Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2013 May/June Paper 2 · Variant 3

This document consists of 27 printed pages and 1 blank page. IB13 06_0654_23/4RP © UCLES 2013 [Turn over *1745671305* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/23 Paper 2 (Core) May/June 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 28. 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 0654/23/M/J/13 BLANK PAGE

3 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use 1 Fig. 1.1 shows an experimental car powered by solar panels. Fig. 1.1 (a) The speed / time graph in Fig. 1.2 shows the motion of the car over a short time. 0 10 20 30 time / s speed / m per s 40 50 60 10 8 6 4 2 0 Fig. 1.2 On Fig. 1.2 label N at a point at which the car was not moving, A at a point when the car was accelerating, C at a point at which the car was travelling at constant speed. [3]

4 © UCLES 2013 0654/23/M/J/13 For Examiner's Use (b) The energy output from the solar panels was measured during one day. Fig. 1.3 is a graph of the results. midnight 2am 4am 6am 8am 10am noon time of day 2pm 4pm 6pm 8pm 10pm midnight 3.0 2.5 2.0 1.5 1.0 0.5 0 energy output in kJ / s Fig. 1.3 (i) Describe how the energy output from the solar panels varies during one day. [2] (ii) Explain why the energy output from the solar panels varies during the day. [1] (c) Generators are used to produce electricity in power stations. Describe how energy from a named fossil fuel is transferred to the generator in a power station. [3]

5 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use (d) Fig. 1.4 shows a small photovoltaic cell (solar cell) being investigated. A resistor photovoltaic cell lamp Fig. 1.4 A voltmeter is added to the circuit to measure the voltage across the photovoltaic cell. Using the correct symbol, draw the voltmeter in the correct position on Fig. 1.4. [2] (e) The car has mirrors to help the driver see behind the car. The driver sees a truck in his mirror as shown on Fig. 1.5. Use Fig. 1.5 to describe two characteristics of an image seen in a plane mirror apart from size. HORSES Fig. 1.5 [2]

6 © UCLES 2013 0654/23/M/J/13 For Examiner's Use 2 Petroleum (crude oil) is a mixture of hydrocarbons. (a) Three useful products obtained from petroleum are refinery gas, gasoline (petrol) and diesel oil (gas oil). (i) State one use for each of these products. refinery gas gasoline diesel oil [3] (ii) Name two compounds that are produced when hydrocarbons undergo complete combustion. 1 2 [2] (iii) Explain why combustion of hydrocarbons is an example of an oxidation reaction. [1] (b) Fig. 2.1 shows a simplified diagram of a process which is used to convert large saturated hydrocarbon molecules into smaller, more useful molecules. solid catalyst in the form of a fine powder mixture of smaller hydrocarbon molecules mixture of large saturated hydrocarbon molecules A B ` Fig. 2.1 (i) Name the process shown in Fig. 2.1. [1]

7 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use (ii) A chemist takes samples of the mixture of compounds from point A and point B in Fig. 2.1. He adds bromine solution to each sample and shakes the mixture. Predict and explain the appearance of each mixture after shaking with bromine solution. sample from point A sample from point B explanation [4]

8 © UCLES 2013 0654/23/M/J/13 For Examiner's Use 3 Fig. 3.1 shows part of a food web in a northern forest. The arrows show the direction of energy flow. bilberry spruce tree lynx goshawk vole Siberian jay red squirrel Fig. 3.1 (a) Complete Table 3.1 by selecting two organisms from the food web that belong in each column. You can use each organism once, more than once or not at all. Table 3.1 producer consumer herbivore carnivore organism 1 organism 2 [4] (b) If the forest is cut down, the species in the food web may not be able to survive. List two other undesirable effects that may occur if the forest is cut down. 1 2 [2] (c) State three ways in which energy is used in the body of an animal, such as a lynx. 1 2 3 [3]

9 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use 4 A student added excess magnesium to dilute hydrochloric acid. During the reaction, the thermometer reading changed. excess magnesium ribbon dilute hydrochloric acid thermometer (a) (i) State two observations which show that a chemical change occurs when magnesium is added to dilute hydrochloric acid. 1 2 [2] (ii) Name the gas that is given off in this reaction and describe a test for this gas. name test [2] (iii) Explain why the pH of the mixture increases during the reaction. [2]

10 © UCLES 2013 0654/23/M/J/13 For Examiner's Use (b) The student set up the apparatus shown in Fig. 4.1. She investigated the rate of reaction between magnesium and dilute hydrochloric acid. water gas measuring cylinder bung side-arm test-tube dilute hydrochloric acid magnesium Fig. 4.1 At the start of the experiment, the measuring cylinder contained no gas and was full of water. (i) The student knew that the speed at which the gas is produced is a good way of measuring the rate of reaction. What should the student measure to find the rate at which gas is produced? [2] (ii) State two variables that affect the rate of reaction between magnesium and dilute hydrochloric acid. 1 2 [2]

11 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use 5 (a) Visible light and γ-(gamma) radiation are two regions of the electromagnetic spectrum. (i) Name a region of the electromagnetic spectrum that is used in remote control devices for televisions. [1] (ii) State one way in which the waves in different regions of the electromagnetic spectrum differ from each other. [1] (b) Fig. 5.1 shows a light ray passing from the air through a glass fibre, and back out into the air. B A C air air glass fibre Fig. 5.1 Use one of the phrases to complete the sentences below. Each phrase can be used once, more than once or not at all. hits at an angle greater than the critical angle. hits at an angle less than the critical angle. is passing into a less dense medium. is passing into a more dense medium. The ray of light changes direction at A because it B because it C because it [3]

12 © UCLES 2013 0654/23/M/J/13 For Examiner's Use (c) One source of background radiation is cosmic rays. Cosmic rays are 90% protons, 9% α-(alpha) particles and 1% electrons. (i) What is an α-particle? [1] (ii) Name a source of background radiation apart from cosmic rays. [1] (d) The following sentence about α-particles was written by a student. The statement is not correct. α–particles can pass through a thin sheet of lead Change the statement to make it correct. Write your correct statement below. [1] (e) Underline the two pieces of equipment that detect ionising radiations. ammeter Geiger-Müller tube litmus paper newton-meter photographic film thermometer [2] (f) Three of the following statements are true. Tick the correct statements. Both α-(alpha) radiation and β-(beta) radiation pass easily through the body. α-radiation damages cells in a very localised area of the body. Ionisation does not always kill cells – sometimes it causes them to mutate. Cancer occurs when a large number of cells are killed. The dose of radiation received depends on the length of exposure. [2]

13 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use (g) Most atoms contain electrons, protons and neutrons. State which of these particles has the least mass, has no charge, has a negative charge, are in the nucleus. and [4]

14 © UCLES 2013 0654/23/M/J/13 For Examiner's Use 6 (a) The words in the list below are all related to human reproduction. Choose words from the list to match each description. You may use each word once, more than once or not at all. oviduct prostate gland sperm testis urethra uterus zygote a cell formed when the nuclei of the male and female gamete fuse a male gamete the organ in which sperms are made the place where fertilisation occurs [4] (b) Fig. 6.1 shows changes in the thickness of a woman’s uterus lining over a time interval of 45 days. 0 5 10 15 20 time / days 25 30 35 40 45 thickness of uterus lining Fig. 6.1 (i) Use Fig. 6.1 to estimate the number of days for which one menstrual cycle lasted. [1] (ii) Suggest the day on which an egg was released from the woman’s ovaries. [1]

15 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use (c) A woman with HIV / AIDS can pass the disease to her child. (i) What does the abbreviation HIV stand for? [1] (ii) Describe how a woman can pass the disease to her child. [2]

16 © UCLES 2013 0654/23/M/J/13 For Examiner's Use 7 (a) (i) Copper is used to make water pipes, cooking pots and electrical wires. State three different properties of copper that make it a suitable material for these uses. 1 2 3 [3] (ii) Name the family of metals in the Periodic Table which includes copper. [1] (b) Bronze is a mixture containing copper and tin. (i) State the general name of materials such as bronze. [1] (ii) State one advantage of bronze compared with copper. [1] (c) Fig. 7.1 shows a process in which a copper compound is split into elements. d.c. power supply orange-brown layer forming bubbles of gas Fig. 7.1 (i) Name the process shown in Fig. 7.1. [1] (ii) On Fig. 7.1 label the cathode. [1]

17 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use (iii) One of the products of the process shown in Fig. 7.1 is a gas. This gas bleaches damp litmus paper. Name the copper compound that is being separated into its elements. Explain your answer. name of compound explanation [2]

18 © UCLES 2013 0654/23/M/J/13 For Examiner's Use 8 Fig. 8.1 shows a washing machine. When the door is closed and the machine is switched on, an electric motor rotates the drum and clothes. drum door Fig. 8.1 (a) Choose words from the list below to complete the sentences. chemical heat kinetic light nuclear gravitational potential sound In an electric motor, the useful energy transfer is electrical energy into energy. Some of the electrical energy supplied to the motor is wasted as energy and energy. [2] (b) Inside the washing machine, some of the water evaporates when the washing machine is being used. (i) During evaporation, water changes state from liquid to gas. Complete the diagrams to show the arrangement of particles in a liquid and in a gas. liquid gas [3]

19 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use (ii) Explain, in terms of particles, the process of evaporation. [3] (c) A current of 3 A passes through the heating element when the voltage across it is 220 V. Calculate the resistance of the heating element. State the formula that you use and show your working. formula working Ω [2]

20 © UCLES 2013 0654/23/M/J/13 For Examiner's Use 9 Fig. 9.1 shows a pitcher plant, which grows in Malaysia and Indonesia. green leaf slippery rim of pitcher pitcher (shown in section) spines solution containing partly-digested insects Fig. 9.1 (a) The leaves of pitcher plants carry out photosynthesis, using carbon dioxide and water to make carbohydrates. They obtain carbon dioxide and water in the same way as other plants. (i) Complete Table 9.1 to show how the leaves obtain carbon dioxide and water. You do not need to write anything in the shaded box. Table 9.1 substance source part of plant that absorbs it process by which it is absorbed carbon dioxide air water [4] (ii) Write the word equation for photosynthesis. [2]

21 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use (b) Pitcher plants grow where the concentration of nitrate ions in the soil is very low. Most plants need nitrate ions to make amino acids and proteins. Pitcher plants use a different way of obtaining amino acids. They trap insects in their pitchers, and produce a solution that digests the proteins in the insects’ bodies. (i) Describe two features of the pitchers, shown in Fig. 9.1, that help to trap insects inside them. 1 2 [2] (ii) Define the term digestion. [2] (iii) Suggest what is present in the solution that the pitcher plant produces inside its pitchers, to enable digestion to take place. [1]

22 © UCLES 2013 0654/23/M/J/13 For Examiner's Use (c) A scientist investigated the hypothesis that a scent produced by the rim of the pitchers acts as a stimulus that attracts insects. She took several identical Petri dishes. • She placed a piece of the rim of a pitcher, or a small amount of solution from inside the pitcher or water, on one side of the dish (side A). • She put a small amount of water on the other side (side B) as shown in Fig. 9.2. • She then placed an insect in the centre of the dish. She recorded which side of the dish the insect moved to. She repeated this 19 more times, using a different insect each time. Petri dish water piece of rim or solution from pitcher or water side A side B Fig. 9.2 Table 9.2 shows her results. Table 9.2 number of insects that moved to each side substance on side A of dish substance on side B of dish A B piece of rim water 16 4 solution from pitcher water 4 16 water water 10 10 (i) Suggest why the scientist placed water on both sides of some dishes. [1] (ii) Do the results support the scientist’s hypothesis? Explain your answer. [2]

23 © UCLES 2013 0654/23/M/J/13 [Turn over For Examiner's Use 10 (a) When wood is burnt, a solid material known as wood ash remains. Wood ash contains calcium carbonate and potassium compounds, which can be used to improve the quality of soil. (i) Explain briefly how calcium carbonate and potassium compounds could improve the quality of soil. calcium carbonate potassium compounds [3] (ii) Suggest how a sample of wood ash could be tested to show that it contained carbonate ions. [2] (b) Soil quality is also improved by the addition of nitrogen compounds such as ammonium sulfate, (NH4)2SO4. (i) State the total number of atoms shown combined in the chemical formula (NH4)2SO4. [1] (ii) Ammonium sulfate is the product of a reaction between an alkaline solution of ammonia and an acid. Name the acid that reacts with ammonia to form ammonium sulfate and state the type of chemical reaction that occurs. name of acid type of reaction [2]

24 © UCLES 2013 0654/23/M/J/13 For Examiner's Use (iii) Outline how crystals of ammonium sulfate could be obtained from a solution of ammonium sulfate. [2]

25 © UCLES 2013 0654/23/M/J/13 [Turn over Please turn over for Question 11.

26 © UCLES 2013 0654/23/M/J/13 For Examiner's Use 11 (a) Complete the graph in Fig. 11.1 to show how enzyme activity is affected by temperature. You should write in at least two values for temperature on the ‘temperature’ axis. rate of enzyme activity temperature / °C 0 [3] Fig. 11.1 (b) The internal body temperature of a human is kept constant, allowing enzymes to work efficiently. The skin helps to do this. Fig. 11.2 shows a section through the skin in two different environmental conditions. environmental condition 1 environmental condition 2 sweat gland blood vessel sweat gland blood vessel Fig. 11.2

27 © UCLES 2013 0654/23/M/J/13 For Examiner's Use (i) Describe two ways in which the skin in environmental condition 2 differs from environmental condition 1. 1 2 [2] (ii) Suggest how environmental condition 2 differs from environmental condition 1. [1] (iii) The muscles also help to maintain a constant body temperature. Explain how the muscles can help to return a low body temperature to normal. [2]

28 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 0654/23/M/J/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 May/June 2013 series 0654 CO-ORDINATED SCIENCES 0654/23 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 May/June 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 – May/June 2013 0654 23 © Cambridge International Examinations 2013 1 (a) N labelled at either 0 s or 50 s ; A labelled between 0 s and 20 s or between 40 s and 50 s ; C labelled between 20 s and 40 s ; [3] (b) (i) maximum of 2.8 at 1.00 p.m. ; goes up then down ; some energy for 17 hours ; other use of data ; [max 2] (ii) energy input from Sun varies ; [1] (c) named fossil fuel is burned ; to release heat energy ; heat turns water into steam ; steam drives turbine ; turbine drives generator ; [max 3] (d) voltmeter in parallel with photocell ; correct symbol ; [2] (e) lateral inversion ; upright ; [2] [Total: 13] 2 (a) (i) refinery gas – bottled gas / camping gas / other correct ; gasoline – car engine fuel / fuel for petrol engines ; diesel – fuel for diesel engines ; [3] (ii) carbon dioxide ; water ; [2] (iii) hydrocarbons react with oxygen / oxygen bonds to the hydrocarbon ; [1] (b) (i) (catalytic) cracking ; [1] (ii) A mixture remains orange ; B mixture changes from orange to colourless ; some unsaturated hydrocarbons formed (during cracking) ; unsaturated hydrocarbons react with bromine / decolorise bromine ; [4] [Total: 11]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 23 © Cambridge International Examinations 2013 3 (a) producer consumer herbivore carnivore bilberry and spruce ; any two of: vole, Siberian jay, red squirrel, lynx, goshawk ; any two of: vole, Siberian jay, red squirrel ; lynx and goshawk ; [4] (b) loss of soil / soil erosion ; flooding ; carbon dioxide build up ; [max 2] (c) muscle contraction ; protein synthesis ; cell division ; passage of nerve impulses ; maintenance of constant body temperature ; digestion ; [max 3] [Total: 9] 4 (a) (i) gas produced ; temperature change ; [2] (ii) hydrogen ; lighted splint pops ; [2] (iii) solution is becoming less acidic ; because dilute hydrochloric acid is reacting / being used up ; [2] (b) (i) the volume of gas trapped in the measuring cylinder ; the time taken for this volume to collect ; [2] (ii) concentration of acid ; temperature of acid ; surface area of magnesium ; [max 2] [Total: 10]

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 23 © Cambridge International Examinations 2013 5 (a) (i) infra-red ; [1] (ii) wavelength / frequency ; [1] (b) A is passing into a more dense medium ; B hits at an angle greater than the critical angle ; C is passing into a less dense medium ; [3] (c) (i) 2 protons and 2 neutrons / helium nucleus ; [1] (ii) rocks etc ; [1] (d) alpha particles cannot pass through a thin sheet of lead / alpha particles can pass through a few centimetres of air ; [1] (e) Geiger-Müller tube ; photographic film ; [2] (f) both alpha radiation and beta radiation pass easily through the body
alpha radiation damages cells in a very localised part of the body  ionisation does not always kill cells- sometimes it causes them to mutate  cancer occurs when a large number of cells are killed
the dose of radiation received depends on the length of exposure  (all 5 boxes correct: 2 marks, 3 or 4 boxes correct: 1 mark) ;; [max 2] (g) electron ; neutron ; electron ; proton and neutron ; [4] [Total: 16]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 23 © Cambridge International Examinations 2013 6 (a) a cell formed when the nuclei of the male and female gamete fuse zygote ; a male gamete sperm ; the organ in which sperms are made testis ; the place where fertilisation occurs oviduct ; [4] (b) (i) 30 days ; [1] (ii) day 25 ; [1] (c) (i) human immunodeficiency virus ; [1] (ii) virus passes from mother to child ; across placenta ; through blood during birth process ; in breast milk ; [max 2] [Total: 9] 7 (a) (i) good heat conductor ; malleable ; good electrical conductor ; ductile ; unreactive / does not react with water ; [max 3] (ii) transition metals ; [1] (b) (i) alloy ; [1] (ii) harder / stronger ; [1] (c) (i) electrolysis ; [1] (ii) left electrode labelled cathode ; [1] (reject labelling of wiring or power pack) (iii) copper chloride ; gas produced is chlorine ; elements in the compound must have been copper and chlorine ; [max 2] [Total: 10]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 23 © Cambridge International Examinations 2013 8 (a) kinetic ; heat and sound ; [2] (b) (i) liquid particles touching ; gas particles not touching ; random arrangement for both ; [3] (ii) faster moving molecules ; can do more work against attractive forces / can break bonds between them ; break free / separate / turn into gas / leave liquid ; energy / heat (from surroundings) used for this ; [max 3] (c) V = I × R ; R= 220/3 = 73.3 (Ω) ; [2] [Total: 10] 9 (a) (i) substance source part of plant that absorbs it process by which it is absorbed carbon dioxide air leaf / stomata ; diffusion ; water soil ; root / root hairs ; [4] (ii) carbon dioxide + water ; glucose / sugar / starch / carbohydrate + oxygen ; [2] (b) (i) pitchers have slippery rim (so insects fall in) ; pitchers have downward-pointing spines (so insects can't crawl out) ; [2] (ii) breakdown of large molecules ; so that they can be absorbed / become soluble ; [2] (iii) enzymes / proteases / trypsin / pepsin ; [1] (c) (i) as a control / to make sure the only variable was the substance used ; [1] (ii) (yes) insects moved towards the piece of rim ; use of figures from table ; [2] [Total: 14]

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 23 © Cambridge International Examinations 2013 10 (a) (i) calcium carbonate reduce acidity / increase pH / neutralise acids ; calcium carbonate reacts with / neutralises acids ; releases nutrients from soil ; potassium compounds increase plant nutrient levels ; potassium compounds are essential for healthy plant growth ; [max 3] (ii) mix ash with dilute acid ; carbon dioxide shows carbonate present ; [2] (b) (i) 15 ; [1] (ii) sulfuric acid ; neutralisation ; [2] (iii) warm solution gently ; allow water to evaporate ; allow solution to cool ; [max 2] [Total: 10] 11 (a) curve goes up and then down again ; peak between 30 and 45 °C ; rate zero by 60 °C ; [3] (b) (i) skin in environmental condition 2 blood vessel is wider ; reference to sweat ; [2] (ii) hotter ; [1] (iii) shiver / contract ; release heat ; [2] [Total: 8]