Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2021 May/June Paper 3 · Variant 3

This document has 28 pages. Any blank pages are indicated. DC (CE/SG) 213460 © UCLES 2021 [Turn over * 7 7 1 4 1 8 8 1 3 9 * CO-ORDINATED SCIENCES 0654/33 Paper 3 Theory (Core) May/June 2021 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. Cambridge IGCSE™

2 0654/33/M/J/21 © UCLES 2021 1 (a) Fig. 1.1 is a diagram of the female reproductive system. A B C D E Fig. 1.1 (i) State the letter from Fig. 1.1 that shows the part where: fertilisation occurs … gametes are produced. … [2] (ii) Identify the part labelled B in Fig. 1.1. … [1] (b) Fig. 1.2 shows a student’s description of fertilisation in humans. The description of fertilisation in humans is incorrect. Circle the two incorrect words in the description in Fig. 1.2. Fertilisation is the separation of the nuclei from a sperm cell and an ovary cell. Fig. 1.2 [2]

3 0654/33/M/J/21 © UCLES 2021 [Turn over (c) Fig. 1.3 shows how the thickness of the uterus lining changes during the menstrual cycle. 0 2 4 6 8 10 12 14 day of menstrual cycle 16 18 20 22 24 26 28 relative thickness of uterus lining Fig. 1.3 Table 1.1 represents the days during an average menstrual cycle. Table 1.1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Use Fig. 1.3 and your own knowledge to: (i) place ticks (3) in Table 1.1 to show the days when the uterus lining is shed [1] (ii) place crosses (✗) in Table 1.1 to show the days when the uterus lining is at its thickest. [1] (d) Complete the sentence to define the term reproduction. Reproduction is the processes that make … of the same … of organism. [2] [Total: 9]

4 0654/33/M/J/21 © UCLES 2021 2 (a) Magnesium is in Period 3 of the Periodic Table. (i) Use the Periodic Table to name the noble gas in Period 3 of the Periodic Table. … [1] (ii) Describe the change in metallic character across Period 3. … … [1] (b) Magnesium reacts with carbon dioxide. Magnesium oxide and carbon are made. (i) Write the word equation for this reaction. … + … … + … [1] (ii) The reaction between magnesium and carbon dioxide is exothermic. Explain what is meant by an exothermic reaction. … … [1] (c) An atom of magnesium has a proton number (atomic number) of 12 and a nucleon number (mass number) of 24. Complete Table 2.1 to show the names and numbers of the two particles contained in the nucleus of this magnesium atom. Table 2.1 name of particle number of particles [2] (d) Magnesium carbonate reacts with dilute hydrochloric acid to make aqueous magnesium chloride. (i) Magnesium carbonate is insoluble in water. State the separation technique used to remove magnesium carbonate from a mixture of magnesium carbonate and water. … [1]

5 0654/33/M/J/21 © UCLES 2021 [Turn over (ii) Magnesium chloride dissolves in water. State the separation technique used to obtain solid magnesium chloride from a solution of magnesium chloride. … [1] (iii) Magnesium carbonate reacts with dilute hydrochloric acid. Complete the balanced symbol equation for this reaction. MgCO3 + …HCl MgCl 2 + CO2 + H2O [1] (iv) Dilute hydrochloric acid contains aqueous chloride ions. State the test for aqueous chloride ions and give the observation for a positive result. test … observation … [2] (e) Table 2.2 shows the composition of a magnesium alloy. Table 2.2 element % by mass magnesium 94 neodymium 2 yttrium 4 (i) Calculate the mass of magnesium in 500 kg of the alloy. … kg [1] (ii) The alloy is used in aircraft bodies. Suggest why the alloy of magnesium is used rather than pure magnesium for aircraft bodies. … … [1] [Total: 13]

6 0654/33/M/J/21 © UCLES 2021 3 (a) A torch (flashlight) contains four cells, a lamp and a switch connected in series. (i) Draw a circuit diagram for the torch using standard electrical symbols. [3] (ii) The potential difference (p.d.) across the lamp is 6.0 V when the switch is closed. The resistance of the lamp is 5.0 Ω when lit. Calculate the current in the lamp. current = …A [2] (iii) Two lamps each of resistance 5.0 Ω are connected together in a series circuit. Calculate the combined resistance of the two lamps in series. resistance = … Ω [1]

7 0654/33/M/J/21 © UCLES 2021 [Turn over (b) Choose words from the list to complete the sentences to describe the energy transfers that occur when the torch is switched on. You may use each word once, more than once or not at all. chemical elastic electrical gravitational light nuclear sound thermal The energy stored in the cells is … potential energy. This energy is transferred into … energy which passes through the lamp. The useful energy from the lamp is … energy. Some energy is wasted as … energy. [3] (c) Solar energy is sometimes used to power torches. Solar energy is a renewable energy resource. State two other renewable energy resources. 1 … 2 … [2] (d) Fig. 3.1 shows a ray of light from a torch shining on a mirror. X Z Fig. 3.1 (i) State the name of line XZ. … [1] (ii) State what happens to the ray of light at point X on Fig. 3.1. … [1] [Total: 13]

8 0654/33/M/J/21 © UCLES 2021 4 (a) Fig. 4.1 is a diagram of the heart. A B C E D Fig. 4.1 (i) Identify the parts labelled B, C and D in Fig. 4.1. B … C … D … [3] (ii) Describe the function of the structure labelled E. … … [1] (iii) The blood vessel labelled A is an artery. Describe the role of arteries in the circulatory system. … … [1] (b) Name two of the main components of blood. 1 … 2 … [2]

9 0654/33/M/J/21 © UCLES 2021 [Turn over (c) A student measures their heart rate over a 24‑hour period. Fig. 4.2 shows a graph of the results. 00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 24:00 midnight midday time of day / hours midnight 60 80 100 120 140 160 180 200 heart rate / bpm Fig. 4.2 (i) Calculate the difference in heart rate between the minimum and maximum heart rate seen in Fig. 4.2. …bpm [1] (ii) At 10:00 hours the student attends a fitness class. Estimate the length of time of the fitness class. …hours [1] (iii) At 18:00 hours the student was scared by a snake. Describe and explain the result seen at 18:00 hours in Fig. 4.2. Use ideas about hormones in your answer. … … … … [2] [Total: 11]

10 0654/33/M/J/21 © UCLES 2021 5 (a) Potassium is a very reactive metal. Potassium is stored under oil as shown in Fig. 5.1. potassium oil pieces of potassium Fig. 5.1 Suggest two reasons why potassium is stored under oil. 1 … 2 … [2] (b) Potassium has a proton number of 19. Complete Fig. 5.2 to show the electronic structure of a potassium atom. The inner shell electrons have been drawn for you. Fig. 5.2 [2] (c) Solid potassium reacts with chlorine gas to make solid potassium chloride. (i) Describe the differences between the structures of a solid and a gas in terms of particle separation and particle arrangement. particle separation … … particle arrangement … … [2]

11 0654/33/M/J/21 © UCLES 2021 [Turn over (ii) When potassium reacts with chlorine, potassium atoms become potassium ions. Describe what happens to a potassium atom when it becomes a potassium ion. … [1] (iii) Potassium and chlorine are elements. Potassium chloride is a compound. Describe the difference between an element and a compound. … … … [2] (d) The maximum mass of potassium chloride that dissolves in 100 cm3 of water is called the solubility of potassium chloride. Fig. 5.3 shows the solubility of potassium chloride in water at different temperatures. 0 10 20 30 40 50 60 70 10 20 30 40 50 temperature / °C solubility g / 100 cm3 of water 60 70 80 90 100 Fig. 5.3 (i) Describe the trend in solubility shown in Fig. 5.3. … [1] (ii) State the mass of potassium chloride that dissolves in 100 cm3 of water at 45 °C. …g [1] [Total: 11]

12 0654/33/M/J/21 © UCLES 2021 6 (a) Fig. 6.1 shows the speed‑time graph for the journey of a train travelling between two stations. 0 0 5 10 15 20 25 50 100 150 200 time / s speed m / s A D C B Fig. 6.1 (i) Use letters from the graph in Fig. 6.1 to identify the two stations on the train’s journey. … and … [1] (ii) On Fig. 6.1, label with a cross (X) a part of the journey when the train is accelerating. [1] (iii) Use Fig. 6.1 to calculate the total distance travelled by the train on this journey. distance = …m [3]

13 0654/33/M/J/21 © UCLES 2021 [Turn over (b) Fig. 6.2 shows the forces acting on the train when it travels at a constant speed. P R Q S direction of travel Fig. 6.2 (i) State which force, P, Q, R or S, is the weight of the train. … [1] (ii) Compare the magnitude and the direction of forces Q and S when the train is travelling at a constant speed. … … [2] [Total: 8]

14 0654/33/M/J/21 © UCLES 2021 7 (a) A scientist investigates the effect of immersion of plant cells in different concentrations of sugar solution. Fig. 7.1 shows the appearance of the plant cells before immersion. Fig. 7.1 Beakers A–D contain different concentrations of sugar solution. Some plant cells are placed in each solution and left for an hour. Table 7.1 shows the results. Table 7.1 beaker A B C D appearance of plant cells after immersion

15 0654/33/M/J/21 © UCLES 2021 [Turn over (i) Describe the change seen to the plant cells placed in beaker A in Table 7.1. … … [1] (ii) Suggest which beaker contains the solution with the same concentration as the plant cells. Give a reason for your answer. beaker … reason … [2] (b) Water enters the plant through the root hair cells. Complete the flow chart to show the pathway of water through the cells of a plant. root hair cell … xylem … [2] (c) Xylem transports water through the plant stem. Name the tissue that transports sugars through the plant stem. … [1] (d) Water and carbon dioxide are raw materials required for photosynthesis. Name two other requirements for photosynthesis. 1 … 2 … [2] (e) Protecting land from deforestation helps stop the loss of soil. This is because tree roots hold the soil together, stopping it being washed away. Suggest two other benefits of protecting land from deforestation. 1 … … 2 … … [2] [Total: 10]

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17 0654/33/M/J/21 © UCLES 2021 [Turn over 8 (a) Fig. 8.1 shows the electrolysis of molten lead(II) bromide. + – molten lead(II) bromide low voltage d.c. supply Fig. 8.1 (i) State the name of the electrode where lead is made. … [1] (ii) Explain why an orange gas is seen above the molten lead(II) bromide. … [1] (b) Lead is extracted from lead oxide by reaction with carbon. The equation for the reaction is shown. lead oxide + carbon lead + carbon dioxide Name the substance that is oxidised and the substance that is reduced in this reaction. substance oxidised … substance reduced … [1] (c) Lead is a metal. Suggest one test to show that lead is a metal. … … [1] (d) Lead reacts very slowly with dilute sulfuric acid. State two ways of increasing the rate of reaction between lead and dilute sulfuric acid. 1 … 2 … [2] [Total: 6]

18 0654/33/M/J/21 © UCLES 2021 9 Fig. 9.1 shows a tumble dryer. Fig. 9.1 In a tumble dryer, wet clothes are warmed and dried. Water on the clothes evaporates. (a) (i) Describe the process of evaporation. Use ideas about molecules in your answer. … … … … [2] (ii) During evaporation the water does not boil. State the boiling point of water. …°C [1] (iii) Inside the tumble dryer, water vapour changes into liquid water. State the term used to describe a gas changing into a liquid. … [1] (iv) Thermal energy passes through the metal casing of the tumble dryer. State the method of thermal energy transfer through metals. … [1]

19 0654/33/M/J/21 © UCLES 2021 [Turn over (b) (i) The tumble dryer is noisy and emits loud sound waves with a low pitch. Describe the sound waves in terms of their amplitude and frequency. amplitude … frequency … [2] (ii) State the lowest audible frequency for a healthy human ear. State the unit of your answer. frequency = … unit … [2] (iii) The speed of sound in air is 340 m / s. Calculate the time taken for a sound wave to travel 85 m. time = … s [2] [Total: 11]

20 0654/33/M/J/21 © UCLES 2021 10 (a) Fig. 10.1 is a diagram of the human alimentary canal and associated organs. … … … Fig. 10.1 (i) Label Fig. 10.1 on the answer lines provided. Choose words from the list. • anus • large intestine • mouth • pancreas • small intestine • stomach [3] (ii) Different processes occur in the alimentary canal. Complete Table 10.1 using words from the list in (a)(i). Table 10.1 process one part of the alimentary canal where process occurs ingestion egestion mechanical digestion [3]

21 0654/33/M/J/21 © UCLES 2021 [Turn over (b) Describe the role of chemical digestion in the alimentary canal. … … … … [2] (c) The boxes contain the beginnings and the endings of some sentences. Join one sentence beginning to one sentence ending to define the term assimilation. beginning ending Assimilation is the movement of digested food molecules into the cells of the body where they are excreted, becoming part of the faeces. Assimilation is the movement of digested food molecules into the lungs of the body where they are excreted, becoming part of the cells. Assimilation is the movement of undigested food molecules into the lungs of the body where they are used, becoming part of the faeces. Assimilation is the movement of undigested food molecules into the cells of the body where they are used, becoming part of the cells. [2] [Total: 10]

22 0654/33/M/J/21 © UCLES 2021 11 Fig. 11.1 shows the structures of five compounds A, B, C, D and E. H H H H H C C H C H H H C H O C O B A C C H H H H D O H H E Fig. 11.1 (a) Use the letters A–E to identify all the hydrocarbon molecules. … [1] (b) Use the letters A–E to identify the two products of the complete combustion of a hydrocarbon. … and … [1] (c) Use Fig. 11.1 to name one greenhouse gas. … [1] (d) Draw a dot‑and‑cross diagram to show the bonding in molecule E. Only show the outer shell electrons. H H O [3]

23 0654/33/M/J/21 © UCLES 2021 [Turn over (e) Compound D is an unsaturated compound. (i) State what is meant by the term unsaturated compound. … … [1] (ii) Name the process that produces smaller unsaturated hydrocarbon molecules from large saturated hydrocarbon molecules. … [1] (iii) State the chemical test for an unsaturated hydrocarbon and give the observation for a positive result. test … observation … [2] [Total: 10]

24 0654/33/M/J/21 © UCLES 2021 12 (a) Electricity is generated in a nuclear power station by the nuclear fission of plutonium‑239. Describe what happens to a nucleus of plutonium‑239 during nuclear fission. … [1] (b) Plutonium‑239 is an isotope of plutonium. (i) State the meaning of isotope. … … [1] (ii) Plutonium‑239 emits β‑radiation. Suggest how a small sample of plutonium‑239 can be stored safely. … [1] (iii) Plutonium‑239 has a half‑life of 24 000 years. A sample of plutonium‑239 has a mass of 800 g. Calculate the mass of plutonium‑239 remaining after 48 000 years. mass = …g [2] (iv) State two differences between β‑radiation and γ‑radiation. 1 … … 2 … … [2] (v) Fig. 12.1 shows an incomplete electromagnetic spectrum. Place γ‑radiation in its correct place in Fig. 12.1. microwaves visible light ultraviolet Fig. 12.1 [1] [Total: 8]

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27 0654/33/M/J/21 © UCLES 2021 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 the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge. BLANK PAGE

28 0654/33/M/J/21 © UCLES 2021 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 13 printed pages. © UCLES 2021 [Turn over Cambridge IGCSE™ CO-ORDINATED SCIENCES 0654/33 Paper 3 Theory (Core) May/June 2021 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 2021 series for most Cambridge IGCSE™, Cambridge International A and AS Level components and some Cambridge O Level components.

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 2 of 13 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.

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 3 of 13 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. 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.

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 4 of 13 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.

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 5 of 13 Examples of how to apply the list rule State three reasons…. [3] A 1. Correct  2 2. Correct  3. Wrong  B 1. Correct, Correct ,  3 (4 responses) 2. Correct  3. Wrong ignore C 1. Correct  2 (4 responses) 2. Correct, Wrong ,  3. Correct ignore D 1. Correct  2 (4 responses) 2. Correct, CON (of 2.) , (discount 2) 3. Correct  E 1. Correct  3 (4 responses) 2. Correct  3. Correct, Wrong  F 1. Correct  2 (4 responses) 2. Correct  3. Correct CON (of 3.)  (discount 3) G 1. Correct  3 (5 responses) 2. Correct  3. Correct Correct CON (of 4.)  ignore ignore H 1. Correct  2 (4 responses) 2. Correct  3. CON (of 2.) Correct (discount 2)  I 1. Correct  2 (4 responses) 2. Correct  3. Correct CON (of 2.)  (discount 2)

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 6 of 13 Question Answer Marks 1(a)(i) A ; E ; 2 1(a)(ii) uterus ; 1 1(b) separation ; ovary; 2 1(c)(i)  under days 1–4 ; 1 1(c)(ii) X under days 24–26 ; 1 1(d) more ; kind ; 2 Question Answer Marks 2(a)(i) argon ; 1 2(a)(ii) metal to non-metal ; 1 2(b)(i) magnesium + carbon dioxide → carbon + magnesium oxide ; 1 2(b)(ii) thermal energy released ; 1 2(c) protons –12 ; neutrons –12 ; 2 2(d)(i) filtration ; 1 2(d)(ii) crystallisation ; 1 2(d)(iii) MgCO3 + 2HCl → MgCl2 + CO2 + H2O ; 1 2(d)(iv) (acidified) (aqueous) silver nitrate ; white precipitate ; 2

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 7 of 13 Question Answer Marks 2(e)(i) 470 (kg) ; 1 2(e)(ii) stronger / less dense ; 1 Question Answer Marks 3(a)(i) all symbols correct ; 4 cells shown (or battery symbol) ; all in series; 3 3(a)(ii) current = voltage / resistance or 6 / 5 ; = 1.2 (A) ; 2 3(a)(iii) 10.0 (Ω) ; 1 3(b) chemical electrical light thermal ;;; 3 3(c) tidal ; geothermal ; HEP ; wind ; wave ; max 2 2 3(d)(i) normal ; 1 3(d)(ii) reflection ; 1

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 8 of 13 Question Answer Marks 4(a)(i) septum ; muscle / muscle wall ; ventricles ; 3 4(a)(ii) ensure one-way flow of blood ; 1 4(a)(iii) transport blood away from the heart ; 1 4(b) any two from red (blood) cells ; white (blood) cells ; platelets ; plasma ; max 2 2 4(c)(i) 110 (bpm) ; 1 4(c)(ii) 4 (hours) ; 1 4(c)(iii) (rapid) increase of heart rate / increase by 70 bpm / increase to 140 bpm ; ref to adrenaline ; 2 Question Answer Marks 5(a) to prevent potassium reacting (with) ; air / oxygen / water vapour ; 2 5(b) 19 electrons shown ; (2).8.8.1 ; 2 5(c)(i) particle separation - further apart in a gas / touching / close in a solid) ; particle arrangement – regular arrangement in solid / random arrangement in gas ; 2 5(c)(ii) loses one electron ; 1

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 9 of 13 Question Answer Marks 5(c)(iii) an element contains only one type of atom ; a compound contains two or more elements / different atoms chemically combined ; 2 5(d)(i) solubility increases as temperature rises ; 1 5(d)(ii) 41 g ; (± 1) 1 Question Answer Marks 6(a)(i) A and D ; 1 6(a)(ii) X anywhere between A and B or between C and D ; 1 6(a)(iii) evidence of calculating area under graph ; 1000 + 1000 + 500 ; 2500 m ; 3 6(b)(i) R ; 1 6(b)(ii) equal (magnitude) ; opposite directions ; 2 Question Answer Marks 7(a)(i) the cell, swells / increases in size ; 1 7(a)(ii) B ; the cell has not changed ; 2 7(b) root cortex (cell) ; mesophyll (cell) ; 2 7(c) phloem ; 1

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 10 of 13 Question Answer Marks 7(d) light ; chlorophyll ; AVP ; 2 7(e) any two from prevents extinction of animals ; conserves habitat ; protects food sources (for humans) ; maintains food, chains / webs ; maintains, wood / fuel (resources) ; idea of protecting natural beauty ; AVP ; max 2 2 Question Answer Marks 8(a)(i) cathode ; 1 8(a)(ii) bromine (vapour) released ; 1 8(b) oxidised carbon and reduced lead oxide ; 1 8(c) suitable test; (e.g. test for electrical conductivity) 1 8(d) increase temperature ; increase surface area (of lead) ; increase concentration (of acid) ; max 2 2 9(a)(i) faster moving / more energetic molecules ; escape / leave surface ; 2

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 11 of 13 Question Answer Marks 9(a)(ii) 100 °C ; 1 9(a)(iii) condensation ; 1 9(a)(iv) conduction ; 1 9(b)(i) large amplitude ; low frequency ; 2 9(b)(ii) 20 ; Hz ; 2 9(b)(iii) t = d / s or correct substitution ; = 0.25 (s) 2 Question Answer Marks 10(a)(i) stomach ; pancreas ; small intestine ; 3 10(a)(ii) mouth ; anus ; mouth / stomach ; 3 10(b) large / insoluble food molecules broken down into small / soluble molecules ; ref to absorption ; AVP ; max 2 2

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 12 of 13 Question Answer Marks 10(c) ;; 2 Question Answer Marks 11(a) B, C and D ; 1 11(b) A and E ; 1 11(c) carbon dioxide / methane ; 1 11(d) one shared pair of electrons ; two shared pairs of electrons oxygen has octet 3 11(e)(i) contains a carbon – carbon double bond ; 1 11(e)(ii) cracking ; 1 11(e)(iii) (aqueous) bromine ; goes from orange to colourless ; 2 Question Answer Marks 12(a) splits ; 1 12(b)(i) two atoms that contain the same number of protons but different number of neutrons ; 1

0654/33 Cambridge IGCSE – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 13 of 13 Question Answer Marks 12(b)(ii) in a lead lined container ; 1 12(b)(iii) 2 half-lives ; 200 g; 2 12(b)(iv) β is more ionising ; γ is more penetrating ; β is charged ; max 2 2 12(b)(v) γ-radiation in left hand box ; 1