Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2015 May/June Paper 2 · Variant 2

This document consists of 28 printed pages. DC (AC/SW) 97593/4 © UCLES 2015 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 5 0 5 8 2 2 6 2 2 3 * CO-ORDINATED SCIENCES 0654/22 Paper 2 (Core) May/June 2015 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, 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 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 0654/22/M/J/15 © UCLES 2015 1 (a) Fig. 1.1 shows a passenger at an airport pulling a suitcase towards the check-in desk. Fig. 1.1 The suitcase has a mass of 18.4 kg and a weight of 180 N. Explain the difference between the terms mass and weight. … … … [2] (b) Fig. 1.2 shows the suitcase being loaded onto an aircraft using a conveyor belt. ground aircraft suitcase conveyor belt Fig. 1.2 (i) State the form of energy which the case has due to its movement. … [1] (ii) State the form of energy gained by the case after it has been lifted up the conveyor belt. … [1]

3 0654/22/M/J/15 © UCLES 2015 [Turn over (c) Fig. 1.3 shows four forces acting on an aircraft. A C B D Fig. 1.3 (i) Complete the sentences using the letters A, B, C or D. Each letter may be used once, more than once or not at all. Initially the aircraft is at rest on the runway because forces … and … are balanced, and also forces … and … are balanced. The aircraft begins to move forward along the runway when forces … and … are unbalanced. [2] (ii) Compare the size and direction of forces B and D when the aircraft flies forward at a steady speed and altitude. … … … [2]

4 0654/22/M/J/15 © UCLES 2015 (d) Fig. 1.4 shows the speed / time graph for the aircraft, during part of its flight. 0 0 100 200 300 400 500 600 20 40 60 80 100 120 time / minutes speed km / hr 140 160 B C D A Fig. 1.4 (i) State which section AB, BC or CD of the graph shows the aircraft travelling at a constant speed. Explain your answer. section … explanation … [1] (ii) State which section AB, BC or CD of the graph shows the aircraft accelerating. Explain your answer. section … explanation … … [1]

5 0654/22/M/J/15 © UCLES 2015 [Turn over 2 (a) A student uses litmus paper to test three colourless aqueous solutions. Complete Table 2.1 to show the colour of the litmus paper in each solution. Table 2.1 solution colour of litmus paper dilute hydrochloric acid dilute sodium hydroxide (an alkali) dilute solution of chlorine [2] (b) Fig. 2.1 shows the apparatus the student uses to measure the pH of dilute hydrochloric acid. pH 2 pH meter dilute hydrochloric acid Fig. 2.1 (i) State what happens to the pH of the mixture when a small volume of dilute sodium hydroxide solution is added to the acid. … [1] (ii) Predict the reading on the pH meter when the student has added just enough sodium hydroxide to react with all the acid. Explain your answer. pH meter reading … explanation … … [2]

6 0654/22/M/J/15 © UCLES 2015 (c) Fig. 2.2 shows apparatus the student uses to investigate the reaction between calcium carbonate and dilute hydrochloric acid. dilute hydrochloric acid calcium carbonate test-tube T colourless solution Fig. 2.2 The student has set up test-tube T to show that carbon dioxide gas is given off. (i) Name the colourless solution in test-tube T. … [1] (ii) State what happens to the solution in test-tube T when calcium carbonate reacts with dilute hydrochloric acid. … [1] (iii) Complete the word chemical equation for the reaction between calcium carbonate and dilute hydrochloric acid. dilute hydrochloric acid carbon dioxide + calcium carbonate + + [2] (iv) State two changes, other than using a catalyst, the student can make that will increase the reaction rate. 1 … … 2 … …[2]

7 0654/22/M/J/15 © UCLES 2015 [Turn over Please turn over for Question 3.

8 0654/22/M/J/15 © UCLES 2015 3 Fig. 3.1 shows part of the carbon cycle. fossil fuels dead and decaying matter fossilisation decay death death carbon dioxide plants animals respiration Fig. 3.1 (a) Fill in the empty boxes in Fig. 3.1, naming the processes involved in the carbon cycle. Choose words from this list. You may use each word once, more than once, or not at all. breathing combustion decomposition photosynthesis respiration transpiration [3] (b) Add an arrow to Fig. 3.1 to show how animals obtain their carbon. [1]

9 0654/22/M/J/15 © UCLES 2015 [Turn over (c) Use the ideas of the carbon cycle to explain why, in a deciduous (temperate) forest, the carbon dioxide concentration in the atmosphere falls slightly in spring and summer, … … rises again in the autumn. … … [2] (d) In many parts of the world, large areas of forest are being cut down. With reference to Fig. 3.1, explain why the carbon dioxide concentration of the atmosphere might be affected by this. … … … [2]

10 0654/22/M/J/15 © UCLES 2015 4 (a) Fig. 4.1 shows the chemical symbols of some elements in the first four periods of the Periodic Table. H Na K Cu Fe Cl Ne Fig. 4.1 Using only those symbols shown in Fig. 4.1, complete Table 4.1 with the element or elements that match the descriptions in the column on the left. Each symbol may be used once, more than once or not at all. Table 4.1 description element symbol(s) it is an unreactive gas it oxidises to form rust its atoms have the lowest proton number they are good electrical conductors they are transition metals they combine to form sodium chloride [6]

11 0654/22/M/J/15 © UCLES 2015 [Turn over (b) Many of the rocks in the Earth’s crust are made of compounds known as feldspars. The chemical formula of one type of feldspar is shown below. CaAl2Si2O8 (i) State the total number of atoms shown in this chemical formula. … [1] (ii) State the name of the element shown in the chemical formula that is found in Group IV of the Periodic Table, … the 4th period of the Periodic Table. … [2] (c) Fluorine is a non-metallic element. Fluorine combines with hydrogen and potassium to form the compounds hydrogen fluoride, HF, and potassium fluoride, KF. (i) Suggest and explain which of these two compounds contains ionic bonding between the elements. compound … explanation … … [1] (ii) Suggest, in terms of electrons, what happens when a fluorine atom is converted into a fluoride ion. … … [1]

12 0654/22/M/J/15 © UCLES 2015 5 On a farm, the wheat yield from one field was recorded over a period of sixty years. Fig. 5.1 shows the results. 1950 200 300 400 500 600 700 1960 1970 1980 year mean yield g / m2 1990 2000 2010 Fig. 5.1 (a) (i) State in which year the yield from this field was lowest. … [1] (ii) Calculate how much the mean yield increased between 1950 and 2010. yield increase … g/m2 [1]

13 0654/22/M/J/15 © UCLES 2015 [Turn over (b) (i) It is suggested that the increase in yield shown in Fig. 5.1 was caused by artificial selection. Describe how artificial selection would have been carried out. … … … [2] (ii) Suggest two other possible explanations of the increase in yield that do not involve artificial selection. 1 … 2 … [2] (c) Suggest a possible reason for the results that were obtained in 1955 and in 1995. … … [1] (d) In addition to yield, give one other characteristic of wheat plants that farmers might try to improve through artificial selection. … [1]

14 0654/22/M/J/15 © UCLES 2015 6 (a) During car journeys, a car becomes electrostatically charged. This is more obvious on a dry day than on a damp, humid day. Explain what happens to cause the car to become charged. … … … [2] (b) A car has two headlamps connected in parallel with each other across a 12 V battery. (i) Complete the circuit diagram below to show how the two lamps are connected to the battery. Include one switch in the circuit which will control both lamps. 12 V [3] (ii) If one bulb fails, the other stays lit. Explain why this happens. … … [1]

15 0654/22/M/J/15 © UCLES 2015 [Turn over (iii) Each lamp has a resistance of 2 Ω. Calculate the current passing through one of the lamps. State the formula that you use and show your working. formula working current = … A [2] (c) A police car uses a blue light and a loud sound from a siren to alert people. (i) State how the sound from the siren changes when the amplitude of the sound waves emitted decreases. … [1] (ii) Sound waves are longitudinal waves but light waves are transverse waves. Describe the difference between a transverse wave and a longitudinal wave. You may draw diagrams if it helps your answer. … … … [2]

16 0654/22/M/J/15 © UCLES 2015 7 Fig. 7.1 shows the female reproductive system. W Fig. 7.1 (a) Name the part of the female reproductive system in which the female gametes are produced. … [1] (b) (i) Name the tubes labelled W. … [1] (ii) Infertility in women can sometimes be caused by the tubes W becoming blocked. Explain why this would lead to infertility. … … [1] (c) The female reproductive system produces hormones. (i) Define a hormone. … … … … [3] (ii) On Fig. 7.1, use a label line to name and identify the part that produces hormones. [1]

17 0654/22/M/J/15 © UCLES 2015 [Turn over 8 The percentages of chemical elements found in the Earth’s crust and in the Earth’s atmosphere are shown in Fig. 8.1 and Fig. 8.2. oxygen silicon 27.7% % of element LQ(DUWK·VFUXVW DOXPLQLXP 8.1% iron 5.0% other elements 12.6% Fig. 8.1 nitrogen oxygen other gases % of element LQWKH(DUWK·V atmosphere Fig. 8.2 (a) (i) Calculate the percentage of oxygen in the Earth’s crust. Write the value above the correct bar in Fig. 8.1. [1] (ii) State the percentages of nitrogen and oxygen in the Earth’s atmosphere. Write the values above the correct bars in Fig. 8.2. [2]

18 0654/22/M/J/15 © UCLES 2015 (b) The Earth’s crust contains useful metals such as iron and aluminium combined with oxygen. (i) The word equation below shows a reaction that is used to extract iron from iron oxide. iron oxide + carbon monoxide iron + carbon dioxide State the term used to describe a chemical reaction in which oxygen is removed from a compound. … [1] (ii) Aluminium is obtained by the electrolysis of an electrolyte containing aluminium oxide. In this process both the anode and the cathode are made of graphite (carbon). Complete the sentences. Electrolysis is a chemical change in which… … … An electrolyte is a liquid that contains … … The cathode is … [3] (c) Aluminium is used to make food containers and to wrap around food during cooking. (i) State the physical property of aluminium that allows it to be formed into thin sheets. … [1] (ii) Suggest two other properties of aluminium that make it a suitable material to wrap around food during cooking. 1 … … 2 … … [2]

19 0654/22/M/J/15 © UCLES 2015 [Turn over 9 (a) Fig. 9.1 shows two dolphins communicating with each other under water using sound waves. 50 m Fig. 9.1 (i) The dolphins are 50 m apart. The speed of sound in water is 1500 m / s. Calculate how long it will take for a sound wave to travel from one dolphin to the other. State the formula that you use and show your working. formula working … s [2] (ii) Some of the sounds made by the dolphins have a frequency of 50 000 Hz. State whether or not humans can hear sounds with a frequency of 50 000 Hz. Explain your answer. … … [1]

20 0654/22/M/J/15 © UCLES 2015 (b) A man on a boat sees a dolphin under the water. Draw a ray of light on Fig. 9.2 to show how light travels from the dolphin’s head to the man’s eye. eye air water [2] Fig. 9.2 (c) The water in the sea is heated by the Sun. When the water is heated, the temperature of the water increases but never reaches the boiling point of water. Some water evaporates. (i) State the meaning of the term boiling point. … … [1] (ii) Describe the process of evaporation in terms of the movement of water molecules. … … … … [3]

21 0654/22/M/J/15 © UCLES 2015 [Turn over (d) Fig. 9.3 shows three different ways in which particles may be arranged in substances. A B C Fig. 9.3 Water in the sea is a liquid and water in the air is a gas. (i) State which diagram best represents the way particles are arranged in liquid water. Explain your answer. diagram … explanation … … [1] (ii) State which diagram best represents the way particles are arranged in gaseous air. Explain your answer. diagram … explanation … … [1]

22 0654/22/M/J/15 © UCLES 2015 10 Fig. 10.1 shows a cell from a plant. The cell absorbs water from the soil. Y X Fig. 10.1 (a) (i) Name this type of cell. … [1] (ii) Name the structures labelled X and Y. X … Y … [2] (b) State one other function of the cell, apart from water absorption. … [1] (c) Most of the water absorbed by this cell later evaporates from the plant. (i) Name the process by which water evaporates from a plant. … [1] (ii) State where most of this evaporation occurs. … [1] (d) Not all of the water absorbed by a plant is lost by evaporation. Suggest one way in which a plant might make use of the absorbed water. … … [1]

23 0654/22/M/J/15 © UCLES 2015 [Turn over 11 Alkanes and alkenes are general names given to two types of hydrocarbons. Alkanes are found in petroleum (crude oil) and alkenes are produced in the chemical industry. (a) (i) Name the type of reaction that is used to produce alkenes in the chemical industry. … [1] (ii) Fig. 11.1 shows the structure of one molecule of a gaseous hydrocarbon, G. H C H H C H Fig. 11.1 State and explain whether hydrocarbon G is an alkane or an alkene. hydrocarbon G is an … explanation … … [1] (iii) Describe the colour change that is observed when hydrocarbon G is shaken with a solution of bromine. from … to … [2]

24 0654/22/M/J/15 © UCLES 2015 (b) Fig. 11.2 shows hydrocarbon G being passed through a reaction vessel to produce a white solid substance that has the appearance of plastic. hydrocarbon G white solid reaction vessel high temperature, high pressure catalyst Fig. 11.2 (i) Name the type of chemical reaction that converts hydrocarbon G into the white solid substance. … [1] (ii) Draw a simple diagram that shows the way a molecule of the white solid is formed from molecules of hydrocarbon G. Use the symbol * to represent a molecule of hydrocarbon G. [1] (iii) State and explain whether or not the white solid compound is a hydrocarbon. … … … [2]

25 0654/22/M/J/15 © UCLES 2015 [Turn over 12 Fig. 12.1 shows the human skull, seen from the side. T1 T2 Fig. 12.1 (a) Name the type of tooth labelled T1. … [1] (b) Describe how tooth T2 is different from tooth T1 in its structure and in its function. structure … … … function … … [3] (c) Explain why it is important to chew food that we eat. … … … [2] (d) Explain how regular brushing of the teeth helps to prevent tooth decay. … … … [2] (e) Apart from brushing the teeth, state two other ways in which tooth decay can be prevented. 1 … 2 … [2]

26 0654/22/M/J/15 © UCLES 2015 13 (a) A doctor uses both X-rays and γ-(gamma) rays in a hospital. (i) X-rays and γ-rays are both examples of ionising radiation. Explain what is meant by the term ionising radiation. … … [1] (ii) Before using an X-ray machine, the doctor moves and stands behind a metal screen. Suggest a reason why the doctor does this. … … … [2] (iii) X-rays and γ-rays are both part of the electromagnetic spectrum. Write each one in its correct box on the incomplete electromagnetic spectrum below. radio waves infra-red ultraviolet increasing frequency [2] (b) Optical fibres are used to see inside the human stomach. Light is sent along a bundle of fibres to enable the doctor to see what is in the stomach. Fig. 13.1 shows an optical fibre with a ray of light travelling down part of it. (i) Complete the path of the ray of light as it travels down the fibre. Fig. 13.1 [1] (ii) Explain why the ray stays inside the fibre. … … [1]

27 0654/22/M/J/15 © UCLES 2015 (c) To study the blood flow in a patient’s lungs, the patient is injected with a radioactive isotope, technetium-99. The γ-radiation given out by the technetium-99 is detected using a gamma camera outside the patient’s body. Identify two statements that explain why γ-radiation is used for this investigation. Place a tick in each of the two correct boxes. It can pass through the human body. It destroys cancer cells. It is safer than α- or β-radiation. [1]

28 0654/22/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 0654 CO-ORDINATED SCIENCES 0654/22 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 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 0654 22 © Cambridge International Examinations 2015 1 (a) mass is a measure of amount of matter in an object ; weight is the gravitational force pulling on the object ; mass will be the same throughout the universe but weight will depend on the gravitational field strength ; mass is measured in kg weight is measured in N ; [max 2] (b) (i) kinetic (energy) ; [1] (ii) (gravitational) potential energy ; [1] (c) (i) B and D, and A and C (either order) ; B and D ; [2] (ii) equal ; opposite ; [2] (d) (i) B–C – horizontal line means constant speed ; [1] (ii) A–B or C–D – (diagonal line means) speed is changing ; [1] [Total: 10] 2 (a) red blue ; colourless / white / is bleached ; (allow red then white but not blue then white) (red and blue correct = 1 chlorine result correct = 1) [2] (b) (i) increases ; [1] (ii) 7 ; mixture is neutral / the acid has been neutralised ; [2] (c) (i) limewater / calcium hydroxide / slaked lime ; [1] (ii) goes cloudy / milky / white precipitate ; [1] (iii) calcium chloride ; water ; in either order [2] (iv) increase acid concentration ; increase (acid) temperature ; increase surface area (of calcium carbonate) / smaller particle size ; [max 2] [Total: 11]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – May / June 2015 0654 22 © Cambridge International Examinations 2015 3 (a) (labels, from top left) photosynthesis ; respiration ; combustion ; [3] (b) arrow from plants to animals ; ignore arrow from died and decaying matter to animals [1] (c) more photosynthesis (than respiration and decay) in spring / summer ; more decay / respiration (than photosynthesis) in autumn ; [2] (d) (increase – no mark) plants remove less CO2 from atmosphere ; by photosynthesis ; removed trees form dead matter ; and decay to produce more CO2 ; burning wood / combustion release CO2 ; [max 2] [Total: 8] 4 (a) description element symbol(s) it is an unreactive gas Ne it oxidises to form rust Fe its atoms have the lowest proton number H they are good electrical conductors Na K Fe Cu they are transition metals Fe Cu they combine to form sodium chloride Na Cl 1 mark for each completely filled box ; ; ; ; ; ; [6] (b) (i) 13 ; [1] (ii) Group 4 – silicon ; 4th period – calcium ; [2] (c) (i) (KF) reference to metal combining with non-metal ; [1] (ii) reference to gain of electrons / outer shell is completed / outer shell electron number goes from 7 to 8 / the ion now has a single negative charge ; [1] [Total: 11]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – May / June 2015 0654 22 © Cambridge International Examinations 2015 5 (a) (i) 1955 ; [1] (ii) 330 (g / m2) ; [1] (b) (i) identify / choose highest yielding plants ; use these for breeding / repeat over many generations / check for appearance of undesirable characteristics ; [2] (ii) more / better / use of fertiliser ; better pest control ; irrigation ; new varieties of wheat from outside ; better soil quality ; better weather ; [max 2] (c) disease / drought / flood / frost / AVP ; [1] (d) disease resistance / pest resistance / hardiness / taste / nutrient content / high germination rate ; [1] [Total: 8] 6 (a) friction ; transfer of electrons / charged particles ; [2] (b) (i) symbols for lamp and switch correct in a working circuit ; lamps connected in parallel ; switch in correct position to control both lamps ; [3] (ii) still a complete circuit for the other lamp ; [1] (iii) current = voltage / resistance ; = 12 / 2 = 6 A ; [2] (c) (i) quieter ; [1] (ii) transverse waves oscillate at right angles to direction of wave / energy transfer ; longitudinal waves oscillate parallel to direction of wave / energy transfer ; [2] [Total: 11]

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – May / June 2015 0654 22 © Cambridge International Examinations 2015 7 (a) ovary ; [1] (b) (i) oviduct / fallopian tube ; [1] (ii) prevents egg reaching uterus / sperm cannot reach egg / prevents fertilisation / sperm cannot enter fallopian tube ; [1] (c) (i) chemical substance produced by gland ; carried in the blood ; affects / alters activity of target organs ; destroyed in liver ; [max 3] (ii) ovary labelled on Fig. 7.1 ; [1] [Total: 7] 8 (a) (i) 46.6% ; [1] (ii) nitrogen 78% ; oxygen 21% ; [2] (b) (i) reduction ; [1] (ii) compounds are broken down by electrical energy / by passing an electric current through them ; contains (mobile) ions / a compound that conducts ; the negative electrode ; [max 3] (c) (i) malleability ; [1] (ii) unreactive / will not react with food / catch fire in oven high melting point / will not melt during cooking ; other science based ideas, e.g. reflects heat back into food ; [max 2] [Total: 10]

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – May / June 2015 0654 22 © Cambridge International Examinations 2015 9 (a) (i) (time) = distance / speed ; = 50 / 1500 = 0.03(3) (s) ; [2] (ii) cannot hear (no mark) max human audible frequency is 20 000 Hz ; [1] (b) ray from head bends at surface ; enters eye ; [2] (c) (i) temperature at which a liquid boils and turns into a vapour ; [1] (ii) thermal energy transferred to (water) particles (from surroundings) / particles gain KE / move faster when heated ; water changes from liquid to vapour / gas ; ref. to attraction between particles in the liquid ; fastest moving particles escape ; (escape) at surface / ref to process happening at temperature below boiling point ; average energy of the rest of the particles reduced / thermal energy removed from liquid ; [max 3] (d) (i) B because most particles are touching and randomly arranged ; [1] (ii) C because particles are widely spaced and randomly arranged ; [1] [Total: 11] 10 (a) (i) root hair (cell) ; [1] (ii) cell wall ; nucleus ; [2] (b) absorbs mineral ions / nitrate / magnesium (ions) / other named mineral ion ; [1] (c) (i) transpiration ; [1] (ii) leaves / stomata / mesophyll ; [1] (d) for photosynthesis ; as part of cytoplasm / for growth ; support / turgor ; for transport (of ions / sugars) ; [max 1] [Total: 7]

Page 7 Mark Scheme Syllabus Paper Cambridge IGCSE – May / June 2015 0654 22 © Cambridge International Examinations 2015 11 (a) (i) cracking ; [1] (ii) (alkene) ref. to double bond / conforms to general formula CnH2n ; [1] (iii) orange ; to colourless ; [2] (b) (i) (addition) polymerisation ; [1] (ii) several G symbols linked into a chain (minimum 4) ; [1] (iii) (white solid is hydrocarbon) made of the elements hydrogen and carbon ; only ; OR G is a hydrocarbon and so Gs linked must be hydrocarbon ; because no other elements are included ; [2] [Total: 8] 12 (a) incisor ; [1] (b) (structure) larger ; two roots ; flatter ; [max 2 for structure] (function) grinding / crushing ; T1 for biting ; [max 3] (c) breaks into small pieces ; (so) easier to swallow ; more surface area for enzyme action ; [max 2] (d) removes plaque / bacteria ; removes sugar / food remnants ; which encourage bacteria ; removes / neutralises acid ; [max 2] (e) flossing ; avoiding sugary / sticky foods ; avoiding snacks between meals ; mouthwash ; fluoride ; regular dental checks / professional cleaning / sealing ; [max 2] [Total: 10]

Page 8 Mark Scheme Syllabus Paper Cambridge IGCSE – May / June 2015 0654 22 © Cambridge International Examinations 2015 13 (a) (i) removes electrons from atoms / turns atoms to ions ; [1] (ii) repeated exposure to X-rays is harmful ; X-rays are harmful to humans / cause cancer, etc. ; metal screen stops X-rays penetrating ; [max 2] (iii) X-rays in 6th box ; γ rays in 7th box ; [2] (b) (i) reflection continues through fibre with angle approx. correct ; [1] (ii) total internal reflection ; angle of incidence always exceeds critical angle ; [max 1] (c) it can pass through the human body and it is safer than α or β radiation ; (both required for 1 mark) [1] [Total: 8]