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

This document has 32 pages. Any blank pages are indicated. [Turn over Cambridge IGCSE™ * 6 3 6 3 9 0 4 2 8 2 * DC (IP/CT) 352886/4 © UCLES 2025 CO-ORDINATED SCIENCES 0654/42 Paper 4 Theory (Extended) October/November 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/O/N/25 © UCLES 2025 1 Organisms are made up of cells, tissues and organs. (a) The boxes on the left show levels of organisation. The boxes on the right show parts of an organism. Draw one straight line from each level of organisation to the correct part of the organism. level of organisation part of organism organ lymphocyte ribosome lung intercostal muscle tissue cell [3] * 0000800000002 * ,










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3 0654/42/ O/N/25 © UCLES 2025 [Turn over (b) Fig. 1.1 is a photograph of blood seen under a light microscope. white blood cell red blood cell Fig. 1.1 (i) State the function of the white blood cell labelled in Fig. 1.1. … … [1] (ii) State the name of the pigment in red blood cells that binds to oxygen. … [1] (c) Plant leaf cells contain chloroplasts. Red blood cells do not contain chloroplasts. (i) State the name of the pigment in chloroplasts. … [1] (ii) State two other differences between the structure of a red blood cell and the structure of a plant leaf cell. 1 … 2 … [2] * 0000800000003 * ,










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4 0654/42/O/N/25 © UCLES 2025 (d) Eggs and sperm are specialised cells. Describe how the sperm cell is specialised to: swim to the egg … … penetrate the egg … … [2] [Total: 10] * 0000800000004 * ,










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5 0654/42/O/N/25 © UCLES 2025 [Turn over Question 2 starts on page 6. * 0000800000005 * ,










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6 0654/42/O/N/25 © UCLES 2025 2 A student investigates transpiration. Fig. 2.1 is a diagram of the apparatus they use. ruler water air bubble plant shoot 0 10 20 30 40 50 60 70 80 90 100 capillary tube Fig. 2.1 The student measures the distance the air bubble moves along the capillary tube in 20 minutes. The student changes the environmental conditions and repeats the experiment. Table 2.1 shows their results. Table 2.1 environmental condition distance the air bubble moves in 20 minutes / mm high wind speed at 15 °C 25 no wind at 15 °C 10 (a) (i) The air bubble moves along the capillary tube as water is lost by transpiration. Explain the effect that high wind speed conditions have on the rate of transpiration. … … … … … [3] * 0000800000006 * ,










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7 0654/42/O/N/25 © UCLES 2025 [Turn over (ii) The student repeats the experiment. The environmental conditions are no wind and a temperature of 25 °C. Suggest the effect on the distance moved by the air bubble compared to no wind and a temperature of 15 °C. Explain your answer. effect on distance … explanation … … … … … [2] (b) (i) Plants transport water in xylem vessels. State one other substance transported in xylem. … [1] (ii) Translocation is a type of transport in plants. Complete the sentence about translocation. Translocation is the movement of … and … from sources to sinks through … vessels. [2] (c) Blood is transported around the body of humans and fish by the blood vessels. (i) Fish have a single circulatory system. Describe the single circulatory system of a fish. … … … [1] * 0000800000007 * ,










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8 0654/42/O/N/25 © UCLES 2025 (ii) Humans have a double circulatory system. State one advantage of a double circulatory system compared to a single circulatory system. … … … [1] [Total: 10] * 0000800000008 * ,










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9 0654/42/O/N/25 © UCLES 2025 [Turn over 3 (a) Amylase is an enzyme in the digestive system in humans. (i) State two places in the digestive system where amylase is secreted. 1 … 2 … [2] (ii) Complete the sentence about amylase. Amylase breaks down starch to simple … [1] (b) A student mixes amylase and starch solution at different temperatures. The student records the time it takes the amylase to break down the starch. (i) The student finds that the amylase breaks down the starch quicker as the temperature increases from 15 °C to 35 °C. Explain why. … … … … … … [3] (ii) The student finds that the amylase does not break down any of the starch at 55 °C. Explain why. … … … … [2] * 0000800000009 * ,










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10 0654/42/O/N/25 © UCLES 2025 (c) Bile is also found in the digestive system. Outline the role of bile in the digestive system. … … … … [2] [Total: 10] * 0000800000010 * ,










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11 0654/42/O/N/25 © UCLES 2025 [Turn over 4 (a) Table 4.1 shows some information about two endocrine glands. Complete Table 4.1. Table 4.1 endocrine gland hormone released from gland adrenal … pancreas … [2] (b) Fig. 4.1 is a diagram of a cross-section through human skin. Fig. 4.1 (i) On Fig. 4.1 draw a label line and the letter S to identify a sweat gland. [1] (ii) On a hot sunny day the body temperature increases. Describe how the body responds to reduce body temperature. … … … … … [3] * 0000800000011 * ,









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12 0654/42/O/N/25 © UCLES 2025 (c) (i) Fig. 4.2 shows an incomplete reflex arc. Complete the reflex arc shown in Fig. 4.2. receptor sensory neurone … neurone motor neurone … Fig. 4.2 [2] (ii) State the names of the two parts of the central nervous system. … and … [1] (iii) The speed of the nerve impulse in the sensory neurone of the arm is 74.0 m / s. The speed of the nerve impulse in the motor neurone is 1.51 times slower. Calculate the speed of the nerve impulse in the motor neurone. Give your answer to 3 significant figures. speed = … m / s [1] [Total: 10] * 0000800000012 * ,









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13 0654/42/O/N/25 © UCLES 2025 [Turn over 5 Propane and propene are both hydrocarbons. Fig. 5.1 shows the displayed formulas. H H H H C H H C H H C propane H H H H H H C C C propene Fig. 5.1 (a) (i) The molecular formula for propane is C3H8. Butane has four carbon atoms. Write the molecular formula for butane. … [1] (ii) Propene is an unsaturated hydrocarbon. Explain the terms unsaturated and hydrocarbon. unsaturated … … hydrocarbon … … [2] (iii) Complete the displayed formula for but-2-ene. C C C C [2] * 0000800000013 * ,









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14 0654/42/O/N/25 © UCLES 2025 (b) Aqueous bromine is used to tell the difference between propane and propene. Table 5.1 shows the effect of propane and of propene on aqueous bromine. Table 5.1 effect on aqueous bromine propane no effect – remains orange propene … Complete Table 5.1. [1] (c) Cracking is used to make propene. Describe how propene is made by cracking. Include the conditions used. … … … … [3] (d) Poly(propene) is the polymer made by the addition polymerisation of propene. Complete the equation to show the formation of poly(propene). C CH3 H H H C C C n n [2] [Total: 11] * 0000800000014 * ,









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15 0654/42/O/N/25 © UCLES 2025 [Turn over 6 Fig. 6.1 shows part of the Periodic Table. K Na Al Cl S P Ar O I He Fig. 6.1 (a) (i) State the symbol of an element with 8 electrons in its outer shell. Choose your answer from Fig. 6.1. … [1] (ii) State the symbol of an element that forms a positive ion. Choose your answer from Fig. 6.1. … [1] (iii) State the symbol of the element with the electronic configuration 2,8,3. Choose your answer from Fig. 6.1. … [1] (b) Sodium reacts with chlorine to make the ionic compound sodium chloride, NaCl. Draw a dot-and-cross diagram to show the ions in sodium chloride. You only need to show the outer-shell electrons. Include the charges on the ions. [2] * 0000800000015 * ,









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16 0654/42/O/N/25 © UCLES 2025 (c) Fig. 6.2 shows a carbon atom. C Fig. 6.2 (i) Carbon is in Period 2 of the Periodic Table. Use Fig. 6.2 to explain why carbon is in Period 2. … … [1] (ii) Carbon exists as isotopes, carbon-12 and carbon-13. Explain why both isotopes have the same chemical properties. … … [1] * 0000800000016 * ,









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17 0654/42/O/N/25 © UCLES 2025 [Turn over (iii) Graphite is one form of the element carbon. Fig. 6.3 shows the structure of graphite. carbon atom Fig. 6.3 Graphite is used to make electrodes because it conducts electricity. Explain why graphite conducts electricity. … … … [2] (iv) Graphite electrodes are used in the electrolysis of aqueous copper(II) sulfate. State the name of the product made at each electrode. anode … cathode … [2] [Total: 11] * 0000800000017 * ,









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18 0654/42/O/N/25 © UCLES 2025 7 (a) Aqueous iron(III) sulfate contains iron(III) ions, Fe3+, and sulfate ions, SO4 2−. Deduce the formula of iron(III) sulfate. formula … [1] (b) Aqueous sodium hydroxide is used to test for iron(III) ions, Fe3+. The iron(III) ions react with the hydroxide ions, OH−, from the aqueous sodium hydroxide. A precipitate of iron(III) hydroxide, Fe(OH)3 is made. (i) State the colour of the precipitate. … [1] (ii) Construct the balanced ionic equation for the reaction. Include state symbols. … [3] (c) Iron is obtained from iron(III) oxide in a blast furnace. The equation for the reaction is shown. Fe2O3 + 3CO 2Fe + 3CO2 (i) State if iron(III) oxide is oxidised or reduced in this reaction. Explain your answer. iron(III) oxide is … explanation … … [1] * 0000800000018 * ,









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19 0654/42/O/N/25 © UCLES 2025 [Turn over (ii) The iron(III) oxide reacts with the carbon monoxide in a blast furnace to make iron. Calculate the minimum mass of iron(III) oxide required to make 28 000 g of iron. [Ar: C, 12; O, 16; Fe, 56] minimum mass of iron(III) oxide = … g [3] [Total: 9] * 0000800000019 * ,









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20 0654/42/O/N/25 © UCLES 2025 8 A student investigates the reaction between calcium carbonate and dilute hydrochloric acid. Carbon dioxide is made in the reaction. (a) Describe the test for carbon dioxide gas and include the observation for a positive result. test … observation … [2] (b) The student measures, every minute, the total volume of carbon dioxide made. Fig. 8.1 shows the student’s results. 00 1 2 3 4 5 6 7 8 9 10 10 20 30 40 50 60 total volume of carbon dioxide gas / cm3 time / min Fig. 8.1 (i) State the time when the reaction stops. time = … minutes [1] (ii) Calculate the average rate of the reaction during the first two minutes of the experiment. rate = … cm3 / minute [2] * 0000800000020 * ,










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21 0654/42/O/N/25 © UCLES 2025 [Turn over (iii) 50 cm3 of carbon dioxide gas is made in the experiment. Calculate the amount of carbon dioxide gas made in moles, at room temperature and pressure. The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). moles of carbon dioxide gas = … [2] (c) The reaction between calcium carbonate and dilute hydrochloric acid is faster if the concentration of the acid used is greater. Explain why, using collision theory. … … … … [2] [Total: 9] * 0000800000021 * ,









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22 0654/42/O/N/25 © UCLES 2025 9 (a) (i) Describe how electrical power is generated from geothermal resources. … … … … [3] (ii) Geothermal resources do not rely on radiation from the Sun. State two other energy resources for generating electrical power which do not rely on radiation from the Sun. 1 … 2 … [2] (b) The radiation incident on a 1.0 m2 panel of solar cells is 1400 W. The efficiency of the solar cells is 32%. (i) Calculate the useful power output of the panel of solar cells. power = … W [2] (ii) Calculate the area of the panel of solar cells required to supply a 2.5 kW oven. area = … m2 [2] (iii) A panel of solar cells has a mass of 8.4 kg. The panel is lifted 6.0 m from the ground to the roof of a house. Calculate the gain in gravitational potential energy of the panel. gain in energy = … J [2] [Total: 11] * 0000800000022 * ,









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23 0654/42/O/N/25 © UCLES 2025 [Turn over 10 (a) Microwaves are transverse electromagnetic waves. (i) State a use of microwaves. … [1] (ii) Describe a transverse wave. … … [2] (b) Fig. 10.1 shows a ray of visible light travelling in air incident on the boundary between air and glass at an angle of 48°. The refractive index of the glass is 1.25. 48° glass air Fig. 10.1 (i) Calculate the angle of refraction of the light ray. angle = … ° [3] (ii) Draw the refracted ray on Fig. 10.1. [2] * 0000800000023 * ,









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24 0654/42/O/N/25 © UCLES 2025 (c) Fig. 10.2 shows a ray of visible light travelling in glass. The light is incident on the boundary between glass and air at an angle greater than the critical angle. glass air Fig. 10.2 Continue the path of the light ray. [2] [Total: 10] * 0000800000024 * ,









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25 0654/42/O/N/25 © UCLES 2025 [Turn over Question 11 starts on page 26. * 0000800000025 * ,









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26 0654/42/O/N/25 © UCLES 2025 11 Fig. 11.1 shows a cell connected to two resistors in parallel. The potential difference (p.d.) across the terminals of the cell is 3.0 V. R 20 Ω Fig. 11.1 (a) (i) The current in the cell is 0.25 A. Calculate the charge which flows through the cell in 5.0 minutes. charge = … C [2] (ii) State the p.d. across the 20 Ω resistor. p.d. = … V [1] (iii) The current in the 20 Ω resistor is 0.15 A. Calculate the current in resistor R. current = … A [1] (iv) Calculate the total resistance of the circuit. resistance = … Ω [2] * 0000800000026 * ,









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27 0654/42/O/N/25 © UCLES 2025 [Turn over (b) The branch of the circuit containing resistor R is removed from the circuit. (i) State and explain the change, if any, to the current in the cell. … … … [2] (ii) State and explain the change, if any, to the current in the 20 Ω resistor. … … … [2] [Total: 10] * 0000800000027 * ,









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28 0654/42/O/N/25 © UCLES 2025 12 (a) An atom of gold is represented as 19 7 7 9Au. (i) Determine the number of protons in the nucleus of this atom. … [1] (ii) Determine the number of neutrons in the nucleus of this atom. … [1] (iii) A different atom of gold is represented as 19 7 8 9Au. Circle the word which describes these two gold atoms. ions isotopes electrons charged [1] (b) 19 7 8 9Au is radioactive. It undergoes beta decay with a half-life of 2.7 days. (i) Complete the equation for this nuclear decay. 19 7 8 9Au … … Hg + … … β [2] (ii) Define the term half-life. … … [2] (iii) Initially a sample of 19 7 8 9Au has a mass of 280 g. Calculate the mass remaining after 8.1 days. mass = … g [2] [Total: 9] * 0000800000028 * ,









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29 0654/42/O/N/25 © UCLES 2025 BLANK PAGE * 0000800000029 * ,









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31 0654/42/O/N/25 © UCLES 2025 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. BLANK PAGE * 0000800000031 * ,









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32 0654/42/O/N/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 – * 0000800000032 * ,









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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) October/November 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 October/November 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 October/November 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 October/November 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 October/November 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 October/November 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 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 incorrect point or mark not awarded

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 6 of 17 Annotation Meaning 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 October/November 2025 © Cambridge University Press & Assessment 2025 Page 7 of 17 Question Answer Marks 1(a) 1 mark for each correct link 3 1(b)(i) engulfing pathogens / phagocytosis ; 1 1(b)(ii) haemoglobin ; 1 1(c)(i) chlorophyll ; 1 1(c)(ii) any two from: • (red blood cell has) no cell wall / ORA ; • (red blood cell has) no vacuole / ORA ; • (red blood cell has) no nucleus / ORA ; 2 1(d) flagellum (to swim to egg) ; enzyme(s) in acrosome (to penetrate egg) ; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 8 of 17 Question Answer Marks 2(a)(i) (rate increases as) (wind) removes water vapour from around the leaf ; (wind) maintains steep concentration gradient ; increased diffusion (of water) from stomata ; 3 2(a)(ii) (effect on distance) increases (for 25 °C) AND any two from (explanation): • increase in rate of transpiration ; • increased rate of water evaporating ; • increased rate of diffusion of water vapour ; 2 2(b)(i) mineral ions ; 1 2(b)(ii) sucrose and amino acids ; phloem ; 2 2(c)(i) (idea that) blood only goes through the heart once (each circuit) OR heart → gills → body ; 1 2(c)(ii) any one from: allows faster metabolism ; high blood pressure around body / low blood pressure to lungs / allows different pressure to lungs / allows different pressure to body ; oxygenated blood and deoxygenated blood kept separate ; 1

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 9 of 17 Question Answer Marks 3(a)(i) any two from: • salivary glands ; • pancreas ; • small intestine ; 2 3(a)(ii) (reducing) sugar(s) ; 1 3(b)(i) (enzyme / substrate) have more kinetic energy ; increased frequency of (effective) collisions ; (the collisions are effective because) more enzyme-substrate complexes formed / increased rate of substrate entering active site (of the enzyme) ; 3 3(b)(ii) any two from: • enzyme denatured ; • active site changes shape ; • no enzyme-substrate complexes formed / enzymes no longer complementary to substrate ; 2 3(c) any two from: • neutralises the acidic mixture (of food and gastric juices entering the duodenum from the stomach) ; • provides suitable pH for enzymes ; • emulsifies fats / emulsifies lipids ; • increases surface area for (chemical) digestion ; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 10 of 17 Question Answer Marks 4(a) endocrine gland hormone released from gland adrenal adrenaline ; pancreas insulin / glucagon ; 2 4(b)(i) label line to sweat gland (with letter S) ; 1 4(b)(ii) increased sweat / increased sweating ; vasodilation / description of vasodilation / arterioles widen ; hairs lie flat ; 3 4(c)(i) relay ; effector ; 2 4(c)(ii) brain and spinal cord ; 1 4(c)(iii) 49.0 ; 1

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 11 of 17 Question Answer Marks 5(a)(i) C4H10 ; 1 5(a)(ii) unsaturated (propene contains) a double carbon-carbon (covalent) bond / one of the carbon-carbon bonds is not a single bond ; hydrocarbon (propene contains) only hydrogen and carbon (atoms) ; 2 5(a)(iii) 1 mark for double bond between carbon 2 and carbon 3 1 mark for rest of structure correct 2 5(b) turns colourless / decolourised ; 1 5(c) any three from: • idea that (large) alkane molecules are broken down (into smaller molecules) ; • (idea that molecules are broken down) into alkene molecules ; conditions • high temperature ; • catalyst ; 3

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 12 of 17 Question Answer Marks 5(d) 1 mark for single bond between carbon atoms 1 mark for rest of structure correct 2 Question Answer Marks 6(a)(i) Ar ; 1 6(a)(ii) Na or K or Al ; 1 6(a)(iii) Al ; 1 6(b) 1 mark for correct sodium ion with charge shown 1 mark for correct chloride ion with charge shown 2 6(c)(i) (carbon has) 2 (occupied) electron shells ; 1 6(c)(ii) same electronic configuration ; 1 6(c)(iii) (graphite has) electrons ; that can move ; 2 + –

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 13 of 17 Question Answer Marks 6(c)(iv) anode: oxygen ; cathode: copper ; 2 Question Answer Marks 7(a) Fe2(SO4)3 ; 1 7(b)(i) red-brown ; 1 7(b)(ii) Fe3+ (aq) + 3OH– (aq) → Fe(OH)3 (s) 1 mark for formulae 1 mark for balancing 1 mark for state symbols 3 7(c)(i) (reduced because) iron (III) oxide loses oxygen / Fe2O3 loses oxygen ; 1 7(c)(ii) (Mr of Fe2O3 =) 160 ; (mass of Fe2O3 =) 160 28000; 112  40 000 (g) ; OR (moles of Fe = 28 000 ÷ 56 =) 500 ; (moles of Fe2O3 =) 500 ÷ 2 or 250 or ratio of moles of Fe: Fe2O3 is 2:1 ; (mass of Fe2O3 = 250  160 =) 40 000 (g) ; 3

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 14 of 17 Question Answer Marks 8(a) (test) limewater ; (observation) white precipitate / (turns) milky ; 2 8(b)(i) any value in the inclusive range 5.6–6 (minutes) ; 1 8(b)(ii) 30 ÷ 2 ; = 15 (cm3 / minute) ; 2 8(b)(iii) mol = volume ÷ 24 or mol = 0.050 ÷ 24 ; 0.0021 ; 2 8(c) more particles per unit volume ; frequency of collision (of particles) is higher ; 2 Question Answer Marks 9(a)(i) hot water / steam (from underground) ; turns turbine ; (turbine) turns generator ; 3 9(a)(ii) nuclear ; tidal ; 2 9(b)(i) efficiency = useful output power ÷ total input power OR 0.32 = useful power output ÷ 1400 ; 450 (W) ; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 15 of 17 Question Answer Marks 9(b)(ii) 2500 ÷ 450 ; 5.6 (m²) ; 2 9(b)(iii) (Ep =) mgh OR 8.4  9.8  6.0 ; 490 (J) ; 2 Question Answer Marks 10(a)(i) any one from: • satellite TV ; • mobile phones ; • (microwave) ovens ; 1 10(a)(ii) vibrations / oscillations are perpendicular ; (vibrations / oscillations are perpendicular), to the direction of propagation / to the direction of travel / to the direction of energy transfer ; 2 10(b)(i) evidence of n = sin i ÷ sin r OR 1.25 = sin 48 ÷ sin r ; r = sin–1 (sin 48 ÷ 1.25) ; r = 36 (°) ; 3

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 16 of 17 Question Answer Marks 10(b)(ii) ray continued as a straight line drawn in top right ; ray drawn refracted towards the normal ; 2 10(c) ray continued as a straight line drawn in bottom right ; with angle of incidence equal to angle of reflection ; 2 Question Answer Marks 11(a)(i) evidence of Q = It OR 0.25  5.0  60 ; 75 (C) ; 2 11(a)(ii) 3 (.0 V) ; 1 11(a)(iii) (0.25 – 0.15 =) 0.1(0 A) ; 1 11(a)(iv) evidence of R = V ÷ I OR 3 ÷ 0.25 ; 12 () ; 2 11(b)(i) (current) decreases ; total resistance of circuit increased ; 2 11(b)(ii) (current) unchanged ; same p.d. across resistor ; 2

0654/42 Cambridge IGCSE – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 17 of 17 Question Answer Marks 12(a)(i) 79 ; 1 12(a)(ii) 118 ; 1 12(a)(iii) isotopes ; 1 12(b)(i) 198 198 0 79 80 –1 + Au Hg →  1 mark for beta completely correct 1 mark for Hg completely correct 2 12(b)(ii) (average) time taken ; for half the nuclei of the isotope in a sample to decay ; 2 12(b)(iii) (8.1 ÷ 2.7 =) 3 half-lives ; (280 ÷ 2³ =) 35 (g) ; 2