Cambridge A Level Marine Science 9693 — 2024 May/June Paper 1 · Variant 3

This document has 16 pages. Any blank pages are indicated. [Turn over DC (WW) 340756 © UCLES 2024 * 1 2 2 1 9 2 3 6 1 3 * MARINE SCIENCE 9693/13 Paper 1 AS Level Theory May/June 2024 1 hour 45 minutes 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 75. ● The number of marks for each question or part question is shown in brackets [ ]. Cambridge International AS & A Level ,

  
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2 9693/13/M/J/24 © UCLES 2024 Section A Answer all questions in this section. 1 Fig. 1.1 shows a section from the surface of the Earth to the centre of the Earth. 3.5 × 104 m 3.4 × 106 m B … ocean C … D … A … NOT TO SCALE Fig. 1.1 (a) (i) On Fig. 1.1, identify the sections labelled A, B, C and D. [4] (ii) The total distance from the surface to the centre of the Earth is 6.36 × 106 m. Calculate the depth of layer C. Give your answer in km. Show your working. … km [3] * 0019654854502 * ,

  
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3 9693/13/M/J/24 © UCLES 2024 [Turn over (b) Fig. 1.2 shows part of three tectonic plates. Nazca plate South American plate African plate X Key land ocean Fig. 1.2 (i) Describe two ways continents provide evidence for the theory of plate tectonics. 1 … … 2 … … [2] There is a mid-ocean ridge at location X on Fig. 1.2. (ii) Draw two arrows on Fig. 1.2 to show the direction of movement of the plates at location X. [1] (iii) State the type of plate boundary at location X. … [1] (iv) Suggest why few fossils are expected to be found in rocks at location X. … … [1] [Total: 12] * 0019654854503 * ,

  
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4 9693/13/M/J/24 © UCLES 2024 2 Fig. 2.1 shows a rocky shore. Fig. 2.1 The rocks in Fig. 2.1 have been weathered. (a) Draw one line from each type of weathering to its description. biological processes that cause cracks in rocks deposition of suspended particles reactions with rock that produce soluble minerals temperature changes or environmental movements that cause the break-up of rocks transportation of rock particles description chemical organic physical type of weathering [3] * 0019654854504 * ,

  
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5 9693/13/M/J/24 © UCLES 2024 [Turn over (b) Small fragments of rock in Fig. 2.1 have been eroded. State the four types of erosion. 1 … 2 … 3 … 4 … [3] (c) Fig. 2.2 shows a group of limpets on a rocky shore. shell impermeable to water very close fit between the base of the shell and the rock surface Fig. 2.2 Explain two ways that limpets are adapted to live on a rocky shore. 1 … … 2 … … [2] [Total: 8] * 0019654854505 * ,

  
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6 9693/13/ M/J/24 © UCLES 2024 3 Fig. 3.1 shows a blue shark, Prionace glauca. A … C … B … Fig. 3.1 (a) On Fig. 3.1, identify the fins labelled A, B and C. [3] (b) Draw one line from each group to the name of that group for the blue shark. domain genus phylum group Animalia Chordata Eukarya glauca Prionace name of group for blue shark [3] * 0019654854506 * ,

  
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7 9693/13/M/J/24 © UCLES 2024 [Turn over (c) Table 3.1 shows the mass of dried shark fins exported from Japan between 1987 and 1997. Table 3.1 year mass of dried shark fins exported / kg 1987 600 000 1989 490 000 1991 410 000 1993 390 000 1995 380 000 1997 360 000 (i) Calculate the percentage decrease in the mass of dried shark fins exported between 1987 and 1997. Show your working. …% [2] (ii) Suggest three reasons for the decrease in the mass of dried shark fins exported. 1 … … 2 … … 3 … … [3] * 0019654854507 * ,

  
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8 9693/13/M/J/24 © UCLES 2024 (d) Blue sharks are generally found in the epipelagic and mesopelagic zones of the open ocean. State the meaning of these two terms. epipelagic … … mesopelagic … … [2] [Total: 13] * 0019654854508 * ,

  
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9 9693/13/M/J/24 © UCLES 2024 [Turn over BLANK PAGE * 0019654854609 * ,

  
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10 9693/13/M/J/24 © UCLES 2024 4 Copepods are small crustaceans that form part of the plankton in the oceans. (a) Define the term plankton. … … … … [2] (b) Fig. 4.1 shows a food chain involving copepods. The biomass of the population of each type of organism is given in mg m–3. phytoplankton copepod mackerel tuna 100 400 10 1 Fig. 4.1 (i) Sketch and label a pyramid of biomass for the food chain shown in Fig. 4.1. [3] (ii) The data for biomass in Fig. 4.1 were collected after a period of high primary productivity. Explain how this caused the relative biomass of the populations of phytoplankton and copepods. … … … … … … … … [4] * 0019654854610 * ,

  
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11 9693/13/M/J/24 © UCLES 2024 [Turn over (c) Fig. 4.2 shows part of a food web. tuna mackerel copepod phytoplankton Fig. 4.2 Sea cucumbers are omnivores that consume phytoplankton and copepods. Turtles are predators of sea cucumbers. Copepods are parasites of sea cucumbers and consume the flesh of sea cucumbers. Add this information to the food web in Fig. 4.2. [3] [Total: 12] * 0019654854611 * ,

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12 9693/13/M/J/24 © UCLES 2024 Section B Answer all questions in this section. 5 (a) Explain how the alignment of the Earth, Sun and Moon results in a spring tide and a neap tide. … … … … … … … … … … … … … … [7] * 0019654854612 * ,

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13 9693/13/M/J/24 © UCLES 2024 [Turn over (b) Explain the factors which affect the height of spring tides at different locations on Earth. … … … … … … … … … … … … … … [7] [Total: 14] * 0019654854613 * ,

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14 9693/13/M/J/24 © UCLES 2024 6 (a) Explain why sea water is described as a chemical solution. Include named examples of the components in sea water in your answer. … … … … … … … … … … … … … … … … [8] * 0019654854614 * ,

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15 9693/13/M/J/24 © UCLES 2024 (b) Explain how the pH of sea water can vary and describe the impact of pH change on coral reefs. … … … … … … … … … … … … … … … … [8] [Total: 16] * 0019654854615 * ,

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16 9693/13/M/J/24 © UCLES 2024 BLANK PAGE The boundaries and names shown, the designations used and the presentation of material on any maps contained in this question paper/insert do not imply official endorsement or acceptance by Cambridge Assessment International Education concerning the legal status of any country, territory, or area or any of its authorities, or of the delimitation of its frontiers or boundaries. 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. * 0019654854616 * ,

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This document consists of 13 printed pages. © Cambridge University Press & Assessment 2024 [Turn over Cambridge International AS & A Level MARINE SCIENCE 9693/13 Paper 1 AS Level Theory May/June 2024 MARK SCHEME Maximum Mark: 75 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 2024 series for most Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 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 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.

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 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.

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 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.

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 5 of 13 This mark scheme will use the following abbreviations: ; separates marking points / separates alternatives within a marking point () contents of brackets are not required but should be implied / the contents set the context of the answer R reject A accept (answers that are correctly cued by the question or guidance you have received) I ignore (mark as if this material was not present) AW alternative wording (where responses vary more than usual, accept other ways of expressing the same idea) AVP alternative valid point (where a greater than usual variety of responses is expected) ORA or reverse argument underline actual word underlined must be used by the candidate (grammatical variants excepted) MAX indicates the maximum number of marks that can be awarded + statements on both sides of the + are needed for that mark OR separates two different routes to a mark point and only one should be awarded ECF error carried forward (credit an operation from a previous incorrect response)

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 6 of 13 Question Answer Marks 1(a)(i) (A) continental crust ; (B) oceanic crust ; (C) mantle ; (D) core ; 4 1(a)(ii) (3 400 000 + 35 000 OR 3.4 × 106 + 3.5 × 104 =) 3 435 000 OR 3.435 × 106 ; (6.36 ×106 – 3.435 × 106 OR 6 360 000 – 3 435 000 =)2 925 000 OR 2.925 × 106 (m) ; (2.925 × 106 ÷ 1000) = 2925 (km) ; 3 1(b)(i) any 2 of: 1 jigsaw fit of continents ; 2 (distribution of) similar fossils / same type of fossil, on both continents ; 3 (distribution of) similar living organisms or species, on both continents ; 4 matching rock, type / formations, on both continents ; 5 AVP ; 2 1(b)(ii) two arrows diverging ; 1 1(b)(iii) divergent / diverging ; 1 1(b)(iv) newly formed, crust / rock / seafloor ; 1

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 7 of 13 Question Answer Marks 2(a) ;;; 3 2(b) ice / glaciers + water + wind + gravity ;;; 3 2(c) any 2 of: 1 close fitting / impermeable, shell to avoid, drying out / desiccation (when tide is out) ; 2 muscular foot to hold (tight) onto rocks ; 3 (thick / ref to shaped) shell protects from, predators / wave action ; 4 AVP ; 2

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 8 of 13 Question Answer Marks 3(a) (A) caudal (fin) ; (B) pelvic (fin) ; (C) dorsal (fin) ; 3 3(b) ;;; 3 3(c)(i) 360 000 – 600 000 = –240 000 240 000 100 600 000   ; (–) 40 (%) ; 2

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 9 of 13 Question Answer Marks 3(c)(ii) any 3 of: 1 idea of fewer people will eat them / less demand / boycott / idea of shark conservation ; 2 fewer / lower, population / supply (of blue sharks) OR named reason for smaller population ; 3 increase in price ; 4 decrease in fishing effort or days / correct ref to quotas ; 5 more people in Japan eating it / larger domestic market ; 6 fresh / frozen, shark (meat / fin) being exported instead ; 7 laws / legislation / designated a protected species ; 3 3(d) (epipelagic) sunlit (open ocean) ; (mesopelagic) twilight (open ocean) ; 2 Question Answer Marks 4(a) any 2 of: 1 (organisms that) have limited motility ; 2 drift in water currents ; 3 (generally) microscopic ; 2 4(b)(i) 4 rectangular closed bars stacked vertically and centrally aligned ; correct relative proportions ; correctly labelled with organisms from food chain in correct order ; 3 4(b)(ii) phytoplankton bloom(ed) ; ref to photosynthesis / light energy transferred to biomass ; more food for copepods / more phytoplankton eaten ; large(r) copepod population ; 4

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 10 of 13 Question Answer Marks 4(c) sea cucumber added with arrow from phytoplankton and from copepod ; arrow from sea cucumber to turtle ; arrow from sea cucumber to copepod ; 3 Question Answer Marks 5(a) any 7 of: 1 Moon and Sun exert gravitational pull on water ; 2 gravitational pull from the Moon is larger than from the Sun ; 3 because the Moon is closer ; spring tide: 4 largest range (consecutive between high and low tides) ; 5 Earth, Moon and Sun are in a (straight) line ; 6 gravitational pull of Sun and Moon in same direction / is amplified ; 7 therefore (total) gravitational pull (on water) is greatest (in one direction) ; neap tide: 8 is smallest range (consecutive between high and low tides) ; 9 Moon and Sun perpendicular to Earth ; 10 gravitational pull of the Moon and Sun are in opposite directions ; 11 so (total) gravitational pull (on water) is weakest (in one direction) ; 7

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 11 of 13 Question Answer Marks 5(b) factors: a wind direction / onshore wind / offshore wind ; b windspeed / high winds ; c air pressure ; d runoff / flooding ; e coastal geomorphology / shape of coast / named example ; f shape of seabed ; g size of the body of water ; h AVP ; explanations 1 onshore wind increases tide height / ORA ; 2 higher wind(speed) pushes more water / ORA ; 3 low air pressure increases tide height / ORA ; 4 increased runoff / flooding rivers, increases tide height / ORA ; 5 funnel-shaped (coastline) increases tide height / ORA ; 6 shallow waters increase tide height / ORA ; 7 large bodies of water (generally) increase tide height / ORA ; 8 steep channels / basins on seabed decrease tidal height or continental ridges / shelves increase tide height ; 9 AVP ; 7

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 12 of 13 Question Answer Marks 6(a) any 4 of: 1 water is the solvent ; 2 salts / (named) solutes, are dissolved in, water / solvent ; 3 by the disassociation of ions / described ; 4 ref to polar property of water molecules ; 5,6 plus any 2 stated salts: Na+ / Cl– / NaCl / sodium chloride ; Mg2+ / SO42– / MgSO4 / magnesium sulfate ; Ca2+ / CO32– / CaCO3 / calcium carbonate ; PO43– / phosphate ions ; NO3 / nitrate ions ; AVP ; 7,8 plus any 2 named nutrients: carbohydrates / glucose ; proteins / amino acids ; lipids / fatty acids ; AVP ; 9,10 plus any 2 gases dissolved: carbon dioxide ; oxygen ; nitrogen ; AVP ; 8

9693/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 13 of 13 Question Answer Marks 6(b) any 8 of: 1 typical sea water pH stated / seawater is (slightly) alkaline ; 2 pH is a measure of the hydrogen ion concentration in water ; 3 reference to precipitation / run-off / melting glaciers (decreasing pH) ; 4 ocean acidification / lower pH (than typical pH) ; 5 less (calcium) carbonate available for shells / (hard) coral ; 6 causing reef erosion ; 7 low pH / acidity, dissolves coral skeleton / calcium carbonate ; 8 reduces ability of coral to absorb calcium carbonate ; 9 zooxanthellae die / leave the coral ; 10 zooxanthellae provide the nutrients for coral ; 11 reef damage faster than reef growth ; 12 AVP ;; 8