[1]

26 0654/32/M/J/16 © UCLES 2016 (b) Fig. 11.2 shows the apparatus and materials used by a teacher to demonstrate the formation of sulfur dioxide by burning sulfur in air. water gas-jar air sulfur burning Fig. 11.2 (i) Some of the sulfur dioxide dissolves and reacts with the water in the bottom of the gas-jar to form an aqueous solution. Predict and explain the colour of full-range indicator (Universal Indicator) when added to this aqueous solution. colour … explanation … … [2] (ii) State the percentages of nitrogen and oxygen in unpolluted air. oxygen … % nitrogen … % [1] (iii) The teacher repeats the demonstration using pure oxygen instead of air. Predict how the rate of burning will change when using pure oxygen instead of air. …[1] (iv) Explain your answer to (b)(iii) in terms of collisions between reactant molecules. … … …[2]

27 0654/32/M/J/16 © UCLES 2016 [Turn over (c) Sulfur is an industrial raw material used in the Contact process. It is burned in air to make sulfur dioxide. Fig. 11.3 is a diagram of part of the Contact process. sulfur dioxide + oxygen vanadium oxide sulfur trioxide reaction vessel 1 water main product reaction vessel 2 Fig. 11.3 (i) The word equation for the reaction in vessel 1 is shown. sulfur dioxide + oxygen sulfur trioxide Explain why the word equation does not include vanadium oxide. … …[2] (ii) Name the main product leaving vessel 2. …[1]

28 0654/32/M/J/16 © UCLES 2016 (d) Sulfur can react with hydrogen to form hydrogen sulfide, H2S. Fig. 11.4 shows a student’s attempt to draw a dot and cross diagram of all the outer electrons in a molecule of hydrogen sulfide. H H S X X X X Fig. 11.4 The student’s diagram is incorrect. Redraw the diagram correctly in the space below. [2]

29 0654/32/M/J/16 © UCLES 2016 [Turn over 12 (a) A torch contains four cells, a filament lamp and a switch connected in series. Draw a circuit diagram for the torch using the correct electrical circuit symbols. [3] (b) The current in the lamp is 0.7 A when it is at normal brightness. The torch is switched on for 20 minutes. Calculate the total charge that passes through the lamp in this time. State the formula you use and show your working. State the unit of your answer. formula working charge = … unit = … [3]

30 0654/32/M/J/16 © UCLES 2016 (c) Two lamps, one of resistance 4 Ω and one of resistance 12 Ω, are connected in parallel. Calculate the total resistance of these two lamps in parallel. State the formula you use and show your working. formula working resistance = … Ω [2] (d) A resistor of 3 Ω and a resistor of 10 Ω can be arranged either in series or in parallel and then connected to a battery. Use ticks () to show which statements in Table 12.1 are correct. Table 12.1 in series in parallel the current in each resistor is the same the potential difference across each resistor is the same [1]

31 0654/32/M/J/16 © UCLES 2016 13 Fig. 13.1 shows a cross-section through a pond. The pond contains plants growing near the surface of the water. At the bottom of the pond there is mud which contains bacteria. plants mud which contains bacteria Fig. 13.1 (a) Explain the advantage for the plants of being at the top of the pond rather than at the bottom. … …[2] (b) A farmer accidentally spills some fertiliser into the pond. Suggest and explain what effect this would have on (i) the plants, … … …[2] (ii) the bacteria, … … …[2] (iii) the fish living in the pond. … … …[2]

32 0654/32/M/J/16 © UCLES 2016 To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Group The Periodic Table of Elements 1 H hydrogen 1 2 He helium 4 I II III IV V VI VII VIII 3 Li lithium 7 4 Be beryllium 9 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23 12 Mg magnesium 24 19 K potassium 39 20 Ca calcium 40 37 Rb rubidium 85 38 Sr strontium 88 55 Cs caesium 133 56 Ba barium 137 87 Fr francium – 88 Ra radium – 5 B boron 11 13 Al aluminium 27 31 Ga gallium 70 49 In indium 115 81 Tl thallium 204 6 C carbon 12 14 Si silicon 28 32 Ge germanium 73 50 Sn tin 119 82 Pb lead 207 22 Ti titanium 48 40 Zr zirconium 91 72 Hf hafnium 178 104 Rf rutherfordium – 23 V vanadium 51 41 Nb niobium 93 73 Ta tantalum 181 105 Db dubnium – 24 Cr chromium 52 42 Mo molybdenum 96 74 W tungsten 184 106 Sg seaborgium – 25 Mn manganese 55 43 Tc technetium – 75 Re rhenium 186 107 Bh bohrium – 26 Fe iron 56 44 Ru ruthenium 101 76 Os osmium 190 108 Hs hassium – 27 Co cobalt 59 45 Rh rhodium 103 77 Ir iridium 192 109 Mt meitnerium – 28 Ni nickel 59 46 Pd palladium 106 78 Pt platinum 195 110 Ds darmstadtium – 29 Cu copper 64 47 Ag silver 108 79 Au gold 197 111 Rg roentgenium – 30 Zn zinc 65 48 Cd cadmium 112 80 Hg mercury 201 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14 15 P phosphorus 31 33 As arsenic 75 51 Sb antimony 122 83 Bi bismuth 209 8 O oxygen 16 16 S sulfur 32 34 Se selenium 79 52 Te tellurium 128 84 Po polonium – 9 F fluorine 19 17 Cl chlorine 35.5 35 Br bromine 80 53 I iodine 127 85 At astatine – 10 Ne neon 20 18 Ar argon 40 36 Kr krypton 84 54 Xe xenon 131 86 Rn radon – 21 Sc scandium 45 39 Y yttrium 89 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 139 89 Ac lanthanoids actinoids The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.) actinium – 58 Ce cerium 140 90 Th thorium 232 59 Pr praseodymium 141 91 Pa protactinium 231 60 Nd neodymium 144 92 U uranium 238 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150 94 Pu plutonium – 63 Eu europium 152 95 Am americium – 64 Gd gadolinium 157 96 Cm curium – 65 Tb terbium 159 97 Bk berkelium – 66 Dy dysprosium 163 98 Cf californium – 67 Ho holmium 165 99 Es einsteinium – 68 Er erbium 167 100 Fm fermium – 69 Tm thulium 169 101 Md mendelevium – 70 Yb ytterbium 173 102 No nobelium – 71 Lu lutetium 175 103 Lr lawrencium –

® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 7 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/32 Paper 3 Extended Theory May/June 2016 MARK SCHEME Maximum Mark: 120 Published 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 May/June 2016 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0654 32 © Cambridge International Examinations 2016 1 (a) (i) C ; carbon dioxide ; [2] (ii) B ; copper is formed / copper ions are lost / solution loses colour / it is a displacement reaction ; [2] (b) (i) (B) reaction causes temperature increase ; [1] (ii) (C) reaction is endothermic / temperature decreases ; because kinetic energy of molecules increases / convers to chemical potential energy ; [2] (iii) no change in temperature suggests no reaction ; because copper is too unreactive to displace hydrogen from dilute acid ; [2] [Total: 9] 2 (a) (i) transpiration ; [1] (ii) more stomata means faster transpiration, because water loss occurs here ; [1] (iii) less exposure to sunlight / lower temperature ; therefore, less water loss ; [2] (b) (i) 16.00 ; 17.00 ; [2] (ii) similar pattern / correlated ; water uptake lags behind water loss ; appropriate comparison of water uptake and water loss ; [max 2] (c) large surface area ; thin / permeable ; [2] [Total: 10] 3 (a) (i) (KE =) 1 2 m v2 / 1 2 × 3.6 × 105 × (60 × 60) ; 6.48 × 108 (J) ; [2] (ii) (acceleration =) change in speed / time / 60 / 30 ; 60 / 30 = 2 (m / s2) ; [2] (b) kinetic and gravitational potential energy ; [1] (c) speed is magnitude only but velocity is magnitude and direction ; [1]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0654 32 © Cambridge International Examinations 2016 (d) area 20 × 0.06 ; (pressure =) force / area / 3.6 × 106 / 20 × 0.06 ; = 3 × 106 (N / m2) ; [3] (e) increased airflow ; increased temperature ; larger surface area ; low humidity ; [max 2] (f) friction between fuel and pipe ; fuel losses electrons to pipe ; [2] [Total: 13] 4 (a) reference to helium being unreactive / greater reactivity of hydrogen ; reference to safety / reducing fire risk ; [2] (b) 3 × carbon and 8 × hydrogen ; all single bonds and no other errors ; [2] (c) reference to greater particle size / mass / surface area of propane ; so greater intermolecular attractive forces in propane ; so more thermal / heat energy required to separate propane molecules ; [max 2] [Total: 6] 5 (a) (i) four ; [1] (ii) tamarind monkey / insect / howler monkey / sloth ; [1] (iii) energy losses at each stage ; so not enough energy left at higher trophic levels ; [2] (iv) decomposer ; [1] (b) (i) carbon dioxide used for photosynthesis ; less photosynthesis / less CO2 absorbed ; decomposition / combustion of trees produces CO2 ; [max 2] (ii) CO2 produced by combustion, and not in construction ; [1] [Total: 8] 6 (a) visible placed to the left of ultraviolet ; [1] (b) (i) cancer / mutations ; [1]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0654 32 © Cambridge International Examinations 2016 (ii) gamma more penetrating ; gamma has no charge, alpha has positive charge ; gamma is a wave, alpha is a particle ; gamma less ionising ; [max 1] (c) two errors circled on diagram ; two errors described ;; [3] (d) (i) v = f × λ / 3 × 108 / 4 × 1014 ; 7.5 × 10–7 (m) ; [2] (ii) 3 × 108 (m / s) (no mark) all electromagnetic waves travel at the same speed ; [1] [Total: 9] 7 (a) set point / steady state ; change away causes a change towards / AW ; [2] (b) (i) pancreas correctly labelled ; [1] (ii) insulin ; liver ; glycogen ; glucagon ; [4] [Total: 7] 8 (a) (i) radiation ; [1] (ii) nuclear fusion ; [1] (iii) black surfaces are better absorbers of radiation than white surfaces / white surfaces are better reflectors of radiation than black surfaces ; [1] (b) coil cuts magnetic field lines ; coil experience a changing magnetic field ; emf included in coil producing a current ; emf / current reverses every half turn ; slip rings prevent tangling of wires ; [max 3] (c) (i) number of waves / vibrations per second or number of waves passing a fixed point / second ; [1] (ii) smaller amplitude and lower pitch ; [1]

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0654 32 © Cambridge International Examinations 2016 (iii) compression – particles closer together – rarefaction further apart or compression – region of high pressure – rarefaction region of low pressure ; [1] [Total: 9] 9 (a) (i) 11 electrons / in shells / energy levels surrounding the nucleus ; 2, 8, 1 configuration ; [2] (ii) same number of outer electrons / both have a single outer electron ; [1] (b) sodium ions are attracted to the cathode ; sodium ions gain an electron / are discharged ; sodium ions converted to sodium atoms ; correct equation ;; [max 2] (c) (i) 8 to 14 ; sodium hydroxide solution is alkaline ; [2] (ii) 2Na + 2H2O → 2NaOH + H2 ;; [2] (d) calculate Mr of lithium hydroxide = 24 ; stoichiometry / use of equation to show 2000 moles lithium hydroxide needed ; calculate mass of 2000 moles lithium hydroxide = 2000 × 24 g / 48 000 g ; [3] [Total: 12] 10 (a) change in a gene / chromosome ; any detail ; [2] (b) (i) P = Nn ; Q = NN ; or Nn ; [3] (ii) CF children born to normal parents ; so these parents must have carried the allele ; e.g. G has normal parents / child of E has CF ; [max 2] [Total: 7] 11 (a) (i) S8 ; [1] (ii) only one type of atom ; [1]

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0654 32 © Cambridge International Examinations 2016 (b) (i) red / orange ; solution is acidic / sulfur dioxide is acidic / non-metal oxides are acidic ; [2] (ii) oxygen 21 and nitrogen 78 ; [1] (iii) rate is greater (in oxygen) ; [1] (iv) the idea that oxygen in air is diluted by other gases ; collision frequency between oxygen and sulfur greater in pure oxygen ; [2] (c) (i) vanadium oxide is the catalyst ; but is not consumed / permanently changed ; [2] (ii) concentrated sulfuric acid ; [1] (d) removes extraneous electron from both H atoms ; includes only two lone pairs of electrons on S atom ; [2] [Total: 13] 12 (a) all components present ; in series circuit ; all symbols correct ; [3] (b) (charge =) current × time / = 0.7 × 20 × 60 ; 840 ; C ; [3] (c) use of 1 / RT = 1 / R1 + 1 / R2 ; RT = 12 / 4 = 3 (Ω) ; [2]

Page 7 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0654 32 © Cambridge International Examinations 2016 (d) in series in parallel the current through each resistor is the same √ the voltage across each resistor is the same √ [1] [Total: 9] 13 (a) more light at the top ; for photosynthesis ; [2] (b) (i) increased growth ; due to more mineral ions ; followed by decreased growth / death because all mineral ions used up / no light / outcompeted by algae ; [max 2] (ii) increased numbers ; because more dead matter ; bacteria respire ; [max 2] (iii) death, because of lack of oxygen ; oxygen used by the bacteria / decomposers ; [2] [Total: 8]