Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2025 May/June Paper 4 · Variant 2

This document has 28 pages. Any blank pages are indicated. [Turn over Cambridge IGCSE™ DC (CE/CB) 344522/5 © UCLES 2025 * 2 9 4 0 8 4 8 2 0 8 * CO‑ORDINATED SCIENCES 0654/42 Paper 4 Theory (Extended) May/June 2025 2 hours You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use a calculator. ● You should show all your working and use appropriate units. ● Take the weight of 1.0 kg to be 9.8 N (acceleration of free fall = 9.8 m / s2). INFORMATION ● The total mark for this paper is 120. ● The number of marks for each question or part question is shown in brackets [ ]. ● The Periodic Table is printed in the question paper. ,










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2 0654/42/M/J/25 © UCLES 2025 1 Fig. 1.1 is a diagram of a root hair cell. B A E D C Fig. 1.1 (a) Using letters A – E in Fig. 1.1, identify the part of the cell: where protein synthesis takes place … made from cellulose. … [2] (b) Amino acids are used in protein synthesis. State the name of the process used to transport amino acids from sources to sinks in plants. … [1] (c) Root hair cells are specialised for absorption. Complete Table 1.1 about substances absorbed by root hair cells. Table 1.1 substance method of absorption one use of substance in plant water … … nitrate ions … … [2] * 0000800000002 * ,










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3 0654/42/M/J/25 © UCLES 2025 [Turn over (d) Fig. 1.2 shows two of the same plant cells, one immersed in pure water (water with no chemical impurities) and the other immersed in concentrated salt solution. cell membrane cytoplasm vacuole cell immersed in pure water cell immersed in concentrated salt solution Fig. 1.2 Complete Fig. 1.2 to show the contents of the plant cell immersed in the concentrated salt solution. [2] (e) Explain the effects of high winds on transpiration rate in plants. … … … … … [3] [Total: 10] * 0000800000003 * ,










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4 0654/42/M/J/25 © UCLES 2025 2 Fig. 2.1 is a diagram of the human breathing system. A B C D E alveoli Fig. 2.1 (a) Using letters A – E in Fig. 2.1, identify the: trachea … diaphragm. … [2] (b) Alveoli are the gas exchange surface in humans. Describe two features of an efficient gas exchange surface. 1 … … 2 … … [2] * 0000800000004 * ,










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5 0654/42/M/J/25 © UCLES 2025 [Turn over (c) Table 2.1 shows the composition of inspired and expired air. Table 2.1 composition / % gas inspired air expired air difference oxygen 21.00 16.00 –5.00 carbon dioxide 0.04 4.00 … water vapour low high increased (i) Calculate the difference in composition of the carbon dioxide in Table 2.1. Write your answer in Table 2.1. [1] (ii) Explain the differences in composition between inspired and expired air. … … … … … … [3] (d) A student runs very fast for 20 minutes. The rate and depth of breathing increases during exercise and stays high after the student has finished running. Explain why the rate and depth of breathing stays high after the student has finished running. … … … … … … … [4] [Total: 12] * 0000800000005 * ,










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6 0654/42/M/J/25 © UCLES 2025 3 (a) Table 3.1 shows the diameter of a flu virus and different types of cells. Table 3.1 diameter / μm flu virus 0.1 bacterial cell 1.0 red blood cell 7.0 lymphocyte 15.0 plant cell 50.0 human egg cell 120.0 (i) Calculate the difference in size between the largest and smallest animal cells in Table 3.1. … μm [2] (ii) State the name of the cell in Table 3.1 that contains haemoglobin. … [1] (b) Complete the sentences about an immune response to a flu virus infection. Use words from the list. active antibodies enzymes lymphocytes passive pathogens phagocytes The flu virus has antigens on its surface. Proteins with a specific shape bind to antigens. These proteins are called … . This causes the virus to be destroyed or marked for engulfing by … . After the infection, a human has … immunity to the flu virus. [3] * 0000800000006 * ,










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7 0654/42/M/J/25 © UCLES 2025 [Turn over (c) Flu vaccinations are used each year to protect people from flu virus infection. Outline how this vaccine gives protection. … … … … … [3] (d) The flu virus reproduces quickly and often mutates. Suggest why a new vaccine is developed every year. … … … … [2] [Total: 11] * 0000800000007 * ,










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8 0654/42/M/J/25 © UCLES 2025 4 Orcas are large mammals that live in the sea. (a) Orcas reproduce using egg cells and sperm cells like humans. Describe two adaptive features of egg cells. 1 … … 2 … … [2] (b) Fig. 4.1 shows part of a marine food web for an orca. orca seal herring fish zooplankton phytoplankton Fig. 4.1 (i) Orcas feed at more than one trophic level. State the name of the lowest trophic level orcas feed at as shown in Fig. 4.1. … [1] (ii) Humans also eat herring fish. Draw an arrow and label for humans on Fig. 4.1. [1] * 0000800000008 * ,










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9 0654/42/M/J/25 © UCLES 2025 [Turn over (c) An orca tangled in a fishing net is found dead on a beach. The orca has a high level of PCB in its body. PCB is a pollutant that stops orcas reproducing. Suggest how human activity is causing the population of orcas to decrease. … … … … … … [3] [Total: 7] * 0000800000009 * ,










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10 0654/42/M/J/25 © UCLES 2025 5 (a) The element carbon has a proton (atomic) number of 6. Complete Fig. 5.1 to show the electronic configuration of a carbon atom. C Fig. 5.1 [1] (b) A carbon atom has 6 neutrons. State the mass number of this carbon atom. mass number = … [1] (c) State the number of atoms in 1 mole of carbon. number of atoms = … [1] (d) Fig. 5.2 shows two different forms of the element carbon. … … … Fig. 5.2 (i) Complete the labels on Fig. 5.2. Use phrases from the list. Each phrase can be used once, more than once, or not at all. weak forces ionic bond metallic bond covalent bond [3] * 0000800000010 * ,










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11 0654/42/M/J/25 © UCLES 2025 [Turn over (ii) One of the forms of carbon in Fig. 5.2 is diamond. Explain why diamond is used in cutting tools. … … … [2] (e) Carbon reacts with hydrogen to form methane, CH4. Complete the dot-and-cross diagram in Fig. 5.3 to show the bonding in methane. Only show the outer-shell electrons. H H H H C Fig. 5.3 [2] [Total: 10] * 0000800000011 * ,









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12 0654/42/M/J/25 © UCLES 2025 6 (a) Fig. 6.1 shows the structural formula of a molecule, X. H H H H N N H H C H H C H H C H H C H H C H H C Fig. 6.1 (i) Deduce the molecular formula of molecule X. molecular formula of X = … [1] (ii) Explain why molecule X is not a hydrocarbon. … … [1] (b) Molecule X can be drawn using a box to represent the carbon chain. This is shown in Fig. 6.2. Fig. 6.2 also shows another molecule, Y. H H N H HO OH C O H X Y N C O Fig. 6.2 Molecules of X react with molecules of Y to make the polymer nylon. Draw the structure of the polymer nylon. [2] * 0000800000012 * ,









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13 0654/42/M/J/25 © UCLES 2025 [Turn over (c) The formation of nylon is an example of condensation polymerisation. Describe two differences between condensation polymerisation and addition polymerisation. 1 … … 2 … … [2] (d) Molecule Y reacts with sodium carbonate. Carbon dioxide is made in the reaction. State the test for carbon dioxide. Include the observation for a positive result. test … observation … [2] (e) Carbon dioxide is a simple molecular compound. Tick (3) two properties of simple molecular compounds. good electrical conductivity when molten high boiling point low melting point malleable poor electrical conductivity when solid [2] [Total: 10] * 0000800000013 * ,









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14 0654/42/M/J/25 © UCLES 2025 7 (a) The ionic compound sodium sulfate contains the ions Na+ and SO4 2–. Determine the formula of sodium sulfate. formula = … [1] (b) Copper sulfate is also an ionic compound. A student investigates the electrolysis of aqueous copper(II) sulfate using copper electrodes. Fig. 7.1 shows the student’s experiment. – – + + copper anode copper cathode d.c. power supply aqueous copper(II) sulfate Fig. 7.1 Describe what the student observes at the anode. … … [1] (c) (i) Copper is deposited at the cathode. Write the ionic half-equation for the formation of copper, Cu, from copper ions, Cu2+. … [2] (ii) The ionic half-equation for the reaction at the anode is shown. Cu Cu2+ + 2e– Explain if the reaction at the anode is oxidation or reduction. … … [1] * 0000800000014 * ,









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15 0654/42/M/J/25 © UCLES 2025 [Turn over (d) A student investigates the displacement reactions of copper, magnesium, zinc and iron. The student adds a piece of each metal to solutions of the metal sulfates. Table 7.1 shows the student’s results. Table 7.1 copper sulfate magnesium sulfate zinc sulfate iron sulfate copper 8 8 8 magnesium 3 3 3 zinc 3 8 3 iron 3 8 8 3 = reaction 8 = no reaction (i) Deduce the order of reactivity of the metals. … most reactive … … … least reactive [2] (ii) Construct the balanced symbol equation for the reaction of magnesium with zinc sulfate, ZnSO4. … [2] * 0000800000015 * ,









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16 0654/42/M/J/25 © UCLES 2025 (e) Brass is an alloy of the metals copper and zinc. Fig. 7.2 shows the structure of a pure metal and of an alloy. pure metal alloy Fig. 7.2 Explain why brass is harder and stronger than copper or zinc. … … … [2] [Total: 11] * 0000800000016 * ,









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17 0654/42/M/J/25 © UCLES 2025 [Turn over BLANK PAGE * 0000800000017 * ,









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18 0654/42/M/J/25 © UCLES 2025 8 A student investigates the reaction between dilute hydrochloric acid and solid pieces of calcium carbonate. (a) The balanced symbol equation for the reaction is shown. Complete the state symbols in the equation. 2HCl (…) + CaCO3 (…) CaCl 2 (aq) + CO2 (…) + H2O (l) [2] (b) The student measures the total volume of carbon dioxide made every minute for 7 minutes. Fig. 8.1 shows a graph of the student’s results. 0 1 2 3 4 5 time / minutes total volume of carbon dioxide / cm3 6 7 0 10 20 30 40 50 60 70 Fig. 8.1 (i) State when the reaction finished. time = … minutes [1] (ii) The student repeats the experiment with larger pieces of calcium carbonate. The student uses the same volume and concentration of hydrochloric acid and the same mass of calcium carbonate. Draw on Fig. 8.1 the line for the student’s results. [1] * 0000800000018 * ,









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19 0654/42/M/J/25 © UCLES 2025 [Turn over (c) The student predicts the reaction will be faster with a higher concentration of hydrochloric acid. Explain why the student is correct. … … … [2] (d) Calculate the mass of calcium chloride, CaCl 2, made when 0.2 moles of hydrochloric acid react with excess calcium carbonate. 2HCl + CaCO3 CaCl 2 + CO2 + H2O [Ar: Ca, 40; Cl, 35.5; H, 1] mass of calcium chloride = … g [3] [Total: 9] * 0000800000019 * ,









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20 0654/42/M/J/25 © UCLES 2025 9 (a) A torch (flashlight) consists of a battery, a switch and a lamp connected in series. Fig. 9.1 shows a torch. Fig. 9.1 (i) State the energy store which decreases when the battery powers the lamp. … [1] (ii) State the energy transfer from the battery to the lamp. … [1] (iii) State the energy transfer from the lamp to the surroundings. … [1] (b) A diver with mass 70 kg stands 5.0 m above a swimming pool as shown in Fig. 9.2. 5.0 m surface of water Fig. 9.2 * 0000800000020 * ,










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21 0654/42/M/J/25 © UCLES 2025 [Turn over (i) The diver falls 5.0 m. Calculate the change in gravitational potential energy of the diver. gravitational potential energy = … J [2] (ii) As the diver falls toward the water, there are no frictional forces acting on the diver. State the kinetic energy of the diver just before entering the water. kinetic energy = … J [1] (iii) Calculate the speed of the diver just before entering the water. speed = … m / s [2] [Total: 8] * 0000800000021 * ,









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22 0654/42/M/J/25 © UCLES 2025 10 (a) (i) State the relationship between the direction of vibration and the direction of propagation of a transverse wave. … [1] (ii) Circle all examples of transverse waves. seismic P wave sound ultraviolet visible light water wave [2] (b) (i) On Fig. 10.1, draw the path of two rays of light from point X which reflect from the plane mirror. Use the rays of light to locate the image of point X formed by the plane mirror. Mark the position of the image with the letter Y. mirror X Fig. 10.1 [3] (ii) Circle all the properties of the image formed by a plane mirror. diminished inverted (upside down) magnified real upright virtual [2] * 0000800000022 * ,









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23 0654/42/M/J/25 © UCLES 2025 [Turn over (c) Blue light waves have a frequency of 6.6 × 1014 Hz. The speed of light is 3.0 × 108 m / s. Calculate the wavelength of the blue light waves. wavelength = … m [2] (d) When white light passes through a prism, it undergoes dispersion. Describe dispersion in terms of wave frequency. You may wish to draw a diagram to illustrate your answer. … … … [2] [Total: 12] * 0000800000023 * ,









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24 0654/42/M/J/25 © UCLES 2025 11 (a) In a nuclear power station, the process of nuclear fission is used to generate electrical power. Describe the process of nuclear fission. … … … [2] (b) Uranium-235 has the nuclide notation 235 92 U. (i) State the number of protons in a nucleus of uranium-235. … [1] (ii) Determine the number of neutrons in a nucleus of uranium-235. … [1] (c) There is a step-up transformer in the nuclear power station. (i) State the change made to the voltage by a step-up transformer. … [1] (ii) Explain why a step-up transformer is used at the nuclear power station before transmission to homes. … … … … [3] (d) A step-down transformer is used near homes. The primary voltage is 30 000 V and the primary coil has 25 000 turns. The secondary coil has 90 turns. Calculate the secondary voltage. secondary voltage = … V [2] [Total: 10] * 0000800000024 * ,









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25 0654/42/M/J/25 © UCLES 2025 12 (a) The explosion of a supernova forms a nebula. State what may form from this nebula. … [1] (b) (i) Describe how energy is released in a star such as the Sun. … … … … [3] (ii) Energy is released in the core of the Sun. Explain how thermal energy travels, by convection, through the outer gas layers of the surface of the Sun. … … … [2] (iii) Energy from the Sun travels to Earth by radiation. Satellites in orbit around the Earth can be in direct sunshine for long periods of time. Suggest the colour and texture chosen for the outer surface of a satellite to limit the temperature of the satellite. … … [2] (c) Complete the sentences to describe the Big Bang Theory. The Universe initially expanded from a place of high … . The Universe is still expanding. The Universe is approximately … years old. [2] [Total: 10] * 0000800000025 * ,









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27 0654/42/M/J/25 © UCLES 2025 BLANK PAGE 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. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge. * 0000800000027 * ,









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28 0654/42/M/J/25 © UCLES 2025 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 204 113 Nh nihonium – 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 209 115 Mc moscovium – 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 – 117 Ts tennessine – 10 Ne neon 20 18 Ar argon 40 36 Kr krypton 84 54 Xe xenon 131 86 Rn radon – 118 Og oganesson – 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 – * 0000800000028 * ,









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This document consists of 17 printed pages. © Cambridge University Press & Assessment 2025 [Turn over Cambridge IGCSE™ CO-ORDINATED SCIENCES 0654/42 Paper 4 Theory (Extended) May/June 2025 MARK SCHEME Maximum Mark: 120 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 International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the May/June 2025 series for most Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level components.

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 2 of 17 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alon gside the specific content of the mark scheme or generic level descriptions for a question. Each question paper and mark scheme will also comply with these marking principles. GENERIC MARKING PRINCIPLE 1: Marks must be awarded in line with: • the specific content of the mark scheme or the generic level descriptors for the question • the specific skills defined in the mark scheme or in the generic level descriptors for the question • the standard of response required by a candidate as exemplified by the standardisation scripts. GENERIC MARKING PRINCIPLE 2: Marks awarded are always whole marks (not half marks, or other fractions). GENERIC MARKING PRINCIPLE 3: Marks must be awarded positively: • marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate • marks are awarded when candidates clearly demonstrate what they know and can do • marks are not deducted for errors • marks are not deducted for omissions • answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the question as indicated by the mark scheme. The meaning, however, should be unambiguous. GENERIC MARKING PRINCIPLE 4: Rules must be applied consistently, e.g. in situations where candidates have not followed instructions or in the application of generic level descriptors.

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 3 of 17 GENERIC MARKING PRINCIPLE 5: Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may be limited according to the quality of the candidate responses seen). GENERIC MARKING PRINCIPLE 6: Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thre sholds or grade descriptors in mind. Science-Specific Marking Principles 1 Examiners should consider the context and scientific use of any keywords when awarding marks. Although keywords may be present, marks should not be awarded if the keywords are used incorrectly. 2 The examiner should not choose between contradictory statements given in the same question part, and credit should not be awarded for any correct statement that is contradicted within the same question part. Wrong science that is irrelevant to the question should be ignored. 3 Although spellings do not have to be correct, spellings of syllabus terms must allow for clear and unambiguous separation fro m other syllabus terms with which they may be confused (e.g. ethane / ethene, glucagon / glycogen, refraction / reflection). 4 The error carried forward (ecf) principle should be applied, where appropriate. If an incorrect answer is subsequently used in a scientifically correct way, the candidate should be awarded these subsequent marking points. Further guidance will be included in the mark scheme where necessary and any exceptions to this general principle will be noted. 5 ‘List rule’ guidance For questions that require n responses (e.g. State two reasons …): • The response should be read as continuous prose, even when numbered answer spaces are provided. • Any response marked ignore in the mark scheme should not count towards n. • Incorrect responses should not be awarded credit but will still count towards n. • Read the entire response to check for any responses that contradict those that would otherwise be credited. Credit should not be awarded for any responses that are contradicted within the rest of the response. Where two responses contradict one another, this should be treated as a single incorrect response. • Non-contradictory responses after the first n responses may be ignored even if they include incorrect science.

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 4 of 17 6 Calculation specific guidance Correct answers to calculations should be given full credit even if there is no working or incorrect working, unless the question states ‘show your working’. For questions in which the number of significant figures required is not stated, credit should be awarded for correct answers when rounded by the examiner to the number of significant figures given in the mark scheme. This may not apply to measured values. For answers given in standard form (e.g. a  10n) in which the convention of restricting the value of the coefficient (a) to a value between 1 and 10 is not followed, credit may still be awarded if the answer can be converted to the answer given in the mark scheme. Unless a separate mark is given for a unit, a missing or incorrect unit will normally mean that the final calculation mark is not awarded. Exceptions to this general principle will be noted in the mark scheme. 7 Guidance for chemical equations Multiples / fractions of coefficients used in chemical equations are acceptable unless stated otherwise in the mark scheme. State symbols given in an equation should be ignored unless asked for in the question or stated otherwise in the mark scheme.

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 5 of 17 Annotations guidance for centres Examiners use a system of annotations as a shorthand for communicating their marking decisions to one another. Examiners are trained during the standardisation process on how and when to use annotations. The purpose of annotations is to inform the standard isation and monitoring processes and guide the supervising examiners when they are checking the work of examiners within their team. The meaning of annotations and how they are used is specific to each component and is understood by all examiners who mark the component. We publish annotations in our mark schemes to help centres understand the annotations they may see on copies of scripts. Note that there may not be a direct correlation between the number of annotations on a script and the mark awarded. Similarly, the use of an annotation may not be an indication of the quality of the response. The annotations listed below were available to examiners marking this component in this series. Annotations Annotation Meaning correct point or mark awarded incorrect point or mark not awarded benefit of the doubt given follow through benefit of doubt was considered, but the response was decided to not be sufficiently close for benefit of doubt to be applied. response is too vague or there is insufficient detail in response error carried forward applied information missing or insufficient for credit unclear response incorrect or insufficient point ignored while marking the rest of the response

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 6 of 17 Annotation Meaning incorrect point or mark not awarded two statements are linked point has been noted, but no credit has been given or blank page seen key point attempted / working towards marking point / incomplete answer / response seen but not credited / blank page seen blank page

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 7 of 17 Question Answer Marks 1(a) D ; A ; 2 1(b) translocation ; 1 1(c) substance method of absorption use in plant water osmosis support / photosynthesis / prevent wilting nitrate ions active transport (making) amino acids ; ; 2 1(d) cell membrane plasmolysed ; smaller vacuole ; 2 1(e) any three from: increases transpiration rate ; wind blows water (vapour) away from leaf (surface) ; increases concentration gradient (from inside the leaf to the air) ; increases (rate of) / faster, evaporation / diffusion ; 3

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 8 of 17 Question Answer Marks 2(a) B ; D ; 2 2(b) any two from: large surface area ; thin (surface / membrane / wall) ; good blood supply ; good ventilation (with air) ; AVP ;; 2 2(c)(i) 3.96 ; 1 2(c)(ii) oxygen used in (aerobic) respiration ; carbon dioxide produced in (aerobic) respiration ; water evaporates from, alveoli / cells ; 3 2(d) any four from: ref to anaerobic respiration (in muscles) ; production / build up, of lactic acid ; ref to oxygen debt ; (extra) oxygen required to, break down / remove, lactic acid ; (lactic acid removed) by aerobic respiration in the liver ; 4

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 9 of 17 Question Answer Marks 3(a)(i) 120.0 – 7.0 ; 113 μm ; 2 3(a)(ii) red blood cell ; 1 3(b) antibodies ; phagocytes ; active ; 3 3(c) any three from: idea that weakened / dead, pathogens / virus OR antigens, given ; antigens stimulate an immune response ; lymphocytes produce antibodies ; correct ref to memory cells / ref to long-term OR active, immunity ; idea of antibodies destroy, (flu) virus or (flu) pathogens in future infections ; 3 3(d) ref to changes in (shape of) antigen (of flu virus) ; idea of new antibodies are required (to match antigen) ; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 10 of 17 Question Answer Marks 4(a) energy store ; jelly coat (which changes when egg is fertilised) ; AVP ; 2 4(b)(i) tertiary consumer ; 1 4(b)(ii) arrow from herring pointing to a label for humans ; 1 4(c) any three from: toxins / poisons / chemicals (kills orcas / stops orcas breeding) ; idea that orca is (physically) harmed by, nets / rubbish / plastic ; (over)fishing of (Orca) prey ; boats / noise, disturbs migration ; hunting ; climate change ; 3

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 11 of 17 Question Answer Marks 5(a) ; 1 5(b) 12 ; 1 5(c) 6.02  1023 ; 1 5(d)(i) 3 5(d)(ii) (diamond is) hard ; (because) each carbon (atom) is bonded to four other carbon (atoms) / tetrahedral arrangement of carbon atoms / there are many strong covalent bonds / it is a giant structure ; 2 weak forces ;

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 12 of 17 Question Answer Marks 5(e) ;; 2 Question Answer Marks 6(a)(i) C6H16N2 ; 1 6(a)(ii) idea that (molecule X) does not contain only carbon and hydrogen (atoms) / contains nitrogen (atoms) ; 1 6(b) ;; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 13 of 17 Question Answer Marks 6(c) Any two rows from: addition polymerisation condensation polymerisation requires, unsaturated monomers / monomers with a C=C bond does not require, unsaturated monomers / monomers with a C=C bond forms polymer (molecule) only / no (additional) small molecule produced forms (polymer molecule and) one small (additional) molecule (requires) one functional group (only) (requires) two functional groups many identical monomers two (different) monomers ;; 2 6(d) test – limewater ; result – turns milky / turns cloudy ; 2 6(e) good electrical conductivity when molten high boiling point low melting point ✓ ; malleable poor electrical conductivity when solid ✓; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 14 of 17 Question Answer Marks 7(a) Na2SO4 ; 1 7(b) anode dissolves / anode gets smaller ; 1 7(c)(i) Cu2+ + 2e– → Cu ;; 2 7(c)(ii) oxidation and loss of electrons ; 1 7(d)(i) magnesium zinc iron copper ;; 2 7(d)(ii) Mg + ZnSO4 → Zn + MgSO4 ;; 2 7(e) different sized atoms in, (the alloy / brass) ; mean the layers can no longer slide over each other ; 2 Question Answer Marks 8(a) 2HCl (aq) + CaCO3 (s) → CaCl2 (aq) + CO2 (g) + H2O (l) ;; 2 8(b)(i) 4.8 (minutes) ; 1 8(b)(ii) curve drawn with less steep gradient ; 1 8(c) more molecules (of acid) per unit volume ; increased frequency of collisions (of molecules) / AW ; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 15 of 17 Question Answer Marks 8(d) moles of CaCl2 = 0.2 ÷ 2 = 0.1 ; relative molecular mass of CaCl2 = 111 ; mass of CaCl2 = 0.1  111 = 11.1 (g) ; 3 Question Answer Marks 9(a)(i) chemical ; 1 9(a)(ii) (chemical →) electrical ; 1 9(a)(iii) (electrical →) light / thermal / EM waves / (EM) radiation ; 1 9(b)(i) evidence of E=mgh or 70  9.8  5.0 ; 3400 (J) ; 2 9(b)(ii) KE = their 9(b)(i) ; 1 9(b)(iii) evidence of KE = 0.5 mv² or 0.5  70  v² ; v = 9.9 m / s ; 2 Question Answer Marks 10(a)(i) perpendicular / at right angles / at 90° ; 1 10(a)(ii) visible light, water, ultraviolet ;; 2 correct = 1 mark, 3 correct = 2 marks 2 10(b)(i) first (correctly) reflected ray ; second reflected ray ; Y labelled in correct position ; 3

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 16 of 17 Question Answer Marks 10(b)(ii) upright ; virtual ; 2 10(c) evidence of λ = v / f or 3.0  108 / 6.6  1014 ; 4.5  10–7 (m) ; 2 10(d) different, colours have different frequencies ; the higher the frequency the greater the refraction / ORA ; 2 Question Answer Marks 11(a) ref to, nucleus / nuclei ; nucleus splits ; 2 11(b)(i) 92 ; 1 11(b)(ii) 143 ; 1 11(c)(i) increases (pd) ; 1 11(c)(ii) (step-up transformer) increases voltage ; reduces current ; less, power / energy, loss (through heat) ; 3 11(d) evidence of Vp / Vs = Np / Ns or 30 000 / Vs = 25 000 / 90 ; 110 (V) ; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 17 of 17 Question Answer Marks 12(a) star / planet / protostars ; 1 12(b)(i) ref to nuclear reaction / nuclear fusion ; fusion of hydrogen nuclei ; formation of helium (nuclei) ; 3 12(b)(ii) hot gas is less dense and rises ; gas cools (becomes more dense) and, sinks / falls ; 2 12(b)(iii) shiny / smooth ; white / silver ; 2 12(c) density / temperature ; 13.8 billion ; 2