Cambridge IGCSE Sciences - Co-ordinated (9-1) 0973 — 2023 May/June Paper 3 · Variant 1

This document has 32 pages. Any blank pages are indicated. [Turn over Cambridge IGCSE™(9–1) DC (LO) 327660 © UCLES 2023 CO-ORDINATED SCIENCES 0973/31 Paper 3 Theory (Core) May/June 2023 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. 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. * 3 2 4 3 3 9 0 2 6 1 *

2 0973/31/M/J/23 © UCLES 2023 1 (a) Fig. 1.1 is a diagram of the alimentary canal and associated organs. A B C D E H J G F Fig. 1.1 (i) State the letter in Fig. 1.1 that identifies where: most absorption occurs … egestion occurs … ingestion occurs … saliva is produced. … [4] (ii) State the names of the parts labelled D and H in Fig. 1.1. D … H … [2] (iii) Complete the sentence to define the term digestion. Digestion is the … of large, insoluble food molecules into small, water-soluble molecules using mechanical and … processes. [2]

3 0973/31/M/J/23 © UCLES 2023 [Turn over (b) The boxes on the left show some nutrients. The boxes on the right show some principal sources of nutrients. Draw one straight line from each nutrient to its principal source. nutrient principal source tuna fish carbohydrate grapefruit vitamin C rice [2] (c) Describe the dietary importance of iron. … … [1] [Total: 11]

4 0973/31/M/J/23 © UCLES 2023 2 (a) (i) An iron nail rusts when it is exposed to damp air. Rusting involves the oxidation of iron. State what is meant by the term oxidation. … … [1] (ii) Describe one method used to prevent the iron nail from rusting. Explain how this method prevents the iron nail from rusting. method … … explanation … … [2] (b) Complete the sentence. Metal ores are a finite resource and therefore, metals need to be … . [1] (c) Iron is a transition element. Put a tick (3) in the boxes next to all the correct statements about iron. iron acts as a catalyst iron forms coloured compounds iron has a low density iron has a low melting point iron is brown in colour [2]

5 0973/31/M/J/23 © UCLES 2023 [Turn over (d) Steel is an alloy of iron. (i) Suggest why steel is used for making cars instead of pure iron. … … [1] (ii) Table 2.1 shows the percentage composition of stainless steel. Table 2.1 element percentage by mass in the alloy / % carbon 1 chromium 18 iron manganese 2 molybdenum 2 nickel 12 Calculate the mass of iron contained in 80 kg of stainless steel. mass of iron = … kg [2] (e) Iron is malleable. State the meaning of malleable. … … [1] [Total: 10]

6 0973/31/M/J/23 © UCLES 2023 3 (a) (i) Fig. 3.1 shows a skier standing on the snow. ski Fig. 3.1 When she stands on the snow without her skis, she sinks into the snow. When she wears her skis, she can stand on the snow without sinking. Explain these observations. … … … [2] (ii) The skier makes a sound near a high wall. The sound travels through the air as a wave. The skier hears an echo. State what happens to the sound wave at the high wall to cause an echo to be heard. … [1]

7 0973/31/M/J/23 © UCLES 2023 [Turn over (b) Fig. 3.2 shows the forces acting on the skier on level snow when she is travelling in a snowmobile. L J direction of travel K M Fig. 3.2 (i) State which force, J, K, L or M, is the weight of the snowmobile and skier. … [1] (ii) State which force, J, K, L or M, is the friction force acting on the snowmobile. … [1]

8 0973/31/M/J/23 © UCLES 2023 (c) Fig. 3.3 shows the speed–time graph for the motion of the skier. 0 1 2 10 0 20 30 40 50 time / s speed m / s 60 70 80 90 100 3 4 5 Fig. 3.3 (i) State the maximum speed of the skier. speed = … m / s [1] (ii) The skier is accelerating during the first 20 s of her journey. Describe how the graph shows that the skier is accelerating. … … [1] (iii) Show that the distance travelled by the skier during the first 20 s is 50 m. [1] (d) The skier is exposed to ultraviolet radiation from the Sun. Ultraviolet radiation is a form of ionising radiation. Describe one danger to humans of being exposed to large quantities of ultraviolet radiation. … … [1] [Total: 9]

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10 0973/31/M/J/23 © UCLES 2023 4 (a) Fig. 4.1 shows some different sources of pollution of the water in seas. agriculture 27% discarded rubbish 5% untreated sewage 27% chemical waste from air pollution 18% chemical waste from industry 14% chemical waste from transport 9% Fig. 4.1 (i) Complete the sentences using information from Fig. 4.1. The two biggest sources of pollution are … and … . The total percentage of pollution caused by chemical waste is … %. The percentage of pollution caused by discarded rubbish is … %. [3] (ii) Suggest one negative impact of untreated sewage on humans. … … [1]

11 0973/31/M/J/23 © UCLES 2023 [Turn over (b) Polluted water affects the growth of plants. A scientist measures the height of two pea plants, A and B, for one month. Plant A is given unpolluted water. Plant B is given polluted water. Table 4.1 shows the increase in height for each plant. Table 4.1 plant type of water increase in height / cm A unpolluted 29 B polluted 11 (i) Calculate the difference in increase in height between plant A and plant B from Table 4.1. … cm [1] (ii) Water is needed for germination of seeds. State two other environmental conditions required for germination. 1 … 2 … [2] [Total: 7]

12 0973/31/M/J/23 © UCLES 2023 5 (a) Substances are separated from mixtures of substances using different methods. Draw one straight line from each substance to the correct method of separating it from the mixture. One line has been drawn for you. substance separated from the mixture method of separation blue dye from black ink chromatography gas oil from petroleum crystallisation salt from salt water distillation sand from sand and water filtration water from salt water fractional distillation [3] (b) One reason for separating mixtures is to purify substances. Explain the importance of purity in the manufacture of substances used in food additives. … … [1] (c) The element lead is obtained from the compound lead(II) bromide by electrolysis. (i) Describe the difference between an element and a compound. … … … [1] (ii) Complete the sentences to describe the electrolysis of lead(II) bromide. Electrolysis is the breakdown of molten lead(II) bromide by the passage of … . The gas released at the positive electrode is … and … is formed at the negative electrode. The negative electrode is called the … . [3]

13 0973/31/M/J/23 © UCLES 2023 [Turn over (d) A student reacts dilute hydrochloric acid with four metals. The student’s observations are shown in Table 5.1. Table 5.1 metal observation calcium reacts very quickly copper does not react lead reacts very slowly magnesium reacts quickly Place the four metals in order of their reactivity from the most reactive to the least reactive. … most reactive … … … least reactive [2] [Total: 10]

14 0973/31/M/J/23 © UCLES 2023 6 (a) (i) Complete the sentences to describe the energy changes that occur during the generation of electricity in a nuclear power station. Nuclear fission releases … energy which heats up water in a boiler. When the turbine and generator are turning, they have … energy. The generator produces … energy. [3] (ii) Nuclear fission occurs in the nuclear power station. State what happens to the nucleus of an atom during nuclear fission. … [1] (b) The radioactive decay of plutonium-239 produces an isotope of uranium, uranium-235. plutonium-239 uranium-235 + α-particle (i) State the charge on an α-particle. … [1] (ii) Describe how the numbers of protons and neutrons change in the nucleus of a plutonium-239 atom when it emits an α-particle. protons … neutrons … [2] (iii) The half-life of plutonium-239 is 24 000 years. A sample of nuclear fuel contains 6.0 g of plutonium-239. Calculate the mass of plutonium-239 remaining after 72 000 years. mass = … g [3] [Total: 10]

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16 0973/31/M/J/23 © UCLES 2023 7 (a) Fig. 7.1 is a drawing of a cross-section of a leaf. A B C Fig. 7.1 State the names of the parts labelled A, B and C in Fig. 7.1. A … B … C … [3] (b) Fig. 7.2 is a cell from the palisade mesophyll layer of the leaf. Fig. 7.2 On Fig. 7.2: • Identify the part where photosynthesis takes place with a label line and the correct name. • Identify the part that contains the genetic material with a label line and the letter X. [3]

17 0973/31/M/J/23 © UCLES 2023 [Turn over (c) Describe the process of photosynthesis. … … … … … [3] (d) Plants need nitrate ions to make an important substance. Circle the name of this substance. amino acid fatty acid starch glycogen glycerol [1] (e) State the name of the cell that absorbs mineral ions in a plant. … [1] (f) State the name of the vessels that transport mineral ions in the stem. … [1] [Total: 12]

18 0973/31/M/J/23 © UCLES 2023 8 (a) (i) Complete the dot-and-cross diagram in Fig. 8.1 to show the bonding in a molecule of methane, CH4. Show only the outer-shell electrons. C H H H H Fig. 8.1 [2] (ii) State the name of the type of chemical bonding present in a molecule of methane. Explain your answer. type of chemical bonding … explanation … … [2] (b) Complete the word equation for the complete combustion of methane. methane + … … + … [2] (c) (i) State the name of the pollutant gas produced during the incomplete combustion of methane. … [1] (ii) State one adverse effect of the gas you have named in (c)(i) on the health of humans. … [1] [Total: 8]

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20 0973/31/M/J/23 © UCLES 2023 9 Fig. 9.1 shows a washing machine. Fig. 9.1 (a) (i) The washing machine uses: • a heater to heat the water • a motor to pump the hot water through the machine. The motor and the heater are connected in a parallel circuit. The motor and the heater are each operated by separate switches. M The circuit symbol for a heater is The circuit symbol for a motor is Fig. 9.2 shows an incomplete circuit diagram for the washing machine. Complete the circuit diagram on Fig. 9.2. 240V Fig. 9.2 [3]

21 0973/31/M/J/23 © UCLES 2023 [Turn over (ii) The resistance of the heater is 20 Ω. The resistance of the motor is 80 Ω. Identify from the list the most likely value for the combined resistance of the heater and motor connected in parallel. Explain your answer. 16 Ω 20 Ω 50 Ω 80 Ω 100 Ω combined resistance = … Ω explanation … … [2] (iii) The current in the wires of the electrical circuit is a flow of charged particles. State the name of the particles that flow in the wires of the electrical circuit. … [1] (iv) The current-carrying coil in the motor experiences a turning effect. This turning effect can be increased by increasing the number of turns on the coil. State two other ways to increase this turning effect. 1 … 2 … [2]

22 0973/31/M/J/23 © UCLES 2023 (b) Inside the washing machine, some of the water evaporates. During evaporation, water changes state from a liquid to a gas. (i) Complete the diagrams in Fig. 9.3 to show the arrangement and separation of molecules in a liquid and in a gas. liquid gas Fig. 9.3 [2] (ii) During evaporation, the water does not boil. State the boiling point of water. … °C [1] [Total: 11]

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24 0973/31/M/J/23 © UCLES 2023 10 (a) A person touches a hot pan and instantly removes their hand. This is a reflex action. The reflex arc is shown in Fig. 10.1. X spinal cord receptor in skin direction of nerve impulse Key effector Fig. 10.1 (i) State the names of the stimulus and the effector in this reflex arc. stimulus … effector … [2] (ii) State the name of the neurone labelled X in Fig. 10.1. … [1] (iii) The spinal cord is one part of the central nervous system. State the name of the other part of the central nervous system. … [1] (b) Neurones are the longest cells in the body. One neurone measures 1.5 m in length. One plant cell measures 0.1 mm in length. Calculate how many times longer the neurone is than the plant cell. … [2]

25 0973/31/M/J/23 © UCLES 2023 [Turn over (c) Hormones and nerve impulses both carry information around the body. Identify if each statement is about hormones or nerve impulses. They are carried in the blood. … They are produced by glands. … They are electrical signals. … [2] (d) Adrenaline is a hormone released in ‘fight or flight’ situations. Describe two effects of adrenaline on the body. 1 … 2 … [2] [Total: 10]

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27 0973/31/M/J/23 © UCLES 2023 [Turn over 11 (a) Limestone is insoluble in water. Limestone is mixed with water and poured through filter paper. (i) Explain how filter paper separates limestone from water. … … … [2] (ii) The filtrate is tested to find its pH number. One way of finding the pH number is to use a pH meter. Describe one other way to find the pH number of the filtrate. … … … [2] (b) Limestone is sometimes added to soil to reduce soil acidity. Limestone is mainly calcium carbonate which reacts with acid. (i) This soil treatment adds carbon dioxide to the atmosphere. State one other reason why the amount of carbon dioxide in the atmosphere is increasing. … [1] (ii) Describe how an increase in carbon dioxide in the atmosphere affects the environment. … … [1]

28 0973/31/M/J/23 © UCLES 2023 (c) A student investigates the rate of reaction between excess dilute hydrochloric acid and a piece of limestone. Fig. 11.1 shows the apparatus used. water measuring cylinder carbon dioxide gas flask limestone dilute hydrochloric acid Fig. 11.1 The student measures the volume of carbon dioxide in the measuring cylinder every 20 seconds for 280 seconds. A graph of the student’s results is shown in Fig. 11.2. 50 40 30 20 10 0 0 40 volume of carbon dioxide / cm3 120 time / s 200 280 80 160 240 20 100 180 260 60 140 220 Fig. 11.2 (i) Use Fig. 11.2 to find the total volume of carbon dioxide released. volume = … cm3 [1] (ii) Use Fig. 11.2 to find the time when the reaction finished. time = … s [1] (iii) The student repeats the experiment at a higher temperature. On Fig. 11.2, sketch a line to show the results. [2]

29 0973/31/M/J/23 © UCLES 2023 (iv) Increasing the temperature increases the rate of reaction. State two other ways the student can increase the rate of the reaction. 1 … 2 … [2] [Total: 12] [Turn over

30 0973/31/M/J/23 © UCLES 2023 12 (a) The mass of the Sun is 1.97 × 1030 kg. The average density of the Sun is 1410 kg / m3. Calculate the volume of the Sun. volume = … m3 [2] (b) The Sun is made of very hot gas. (i) Suggest the main method of thermal energy transfer from the inside of the Sun to the surface of the Sun. … [1] (ii) State the main method of energy transfer that occurs when infrared waves travel from the Sun to the Earth through space. … [1] (iii) Sound energy is produced by the Sun. Explain why we are unable to hear this sound on Earth. … … [1] (c) (i) Fig. 12.1 shows an incomplete electromagnetic spectrum. Write infrared radiation in its correct place. X-rays visible light increasing frequency Fig. 12.1 [1] (ii) State the electromagnetic radiation which has the highest frequency. … [1] (iii) Explain why it takes the same time for infrared and visible light to travel from the Sun to the Earth. … [1]

31 0973/31/M/J/23 © UCLES 2023 (d) Fig. 12.2 shows a sound wave. Fig. 12.2 (i) On Fig. 12.2, label the amplitude of the wave with a double-headed arrow (↔) or (↕) and the letter A. [1] (ii) On Fig. 12.2, label the wavelength of one wave with a double-headed arrow (↔) or (↕) and the letter W. [1] [Total: 10] 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.

32 0973/31/M/J/23 © UCLES 2023 Group The Periodic Table of Elements 1 H hydrogen 1 2 He helium 4 I II III IV V VI VII VIII 3 Li lithium 7 4 Be beryllium 9 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23 12 Mg magnesium 24 19 K potassium 39 20 Ca calcium 40 37 Rb rubidium 85 38 Sr strontium 88 55 Cs caesium 133 56 Ba barium 137 87 Fr francium – 88 Ra radium – 5 B boron 11 13 Al aluminium 27 31 Ga gallium 70 49 In indium 115 81 Tl thallium 204 6 C carbon 12 14 Si silicon 28 32 Ge germanium 73 50 Sn tin 119 82 Pb lead 207 22 Ti titanium 48 40 Zr zirconium 91 72 Hf hafnium 178 104 Rf rutherfordium – 23 V vanadium 51 41 Nb niobium 93 73 Ta tantalum 181 105 Db dubnium – 24 Cr chromium 52 42 Mo molybdenum 96 74 W tungsten 184 106 Sg seaborgium – 25 Mn manganese 55 43 Tc technetium – 75 Re rhenium 186 107 Bh bohrium – 26 Fe iron 56 44 Ru ruthenium 101 76 Os osmium 190 108 Hs hassium – 27 Co cobalt 59 45 Rh rhodium 103 77 Ir iridium 192 109 Mt meitnerium – 28 Ni nickel 59 46 Pd palladium 106 78 Pt platinum 195 110 Ds darmstadtium – 29 Cu copper 64 47 Ag silver 108 79 Au gold 197 111 Rg roentgenium – 30 Zn zinc 65 48 Cd cadmium 112 80 Hg mercury 201 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14 15 P phosphorus 31 33 As arsenic 75 51 Sb antimony 122 83 Bi bismuth 209 8 O oxygen 16 16 S sulfur 32 34 Se selenium 79 52 Te tellurium 128 84 Po polonium – 9 F fluorine 19 17 Cl chlorine 35.5 35 Br bromine 80 53 I iodine 127 85 At astatine – 10 Ne neon 20 18 Ar argon 40 36 Kr krypton 84 54 Xe xenon 131 86 Rn radon – 21 Sc scandium 45 39 Y yttrium 89 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 139 89 Ac lanthanoids actinoids The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). actinium – 58 Ce cerium 140 90 Th thorium 232 59 Pr praseodymium 141 91 Pa protactinium 231 60 Nd neodymium 144 92 U uranium 238 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150 94 Pu plutonium – 63 Eu europium 152 95 Am americium – 64 Gd gadolinium 157 96 Cm curium – 65 Tb terbium 159 97 Bk berkelium – 66 Dy dysprosium 163 98 Cf californium – 67 Ho holmium 165 99 Es einsteinium – 68 Er erbium 167 100 Fm fermium – 69 Tm thulium 169 101 Md mendelevium – 70 Yb ytterbium 173 102 No nobelium – 71 Lu lutetium 175 103 Lr lawrencium –

This document consists of 14 printed pages. © UCLES 2023 [Turn over Cambridge IGCSE™ (9–1) CO-ORDINATED SCIENCES (9–1) 0973/31 Paper 3 Theory (Core) May/June 2023 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 2023 series for most Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 2 of 14 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the specific content of the mark scheme or generic level descriptors 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.

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 3 of 14 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 thresholds or grade descriptors in mind.

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 4 of 14 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 from 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.

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 5 of 14 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.

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 6 of 14 Acronyms and shorthand in the mark scheme Acronym / shorthand Explanation Brackets ( ) Words not explicitly needed in an answer, however if a contradictory word / phrase / unit to that in the brackets is seen the mark is not awarded. Underlining The underlined word (or a synonym) must be present for the mark to be scored. If the word is a technical scientific term, the word must be there. / or OR Alternative answers any one of which gains the credit for that mark. owtte Or words to that effect. ORA Or reverse argument. AW Alternative wording AVP Alternative valid point

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 7 of 14 Question Answer Marks 1(a)(i) F ; E ; J ; A ; 4 1(a)(ii) D – pancreas ; H – liver ; 2 1(a)(iii) breakdown ; chemical ; 2 1(b) tuna fish carbohydrate grapefruit vitamin C rice ;; 2 1(c) making haemoglobin / prevent anaemia / AVP ; 1 Question Answer Marks 2(a)(i) gain of oxygen ; 1 2(a)(ii) paint it ; stops contact with air and water ; etc. 2

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 8 of 14 Question Answer Marks 2(b) recycled ; OWTTE 1 2(c) iron acts as a catalyst ; iron forms coloured compounds ; 2 2(d)(i) stronger ; 1 2(d)(ii) iron % 65 ; 80  65 / 100 = 52 (kg) ; 2 2(e) can be shaped or bent ; 1 Question Answer Marks 3(a)(i) skis increase surface area ; pressure is less with skis ; ORA 2 3(a)(ii) sound wave is reflected ; 1 3(b)(i) L ; 1 3(b)(ii) K ; 1 3(c)(i) 5 (m / s) ; 1 3(c)(ii) line has a slope / gradient ; 1 3(c)(iii) area under graph or ½  5  20 ; 1 3(d) skin cancer ; 1

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 9 of 14 Question Answer Marks 4(a)(i) agriculture and (untreated) sewage ; 41 (%) ; 5 (%) ; 3 4(a)(ii) any one from: spread diseases ; AVP ; 1 4(b)(i) (29 – 11) = 18 (cm) ; 1 4(b)(ii) warm / suitable temperature ; oxygen ; 2 Question Answer Marks 5(a) substance in mixture method of separation blue dye from black ink chromatography gas oil from petroleum crystallisation salt from salt water distillation sand from sand and water filtration water from salt water fractional distillation ;;; 3 5(b) to avoid poisoning ; 1 5(c)(i) element contains only one type of atom / compound consists of (atoms of) two or more elements (chemically combined) ; 1

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 10 of 14 Question Answer Marks 5(c)(ii) electricity ; bromine and lead ; cathode ; 3 5(d) calcium magnesium lead copper ;; 2 Question Answer Marks 6(a)(i) thermal ; kinetic ; electrical ; 3 6(a)(ii) splits ; 1 6(b)(i) (2) positive ; 1 6(b)(ii) protons decrease by 2 or down to 92 ; neutrons decrease by 2 or down to 143 ; 2 6(b)(iii) 3 half lives ; 6.0 divided by 2 three times ; 0.75 (g) ; 3

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 11 of 14 Question Answer Marks 7(a) A – cuticle ; B – (lower) epidermis ; C – stoma / stomata ; 3 7(b) one chloroplast with label line ; with correct name ; nucleus labelled with an X ; 3 7(c) (process used in plants / producers) to manufacture glucose ; from raw materials / carbon dioxide and water ; using light energy ; 3 7(d) amino acids circled ; 1 7(e) root hair (cell) ; 1 7(f) xylem ; 1 Question Answer Marks 8(a)(i) 1 shared pair of electrons ; all else correct ; 2 8(a)(ii) covalent ; bonding between 2 non-metals / shared electron pairs ; 2 8(b) oxygen ; carbon dioxide and water ; 2 8(c)(i) carbon monoxide ; 1 8(c)(ii) poisonous ; 1

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 12 of 14 Question Answer Marks 9(a)(i) all symbols correct ; heater and motor in parallel connection ; switches correctly placed ; 3 9(a)(ii) 16 () ; combined resistance in parallel is less than either individual resistance ; 2 9(a)(iii) electrons ; 1 9(a)(iv) increase current ; increase strength of magnetic field ; 2 9(b)(i) liquid - all molecules touching random arrangement ; gas – molecules widely separated (no more than seven shown) and random arrangement ; 2 9(b)(ii) 100 (°C) ; 1 Question Answer Marks 10(a)(i) stimulus – (change in) temperature ; effector – muscle (in arm) ; 2 10(a)(ii) X – motor neurone ; 1 10(a)(iii) brain ; 1 10(b) evidence of conversion ; (1500 / 0.1 or 1.5 / 0.0001) = 15000 / 1.5  104 ; 2 10(c) hormone hormone nerve impulse ;; 2

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 13 of 14 Question Answer Marks 10(d) any two from: increased depth of breathing / breathing rate ; increased pulse rate / heart rate ; widened pupils ; AVP ;; 2 Question Answer Marks 11(a)(i) limestone does not pass through (the holes in) the filter paper and water does pass through (the holes in) the filter paper ; limestone particles are larger / water particles are smaller (than the holes in the filter paper) ; 2 11(a)(ii) use universal indicator (paper / solution) ; use colour to determine pH from chart ; 2 11(b)(i) combustion of carbon containing fuels ; 1 11(b)(ii) global warming / climate change ; 1 11(c)(i) 45 (cm3) ; 1 11(c)(ii) 190 (s) ; 1 11(c)(iii) steeper line ; but levelling off at 45 (cm3) ; 2 11(c)(iv) decrease particle size / use powder / increase surface area ; increase acid concentration ; 2 Question Answer Marks 12(a) volume = mass/density (in any form) or 1.97  1030 / 1410 ; = 1.4  1027 (m3) ; 2 12(b)(i) convection ; 1

0973/31 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 14 of 14 Question Answer Marks 12(b)(ii) radiation ; 1 12(b)(iii) sound waves need a medium / cannot travel through a vacuum ; 1 12(c)(i) infrared to the right of visible light ; 1 12(c)(ii) gamma radiation ; 1 12(c)(iii) all electromagnetic waves / they travel at same speed ; 1 12(d)(i) amplitude correctly labelled ; 1 12(d)(ii) wavelength correctly labelled ; 1