Tectonic processes — Paper 2 · A Level Marine Science 9693

4 (a) Explain how volcanic activity affects the chemical composition of sea water. … … … … … … … … … … [5] (b) Describe how temperature gradients form in water columns to produce ocean layers and how mixing of these layers may occur. … … … … … … … … … … [5] (c) The concentration of dissolved oxygen in the surface water of open oceans ranges from 4 mg dm–3 to 9 mg dm–3. The concentration of dissolved oxygen in a tropical lagoon was measured and found to be 2.9 mg dm–3. Suggest explanations for this difference. … … … … … … … … … … … … [5] [Total: 15]

15 marks

Mark scheme: 4(a) any five of: 1 idea of, (named) salt / (named) mineral input from volcanoes (increases) salinity ; 2 volcanic gases contain, carbon dioxide / sulfur dioxide / hydrogen sulfide / hydrogen chloride ; 3 gases dissolve / (atmospheric) dissolution ; 4 carried into sea water in rain water / reference to hydrological cycle ; 5 (ions) enter water directly through underwater volcano / hydrothermal vent ; 6 idea of, (sea) water becomes more acidic / decreased pH ; 7 gases are less soluble in hot water ; 8 idea of, a lot of volcanic ash would raise pH ; 5 A CO2 / SO2 / H2S / sulfides / S2– / HCl hydrochloric acid / chloride (ions) / Cl – I mixing A ref. to hydrosphere Question Answer Marks Guidance 4(b) any five of: 1 warming of surface layers ; 2 warm water less dense than cold water ; 3 (therefore) floats on colder water ; 4 temperature decreases as depth increases ; 5 ref. to thermocline / description of ; 6 (mixing by) wind / storms / cyclones / hurricanes / typhoons ; 7 (mixing by) currents / upwelling ; 8 (leads to) cooling of surface water ; 9 results in convection (mixing) ; 5 description of thermocline must imply sudden change in temp. with depth Question Answer Marks Guidance 4(c) (the concentration of DO is lower in a tropical lagoon because:) any five of: 1 higher temperature (than open ocean) ; 2 solubility of oxygen decreases (as temperature increases) ; 3 less, wave action / mixing / turbulence ; 4 waves help atmospheric oxygen to dissolve ; 5 higher salinity in a lagoon (due to evaporation) ; 6 oxygen less soluble in more saline water ; 7 fewer producers in lagoon ; 8 less (production of oxygen by) photosynthesis ; 9 higher nutrient concentration (in lagoon) / idea of, eutrophication ; 10 lagoon is an enclosed body of water (vs open ocean with lots of mixing) ; 5 Implication of a comparison is needed in the answer. A reference to a lagoon being, a closed system / isolated, or surrounded by a reef / atolls

This question in 9693/21 May/June 2017

3 (a) Describe how a tropical cyclone develops. … … … … … … … … … … [5] (b) Explain the meaning of the terms ecosystem and biodiversity. … … … … … … … … … … [5] (c) Outline how mangroves protect tropical coastlines. … … … … … … … … … … [5] [Total: 15]

15 marks

Mark scheme: 3(a) any five of sea surface (temperature) at least 26.5 °C / 80 °F ; low (air) pressure / low (air) pressure system ; minimum sea depth of 50 m ; idea of, sufficiently far from equator to provide spin or twist / Coriolis effect ; idea of, rotating winds OR winds from different directions ; evaporation ; (gives rise to warm) moist air ; (air) rises and cools OR rises and draws in/up cooler air ; condensation ; release of latent heat ; idea of, this energy perpetuates cyclone further ; low wind-shear ; 5 A sea at least 26.5 °C A warm water at surface warm sea water unqualified is insufficient A circling / spiralling I strong wind unqualified Question Answer Marks Guidance 3(b) any five of ecosystem interaction between ; (community of) living organisms AND non-living components / biotic AND abiotic factors ; linked through, nutrient cycles ; (and) movement of, energy / nutrients, through, food chains / food webs ; biodiversity ref. number of species ; idea of, ref. evenness / relative abundance of each / AW ; (in an) ecosystem / habitat ; 5 3(c) any five of idea of, mangroves live in intertidal regions / delta regions / salt tolerant ; idea of, interlocking / thick / complex, root (system) ; idea of, protect from wave (action) ; energy dissipation ; reduction in, current / flow, speed ; reduce erosion ; increase sedimentation / fine sediment accumulates ; AVP ; 5 e.g. ref. extreme events

This question in 9693/22 May/June 2018

3 (a) Describe how a tropical cyclone develops. … … … … … … … … … … [5] (b) Explain the meaning of the terms ecosystem and biodiversity. … … … … … … … … … … [5] (c) Outline how mangroves protect tropical coastlines. … … … … … … … … … … [5] [Total: 15]

15 marks

Mark scheme: 3(a) any five of sea surface (temperature) at least 26.5 °C / 80 °F ; low (air) pressure / low (air) pressure system ; minimum sea depth of 50 m ; idea of, sufficiently far from equator to provide spin or twist / Coriolis effect ; idea of, rotating winds OR winds from different directions ; evaporation ; (gives rise to warm) moist air ; (air) rises and cools OR rises and draws in/up cooler air ; condensation ; release of latent heat ; idea of, this energy perpetuates cyclone further ; low wind-shear ; 5 A sea at least 26.5 °C A warm water at surface warm sea water unqualified is insufficient A circling / spiralling I strong wind unqualified Question Answer Marks Guidance 3(b) any five of ecosystem interaction between ; (community of) living organisms AND non-living components / biotic AND abiotic factors ; linked through, nutrient cycles ; (and) movement of, energy / nutrients, through, food chains / food webs ; biodiversity ref. number of species ; idea of, ref. evenness / relative abundance of each / AW ; (in an) ecosystem / habitat ; 5 3(c) any five of idea of, mangroves live in intertidal regions / delta regions / salt tolerant ; idea of, interlocking / thick / complex, root (system) ; idea of, protect from wave (action) ; energy dissipation ; reduction in, current / flow, speed ; reduce erosion ; increase sedimentation / fine sediment accumulates ; AVP ; 5 e.g. ref. extreme events

This question in 9693/23 May/June 2018

4 (a) Hydrothermal vent communities are areas of higher productivity than the surrounding areas. (i) State the meaning of the term community. … … … … [2] (ii) Describe how hydrothermal vents are formed. … … … … … … … … … … [5] (b) At hydrothermal vents, there is a mutualistic relationship between hydrothermal vent bacteria and tubeworms. Tropical coral polyps and zooxanthellae also have a mutualistic relationship. Discuss the similarities and differences between these two relationships. similarities … … … … … … … … differences … … … … … … … … [8] [Total: 15]

15 marks

This question in 9693/20 Oct/Nov 2018

4 (a) Explain how tectonic processes can lead to a tsunami. … … … … … … … … [4] (b) Outline the Darwin-Dana-Daly theory of atoll formation. … … … … … … … … … … [5] (c) Tidal range is affected by the relative positions of the Earth, Moon and Sun. Describe how other factors can affect the tidal range. … … … … … … … … … … … … [6] [Total: 15]

15 marks

Mark scheme: 4(a) any 4 of: movement of convergent / transform (plate) boundaries ; build-up of pressure / tension ; sudden release / sudden slippage; (of) large amounts of energy ; (from) earthquake below seabed / underwater earthquake ; (causing) vertical displacement of seabed ; large displacement of (sea)water ; 4 Question Answer Marks Guidance 4(b) any 5 of: 1 oceanic volcano emerges / volcanic island ; 2 colonised / settling, by, reef-building / hermatypic, coral OR colonised / settling, by coral polyps / coral larvae ; 3 so, fringing reef develops ; 4 volcano becomes dormant / extinct ; 5 volcano / island, begins to sink / subside ; 6 so, barrier reef develops ; 7 lagoon / description of, forms between reef and island ; 8 volcano / island, eventually sinks below sea level / disappears ; 5 Accept marking points from well labelled / annotated diagrams. I coral unqualified R if answer implies barrier formed before fringing 4(c) any 6 of: 1 shape / morphology / configuration / geomorphology, of coastline ; 2 funnelling / channelling, of water into small area increases range ; 3 slope / relief of shore ; 4 lower range on shallower relief ; 5 size / volume, of water body ; 6 larger body has greater range; 7 air / atmospheric pressure ; 8 lower pressure causes greater range / higher tide ; 9 speed / strength of wind; 10 greater wind speed increases range / higher tide ; 11 wind direction (onshore / offshore) ; 12 correct description e.g. onshore causing higher tide ; 6

This question in 9693/21 May/June 2019

3 (a) Explain the effect of volcanic activity on the chemical composition of sea water. … … … … … … … … … … [5] (b) Describe and explain the effects of evaporation and precipitation on the salinity of sea water. … … … … … … … … [4] (c) Explain how the concentration of dissolved oxygen varies with depth in the open ocean. … … … … … … … … … … … … [6] [Total: 15]

15 marks

Mark scheme: 3(a) any five from: 1 idea of, (named) salt / (named) mineral input from volcanoes (increases) salinity ; 2 volcanic gases contain, carbon dioxide / sulfur dioxide / hydrogen sulfide / hydrogen chloride ; 3 gases dissolve / (atmospheric) dissolution ; 4 carried into sea water in rain water / reference to hydrological cycle ; 5 (ions) enter water directly through underwater volcano / hydrothermal vent ; 6 idea of, (sea) water becomes more acidic / decreased pH ; 7 gases are less soluble in hot water ; 8 idea of, a lot of volcanic ash would raise pH ; 5 I mixing 3(b) any four from evaporation increases salinity ; evaporation removes water (leaves salt behind) ; ref. shallow seas / coastal ; direct precipitation adds (fresh) water / (fresh)-water run-off / melting glaciers (from precipitation) ; lowers salinity ; 4 effect is greater in shallow seas / along coastline 3(c) any six from high(est) at surface ; due to turbulence ; lots of producers / primary productivity (in surface layers) ; photosynthesis (releases oxygen) ; decrease with increasing depth (to oxygen minimum layer) ; lots of respiration vs photosynthesis ; usually at 500 m (allow 100 to 1000 m) ; at greater depths starts to increase ; lack of food – less respiration ; increase solubility with lower temperatures ; increasing pressure increases solubility ; 6

This question in 9693/22 May/June 2019

3 (a) Explain the effect of volcanic activity on the chemical composition of sea water. … … … … … … … … … … [5] (b) Describe and explain the effects of evaporation and precipitation on the salinity of sea water. … … … … … … … … [4] (c) Explain how the concentration of dissolved oxygen varies with depth in the open ocean. … … … … … … … … … … … … [6] [Total: 15]

15 marks

Mark scheme: 3(a) any five from: 1 idea of, (named) salt / (named) mineral input from volcanoes (increases) salinity ; 2 volcanic gases contain, carbon dioxide / sulfur dioxide / hydrogen sulfide / hydrogen chloride ; 3 gases dissolve / (atmospheric) dissolution ; 4 carried into sea water in rain water / reference to hydrological cycle ; 5 (ions) enter water directly through underwater volcano / hydrothermal vent ; 6 idea of, (sea) water becomes more acidic / decreased pH ; 7 gases are less soluble in hot water ; 8 idea of, a lot of volcanic ash would raise pH ; 5 I mixing 3(b) any four from evaporation increases salinity ; evaporation removes water (leaves salt behind) ; ref. shallow seas / coastal ; direct precipitation adds (fresh) water / (fresh)-water run-off / melting glaciers (from precipitation) ; lowers salinity ; 4 effect is greater in shallow seas / along coastline 3(c) any six from high(est) at surface ; due to turbulence ; lots of producers / primary productivity (in surface layers) ; photosynthesis (releases oxygen) ; decrease with increasing depth (to oxygen minimum layer) ; lots of respiration vs photosynthesis ; usually at 500 m (allow 100 to 1000 m) ; at greater depths starts to increase ; lack of food – less respiration ; increase solubility with lower temperatures ; increasing pressure increases solubility ; 6

This question in 9693/23 May/June 2019

4 (a) (i) Describe how hydrothermal vents are formed. … … … … … … … … [4] (ii) Succession occurs at newly formed hydrothermal vents. Explain the meaning of the term succession and describe the succession at hydrothermal vents. … … … … … … … … … … … … [6] (b) Ocean acidification is a threat to many marine ecosystems. Explain the causes and effects of ocean acidification. … … … … … … … … … … [5] [Total: 15]

15 marks

This question in 9693/20 Oct/Nov 2019

4 Hunga Tonga is an underwater volcano in the tropical South Pacific Ocean near Tonga. (a) Use the theory of plate tectonics to describe how the Hunga Tonga volcano formed. … … … … … … … … [4] (b) In January 2015 the Hunga Tonga volcano created a new island. It measured 500 m across and 250 m high. Use the Darwin-Dana-Daly theory to suggest what might eventually happen to the new island over time. … … … … … … … … [4] (c) Describe and explain how volcanic activity and other factors can affect the concentration of dissolved gases in sea water. … … … … … … … … … … … … … … [7] [Total: 15]

15 marks

Mark scheme: 4(a) any 4 from: volcano will have formed at plate boundary ; named plate boundary, convergent or divergent ; magma / lava / molten rock, released from below Earth’s crust / from mantle ; (lava) cools AND solidifies ; forms new igneous rock ; ref. to formation in subduction zone ; Question Answer Marks 4(b) any 4 from: 1 colonised / settling, by, reef-building / hermatypic, coral OR colonised / settling, by coral polyps / coral larvae ; 2 so, fringing reef develops ; 3 volcano becomes dormant / extinct ; 4 volcano / island, begins to sink / subside ; 5 so, barrier reef develops ; 6 lagoon / description of, forms between reef and island ; 7 volcano / island, eventually sinks below sea level / disappears ; 4 Question Answer Marks 4(c) any 7 from: 1 gases from volcanic action dissolve ; 2 named volcanic gas ; 3 change in temperature ; 4 higher temperature decreases solubility / ORA ; 5 suggested cause for change e.g. vent / volcano / glacial melt / global warming ; 6 wave action ; 7 (increased turbulence) increases dissolution ; 8 salinity ; 9 increased salinity decreases solubility / ORA ; 10 pressure ; 11 increased pressure increases solubility / ORA ; 12 ref to photosynthesis, increasing O2 / decreasing CO2 ; 13 ref to respiration, decreasing O2 / increasing CO2 ; 7

This question in 9693/22 May/June 2020

4 Hunga Tonga is an underwater volcano in the tropical South Pacific Ocean near Tonga. (a) Use the theory of plate tectonics to describe how the Hunga Tonga volcano formed. … … … … … … … … [4] (b) In January 2015 the Hunga Tonga volcano created a new island. It measured 500 m across and 250 m high. Use the Darwin-Dana-Daly theory to suggest what might eventually happen to the new island over time. … … … … … … … … [4] (c) Describe and explain how volcanic activity and other factors can affect the concentration of dissolved gases in sea water. … … … … … … … … … … … … … … [7] [Total: 15]

15 marks

Mark scheme: 4(a) any 4 from: 4 volcano will have formed at plate boundary ; named plate boundary, convergent or divergent ; magma / lava / molten rock, released from below Earth’s crust / from mantle ; (lava) cools AND solidifies ; forms new igneous rock ; ref. to formation in subduction zone ; 4(b) any 4 from: 4 1 colonised / settling, by, reef-building / hermatypic, coral OR colonised / settling, by coral polyps / coral larvae ; 2 so, fringing reef develops ; 3 volcano becomes dormant / extinct ; 4 volcano / island, begins to sink / subside ; 5 so, barrier reef develops ; 6 lagoon / description of, forms between reef and island ; 7 volcano / island, eventually sinks below sea level / disappears ; 4(c) any 7 from: 7 1 gases from volcanic action dissolve ; 2 named volcanic gas ; 3 change in temperature ; 4 higher temperature decreases solubility / ORA ; 5 suggested cause for change e.g. vent / volcano / glacial melt / global warming ; 6 wave action ; 7 (increased turbulence) increases dissolution ; 8 salinity ; 9 increased salinity decreases solubility / ORA ; 10 pressure ; 11 increased pressure increases solubility / ORA ; 12 ref to photosynthesis, increasing O2 / decreasing CO2 ; 13 ref to respiration, decreasing O2 / increasing CO2 ;

This question in 9693/23 May/June 2020

4 (a) Explain why volcanoes occur along plate boundaries that are spreading apart (divergent plate boundaries) but not usually along plate boundaries that slide past each other (transform boundaries). … … … … … … … … [4] (b) Describe how volcanic activity can affect the chemical composition of sea water. … … … … … … … … … … [5] (c) Explain how the environment around a hydrothermal vent affects the biodiversity of the organisms living there. … … … … … … … … … … … … [6] [Total: 15]

15 marks

This question in 9693/20 Oct/Nov 2020

3 (a) (i) Explain why hydrothermal vents are described as extreme environments. … … … … … … [3] (ii) Explain the meaning of the term succession. Use examples from hydrothermal vent communities in your answer. … … … … … … … … … … [5] (b) Describe the theory of plate tectonics. Include evidence that supports the theory. … … … … … … … … … … … … … … [7] [Total: 15]

15 marks

Mark scheme: 3(a)(i) any 3 of: (few) organisms, adapted / able, to tolerate / survive conditions ; high / intense pressure (at great depth) ; high temperature (of water leaving vents)… ; causing lack of oxygen ; water with, low pH / highly acidic / high salinity / high mineral content, around vent ; named mineral ion / toxic gas ; 3(a)(ii) two examples of an organism from hydrothermal vents ; plus any 4 of: (idea of) change in community structure ; over time ; one species replaces another ; (initial colonisation by) pioneer species ; climax community ; (idea of) one species helping create conditions for subsequent species ; 5 Question Answer Marks 3(b) any 7 of: Theory: 1 Earth’s crust / lithosphere made up of plates ; 2 (plates float) on mantle / asthenosphere ; 3 (plates) moving / colliding / sliding AW ; 4 convection currents in magma / mantle below plate is moving ; 5 driven by heat / density ; Evidence: 6 fit (like jigsaw puzzles) between coastlines of continents ; 7 ref. to distribution of fossils / palaeontology; 8 distribution of similar terrestrial living creatures, e.g. marsupials in Australia and S. America 9 ref. similarities in rock, types / ages ; 10 magnetic stripes (in rocks) on the ocean floor / sea bed ; 11 stated activity near plate boundaries ; 7

This question in 9693/21 May/June 2021

4 (a) Describe how abyssal plains form on the sea bed. … … … … … … [3] (b) Marine snow is the remains of dead organisms and faeces that sink to the abyssal plain from above. (i) Explain why most food chains on the abyssal plain depend on marine snow as a source of energy. … … … … … … … … [4] (ii) Marine snow also provides nutrients for organisms living on the abyssal plain. State the roles of different named examples of nutrients in marine organisms. … … … … … … … … … … … … … … … … [8] [Total: 15]

15 marks

Mark scheme: 4(a) any 3 from: between mid-ocean ridges and continental rise ; upwards movement of molten material / magma ; which solidifies and forms new ocean crust ; ref. mantle convection ; uneven rock surface becomes covered by sediments from above ; Question Answer Marks 4(b)(i) any 4 from: absence of light (on deep ocean floor) ; absence of photosynthetic organisms ; lack of primary productivity / synthesis of organic molecules by producers ; cold temperatures ; limited input from chemosynthesis ; 4 4(b)(ii) any 8 from: (source of) nitrogen ; required for protein synthesis / amino acids / DNA / RNA / ATP ; (source of) calcium ; required for bones / shells ; (source of) phosphorus ; required for bone / DNA / RNA / ATP ; (source of) carbon ; (required for) organic molecules ; (source of) magnesium ; required for chlorophyll / bones ; other correct named example ; other correct use ; 8

This question in 9693/22 May/June 2021

4 (a) Describe how abyssal plains form on the sea bed. … … … … … … [3] (b) Marine snow is the remains of dead organisms and faeces that sink to the abyssal plain from above. (i) Explain why most food chains on the abyssal plain depend on marine snow as a source of energy. … … … … … … … … [4] (ii) Marine snow also provides nutrients for organisms living on the abyssal plain. State the roles of different named examples of nutrients in marine organisms. … … … … … … … … … … … … … … … … [8] [Total: 15]

15 marks

Mark scheme: 4(a) any 3 from: between mid-ocean ridges and continental rise ; upwards movement of molten material / magma ; which solidifies and forms new ocean crust ; ref. mantle convection ; uneven rock surface becomes covered by sediments from above ; Question Answer Marks 4(b)(i) any 4 from: absence of light (on deep ocean floor) ; absence of photosynthetic organisms ; lack of primary productivity / synthesis of organic molecules by producers ; cold temperatures ; limited input from chemosynthesis ; 4 4(b)(ii) any 8 from: (source of) nitrogen ; required for protein synthesis / amino acids / DNA / RNA / ATP ; (source of) calcium ; required for bones / shells ; (source of) phosphorus ; required for bone / DNA / RNA / ATP ; (source of) carbon ; (required for) organic molecules ; (source of) magnesium ; required for chlorophyll / bones ; other correct named example ; other correct use ; 8

This question in 9693/23 May/June 2021

5 A mid-ocean ridge is a tectonic feature found in the Earth’s crust in the larger oceans. (a) (i) Name the type of plate boundary usually found at a mid-ocean ridge. … … [1] (ii) Explain how the ocean floor forms at this plate boundary. … … … … … … [3] (b) A magnetometer is a scientific instrument that is used to survey the magnetic polarity of rocks on the ocean floor. A survey ship towed a magnetometer in a straight line for 100 km as it passed across a mid-ocean ridge. The direction of travel was perpendicular (at right angles) to the position of the mid-ocean ridge, as shown in Fig. 5.1. aerial view of ship direction of ship travel mid-ocean ridge NOT TO SCALE Fig. 5.1 Fig. 5.2 shows the data that was collected. magnetometer magnetic signal Z positive magnetic + anomaly 0 negative magnetic – anomaly 0 10 20 30 40 50 60 70 80 90 100 distance travelled by survey ship / km Fig. 5.2 (i) Explain the pattern shown by the data in Fig. 5.2. … … … … [2] (ii) Suggest how many kilometres the boat had travelled before it was directly over the centre of the mid-ocean ridge. Explain your answer. … … … … [2] (iii) The ocean floor at this mid-ocean ridge is spreading at a rate of 0.02 m per year. Use this information to estimate the age of rocks at point Z. … [1] (c) Research suggests a link between ocean floor spreading and the carbon cycle, as the formation of rock will act as a sink for carbon. Fig. 5.3 on page 23 shows data for atmospheric carbon dioxide concentration in parts per million (ppm), the total global length of mid-ocean ridge plate boundaries, and the mean rate of ocean floor spreading. Discuss whether the data shown in Fig. 5.3 support the idea that there is a link between ocean floor spreading and the carbon cycle. Explain your answer. … … … … … … … … … … [4] [Total: 13]

13 marks

Mark scheme: 5(a)(i) divergent ; 1 5(a)(ii) any three from: as plate boundaries move apart ; molten magma (from mantle) pushes through crust ; driven by convection currents in mantle ; solidifies due to (cold) sea water ; 3 5(b)(i) any two from: idea of, the polarity of the rocks reverses at different points (on the seabed) ; idea of, polarity of rocks determined when rocks formed ; Earth’s magnetic field reverses over time ; 2 5(b)(ii) 45 km ; pattern either side of ridge will be symmetrical ; 2 5(b)(iii) 1 500 000 years old ; 1 Question Answer Marks 5(c) any four from: (supported as) overall concentration of CO2 has decreased over time AND length of plate boundaries has increased ; (not supported as) concentration of CO2 and length of plate boundaries do not, mirror each other exactly / follow / AW ; between 120 mya and present day, plate boundary length decreased yet concentration of CO2 decreased; rate of seafloor spreading decreased over time but concentration of CO2 decreasing ; idea of correlation not being evidence of causation ; 4

This question in 9693/22 May/June 2022

5 A mid-ocean ridge is a tectonic feature found in the Earth’s crust in the larger oceans. (a) (i) Name the type of plate boundary usually found at a mid-ocean ridge. … … [1] (ii) Explain how the ocean floor forms at this plate boundary. … … … … … … [3] (b) A magnetometer is a scientific instrument that is used to survey the magnetic polarity of rocks on the ocean floor. A survey ship towed a magnetometer in a straight line for 100 km as it passed across a mid-ocean ridge. The direction of travel was perpendicular (at right angles) to the position of the mid-ocean ridge, as shown in Fig. 5.1. aerial view of ship direction of ship travel mid-ocean ridge NOT TO SCALE Fig. 5.1 Fig. 5.2 shows the data that was collected. magnetometer magnetic signal Z positive magnetic + anomaly 0 negative magnetic – anomaly 0 10 20 30 40 50 60 70 80 90 100 distance travelled by survey ship / km Fig. 5.2 (i) Explain the pattern shown by the data in Fig. 5.2. … … … … [2] (ii) Suggest how many kilometres the boat had travelled before it was directly over the centre of the mid-ocean ridge. Explain your answer. … … … … [2] (iii) The ocean floor at this mid-ocean ridge is spreading at a rate of 0.02 m per year. Use this information to estimate the age of rocks at point Z. … [1] (c) Research suggests a link between ocean floor spreading and the carbon cycle, as the formation of rock will act as a sink for carbon. Fig. 5.3 on page 23 shows data for atmospheric carbon dioxide concentration in parts per million (ppm), the total global length of mid-ocean ridge plate boundaries, and the mean rate of ocean floor spreading. Discuss whether the data shown in Fig. 5.3 support the idea that there is a link between ocean floor spreading and the carbon cycle. Explain your answer. … … … … … … … … … … [4] [Total: 13]

13 marks

Mark scheme: 5(a)(i) divergent ; 1 5(a)(ii) any 3 from: as plate boundaries move apart ; molten magma (from mantle) pushes through crust ; driven by convection currents in mantle ; solidifies due to (cold) sea water ; 3 5(b)(i) any 2 from: idea of, the polarity of the rocks reverses at different points (on the seabed) ; idea of, polarity of rocks determined when rocks formed ; Earth’s magnetic field reverses over time ; 2 5(b)(ii) 45 km ; pattern either side of ridge will be symmetrical ; 2 5(b)(iii) 1 500 000 years old ; 1 Question Answer Marks 5(c) any 4 from: (supported as) overall concentration of CO2 has decreased over time AND length of plate boundaries has increased ; (not supported as) concentration of CO2 and length of plate boundaries do not, mirror each other exactly / follow / AW ; between 120 mya and present day, plate boundary length decreased yet concentration of CO2 decreased; rate of seafloor spreading decreased over time but concentration of CO2 decreasing ; idea of correlation not being evidence of causation ; 4

This question in 9693/23 May/June 2022

5 (a) Magnesium sulfate and sodium chloride are examples of solutes. (i) Define the term solute. … … [1] (ii) State the chemical formulae for magnesium sulfate and sodium chloride. magnesium sulfate … sodium chloride … [1] A student investigated the solubility of magnesium sulfate and sodium chloride in water at different temperatures. (b) (i) Describe how the student could determine the solubility of each salt in water. … … … … [2] Fig. 5.1 shows the student’s results. 500 magnesium sulfate 400 sodium chloride solubility 300/ g dm–3 200 100 0 5 10 15 20 25 30 35 water temperature / °C Fig. 5.1 Table 5.1 shows the ocean surface temperature at a location in the Atlantic Ocean and at a location in the Indian Ocean. Table 5.1 ocean location ocean surface temperature / °C Atlantic Ocean 8 Indian Ocean 27 (ii) Use the results in Fig. 5.1 and the information in Table 5.1 to compare the solubilities of magnesium sulfate and sodium chloride at the two ocean locations. … … … … … … [3] (c) Hydrothermal vents are usually found along plate boundaries close to mid-ocean ridges. (i) State the type of plate boundary found at mid-ocean ridges. … [1] The water coming out of these hydrothermal vents is usually under pressure, at a high temperature and contains a high concentration of dissolved salts. (ii) Explain how chimneys form at hydrothermal vents. Use the trends shown in Fig. 5.1 and your own knowledge in your answer. … … … … … … [3]

11 marks

Mark scheme: 5(a)(i) a substance / chemical, that dissolves in a solvent ; 1 5(a)(ii) MgSO4 AND NaCl ; 1 5(b)(i) use a known volume of water ; determine mass of salt that dissolves ; 2 Question Answer Marks 5(b)(ii) any 3 from: 1 The Atlantic Ocean is colder than the Indian Ocean ORA ; 2 Magnesium sulphate is more soluble (than sodium chloride), in the Indian Ocean / at 27 °C ORA ; 3 both sodium chloride and magnesium sulphate are more soluble in the Indian ocean / at 27 °C ORA ; 4 Sodium chloride is more soluble than magnesium sulphate, in the Atlantic Ocean / 8 °C ORA ; 5 There is a greater difference in the solubility between magnesium sulphate and sodium chloride in the Atlantic Ocean (compared to the Indian Ocean) ORA ; 6 comparing manipulated data ; ; 3 5(c)(i) divergent / constructive ; 1 5(c)(ii) solubility of, salts / minerals, higher at high temperature / minerals dissolve in the water as it’s heated ; sudden cooling reduces solubility ; idea of cold (water) causing, salts / minerals, deposited / precipitate / build up / settle around the (vent)(to form chimney) ; 3 5(d)(i) 117–55 ; 62 (cm per year) ; 2 5(d)(ii) ppt ; 1 5(d)(iii) 1.8 (ppt) ; 1 5(d)(iv) salinity at 50 °N is lower than 30 °S ORA ; at 50 °N precipitation is (much) greater (than evaporation) ORA for 30 °S OR at 30 °S precipitation is (much) lower (than evaporation) ORA for 50 °N ; 2

This question in 9693/21 May/June 2024

7 (a) A major earthquake resulted in the formation of a tsunami. The earthquake occurred at the plate boundary shown in Fig. 7.1. ocean continental oceanic crust crust mantle mantle Fig. 7.1 (i) Explain why the earthquake occurred at the plate boundary shown in Fig. 7.1. … … … … … … [3] (ii) Explain how the earthquake formed a tsunami. … … … … [2] (b) Table 7.1 shows the height of the tsunami at fishing ports along the coast close to the centre of the earthquake. Table 7.1 coastal location maximum tsunami height / m 1 9.9 2 8.1 3 18.9 4 14.6 5 34.7 (i) Suggest why the height of the tsunami varied so much, using ideas about the geomorphology of coastlines. … … … … … [2] (ii) Explain how the tsunami caused weathering and erosion along the coastline. … … … … … [2] (iii) Suggest possible impacts of the tsunami on a sandy shore, other than weathering and erosion. … … … … … [2] [Total: 11]

11 marks

Mark scheme: 7(a)(i) any 3 from: 3 idea of (convergent) plates stuck / movement not occurring (towards each other) ; causing build up of, pressure / tension (in the plates) ; sudden slippage of the plates ; releasing large amount of energy (during earthquake) ; 7(a)(ii) any 2 from: 2 large volume / body of water AND displaced / moves ; idea of pushed upwards / drops down / vertical displacement (of water) ; idea of (water / tsunami wave) moves away from the source of the earthquake event / tsunami (wave) (redistributing the water level) ; 7(b)(i) any 2 from: 2 idea that funnel shaped bays would result in water being pushed higher as the channel gets narrower ; (differences in relative) steepness of the shore / coast / depth of water ; relative orientation of the (fishing) port to incoming tsunami ; 7(b)(ii) (weathering) idea of (water) breaking rock / sediment (into smaller pieces) ; 2 (erosion) idea of sediments (re)moved by the water ; 7(b)(iii) removal / deposit of organisms on shoreline ; 2 deposition of waste / debris from inland (after waves recede) ;

This question in 9693/21 Oct/Nov 2024

7 (a) A major earthquake resulted in the formation of a tsunami. The earthquake occurred at the plate boundary shown in Fig. 7.1. ocean continental oceanic crust crust mantle mantle Fig. 7.1 (i) Explain why the earthquake occurred at the plate boundary shown in Fig. 7.1. … … … … … … [3] (ii) Explain how the earthquake formed a tsunami. … … … … [2] (b) Table 7.1 shows the height of the tsunami at fishing ports along the coast close to the centre of the earthquake. Table 7.1 coastal location maximum tsunami height / m 1 9.9 2 8.1 3 18.9 4 14.6 5 34.7 (i) Suggest why the height of the tsunami varied so much, using ideas about the geomorphology of coastlines. … … … … … [2] (ii) Explain how the tsunami caused weathering and erosion along the coastline. … … … … … [2] (iii) Suggest possible impacts of the tsunami on a sandy shore, other than weathering and erosion. … … … … … [2] [Total: 11]

11 marks

Mark scheme: 7(a)(i) any 3 from: 3 idea of (convergent) plates stuck / movement not occurring (towards each other) ; causing build up of, pressure / tension (in the plates) ; sudden slippage of the plates ; releasing large amount of energy (during earthquake) ; 7(a)(ii) any 2 from: 2 large volume / body of water AND displaced / moves ; idea of pushed upwards / drops down / vertical displacement (of water) ; idea of (water / tsunami wave) moves away from the source of the earthquake event / tsunami (wave) (redistributing the water level) ; 7(b)(i) any 2 from: 2 idea that funnel shaped bays would result in water being pushed higher as the channel gets narrower ; (differences in relative) steepness of the shore / coast / depth of water ; relative orientation of the (fishing) port to incoming tsunami ; 7(b)(ii) (weathering) idea of (water) breaking rock / sediment (into smaller pieces) ; 2 (erosion) idea of sediments (re)moved by the water ; 7(b)(iii) removal / deposit of organisms on shoreline ; 2 deposition of waste / debris from inland (after waves recede) ;

This question in 9693/22 Oct/Nov 2024

7 (a) A major earthquake resulted in the formation of a tsunami. The earthquake occurred at the plate boundary shown in Fig. 7.1. ocean continental oceanic crust crust mantle mantle Fig. 7.1 (i) Explain why the earthquake occurred at the plate boundary shown in Fig. 7.1. … … … … … … [3] (ii) Explain how the earthquake formed a tsunami. … … … … [2] (b) Table 7.1 shows the height of the tsunami at fishing ports along the coast close to the centre of the earthquake. Table 7.1 coastal location maximum tsunami height / m 1 9.9 2 8.1 3 18.9 4 14.6 5 34.7 (i) Suggest why the height of the tsunami varied so much, using ideas about the geomorphology of coastlines. … … … … … [2] (ii) Explain how the tsunami caused weathering and erosion along the coastline. … … … … … [2] (iii) Suggest possible impacts of the tsunami on a sandy shore, other than weathering and erosion. … … … … … [2] [Total: 11]

11 marks

Mark scheme: 7(a)(i) any 3 from: 3 idea of (convergent) plates stuck / movement not occurring (towards each other) ; causing build up of, pressure / tension (in the plates) ; sudden slippage of the plates ; releasing large amount of energy (during earthquake) ; 7(a)(ii) any 2 from: 2 large volume / body of water AND displaced / moves ; idea of pushed upwards / drops down / vertical displacement (of water) ; idea of (water / tsunami wave) moves away from the source of the earthquake event / tsunami (wave) (redistributing the water level) ; 7(b)(i) any 2 from: 2 idea that funnel shaped bays would result in water being pushed higher as the channel gets narrower ; (differences in relative) steepness of the shore / coast / depth of water ; relative orientation of the (fishing) port to incoming tsunami ; 7(b)(ii) (weathering) idea of (water) breaking rock / sediment (into smaller pieces) ; 2 (erosion) idea of sediments (re)moved by the water ; 7(b)(iii) removal / deposit of organisms on shoreline ; 2 deposition of waste / debris from inland (after waves recede) ;

This question in 9693/23 Oct/Nov 2024

3 Hydrothermal vents occur close to plate boundaries. (a) State the type of plate boundary where ocean floor spreading occurs. … … [1] (b) Scientists investigated whether the rate of ocean floor spreading affects the number of hydrothermal vents along the length of an ocean ridge. Table 3.1 shows the data collected by the scientists. Table 3.1 rate of ocean floor spreading mean number of hydrothermal / mm per year vents per 100 km 39 1.8 55 2.5 67 3.1 88 3.6 100 4.0 115 4.8 140 6.2 (i) Plot a line graph showing the relationship between the rate of ocean floor spreading and the mean number of hydrothermal vents. [4] (ii) Name the statistical test that could be used to test if there is a correlation between the two variables. … … [1] (c) A probe was moved at a fixed depth into the vent plume over a total distance of 6 km, as shown in Fig. 3.1. vent plume horizontal movement of probe through plume hydrothermal vent Fig. 3.1 Fig. 3.2 shows the concentration of hydrogen sulfide and the turbidity of the water recorded by the probe across the hydrothermal vent plume. 1.50 3.0 Key turbidity concentration of 1.25 2.5 hydrogen sulfide 1.00 2.0 concentration of hydrogen turbidity 0.75 1.5 sulfide / a.u. / nmol dm–3 0.50 1.0 0.25 0.5 0 0.0 0 2 4 6 distance moved by probe / km start of vent plume Fig. 3.2 (i) Compare the trends for the concentration of hydrogen sulfide and the turbidity of the water shown in Fig. 3.2. … … … … … … [3] (ii) Use Fig. 3.2 to calculate the range in turbidity recorded by the probe. … a.u. [1] (iii) State two other conditions in the sea water that are affected by the hydrothermal vent plume. 1 … 2 … [2] (iv) Suggest how conditions caused by the hydrothermal vent plume affect the organisms in the surrounding water. … … … … … … [3] [Total: 15]

15 marks

Mark scheme: 3(a) divergent (plate boundary) ; 1 3(b)(i) both axes labelled with units ; 4 suitable linear scale ; points, plotted correctly  ½ small square ; suitable line ; rate of ocean floor spreading / mm mean number of hydrothermal per year vents per 100 km 39 1.8 55 2.5 67 3.1 88 3.6 100 4.0 115 4.8 140 6.2 3(b)(ii) Spearman’s (rank); 1 3(c)(i) any three from: 3 both factors start low; both factors show increase AND decrease (thereafter) ; both factors increase more rapidly than they decrease ; decrease in hydrogen sulfide concentration more rapid than turbidity / ORA ; both peak at (around) the same distance / both reach their highest point at the same distance / both peak at 2 km ; concentration of hydrogen sulfide has a larger range than the turbidity ; 3(c)(ii) 2.2 / 2.20 (a.u) ; 1 3(c)(iii) any two from: 2 temperature ; pH ; (dissolved) oxygen concentration ; salinity ; density ; 3(c)(iv) any three from: 3 organisms cannot tolerate extreme conditions in the plume / temperature of water is beyond that suitable for organisms to survive / ORA ; dissolved, minerals / ions AND affect / lower pH / more acidic, (of) water which organisms cannot tolerate ; temperature change AND affects solubility of gases so there is less O2 available (for organisms) ; temperature change AND could affect growth rates (of organisms) ; increased turbidity AND affects bioluminescent organisms ; increases biodiversity / productivity ; (availability of) hydrogen sulfide for, chemosynthetic organisms / Endoriftia* producers / chemosynthesis ; AVP ;

This question in 9693/21 May/June 2025

3 (a) State three conditions that affect the density of sea water. 1 … 2 … 3 … [2] (b) (i) The density of small, irregular-shaped rocks was investigated. Outline a method that could be used to collect the data needed to calculate the density. … … … … … … [3] (ii) Draw a table to record the data needed to calculate the density from the method planned in 3(b)(i). Include full headings and units in the results table. Do not write in any results. [2] (c) Pumice is one type of rock produced by volcanic activity along a mid-ocean ridge. (i) Explain how a mid-ocean ridge is formed. … … … … … … [3] Fig. 3.1 shows a pumice rock. Pumice contains large air spaces. These spaces are created by bubbles of gas in the lava when the rock forms. 1 cm Fig. 3.1 A student investigated the density of pumice. The results are shown in Table 3.1. The data contains an anomalous result. Table 3.1 sample density / kg m–3 1 806 2 954 3 910 4 923 5 946 mean … (ii) Calculate the mean density for the samples. Do not include the anomalous result. Write your answer in Table 3.1. [1] (iii) Suggest two reasons why the measurements for the density of pumice samples shown in Table 3.1 show a wide variation. 1 … … 2 … … [2] (iv) Pure water has a density of 998.2 kg m–3 at 20 °C. Use Fig. 3.1 and your answer to 3(c)(ii) to explain why recording accurate measurements of the density of the samples of pumice in Table 3.1 was difficult. … … … … … … … … [4] (d) Pumice is found as rounded porous rocks on shorelines and beaches at many locations around the world. (i) Explain why pumice from the mid-ocean ridge in the Atlantic is found on beaches all around the world. … … … … [2] (ii) Suggest why pumice rocks are rounded in shape and found on beaches. … … … … … … [3] [Total: 22]

22 marks

Mark scheme: 3(a) temperature ; 2 salinity ; pressure ; 3(b)(i) (use a balance to) measure the mass ; 3 (use a measuring cylinder) to measure the volume ; use of measuring cylinder AND (electronic) balance ; 3(b)(ii) headings for mass and volume ; 2 correct units for mass and volume ; 3(c)(i) any three from: 3 idea of convection currents causing plate movement ; idea of (mid-Atlantic / mid-ocean ridge is) divergent (plate) boundary ; idea of molten rock / lava / magma, moving up from mantle ; idea of solidification of, molten rock / magma / lava ; 3(c)(ii) 933.25 1 3(c)(iii) any two from: 2 idea that pores could vary in size ; idea that the conditions in the eruption could be different e.g. temperature or cooling rates ; idea that samples may come from different eruptions / contain different minerals ; idea that water may not enter all the pores ; idea that magma contains variable volumes of gas ; 3(c)(iv) any four from: 4 idea that density of samples is, less / lower, than density of water ; pumice will float ; idea that it is difficult to fully submerge the samples ; idea of may not be dry / water may be in the holes in the rock ; idea of increased mass recorded ; idea of decreased volume recorded ; idea of temperature not 20 °C AND affecting, density / volume ; 3(d)(i) idea that (horizontal / surface) currents move the pumice ; 2 idea that oceans and sea are all connected ; 3(d)(ii) idea that weathering has occurred ; 3 description of physical weathering as stones / rocks banging against each other (resulting in rounded shape) ; idea of deposition of sediment onto beaches ;

This question in 9693/22 May/June 2025

3 (a) State three conditions that affect the density of sea water. 1 … 2 … 3 … [2] (b) (i) The density of small, irregular-shaped rocks was investigated. Outline a method that could be used to collect the data needed to calculate the density. … … … … … … [3] (ii) Draw a table to record the data needed to calculate the density from the method planned in 3(b)(i). Include full headings and units in the results table. Do not write in any results. [2] (c) Pumice is one type of rock produced by volcanic activity along a mid-ocean ridge. (i) Explain how a mid-ocean ridge is formed. … … … … … … [3] Fig. 3.1 shows a pumice rock. Pumice contains large air spaces. These spaces are created by bubbles of gas in the lava when the rock forms. 1 cm Fig. 3.1 A student investigated the density of pumice. The results are shown in Table 3.1. The data contains an anomalous result. Table 3.1 sample density / kg m–3 1 806 2 954 3 910 4 923 5 946 mean … (ii) Calculate the mean density for the samples. Do not include the anomalous result. Write your answer in Table 3.1. [1] (iii) Suggest two reasons why the measurements for the density of pumice samples shown in Table 3.1 show a wide variation. 1 … … 2 … … [2] (iv) Pure water has a density of 998.2 kg m–3 at 20 °C. Use Fig. 3.1 and your answer to 3(c)(ii) to explain why recording accurate measurements of the density of the samples of pumice in Table 3.1 was difficult. … … … … … … … … [4] (d) Pumice is found as rounded porous rocks on shorelines and beaches at many locations around the world. (i) Explain why pumice from the mid-ocean ridge in the Atlantic is found on beaches all around the world. … … … … [2] (ii) Suggest why pumice rocks are rounded in shape and found on beaches. … … … … … … [3] [Total: 22]

22 marks

Mark scheme: 3(a) temperature ; 2 salinity ; pressure ; 3(b)(i) (use a balance to) measure the mass ; 3 (use a measuring cylinder) to measure the volume ; use of measuring cylinder AND (electronic) balance ; 3(b)(ii) headings for mass and volume ; 2 correct units for mass and volume ; 3(c)(i) any three from: 3 idea of convection currents causing plate movement ; idea of (mid-Atlantic / mid-ocean ridge is) divergent (plate) boundary ; idea of molten rock / lava / magma, moving up from mantle ; idea of solidification of, molten rock / magma / lava ; 3(c)(ii) 933.25 1 3(c)(iii) any two from: 2 idea that pores could vary in size ; idea that the conditions in the eruption could be different e.g. temperature or cooling rates ; idea that samples may come from different eruptions / contain different minerals ; idea that water may not enter all the pores ; idea that magma contains variable volumes of gas ; 3(c)(iv) any four from: 4 idea that density of samples is, less / lower, than density of water ; pumice will float ; idea that it is difficult to fully submerge the samples ; idea of may not be dry / water may be in the holes in the rock ; idea of increased mass recorded ; idea of decreased volume recorded ; idea of temperature not 20 °C AND affecting, density / volume ; 3(d)(i) idea that (horizontal / surface) currents move the pumice ; 2 idea that oceans and sea are all connected ; 3(d)(ii) idea that weathering has occurred ; 3 description of physical weathering as stones / rocks banging against each other (resulting in rounded shape) ; idea of deposition of sediment onto beaches ;

This question in 9693/23 May/June 2025