Cambridge IGCSE Science - Combined 0653 — 2015 May/June Paper 3 · Variant 3

This document consists of 20 printed pages. DC (FD) 110067 © UCLES 2015 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 8 1 3 0 4 5 9 4 9 8 * COMBINED SCIENCE 0653/33 Paper 3 (Extended) May/June 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 soft pencil for any diagrams, graphs, tables or rough working. 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 20. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

2 0653/33/M/J/15 © UCLES 2015 1 (a) Fig. 1.1 shows an early type of airship filled with hydrogen gas. Fig. 1.1 A hydrogen molecule consists of two hydrogen atoms bonded together. (i) Draw a diagram to show the electronic structure of a hydrogen molecule. [2] (ii) Suggest how the electronic structure causes the positively charged nuclei of the two atoms to be held together. … … … [1]

3 0653/33/M/J/15 © UCLES 2015 [Turn over (iii) The use of hydrogen for airships declined following a disaster in which an airship caught fire. Fig. 1.2 Write a balanced symbol equation for the combustion of hydrogen. … [2] (iv) Describe the energy transformation which occurs in this exothermic reaction. … … [1] (b) Fig. 1.3 shows a modern weather balloon containing hydrogen or helium gas. ER[RIZHDWKHULQVWUXPHQWV EDOORRQ K\GURJHQRUKHOLXPJDV Fig. 1.3 Explain why the electronic structure of helium means that it is safer than hydrogen to use in a balloon. … … … [2]

4 0653/33/M/J/15 © UCLES 2015 2 (a) Fig 2.1 shows an animal cell. Fig. 2.1 (i) Identify the functions of the cell parts on Fig. 2.1 using label lines and the letters shown. Use C to show the part which controls the cell. Use R to show where chemical reactions, such as respiration, take place. [2] (ii) One of the chemical reactions that takes place in the cell is aerobic respiration. Complete the balanced symbol equation for aerobic respiration. C6H12O6 + … 6CO2 + … [2] (b) During exercise food stores are broken down in the body by respiration to release energy for muscles to contract. Some people exercise when they are trying to lose weight. Anna is trying to lose weight by exercising. Table 2.1 shows the approximate energy needed for 30 minutes each of four different types of exercise for Anna. Table 2.1 type of exercise energy needed for 30 minutes of exercise / kJ cycling 850 golf 670 swimming 830 walking 580 (i) Anna went swimming for 30 minutes and then spent 30 minutes playing golf. Calculate the total amount of energy she needs for these activities. amount of energy needed = … kJ [1]

5 0653/33/M/J/15 © UCLES 2015 [Turn over (ii) From Table 2.1, suggest which two 30-minute activities cause Anna to break down the most of her food stores. Explain your answer. activities … and … explanation … … [2] (iii) The exercise made Anna’s pulse rate increase. This meant that her heart was beating more quickly. Explain fully how this change in heart rate helps Anna to carry out the exercise. … … … … [2] (iv) Suggest a reason why the energy values given in Table 2.1 cannot be exactly the same for everyone doing the exercise. … … [1]

6 0653/33/M/J/15 © UCLES 2015 3 Fig. 3.1 shows a man on a snowboard moving down a hill. Fig. 3.1 Fig. 3.2 shows a graph of the man’s speed as he goes down the hill. 0 0 10 20 30 speed m / s time / s D 10 20 30 40 50 60 C B A Fig. 3.2 (a) Describe the motion of the man between points A and B, … … B and C. … … [2]

7 0653/33/M/J/15 © UCLES 2015 [Turn over (b) Use the area under the graph to calculate the distance travelled by the man between points C and D. Show your working. distance = … m [2] (c) Calculate the acceleration of the man between points C and D. State the formula you use, show your working and state the unit of your answer. formula working acceleration = … unit … [3] (d) Snow is made of solid ice crystals. In the box below, draw a diagram to show the arrangement of particles in a solid. One particle has been drawn for you. You need to draw at least 11 more. [2]

8 0653/33/M/J/15 © UCLES 2015 4 (a) A sample of soil is mixed with water and filtered. (i) Describe a test that would show that the soil is acidic. … … … [2] (ii) In order to reduce soil acidity, limestone is sometimes added. Limestone consists mainly of calcium carbonate. Complete the word equation for the reaction occurring between calcium carbonate and dilute hydrochloric acid. calcium carbonate + hydrochloric acid carbon dioxide + … + … [2] (b) Fig 4.1 shows apparatus some students use to investigate the effect of temperature on the rate of reaction between calcium carbonate and dilute hydrochloric acid. gas jar water calcium carbonate HEAT dilute hydrochloric acid water bath to control the temperature of the mixture thermometer carbon dioxide Fig. 4.1 They add pieces of calcium carbonate to the dilute hydrochloric acid and time how long it takes for carbon dioxide to fill the inverted gas jar. They repeat the experiment several times. Each time the experiment is repeated, the only difference is the temperature of the dilute hydrochloric acid.

9 0653/33/M/J/15 © UCLES 2015 [Turn over Table 4.1 shows the results of the investigation. Table 4.1 temperature / °C time taken to fill the gas jar / s 20 156 30 75 40 37 50 20 60 10 (i) Use Table 4.1 to state how the rate of reaction changes when the experiment is repeated at higher temperatures. … … [1] (ii) Explain your answer to (i) in terms of the collisions between particles. … … … … [2] (c) The soil treatment described in (a)(ii) adds to the amount of carbon dioxide in the atmosphere. (i) State another reason why the amount of carbon dioxide in the atmosphere is increasing. … … [1] (ii) Describe how this increase could be affecting the environment. … … [1]

10 0653/33/M/J/15 © UCLES 2015 5 (a) Fig. 5.1 shows two small flowers of a wind-pollinated grass. IORZHU$ IORZHU% Fig. 5.1 (i) On Fig. 5.1 draw an arrow to show the transfer of pollen from flower A to flower B during pollination. [2] (ii) Describe two adaptations of this grass flower for wind pollination. Use only features visible in Fig. 5.1. 1 … … 2 … … [2] (b) A student sets up an experiment to investigate the conditions needed for germination of seeds. She uses cotton wool and seeds as shown in Fig. 5.2. Dish 3 is placed in a fridge with a glass door. The rest of the dishes are left by a window in the laboratory. GLVK GLVK GLVK GLVK FRQGLWLRQV VHHG FRWWRQZRRO W\SHRI ZDWHUXVH WDSZDWHU S+ ƒ& ƒ& ƒ& ƒ& WDSZDWHU S+ QRZDWHU DFLGUDLQZDWHU S+ WHPSHUDWXUH Fig. 5.2

11 0653/33/M/J/15 © UCLES 2015 [Turn over After a few days the dishes are examined. Table 5.1 shows what the student observes. Table 5.1 dish number observations 1 all seeds germinated, seedlings 1 cm tall 2 no germination 3 no germination 4 no germination Using the results in Table 5.1, describe evidence that the following conditions affect germination. (i) temperature … … [1] (ii) pH … … [1] (iii) State one other condition, not investigated in this experiment, that is needed for germination of seeds. … [1] (iv) For germination to take place the enzymes in the seeds must be active. Use this information to explain fully why the seeds did not germinate in dish 4. … … … [2]

12 0653/33/M/J/15 © UCLES 2015 6 Many different musical instruments are played in an orchestra. Table 6.1 shows the lowest and highest frequencies for the sounds of the musical notes produced by some instruments in an orchestra. Table 6.1 instrument lowest frequency / Hz highest frequency / Hz bassoon 58 932 cello 65 659 clarinet 147 1865 flute 262 2093 harp 31 3322 trumpet 165 1000 violin 196 2637 (a) Identify which instrument in Table 6.1 (i) has the largest difference between highest and lowest pitch, … [1] (ii) produces a sound with the longest wavelength. … [1] (b) A large drum emits sound of frequency 30 Hz. Explain why a drum that emits a frequency of 15 Hz would not be used in an orchestra. … … [1]

13 0653/33/M/J/15 © UCLES 2015 [Turn over (c) Calculate the wavelength for the highest frequency sound made by a trumpet. The speed of sound in air is 330 m / s. State the formula you use and show your working. formula working wavelength = … m [2] (d) Fig. 6.1 shows a violin string before the violinist plays. Fig. 6.1 On Fig. 6.2 draw a diagram to show how the violin string vibrates when the violinist plucks the string and use your diagram to explain why this produces sound waves Fig. 6.2 … … … … [3]

14 0653/33/M/J/15 © UCLES 2015 7 (a) When a hydrocarbon D undergoes cracking, two new compounds, X and Y, are obtained. X and Y are tested using bromine solution. These processes are shown in Fig. 7.1. FUDFNLQJ FRPSRXQG' FRPSRXQG; PL[HGZLWKRUDQJH EURPLQHVROXWLRQ PL[HGZLWKRUDQJH EURPLQHVROXWLRQ FRPSRXQG< Fig. 7.1 X is an alkane. Y is an alkene. (i) State two conditions needed for cracking. 1 … 2 … [2] (ii) Compare the size of the molecules of compounds X and Y with the size of the molecules of compound D. … … [1] (iii) Describe the effects on the bromine solution caused by X and Y. X … … Y … … [1] (b) Draw the molecular structures of ethane and ethene. ethane ethene [3]

15 0653/33/M/J/15 © UCLES 2015 [Turn over (c) Fig. 7.2 shows how bromine is produced from molten lead bromide in a laboratory experiment, PbBr2. SRZHU VXSSO\ FDUERQHOHFWURGHV DQRGH FDWKRGH PROWHQOHDGEURPLGH +($7  ² Fig. 7.2 (i) Explain why bromide ions move to the anode when the switch is closed. … … [1] (ii) Describe how bromine atoms are formed at the anode. … … [1]

16 0653/33/M/J/15 © UCLES 2015 8 (a) Fig. 8.1 shows the flow of chemical energy through the food chains in a habitat. The numbers represent the amount of chemical energy per square metre per year. SURGXFHUV N- N- N- SULPDU\FRQVXPHUV  KHUELYRUHV VHFRQGDU\FRQVXPHUV  FDUQLYRUHV Fig. 8.1 (i) Calculate the percentage of the chemical energy in the producers that is not transferred to the carnivores. Show your working. answer = …% [2] (ii) The source of energy for the producers is sunlight which is needed for photosynthesis. Describe the role of chlorophyll in energy transformation during photosynthesis. … … … [2] (b) Fig. 8.2 shows a food chain in Africa. The information inside the box includes details about the flow of energy into and out of the zebra. JUDVV GHFRPSRVHUV UHVSLUDWLRQ GLHV ; ]HEUD OLRQ Fig 8.2

17 0653/33/M/J/15 © UCLES 2015 [Turn over (i) Suggest ways in which energy could be lost at X. … … … [2] (ii) Explain the importance of the decomposers shown in Fig. 8.2. … … … [2]

18 0653/33/M/J/15 © UCLES 2015 9 Fig. 9.1 shows a caravan which uses an electric heater to supply warm air to heat the caravan and to heat water. FDUDYDQ PDLQVHOHFWULFLW\ VXSSO\FDEOH Fig. 9.1 Fig. 9.2 shows a circuit diagram for the electric heater. It contains two elements, one for heating the air and one for heating the water. mains electricity supply element heating air element heating water hot water tank Fig. 9.2 (a) (i) The air around the electric heater is heated. The heated air then flows around the caravan and warms the people sitting inside. Name the process by which the heated air warms up the caravan. … [1] (ii) Explain why the heater causes the warm air to circulate inside the caravan. … … [2] (iii) The hot water must be kept hot in the hot water tank after the heater is switched off. Suggest a method of keeping the water hot for a long time in the tank after heating. … … [1]

19 0653/33/M/J/15 © UCLES 2015 (b) The circuit diagram in Fig. 9.2 only allows both heating elements to be switched on or both heating elements to be switched off. Complete the circuit diagram in Fig. 9.3 to show a different circuit which allows the people in the caravan to have one element switched on and the other element switched off. Fig. 9.3 [2] (c) The resistance of the water heater is 30 Ω. When both elements are switched on, the current in the water-heating element is 8 A and the current in the air-heating element is 4 A. (i) Calculate the potential difference across the heating elements from the mains electricity supply. State any formula that you use, show your working and state the unit of your answer. formula working potential difference = … unit … [3] (ii) Use the formula P = IV to calculate the electrical power taken by the warm air heater. Show your working. power = … W [1]

20 0653/33/M/J/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 May/June 2015 series 0653 COMBINED SCIENCE 0653/33 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 May/June 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 – May/June 2015 0653 33 © Cambridge International Examinations 2015 1 (a) (i) shared pair of electrons ; hydrogen atoms labelled and no other electrons ; [2] (ii) ref. to the sharing of electrons / the idea that nuclei attracted to the electrons / opposite charges attract ; [1] (iii) 2H2 + O2 → 2H2O formulae ; balanced ; [2] (iv) chemical (potential) to heat / thermal ; [1] (b) full outer electron shell ; so, unreactive (with oxygen) / not flammable ; [2] 2 (a) (i) label line and letter C showing the nucleus ; label line and letter R showing the cytoplasm ; [2] (ii) O2 and H2O in correct places ; equation correctly balanced ; [2] (b) (i) (830 + 670 = ) 1500 kJ ; [1] (ii) cycling and swimming ; needs 1680 kJ / greater amount of energy needed ; [2] (iii) carry more oxygen / oxygen more quickly (to muscle cells) ; carry more glucose / glucose more quickly (to muscle cells) ; reference to respiration / energy release (in muscle cells) ; carry more carbon dioxide / carbon dioxide more quickly (from muscle cells) ; [max 2] (iv) activities may be done at a faster / slower rate ; avp ; [1] 3 (a) A to B: accelerating / going faster ; B to C: constant speed ; [2] (b) ½ × base × height / ½ × 10 × 25 ; (squares counted allowed) = 125 (m) ; [2] (c) (acceleration =) change in speed ÷ time ; = − 25 / 10 = − 2.5 (accept 2.5) ; m / s2 ; [3]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0653 33 © Cambridge International Examinations 2015 (d) or (at least 12 circles in total with approximately uniform diameter) diagram must show a regular arrangement ; most circles touching ; [2] 4 (a) (i) named indicator / pH meter ; correct colour change / pH value <7 ; [2] (ii) calcium chloride ; water ; [2] (b) (i) rate increases ; [1] (ii) reference to particles moving (not vibrating) faster / gaining kinetic energy ; rate of collision / collision frequency increases ; the chance of reaction / reactive collisions is increased ; [max 2] (allow correct reference to increased energy of collision) (c) (i) (increasing) combustion of fossil fuels / named fossil fuel ; [1] (ii) global warming / increased greenhouse effect / consequence of global warming described e.g. rising sea level / climate change / examples of extreme weather events ; [1] 5 (a) (i) arrow tail shown on any anther ; arrow head on any stigma on the other flower ; [2] (allow 1 if the arrow links the correct structures but in reverse) (ii) anthers hanging outside the flower ; stigma hanging outside the floret / flower ; stigma feathery / has large surface area ; [max 2] (b) (i) germination took place in dish 1 and did not take place in dish 3 (because it was too cold in dish 3) ; [1] (ii) germination took place in dish 1 but not dish 4 ; [1] (because it was too acidic in dish 4) (iii) oxygen ; [1] (iv) enzymes do not work / are not active ; acidity too high / pH too low ; ref. to denaturation / active site destroyed / shape of molecule changed ; [max 2]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0653 33 © Cambridge International Examinations 2015 6 (a) (i) harp ; [1] (ii) harp ; [1] (b) frequency below the lower limit of hearing / owtte ; [1] (c) (λ =) v/f ; (λ =) 330 ÷ 1000 = 0.33 (m) ; [2] (d) diagram illustrates a string vibrating after being plucked ; vibrating string collides with air molecules / implication that sound / the wave requires a medium to travel ; producing compressions and rarefactions in air / longitudinal waves / pressure waves ; [3] 7 (a) (i) high temperature ; catalyst ; high pressure ; [max 2] (ii) molecules of X and Y are smaller than molecules of D / ora ; [1] (iii) X has no effect on bromine solution and Y decolourises bromine solution ; [1] (b) two Cs in each ; single C-C bond in ethane and double C=C bond in ethene ; all else correct ; [3] (c) (i) opposite charges attract / the ions are negative / have the opposite charge ; [1] (ii) electrons move from bromide ions to the anode ; [1] (allow bromide ions are oxidised)

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