Cambridge IGCSE Science - Combined 0653 — 2016 May/June Paper 2 · Variant 3

This document consists of 20 printed pages. DC (KN/SG) 128058 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 2 5 1 1 7 9 8 1 1 1 * COMBINED SCIENCE 0653/23 Paper 2 (Core) May/June 2016 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 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 0653/23/M/J/16 © UCLES 2016 1 Fig. 1.1 shows some parts of the human alimentary canal and its associated organs. mouth salivary gland tongue liver stomach pancreas small intestine colon rectum Fig. 1.1 (a) Use the labels in Fig. 1.1 to complete Table 1.1. Table 1.1 function name of organ(s) ingestion … absorption of digested food … secrete digestive enzymes stomach and … and … [4] (b) After the absorption of digested food, the blood takes the nutrients to the body cells. State the part of the blood that transports dissolved nutrients. … [1]

3 0653/23/M/J/16 © UCLES 2016 [Turn over (c) Fig. 1.2 shows a section of a capillary next to some body cells. wall of capillary body cell Fig. 1.2 Describe the process by which glucose moves in the direction shown by the arrows. … … … [2] (d) Fig. 1.3 shows the effect of pH on the activity of an enzyme which is secreted into the food in the stomach. The environment in the stomach has a low pH because of the presence of hydrochloric acid. 1 2 3 4 5 6 7 8 9 10 pH of reaction enzyme activity Fig. 1.3 (i) State the optimum pH for this enzyme. … [1] (ii) The stomach contents enter the duodenum. The pH in the duodenum is approximately 8. Suggest what happens to the activity of the enzyme when it enters the duodenum. Explain your answer. … … … … [2]

4 0653/23/M/J/16 © UCLES 2016 2 (a) Lead bromide can be broken down into its elements using the apparatus shown in Fig. 2.1. – + d.c. power supply electrode A molten lead bromide Fig. 2.1 (i) Name the process shown in Fig. 2.1. … [1] (ii) Name the element produced at electrode A and state the colour of this element. name … colour … [2] (b) In a similar process, copper chloride is broken down into a metal and chlorine. Write the word equation for this reaction. … [1] (c) (i) Describe the trend in the boiling points of the elements going down Group VII of the Periodic Table, from chlorine to iodine. … [1]

5 0653/23/M/J/16 © UCLES 2016 [Turn over (ii) Fluorine is another element in Group VII. Fig. 2.2 shows an atom of fluorine. + + + – – – – – – – – – … … … Fig. 2.2 Not all of the particles present in the atom of fluorine are shown. Label the particles shown in Fig. 2.2. [3] (iii) State what is meant by the term nucleon number. … … [1]

6 0653/23/M/J/16 © UCLES 2016 3 Fig. 3.1 shows a small cart on 4 wheels with no engine. The cart runs down a sloping track steered by a driver. Fig. 3.1 (a) Name the force that causes the cart to move down the slope. … [1] (b) Fig. 3.2 shows the track becoming horizontal at the bottom of the slope. Fig. 3.2 (i) The force in part (a) may change the motion of the cart along the horizontal track. Tick the box alongside the statement that describes the effect of this force. Give a reason for your choice. It increases the speed of the cart. It does not affect the speed of the cart. It decreases the speed of the cart. … … [1]

7 0653/23/M/J/16 © UCLES 2016 [Turn over (ii) The cart moves along the horizontal track at an average speed of 8 m / s for a distance of 20 m before the driver applies the brakes. Calculate the time taken to travel this distance. State the formula you use, and show your working. formula working time = … s [2] (iii) After applying the brakes, the cart comes to a stop in 10 m. On the axes in Fig. 3.3, sketch the speed / time graph for the journey of the cart from the start of the horizontal track until it stops. (Scales and numbers are NOT required). speed time Fig. 3.3 [2] (c) Complete the energy transfers that take place while the cart is moving. From … energy at the top of the slope kinetic to … energy on the track to … energy as the cart stops. [2]

8 0653/23/M/J/16 © UCLES 2016 4 Fig. 4.1 shows a germinating seed and a diagram of one of the root hair cells. root hair area soil particles root hair cell Fig. 4.1 (a) Use the following terms to complete the sentences. You may use each term once, more than once, or not at all. amino acids cell membrane cell wall ions nucleus phloem photosynthesis respiration transpiration xylem The root hair cell has a … to control what enters and leaves the cell. The main function of this cell is to absorb water and … . Water goes from the root hair cell to the … to be taken to the rest of the plant. Water evaporates from the plant by … . [4] (b) Study the germinating seed in Fig. 4.1. Suggest why the root hair cells constantly have to be replaced as the root grows. … … … [1] (c) A few days later the germinated seed in Fig. 4.1 develops leaves above ground and starts to photosynthesise. (i) Write the word equation for photosynthesis. … [2] (ii) List two conditions needed for photosynthesis. 1. … 2. … [2]

9 0653/23/M/J/16 © UCLES 2016 [Turn over 5 Petroleum is a mixture of hydrocarbons. Fig. 5.1 shows how it is separated into useful products. hot petroleum Fig. 5.1 (a) (i) Name the process shown in Fig. 5.1. … [1] (ii) State what is meant by a hydrocarbon. … … [2] (b) Natural gas is often found with petroleum when it is extracted from the Earth’s crust. It burns in air. (i) Name the main constituent of natural gas. … [1] (ii) Name the gas in air that reacts with natural gas when it burns. … [1]

10 0653/23/M/J/16 © UCLES 2016 (c) Ethanol, C2H5OH, is a compound made from petroleum. (i) Complete the diagram to show the structure of one molecule of ethanol. C O [2] (ii) Ethanol and hydrocarbons burn to form the same products. Name the two substances formed during the complete combustion of ethanol. 1. … 2. … [2]

11 0653/23/M/J/16 © UCLES 2016 [Turn over 6 Global warming causes ice caps to melt. This causes a rise in sea level. (a) Warming of the water in the oceans causes the sea level to rise for a different reason. Explain this reason. … … [1] (b) Global warming causes more water from the sea to move into the atmosphere. (i) Name the process that causes this movement. … [1] (ii) In the process named in (b)(i), the more energetic water molecules escape from the surface of the sea. Suggest the effect this will have on 1. the energy of the molecules remaining in the sea water. … 2. the temperature of the sea water. … [2] (c) Global warming happens when more of the energy coming from the Sun is trapped in the Earth’s surface and atmosphere. (i) State the form of energy transfer between the Sun and the Earth. … [1] (ii) Table 6.1 shows part of the electromagnetic spectrum. Table 6.1 gamma rays X-rays radio waves In Table 6.1, write in the correct boxes 1. the name of the part of the spectrum often involved in thermal energy transfer. Circle your answer. 2. the name of the part of the spectrum that enables you to read this question. Do not circle your answer. [4]

12 0653/23/M/J/16 © UCLES 2016 7 Fig. 7.1 shows the members of a food chain in a habitat. snail buzzard thrush grass Fig. 7.1 The buzzard eats the thrush. The snail eats grass and the thrush is the snail’s predator. (a) (i) Complete each row of Table 7.1 by ticking the boxes that apply to each organism. One has been done for you. Table 7.1 organism producer consumer herbivore carnivore buzzard grass snail thrush   [3] (ii) Construct a food chain showing all of the organisms in Fig. 7.1. [2]

13 0653/23/M/J/16 © UCLES 2016 [Turn over (b) The activities of humans can cause air pollution by gases such as methane. (i) State one large-scale activity of humans that adds methane to the atmosphere. … … [1] (ii) Explain why large amounts of methane in the atmosphere are harmful. … … … [2]

14 0653/23/M/J/16 © UCLES 2016 8 Four metals are added to a dilute acid. Fig. 8.1 shows the pieces of metal before they are added to the acid. calcium copper iron zinc beaker containing dilute acid Fig. 8.1 (a) (i) Place the four metals named in Fig. 8.1 in order of reactivity. most reactive … … … least reactive … [1] (ii) The pieces of metal are added to the acid in the beakers. Describe what is seen in the beakers where a reaction takes place. … … [1] (b) One student thinks that iron reacts to form iron(II) ions. Another student thinks that iron reacts to form iron(III) ions. Suggest a test for iron(II) ions and iron(III) ions, and state the observations for each. test … iron(II) ions … iron(III) ions … [3]

15 0653/23/M/J/16 © UCLES 2016 [Turn over (c) Fig. 8.2 shows a piece of sodium added to water in a beaker. sodium thermometer water Fig. 8.2 The thermometer is used to measure the temperature of the water before and during the reaction. The temperature of the water increases. The equation for the reaction is sodium + water  sodium hydroxide + hydrogen. (i) State the type of chemical reaction that causes an increase in temperature. … [1] (ii) In this reaction sodium atoms turn into sodium ions. State the charge of a sodium ion. … [1] (iii) Describe how sodium ions are formed from sodium atoms. … … [1]

16 0653/23/M/J/16 © UCLES 2016 9 A student investigates the current through an electric buzzer. He designs the circuit in Fig. 9.1 to use in his investigation. V buzzer Fig. 9.1 (a) (i) Name the component represented by this symbol. … [1] (ii) State and explain why the student includes this component in his circuit. … … … … [2]

17 0653/23/M/J/16 © UCLES 2016 [Turn over (iii) The student has left out an important component from his circuit that is needed to measure the current. On Fig. 9.2 complete the circuit diagram and include the symbol for this missing component in its correct place. V Fig. 9.2 [3]

18 0653/23/M/J/16 © UCLES 2016 (b) The student used the correct circuit for his experiment. Fig. 9.3 shows his results plotted as a graph. 0 2 4 6 8 10 12 0.060 0.050 0.040 0.030 0.020 0.010 0 current / A potential difference / V Fig. 9.3 The resistance of the buzzer is given by the formula resistance = potential difference (p.d.) current The student says that the resistance of the buzzer is lower when the p.d. is 12 V than when the p.d. is 6 V. The resistance at 12 V is 200 Ω. Use the graph in Fig. 9.3 to calculate the resistance at 6 V to show that he was correct. resistance at 6 V = … Ω [2]

19 0653/23/M/J/16 © UCLES 2016 (c) As the current increases the sound emitted by the buzzer becomes louder but has the same pitch. State what happens to the frequency of the sound waves, … the amplitude of the sound waves. … [2]

20 0653/23/M/J/16 © UCLES 2016 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 – 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. This document consists of 5 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education COMBINED SCIENCE 0653/23 Paper 2 Core Theory May/June 2016 MARK SCHEME Maximum Mark: 80 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 0653 23 © Cambridge International Examinations 2016 1 (a) function name of organ(s) ingestion mouth ; absorption of digested food small intestine ; secrete digestive enzymes salivary glands ; small intestine ; pancreas ; max 2 [4] (b) plasma ; [1] (c) diffusion ; from high concentration to low concentration ; [2] (d) (i) pH 2.7 allow 0.1 pH tolerance ; [1] (ii) activity would disappear ; graph shows no activity above pH 4.5 ; [2] 2 (a) (i) electrolysis ; [1] (ii) name: bromine ; colour: brown / orange-brown ; [2] (b) copper chloride → copper + chlorine ; [1] (c) (i) increase ; [1] (ii) electron ; proton ; neutron ; [3] (iii) no. protons + no. neutrons / number of particles in the nucleus ; [1] 3 (a) weight / gravitational (force) ; accept gravity [1] (b) (i) Either it does not affect the speed (no mark) weight / force / gravity acts downwards ; or it decreases the speed of the cart (no mark) due to friction / frictional forces ; [1] (ii) (average) speed = distance / time (or rearranged) ; time = (distance / speed) = 20 / 8 = 2.5 (s) [2]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0653 23 © Cambridge International Examinations 2016 (iii) horizontal straight line for constant speed / slightly sloping line for decreasing speed ; smooth sloping line (straight or curved) down to speed = 0 ; [2] (c) (from) potential (energy) / gravitational potential (energy) ; (to) thermal / heat (energy) ; [2] 4 (a) cell membrane ; ions ; xylem ; transpiration ; [4] (b) idea of: root hair cells are very delicate / fine / are easily damaged (by soil) / owtte ; [1] (c) (i) carbon dioxide + water ; (→) sugar / glucose + oxygen ; [2] (ii) light ; supply of carbon dioxide ; chlorophyll / chloroplasts ; (suitable temperature) ; [max 2] 5 (a) (i) fractional distillation ; [1] (ii) (compound / molecule) containing hydrogen and carbon ; only ; [2] (b) (i) methane ; [1] (ii) oxygen ; [1] (c) (i) C2H5 correct ; –O-H correct ; [2] (ii) carbon dioxide ; water / steam / water vapour ; [2] 6 (a) thermal expansion (of sea water) ; owtte [1] (b) (i) evaporation ; [1] (ii) no effect ; decrease / cool ; [2]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2016 0653 23 © Cambridge International Examinations 2016 (c) (i) radiation ; [1] (ii) gamma rays X-rays (visible) light infrared radio waves 1. infrared ; – must be circled 2. (visible) light ; – must not be circled infrared in correct space ; light in correct space ; [4] 7 (a) (i) organism producer consumer herbivore carnivore buzzard

grass
snail

thrush

one mark for each correct line ;;; [3] (ii) grass → snail → thrush → buzzard organisms in correct order ; arrows in correct direction ; [2] (b) (i) keeping cattle / growing rice / leaving rubbish in dumps / avp ; [1] (ii) it is a greenhouse gas / traps heat / infra-red radiation ; it contributes to global warming ; [2] 8 (a) (i) (most reactive) calcium zinc iron copper ; [1] (ii) bubbles of gas / fizzing / effervescence / dissolving ; [1] (b) (test) aqueous sodium hydroxide / aqueous ammonia ; (iron(II) ions) (gelatinous) green precipitate / green solid ; (iron(III) ions) brown precipitate / brown solid ; [3] (c) (i) exothermic ; [1] (ii) 1+ / +1 / Na+ / Na1+ ; [1] (iii) (sodium atom) loses one / an electron ; [1]

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