Science Stage 9 Paper 2 Cambridge Lower Secondary Progression Test Mark Scheme 3146_02_MS_4RP © UCLES 2023 2023 3146/02 Science Stage 9 Paper 2 Mark Scheme 2023 General guidelines on marking Many descriptive answers can be expressed in a variety of ways. Professional judgement can be used in these cases, providing it matches the marking points and further information in the mark scheme. Answers may have words spelt incorrectly. Credit is normally given for phonetically correct answers, unless the word has a scientifically different meaning. For example, where the answer should be antennae, credit will be given for antena but not for anthen (too close to anther). Only the science is being assessed, so answers do not need to be grammatically correct. Significant figures will be indicated in the question or in the mark scheme. Unless specified all marking points are independent. Annotations and abbreviations / or alternate responses for the same marking point ( ) brackets the words or units in brackets do not need to be stated, for example, (recycles or releases or provides) minerals = minerals scores the mark underline exact word is required Accept an acceptable response Do not accept indicates an incorrect response that would contradict another otherwise correct alternative Ignore indicates an irrelevant answer that is not creditworthy. Full marks can still be achieved even with answers that are ignored. Note provides extra information when necessary ecf error carried forward; marks are awarded if an incorrect response has been carried forward from earlier working provided the subsequent working is correct ora or reverse argument; for example, as mass increases, volume increases could be written as mass decreases, volume decreases © UCLES 2023 Page 2 of 12 © UCLES 2023 1 Question 3146/02 Accept magnesium ions are needed for photosynthesis magnesium ions are needed to make chlorophyll Page 3 of 12 Accept nitrate ions are needed to make DNA or amino acids nitrate ions are needed to make proteins 4 each correct answer = 1 mark Further Information Accept the seedling with just nitrate ions grows more than the seedling with just magnesium ions / ora Marks 2023 nitrate ions have a greater effect on the dry mass than magnesium ions / ora when nitrate ions and magnesium ions are both present the (barley seedlings) have the greatest dry mass Answer Science Stage 9 Paper 2 Mark Scheme © UCLES 2023 2(b) 2(a)(iii) (dependent variable) volume of gas 2(a)(ii) Page 4 of 12 Accept wear gloves (how to control the risk) wear eye protection 2 each correct answer = 1 mark Do not accept (same) concentration of acid 1 both answers correct for the mark 1 both answers correct for the mark 1 Further Information Accept acid can burn skin or eyes or acid can irritate skin or eyes or acid can harm skin or eyes Marks 2023 (safety risk) acid is corrosive (same) volume (of acid) (same) temperature (same) particle size or same surface area (of calcium carbonate) (same) mass (of calcium carbonate) any two from (how it is measured) water level in measuring cylinder concentration (of acid) Answer Science Stage 9 Paper 2 Mark Scheme 2(a)(i) Question 3146/02 90 000 (Hz) 3(b) Answer 4 (times) 2 (times) 3(d)(i) 3(d)(ii) Page 5 of 12 increases the loudness or increases the volume 3(c)(ii) © UCLES 2023 increases the pitch 3(c)(i) Marks Science Stage 9 Paper 2 Mark Scheme (range is from) 1000 (Hz) to 90 000 (Hz) or 100 (Hz) 3(a) Question 3146/02 1 Accept waveform A has twice the frequency of waveform B 1 Note answer must be comparative 1 Accept louder sound Note answer must be comparative 1 Accept higher pitch no tolerance on the value of 1000 (Hz) Accept between 80 000 and 99 000 (Hz) for the value of 90 000 (Hz) 1 Accept between 80 000 and 99 000 (Hz) 1 no tolerance Further Information 2023 © UCLES 2023 4(b)(ii) 4(b)(i) 4(a)(iii) line of best fit extended to the x-axis 4(a)(ii) Page 6 of 12 (reason 2) the offspring will drown or the offspring will have insufficient oxygen to respire (reason 1) (idea of) the nesting sites will be flooded (effect on the population) decreases (no marks) (decreases) there will be fewer males to mate with the females (increases) there are more females to produce offspring advantageous adaptions passed on to offspring (idea of) best adapted survive or (idea of) competition variation within the species any two from correct year read from the line to the nearest year decreases Answer Marks Science Stage 9 Paper 2 Mark Scheme 4(a)(i) Question 3146/02 each correct reason= 1 mark 2 increase = 0 marks for the question 2 each correct explanation = 1 mark Accept survival of the fittest 2 each correct answer = 1 mark 2 each correct answer = 1 mark 1 Further Information 2023 © UCLES 2023 5(b) 5(a) Question 3146/02 Page 7 of 12 (explanation) (idea of) lowest density or density much lower than others or has a very low density (substance) B correct answer 8.9 2023 Accept density of gas usually less than solids or liquids 2 each correct answer = 1 mark Accept truncated answers or incorrect rounding correct division using their values from substitution correct division, e.g. 8.947368 Accept 8.947368 with or without working = 2 marks 3 Accept 8.9 with or without working = 3 marks Further Information correct construction of formula mass ÷ volume or 340 ÷ 38 Marks correct substitution of numbers into formula or 340 ÷ 38 Answer Science Stage 9 Paper 2 Mark Scheme © UCLES 2023 6 Question 3146/02 Accept heat for thermal energy thermal energy transfers from body or skin Page 8 of 12 Accept slower (water) particles remain less energetic (water) particles remain (on skin) 2023 Accept evaporation is endothermic as an extra marking point Accept faster molecules escape more energetic (water) particles escape (from surface of skin or to air) 3 each correct answer = 1 mark Further Information Accept molecules for particles throughout Marks (water) particles gain energy from skin any three from Answer Science Stage 9 Paper 2 Mark Scheme © UCLES 2023 7(b) 7(a) Question 3146/02 the burning of fossil fuels the release of energy from the breakdown of glucose the formation of glucose and oxygen by green plants decomposition feeding photosynthesis respiration Page 9 of 12 the breakdown of dead and decaying waste material combustion photosynthesis carbohydrate moves from one organism to another organism Answer Marks Science Stage 9 Paper 2 Mark Scheme 1 if two lines from one process to different descriptions = 0 marks for that process one correct = 1 mark two correct = 2 marks three or four correct = 3 marks 4 all five correct = 4 marks Further Information 2023 © UCLES 2023 Page 10 of 12 no boundaries near South Africa 8(c)(ii) mantle mantle (idea of) they follow the same pattern or active volcanoes are found where the boundaries of the floating rocks or tectonics plates are located crust crust tectonic plates Answer Marks Science Stage 9 Paper 2 Mark Scheme 8(c)(i) 8(b)(ii) 8(b)(i) 8(a) Question 3146/02 1 1 Accept a full convection current 1 arrow heads must be in the correct direction on all arrows drawn 1 arrow heads must be in the correct direction on all arrows drawn 1 Further Information 2023 © UCLES 2023 9(c) (description) shared pair of electrons (name) covalent bond Page 11 of 12 (idea that) mass of reactants is the same as mass of products or no loss or gain of mass during the reaction 9(b) Answer copper nitrate Question Marks Further Information 2 each correct answer = 1 mark 1 1 Science Stage 9 Paper 2 Mark Scheme 9(a) 3146/02 2023 Question © UCLES 2023 10(b) 10(a) 3146/02 Page 12 of 12 water can leak (out of pipes) but current cannot leak (out of wires) it takes time for radiator to get hot (but the lamp turns on straight away) it takes time for the water to reach the radiator you cannot see what is happening to the water in the pipes any one limitation from same rate of flow of water or current or charge at all points there is the same amount of water or current at all points both water and current are not ‘used up’ as they pass around the pipes/circuit any one strength from (hot water) charge or electrons or current (pump) cell(s) or battery or power supply Answer Marks Further Information 2023 Accept to help explain a difficult idea, e.g. current Accept looks like a circuit so easy to visualise Accept (idea that) the pump requires energy to work but the cell provides the electrical energy 2 each correct answer = 1 mark Ignore wire 2 each correct answer = 1 mark Science Stage 9 Paper 2 Mark Scheme
