Cambridge IGCSE Science - Combined 0653 — 2015 Oct/Nov Paper 3 · Variant 2

This document consists of 24 printed pages. DC (NH/SG) 103610/3 © UCLES 2015 [Turn over * 5 2 0 2 3 7 7 2 0 3 * COMBINED SCIENCE 0653/32 Paper 3 (Extended) October/November 2015 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 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 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. Cambridge International Examinations Cambridge International General Certificate of Secondary Education

2 0653/32/O/N/15 © UCLES 2015 1 Fig. 1.1 shows a van being driven along a flat road at a constant speed. The arrows on the diagram represent the four main forces acting on the van. reaction force Fig. 1.1 (a) (i) On Fig. 1.1, use words from the list to complete the boxes next to the arrows to label the three missing forces. Each word from the list can be used once, more than once or not all. driving friction gravity mass pressure weight [2] (ii) The reaction force is 30 000 N. State the value of the downward force. Give a reason for your answer. downward force = … N reason … …[2] (iii) Explain where the downward force in (a)(ii) comes from. … …[1]

3 0653/32/O/N/15 © UCLES 2015 [Turn over (b) Fig. 1.2 shows a speed / time graph for the van for a short journey. 20 10 0 0 30 60 90 120 speed m / s time / s Fig. 1.2 (i) Describe the motion of the van between 30 s and 120 s … … …[2] (ii) Use the speed / time graph in Fig. 1.2 to calculate the distance travelled in kilometres in the first 90 s of the journey. Show your working. distance travelled = … km [3]

4 0653/32/O/N/15 © UCLES 2015 2 (a) Yoghurt is made by adding bacteria to milk. • The milk is heated to 85 °C, then allowed to cool before adding the bacteria. • The bacteria use the nutrients in the milk as their food source. • Lactic acid is a waste product which lowers the pH of the milk. • This causes the yoghurt to be made. Explain why (i) the milk used to make yoghurt is heated to 85 °C before it is used, … …[1] (ii) the milk is then cooled before adding the bacteria. … …[1] (b) Many manufacturers use two types of bacteria to make yoghurt instead of just one. Both types produce lactic acid. They also produce other chemicals which are helpful in the process of making yoghurt as shown in Fig. 2.1. bacterium A bacterium B growth factors amino acids milk reaction vessel Fig. 2.1 Bacterium B produces amino acids by breaking down much larger molecules that are present in the milk. (i) Name these larger molecules. …[1] (ii) Suggest how bacterium B breaks down these larger molecules into amino acids. … …[1]

5 0653/32/O/N/15 © UCLES 2015 [Turn over (iii) Use the information in Fig. 2.1 to explain why manufacturers prefer to use two types of bacteria instead of one. … … … …[2] (c) Some of the nutrients in two types of yoghurt are illustrated in Table 2.1. Table 2.1 nutrient amount in 100 g yoghurt C yoghurt D protein / g 3.6 4.7 carbohydrate / g 10.6 8.8 fat / g 4.2 0.2 calcium / mg 124 202 Suggest and explain which type of yoghurt would be the better choice (i) for avoiding coronary heart disease, … …[1] (ii) for building strong bones. … …[1]

6 0653/32/O/N/15 © UCLES 2015 3 Petroleum (crude oil) is a mixture of compounds. Some of these compounds are used as fuels. (a) (i) Name the process used to separate the petroleum mixture into useful fractions. …[1] (ii) State and explain whether this process involves a physical or a chemical change. … …[1] (b) Fig. 3.1 shows how petroleum fractions can be separated in the laboratory. thermometer side-arm test-tube petroleum heat cool delivery tube small test-tube fraction A Fig. 3.1 The petroleum is heated and petroleum vapour is formed. When the thermometer shows a temperature of 100 °C, fraction A collects in the small test-tube.

7 0653/32/O/N/15 © UCLES 2015 [Turn over The small test-tube used to collect the fraction is replaced with a fresh test-tube. Heating is continued, and three further fractions, B, C, and D, are collected. All four fractions are shown in Fig. 3.2. A B C D Fig. 3.2 The fractions become darker from A to D. The fractions are collected over the temperature ranges shown in Table 3.1. Table 3.1 fraction temperature range / °C A room temperature to 100 B 100 to 150 C 150 to 200 D 200 to 250 (i) Use the information in Table 3.1 to state one trend in a physical property of the fractions A to D apart from colour. … …[1] (ii) Suggest how the average size of the molecules in the fractions changes from A to D. Explain your answer. … … … …[2]

8 0653/32/O/N/15 © UCLES 2015 (c) Ethane is one of the compounds found in petroleum. Complete the drawing of the structure of a molecule of ethane. C H [2] (d) The cracking of petroleum produces compounds which react readily with bromine. State the type of compound produced by cracking that reacts with bromine. …[1]

9 0653/32/O/N/15 © UCLES 2015 [Turn over Please turn over for Question 4.

10 0653/32/O/N/15 © UCLES 2015 4 Fig. 4.1 shows an electric fan heater used to keep people warm. cooler air in warmer air out Fig. 4.1 (a) The fan heater contains • a switch to control the mains electricity supply, • an electric heater to warm the air, • an electric motor to drive the fan, • a fuse to protect the circuit. The fan must continue to work, even when the heater is not working. Fig. 4.2 shows the circuit symbols for a heater, an electric motor and a fuse. M electric heater electric motor fuse Fig. 4.2 On Fig. 4.3 complete the circuit diagram for the fan heater connected to the mains electricity supply, using the correct circuit symbols for the components listed above. The mains electricity supply has been drawn for you. mains electricity supply Fig. 4.3 [3]

11 0653/32/O/N/15 © UCLES 2015 [Turn over (b) Another type of switch is also needed in the circuit as a safety device to cut off the heater if the temperature rises too much. This is called a thermal cut-out. The thermal cut-out must switch off the heater but not the fan. The fan must continue to operate to reduce the temperature. Fig. 4.4 shows the structure of this switch. contacts bimetallic strip iron brass Fig. 4.4 (i) On Fig. 4.3 in (a), mark with an X a point in your completed circuit where this switch could be put into the circuit to switch off the heater but not the fan. [1] (ii) As the temperature rises, the bimetallic strip bends upwards, so breaking the contact and switching off the heater. Explain in terms of the particles in the brass and iron why the strip bends in this way. … … …[2] (iii) Suggest a suitable position inside the fan heater to place the thermal cut-out so that, when the temperature of the room is warm enough, the heater is switched off. Give a reason for your answer. … … …[2]

12 0653/32/O/N/15 © UCLES 2015 5 (a) Fig. 5.1 shows a male and a female gamete. They are not drawn to scale. male gamete female gamete Fig. 5.1 (i) The actual diameter of the female gamete is 100 micrometres. Estimate a value for the length of the male gamete. … micrometres [1] (ii) Estimate how many gametes are produced during the lifetime of the average human male, … female. …[2] (iii) State how the nucleus of the male gamete differs from the nucleus of a zygote. … …[1]

13 0653/32/O/N/15 © UCLES 2015 [Turn over (b) Fig. 5.2 shows a fetus developing in the uterus of a pregnant woman. placenta umbilical cord X Fig. 5.2 Name part X and describe its function. name … function … …[2] (c) During pregnancy a possible complication is narrowing of the blood vessels in the umbilical cord. (i) Explain why this affects the amount of blood flowing to and from the placenta. … …[1] (ii) Describe how this will affect the fetus. … … …[2]

14 0653/32/O/N/15 © UCLES 2015 6 Table 6.1 shows some elements placed in order of reactivity. Table 6.1 potassium sodium calcium magnesium zinc iron hydrogen copper (a) Table 6.2 shows the reactions of some of the elements when added to dilute hydrochloric acid. Table 6.2 element added to acid observation calcium bubbles vigorously copper no reaction zinc (i) Complete Table 6.2 by adding the observation you would expect when zinc is added to the acid. [1] (ii) Explain your answer to (a)(i) by referring to the reactivity series. … … …[2]

15 0653/32/O/N/15 © UCLES 2015 [Turn over (b) Fig. 6.1 shows what happens when a student places a zinc rod in copper sulfate solution. zinc rod blue copper sulfate solution brown deposit colourless solution Fig. 6.1 The rod becomes coated in a brown deposit and the solution slowly changes from blue to colourless. The zinc rod consists of zinc atoms. Copper sulfate solution contains aqueous copper ions, Cu2+, which are coloured blue. (i) State the type of particles which form the brown coating on the zinc rod. … [1] (ii) Suggest why the colour of the solution changes during the reaction. … …[1] (iii) Use the reactivity series in Table 6.1 to explain why this reaction occurs. … … …[2]

16 0653/32/O/N/15 © UCLES 2015 (c) A student investigates the position of tin in the reactivity series. Her experiments are shown in Fig. 6.2. tin rod blue copper sulfate solution brown deposit colourless solution tin rod pale green iron sulfate solution no change Fig. 6.2 (i) Add tin to the section of the reactivity series in Table 6.3. Table 6.3 zinc iron copper [1]

17 0653/32/O/N/15 © UCLES 2015 [Turn over (ii) By referring to Fig. 6.2, explain your answer to (c)(i). … … … …[2]

18 0653/32/O/N/15 © UCLES 2015 7 (a) A motorcyclist needs to see other vehicles and pedestrians. Fig. 7.1 shows a motorcyclist from above and a car some distance behind him. The motorcyclist looks in his rear view mirror to see the car. rear view mirror Fig. 7.1 On Fig. 7.2 construct an accurate ray diagram for the reflection in the motorcycle’s rear view mirror. Use arrowheads to show the direction of the ray mirror eye car Fig. 7.2 [2] (b) The motorcyclist follows directions to his destination using his satellite navigation system (Satnav). The Satnav picks up signals from satellites orbiting the Earth to show the position of the motorcycle on a map displayed on the Satnav screen in front of him. State the type of electromagnetic wave used by satellites sending signals to Earth. …[1]

19 0653/32/O/N/15 © UCLES 2015 [Turn over (c) The motorcyclist travels along a street at night. The street is lit by lamps which emit yellow light with a wavelength of 589 nanometres (nm) or 589 × 10–9 m. (i) State the formula that relates the speed, frequency and wavelength of a wave motion. …[1] (ii) Calculate the frequency of the electromagnetic waves of yellow light from the street lights. Speed of light = 3 × 108 m/s. Show your working and state the unit of your answer. frequency = … unit = … [2] (d) The motorcycle has two headlamps and a rear lamp, powered by a 6V battery. The headlamps are identical, and are rated at 6V 36W. The rear lamp is rated at 6V 6W and takes a current of 1A. (i) Calculate the current taken by one headlamp when lit. State the formula used and show your working. formula working current = … A [2] (ii) The lamps are all connected in parallel. Calculate the total current drawn from the battery by the three lamps when all are lit. total current = … A [1]

20 0653/32/O/N/15 © UCLES 2015 8 (a) Fig. 8. 1 shows part of a simple food chain in a field of wheat. wheat seeds mouse grass snake Fig. 8.1 (i) There are three trophic levels in the food chain shown in Fig. 8.1. Define the term trophic level. … …[1] (ii) Explain why food chains usually have fewer than five trophic levels. … … …[2] (iii) A badger also lives in the habitat. The badger eats all of the organisms in the food chain. These organisms and the badger form a food web. Complete Fig. 8.2 to show the food web. wheat seeds mouse grass snake Fig. 8.2 [2] (b) All food chains must have decomposers, though they are not always included in diagrams. Explain the importance of decomposers in the habitat. … … …[2]

21 0653/32/O/N/15 © UCLES 2015 (c) The wheat is harvested. Suggest two possible ways in which the mice respond to the removal of their food supply. 1 … … 2 … …[2]

22 0653/32/O/N/15 © UCLES 2015 9 A copy of the Periodic Table is printed on page 24. (a) (i) State how the position of chlorine in the Periodic Table shows that it is a non-metal. … …[1] (ii) State how the Periodic Table is used to predict the number of outer shell electrons in a fluorine atom. … …[1] (iii) State how the number of outer shell electrons in an atom of an element can be used to predict whether the element is likely to be a metal or a non-metal. … …[1] (b) Hydrogen and chlorine react to form hydrogen chloride gas. (i) Write a balanced chemical equation for the reaction between hydrogen and chlorine. …[2] (ii) Fig. 9.1 shows the outer shell electrons in a hydrogen atom and in a chlorine atom. H Cl Fig. 9.1

23 0653/32/O/N/15 © UCLES 2015 Draw a diagram to show how these atoms form a hydrogen chloride molecule. [2] (c) Fig. 9.2 shows apparatus used to dissolve hydrogen chloride gas in water to form hydrochloric acid. hydrogen chloride funnel water with indicator Fig. 9.2 The water contains full-range indicator (Universal Indicator) added before the hydrogen chloride dissolves. (i) State the colour of the indicator in pure water. …[1] (ii) The indicator turns red. Suggest the change in pH. from pH … to pH … [1]

24 0653/32/O/N/15 © UCLES 2015 Group The Periodic Table of the Elements 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 91 238 231 147 237 244 243 247 247 251 252 257 258 259 260 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 82 209 209 210 222 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 55 226 223 Ra Radium 88 a X b a = relative atomic mass X = atomic symbol b = atomic (proton) number Key DATA SHEET * 58–71 Lanthanoid series † 90–103 Actinoid series The volume of one mole of any gas is 24dm3 at room temperature and pressure (r.t.p.). 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.

® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series 0653 COMBINED SCIENCE 0653/32 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, 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 2015 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 – October/November 2015 0653 32 © Cambridge International Examinations 2015 1 (a) (i) ← frictional force,→ driving force (both required) ; ↓ weight ; [2] (ii) 30 000 (N) ; no movement / acceleration vertically, so must be balanced / owtte ; [2] (iii) pull of Earth / gravitational pull / gravity ; [1] (b) (i) (30–90 s) constant speed ; (90–120 s) (negative) acceleration / deceleration (do not accept: braking) ; [2] (ii) distance travelled = area under graph ; = (20 × 30 × ½) + [20 × (90–30)] ; = 1500 m = 1.5 (km) ; [3] [Total: 10] 2 (a) (i) to kill any existing microbes ; [1] (ii) so that the enzymes in the bacteria are not denatured / optimum temperature for fermentation ; [1] (b) (i) proteins ; [1] (ii) by action of enzymes / protease / reference to digestion ; [1] (iii) amino acids produced by bacterium B will help growth / protein synthesis of bacterium A ; growth factors produced by bacterium A will speed up growth of bacterium B ; faster yoghurt production / more profit ; (if marking points 1 and 2 are not present then allow 1 mark for the idea that they each speed up the growth of the other) [max 2] (c) (i) (yoghurt D) contains less fat ; [1] (ii) (yoghurt D) contains more calcium ; [1] [Total: 8] 3 (a) (i) fractional distillation ; [1] (ii) physical because new substances are not made / involve only changes of state / owtte ; [1]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0653 32 © Cambridge International Examinations 2015 (b) (i) increasing boiling point from A to D ; [1] (ii) increasing size of molecules from A to D ; increasing force between molecules from A to D ; increasing energy required to separate molecules from A to D ; [max 2] (c) 2C and 6H ; correct single bonds between C and H atoms ; [2] (d) produces alkenes / compounds with double bonds / unsaturated compounds ; [1] [Total: 8] 4 (a) complete circuit with no open branches or short circuits ; on-off switch and fuse in main circuit using correct symbols (fuse either side of supply, order of fuse and switch either way round) ; heater and fan motor in parallel ; [3] (b) (i) X marked in the heater branch, either side of heater ; [1] (ii) (as temperature rises, particle motion increases) and particles separate (expansion) ; (expansion) greater in brass than in iron ; [2] (iii) in the air coming into the heater / owtte ; senses / switches off when air temperature in room is too high ; [2] [Total: 8]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0653 32 © Cambridge International Examinations 2015 5 (a) (i) any value between 1 and 10 (micrometres) inclusive ; [1] (ii) any answer of a million or more ; any answer in hundreds ; [2] (iii) male gamete is haploid and zygote is diploid / it has half the number of chromosomes ; (assume ‘it’ refers to the male gamete) [1] (b) amniotic fluid ; protects against physical damage ; [2] (c) (i) reference to reduced rate of flow of blood to (and from) placenta ; [1] (ii) reduces growth rate ; supply of nutrients / oxygen is reduced ; (accept AVPs about lower rate of removal of waste products) [2] [Total 9] 6 (a) (i) bubbles (gently) / owtte ; [1] (ii) zinc is above hydrogen in the reactivity series ; zinc is below calcium / above copper in the reactivity series ; [2] (b) (i) (copper) atoms ; [1] (ii) loss of copper ions ; [1] (iii) zinc displaces copper ; zinc has a greater tendency to form ions than copper ; zinc is above copper in the reactivity series ; [max 2]

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0653 32 © Cambridge International Examinations 2015 (c) (i) (zinc) (iron) tin ; (copper) [1] (ii) tin displaces copper so is above copper in the reactivity series ; tin does not displace iron so is below iron in the reactivity series ; [2] [Total: 10] 7 (a) (normal to mirror as shown) incident ray drawn so that angles of incidence and reflection are equal by inspection ; incident and reflected rays carefully drawn, with arrows in the correct direction and meeting at one point on mirror ; [2] (b) microwaves ; [1] (c) (i) v = fλ ; [1] (ii) f = λ v = 9 8 10 589 10 3 − × × ; = 509 × 1012 Hz ; [2]

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0653 32 © Cambridge International Examinations 2015 (d) (i) P = IV or (I =) V P or 6 36 ; = 6 (A) ; [2] (ii) total current = 6 + 6 + 1 = 13 (A) / ecf ; [1] [Total: 9] 8 (a) (i) the position of an organism in a food chain or food web ; [1] (ii) energy lost at each stage (of food chain) ; less energy for organisms further along chain ; [2] (iii) badger correctly linked to all 3 organisms ; arrows all present and in correct direction ; [2] (b) breaking down removal of dead bodies / waste ; recycling of nutrients ; [2] (c) use an alternative source of food ; move to a different habitat ; [2] [Total 9] 9 (a) (i) non-metals are on right-hand side of Periodic Table ; [1] (ii) number of outer shell electrons = group number ; [1] (iii) small number of outer shell electrons in metals / owtte ; [1] (b) (i) H2 + Cl 2 → 2HCl 1 mark for formulae ; balancing mark dependent on formulae ; [2] (ii) 1 shared pair ; no extra electrons ; [2] (c) (i) green ; [1] (ii) 7 to any less than 4 ; [1] [Total: 9]