Biodiversity — Paper 2 · A Level Marine Science 9693

3 (a) Explain what is meant by the term succession and give one example from the marine environment. … … … … … … [3] (b) Explain how the processes of erosion and sedimentation give rise to the formation of muddy shores and rocky shores. … … … … … … … … … … … … [6] (c) Discuss the factors that can lead to a transition from the growth of a coral reef to reef erosion. … … … … … … … … … … … … … … [6] [Total: 15]

15 marks

Mark scheme: 3(a) idea of, change in community (structure) / change in numbers of different species ; over time ; e.g. (Tevnia replaced with Riftia) at hydrothermal vents ; 3 A other marine examples, e.g. succession on a whale carcass or on an artificial reef Individual species names are not required, but a relevant successional scenario is required Question Answer Marks Guidance 3(b) any six of: 1 idea of, erosion explained as removal of particles / sediment / silt ; 2 idea of, sedimentation as settling of particles / sediment / silt ; 3 rocky shore develops where there is (a lot of) erosion ; 4 rate of erosion exceeds sedimentation (at rocky shores) ; 5 rocky shores associated with (fast) currents / (strong) wave action ; 6 muddy shores develop where there is (a lot of) sedimentation ; 7 rate of sedimentation exceeds erosion (at muddy shores) ; 8 muddy shores associated with slow water flow / low, wave energy / action (which encourages sedimentation) ; 9 credit reference to different sized particles ; 6 (silt particle size 0.02 mm or smaller) Question Answer Marks Guidance 3(c) any 6 of: 1 damage due to, storms / cyclones / physical effects ; 2 drying / exposure to air ; 3 temperature change / global warming ; 4 causes bleaching / loss of zooxanthellae ; 5 presence of predators / crown of thorns starfish (COTS) / parrot fish / corals are eaten ; 6 increased carbon dioxide / acid rain ; 7 decreased pH / increased acidity ; 8 dissolves coral skeleton / can’t form (CaCO3) exoskeleton ; 9 sedimentation / sediment / silt, blocks mouth of polyp / physical damage ; 10 damage due to named human disturbance ; 11 idea of, nutrient enrichment / chemicals in run off ; 12 leading to, eutrophication / algal growth / toxicity to coral ; 13 blocking / reduction, of light (by sediment / turbidity / algae) ; 14 (coral) disease ; 6 A H+ increase as a decrease in pH e.g. tourist trampling, blast fishing, dredging, anchorage of boats

This question in 9693/21 May/June 2017

1 A diversity index (D ) can be used to compare the biodiversity of two habitats. One diversity index is calculated using the formula N (N - 1 ) D = - 1 ) /n (n where N is the total number of organisms found n is the number of individuals of each species / means ‘the sum of’. For this diversity index, a higher value of D indicates a higher biodiversity. Researchers carried out an investigation to compare the biodiversity of two rocky shores, shore A and shore B. Ten random samples were taken on each shore, using a quadrat, and the numbers of each species were recorded. Table 1.1 shows the results of this investigation. Table 1.1 number of each species found (n) common name of species shore A shore B beadlet anemone 3 7 dog whelk 12 16 limpet 5 11 mussel 18 23 periwinkle 6 14 shore crab 2 3 topshell 4 5 Table 1.2 shows some of the stages in the calculation of the diversity index, for shore A. Table 1.2 common name of species number (n) on shore A n(n-1) beadlet anemone 3 6 dog whelk 12 132 limpet 5 20 mussel 18 306 periwinkle 6 30 shore crab 2 2 topshell 4 12 Total (N ) = 50 /n(n-1) = 508 (a) Complete Table 1.3, by calculating N, n(n-1) and /n(n-1) for shore B. Write your answers in the spaces in Table 1.3. Table 1.3 common name of species number (n) on shore B n(n-1) beadlet anemone 7 dog whelk 16 limpet 11 mussel 23 periwinkle 14 shore crab 3 topshell 5 Total (N ) = /n(n-1) = [3] (b) The diversity index for shore A is 4.8. Use the information in Table 1.3 to calculate the diversity index for shore B. Show your working. … [2] (c) Compare the biodiversity of shore A with the biodiversity of shore B. … … … … … … [3] (d) Based on the results of this investigation, the researchers proposed the following hypothesis. Dog whelks and mussels are more numerous than other species on rocky shores. State two variables you would need to control in a further investigation to test this hypothesis. 1 … 2 … [2] [Total: 10]

10 marks

Mark scheme: 1(a) number (n) n(n–1) 7 42 16 240 11 110 23 506 14 182 3 6 5 20 ; Total (N) = 79 ; Σn(n–1) = 1106 ; 3 for 1 mark 1(b) figures correctly substituted into formula ; 79 × 78 / 1106 diversity index for shore B = 5.6 ; 2 A ECF from 1(a) 1(c) any 3 of: shore B has a higher biodiversity than shore A ; both shores have the same (7) number of species present / same species richness ; idea that shore B has higher populations of each species than shore A ; total number of organisms greater at shore B / shore B has 29 more organisms ; 3 Question Answer Marks Guidance 1(d) any 2 of: type / location, of shore ; height / position, on shore ; sampling area ; time of year ; state of the tide ; abiotic factor ; 2

This question in 9693/21 Oct/Nov 2017

2 Fig. 2.1 shows a settlement of acorn barnacles, Semibalanus balanoides, on a rocky shore. 1 cm Fig. 2.1 A student decided to look at the distribution of three different barnacle species on a rocky shore. The results of this investigation are shown in Table 2.1. Table 2.1 distance above number of barnacles per unit area low water spring tide line / m species 1 species 2 species 3 0 0 98 13 2 1 42 49 4 6 3 87 6 49 0 63 8 91 0 15 10 84 0 5 (a) Describe an experimental procedure the student could use to carry out this investigation. … … … … … … … … [4] (b) Use the data in Table 2.1 to determine where the greatest biodiversity of barnacles is found. … m [1] (c) Use the data in Table 2.1 to compare the distribution of the three barnacle species. Suggest reasons for the differences in distribution. … … … … … … … … [4] [Total: 9]

9 marks

This question in 9693/20 Oct/Nov 2018

4 (a) Describe the processes that give rise to the morphology of sandy shores. … … … … … … … … [4] (b) Describe how environmental factors influence the communities of rocky shores. … … … … … … … … … … … … … … [7] (c) Explain, with reference to marine examples, why habitats with high biodiversity tend to contain narrow ecological niches. … … … … … … … … [4] [Total: 15]

15 marks

Mark scheme: 4(a) any four from ref. deposition / sedimentation, greater than erosion ; loose deposit / unconsolidated ; ref. to size range of particles ; shifting substrate / movement / unstable ; ref. shallow slope / how slope allows for deposition ; ref. action of tides / waves / storms / currents, related to erosion and/or movement ; ref. long shore drift ; 4 4(b) any seven from ref. rock / stable substrate ; (idea that substrate isn’t shifting) ref. allows for attachment ; idea of, resistance to erosion ; idea of, shape of rocks creates habitat (e.g. rock pools, overhangs) ; (exposure to) wave action ; tides / tidal cycle, affects length of exposure ; (exposure to) desiccation ; effect of variable temp. / salinity / dissolved oxygen ; idea of, zonation ; (because) length of exposure to air impacts on position up the shore ; ref. competition / predation (sets lower limit) ; (community made up of) organisms with specific adaptation(s) / particular niches available ; 7 A stated hard rock type e.g. granite A differing degrees of tolerance to temp / drying impacts position up shore 4(c) any 4 from: ref. to example of marine ecosystem with high biodiversity(e.g. coral reef) ; (high biodiversity =) many different species (within one ecosystem / habitat); high degree competition ; idea of, narrow niches, prevent overlap OR reduce / avoid competition ; ref. to specialist feeders / only eats coral / may only feed on one type of food ; 4

This question in 9693/22 May/June 2019

4 (a) Describe the processes that give rise to the morphology of sandy shores. … … … … … … … … [4] (b) Describe how environmental factors influence the communities of rocky shores. … … … … … … … … … … … … … … [7] (c) Explain, with reference to marine examples, why habitats with high biodiversity tend to contain narrow ecological niches. … … … … … … … … [4] [Total: 15]

15 marks

Mark scheme: 4(a) any four from ref. deposition / sedimentation, greater than erosion ; loose deposit / unconsolidated ; ref. to size range of particles ; shifting substrate / movement / unstable ; ref. shallow slope / how slope allows for deposition ; ref. action of tides / waves / storms / currents, related to erosion and/or movement ; ref. long shore drift ; 4 4(b) any seven from ref. rock / stable substrate ; (idea that substrate isn’t shifting) ref. allows for attachment ; idea of, resistance to erosion ; idea of, shape of rocks creates habitat (e.g. rock pools, overhangs) ; (exposure to) wave action ; tides / tidal cycle, affects length of exposure ; (exposure to) desiccation ; effect of variable temp. / salinity / dissolved oxygen ; idea of, zonation ; (because) length of exposure to air impacts on position up the shore ; ref. competition / predation (sets lower limit) ; (community made up of) organisms with specific adaptation(s) / particular niches available ; 7 A stated hard rock type e.g. granite A differing degrees of tolerance to temp / drying impacts position up shore 4(c) any 4 from: ref. to example of marine ecosystem with high biodiversity(e.g. coral reef) ; (high biodiversity =) many different species (within one ecosystem / habitat); high degree competition ; idea of, narrow niches, prevent overlap OR reduce / avoid competition ; ref. to specialist feeders / only eats coral / may only feed on one type of food ; 4

This question in 9693/23 May/June 2019

1 Scientists investigated the effect of red grouper and lionfish on the numbers of juvenile fish in an area of sea bed. Red grouper feed mainly on marine invertebrates. They often live in natural hollows in the sea bed which also act as nurseries for juvenile fish. Lionfish have been introduced into this area by humans and feed mainly on juvenile fish. Red grouper and lionfish do not consume each other. The scientists randomly assigned sixteen natural hollows of equal size to one of four treatments: • no red grouper or lionfish present • one lionfish present • one red grouper present • one red grouper and one lionfish present. The percentage change in the numbers of juvenile fish in each hollow was calculated every week for 6 weeks. Fig. 1.1 shows the results of this investigation. (a) Describe the effect of the following on the percentage change of juvenile fish numbers. Use the data in Fig. 1.1 to support your answer. one lionfish present … … … … one red grouper present … … … … [4] (b) The scientists concluded that the presence of red grouper reduces the effect of lionfish on the numbers of juvenile fish. Explain whether the results in Fig. 1.1 support this conclusion. … … [1] (c) The scientists calculated the percentage of juvenile fish and shrimp in the diet of the lionfish when red grouper were present and absent. Table 1.1 shows the composition of the diet of the lionfish. Table 1.1 percentage composition of lionfish diet red grouper juvenile fish shrimp present 43 57 absent 78 22 (d) Discuss the extent to which the whole investigation supports the idea that red grouper presence increases biodiversity. … … … … … … [3] [Total: 13]

13 marks

Mark scheme: 1(a) one lionfish present causes (large) decrease in juvenile fish number ; decreases by 90% (after 6 weeks) ; one red grouper present causes (large) increase in juvenile fish number ; increases by 110% (after 6 weeks) ; 4 1(b) Yes because… presence of red grouper seems to reduce impact of Lionfish (predation) on juvenile fish ; presence of red grouper may also deter other predators of juvenile fish : 1 1(c)(i) Axes: labels correct for both axes ; Scale : y axis allows bars to cover at least half of grid ; Bars: correctly plotted ±1 / 2 small square ; Bars: equal in width and not touching ; 4 1(c)(ii) generalist / generalised niche ; 1 1(d) any 3 from: supports idea as more juvenile fish present ; idea not supported by decrease in shrimp species ; no information on, other invertebrates / other predators ; no information on relative abundance ; only one study ; results may be different in other habitats ; 3

This question in 9693/22 May/June 2021

1 Scientists investigated the effect of red grouper and lionfish on the numbers of juvenile fish in an area of sea bed. Red grouper feed mainly on marine invertebrates. They often live in natural hollows in the sea bed which also act as nurseries for juvenile fish. Lionfish have been introduced into this area by humans and feed mainly on juvenile fish. Red grouper and lionfish do not consume each other. The scientists randomly assigned sixteen natural hollows of equal size to one of four treatments: • no red grouper or lionfish present • one lionfish present • one red grouper present • one red grouper and one lionfish present. The percentage change in the numbers of juvenile fish in each hollow was calculated every week for 6 weeks. Fig. 1.1 shows the results of this investigation. (a) Describe the effect of the following on the percentage change of juvenile fish numbers. Use the data in Fig. 1.1 to support your answer. one lionfish present … … … … one red grouper present … … … … [4] (b) The scientists concluded that the presence of red grouper reduces the effect of lionfish on the numbers of juvenile fish. Explain whether the results in Fig. 1.1 support this conclusion. … … [1] (c) The scientists calculated the percentage of juvenile fish and shrimp in the diet of the lionfish when red grouper were present and absent. Table 1.1 shows the composition of the diet of the lionfish. Table 1.1 percentage composition of lionfish diet red grouper juvenile fish shrimp present 43 57 absent 78 22 (d) Discuss the extent to which the whole investigation supports the idea that red grouper presence increases biodiversity. … … … … … … [3] [Total: 13]

13 marks

Mark scheme: 1(a) one lionfish present causes (large) decrease in juvenile fish number ; decreases by 90% (after 6 weeks) ; one red grouper present causes (large) increase in juvenile fish number ; increases by 110% (after 6 weeks) ; 4 1(b) Yes because… presence of red grouper seems to reduce impact of Lionfish (predation) on juvenile fish ; presence of red grouper may also deter other predators of juvenile fish : 1 1(c)(i) Axes: labels correct for both axes ; Scale : y axis allows bars to cover at least half of grid ; Bars: correctly plotted ±1 / 2 small square ; Bars: equal in width and not touching ; 4 1(c)(ii) generalist / generalised niche ; 1 1(d) any 3 from: supports idea as more juvenile fish present ; idea not supported by decrease in shrimp species ; no information on, other invertebrates / other predators ; no information on relative abundance ; only one study ; results may be different in other habitats ; 3

This question in 9693/23 May/June 2021

3 Rockpools are a common feature of rocky shores. A student investigated the relationship between the size of a rockpool and the diversity of the macroalgae (seaweeds) that live in it. They used the following hypothesis: ‘The larger the rockpool volume the greater the diversity of macroalgae.’ They spent a day on a rocky shore surveying 35 rockpools. The approximate size of each rockpool was recorded by measuring its volume in arbitrary units. The number of species of macroalgae present was counted in each rockpool. Fig. 3.1 shows the results of their survey. 10 9 8 7 6 number of macroalgae 5 species 4 3 2 1 0 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 rockpool volume / arbitrary units Fig. 3.1 (a) Identify any correlation within the data in Fig. 3.1. Use the data to support your answer. … … … … [2] (b) The student gathered additional information about two rockpools of different sizes. They chose the largest rockpool and one of the smaller rockpools. They identified the species and recorded the abundance of each species. The results are shown in Table 3.1. Table 3.1 abundance species of macroalgae largest smaller rockpool rockpool Corallina officinalis 11 5 Ulva lactuca 8 4 Fucus spiralis 9 0 Fucus serratus 4 0 Chondrus crispus 7 3 Cladophora rupestris 5 2 Bryopsis plumosa 2 0 Codium tomentosum 1 0 Pelvetia canaliculata 7 5 Total of all species 54 19 They used Simpson’s index of diversity to compare the diversity of the two rockpools. The equation for Simpson’s index of diversity is: n 2 D = 1 – / e b N l o Where / = sum of (total) n = number of individuals of each different species N = the total number of individuals of all the species (i) Table 3.2 shows the data for the smaller rockpool. n n 2 The values for and have already been calculated. N b N l Table 3.2 value of value of species value of n value of N n n 2 N b N l Corallina officinalis 5 19 0.2632 0.0693 Ulva lactuca 4 19 0.2105 0.0443 Chondrus crispus 3 19 0.1579 0.0249 Cladophora rupestris 2 19 0.1053 0.0111 Pelvetia canaliculata 5 19 0.2632 0.0693 Use the data in Table 3.2 to calculate D for the smaller rockpool. State your answer for D to 2 significant figures. n 2 / = … b N l D = … [3] (ii) The student’s hypothesis was: ‘The larger the rockpool volume the greater the diversity of macroalgae.’ The student calculated the value for D for the largest rockpool as 0.86. Use this value for D for the largest rockpool and the value for D calculated in (b)(i) for the smaller rockpool to decide whether their hypothesis is supported. Explain your answer. … … … … … … [3] (c) Another student stated that the hypothesis was not supported. Suggest reasons for this conclusion. … … … … … … … … [4] [Total: 12]

12 marks

Mark scheme: 3(a) positive correlation / correct description of correlation ; use of data demonstrating positive correlation / use of data to show that larger rock pools contain more species / ORA ; 2 3(b)(i) 0.2189 ; 0.7811 ; 0.78 ; 3 3(b)(ii) a higher value for D means greater diversity / the closer the number is to 1 the greater the diversity ; D for largest rockpool greater than D for smaller rockpool ; hypothesis should be accepted and justification ; 3 3(c) any 4 from: data for only two rockpools / need to sample more rockpools / sample too small ; small sample size less reliable ; (other student) chose different rockpools / different sized rock pools may have the same number of species ; numbers of individuals quite small ; needs more sampling over several days / weeks ; miscounted number of individuals / misidentified species ; number of species quite small ; idea of correlation not causation / AW ; suggested other factor involved, e.g exact position on shore / depth of rockpool ; ref. to significant difference ; 4

This question in 9693/21 May/June 2022

6 A report was made to scientists that an invasive tree species, Nypa fruticans, had become established within an area of mangrove forest on the west coast of Africa. An invasive species is an organism that is not native to an area and that easily spreads to cause ecological damage in the new habitat. The scientists investigated this using the hypothesis: The presence of an invasive species reduces biodiversity. Scientists studied two areas of mangrove of equal size. The invasive Nypa species was present in area Y, but not in area X. Large mangrove plant species were identified and the number of each species of plant in each transect was recorded. The results are shown in Table 6.1. (a) Calculate the total number of all species in mangrove area X and record it in Table. 6.1. Table 6.1 number of individuals number of individuals species name in mangrove area X in mangrove area Y Acrostichum aureum 24 3 Avicennia germinans 19 14 Drepanocarpus lanatus 24 4 Nypa fruticans 0 53 Rhizophora harrisonii 3 0 Rhizophora racemosa 50 35 Total number of all species 109 … [1] (b) Simpson’s index of diversity is used to calculate the species diversity of each habitat. Table 6.2 shows the data calculated for mangrove area X. The equation for Simpson’s index of diversity is: n D = 1 – (Σ( N) 2) where: D = Simpson’s index of diversity Σ = sum of (total) n = number of individuals of each different species N = the total number of individuals of all species Use the formula and the data from Table 6.1 to complete Table 6.2 and calculate the Simpson’s index of diversity for mangrove area Y. Table 6.2 mangrove mangrove mangrove mangrove species name area X area X area Y area Y n / N (n / N)2 n / N (n / N )2 Acrostichum aureum 0.20 0.0400 0.03 0.0009 Avicennia germinans 0.16 0.0256 0.13 0.0169 Drepanocarpus lanatus 0.20 0.0400 0.04 0.0016 Nypa fruticans 0 0 … … Rhizophora harrisonii 0.03 0.0009 … … Rhizophora racemosa 0.42 0.1764 … … Σ 0.2829 … Simpson’s index of diversity for mangrove area X = 1 – 0.2829 = 0.7171 Simpson’s index of diversity for mangrove area Y = … [5] (c) Discuss the extent to which the hypothesis is proven. … … … … … … [3] [Total: 9] 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.

9 marks

Mark scheme: 6(a) 120 ; 1 6(b) 5 mangrove area Y mangrove area Y n / N (n / N)2 Nypa fruticans 0.49 0.2401 ; / (A range of 0.2334–0.2364) Rhizophora harrisonii 0 0 ; Rhizophora racemosa 0.32 0.1024 ; (A 0.1031)  0.3619 ; (A range 0.3555–0.3589) 1 – 0.3619 = 0.6381 ; (0.6411 – 0.6445) 6(c) any 3 from: 3 inconclusive ; diversity index lower for mangrove area Y by 0.079 (A ECF from 6(b)) / ORA ; (but) not by a large amount / need to do (named) significance test ; but species richness is unchanged ; (looking at raw data) 2 species (Acrosichum aureum and Drepanocarpus lanatus) reduced by a large amount (in area Y) ; one species (Rhizophora harrisonii) disappeared but numbers low in mangrove area X ; dominant species in mangrove area X (Rhizophora racemosa) is no longer the dominant species ; need to test in more areas / more data needs to be collected ; AVP ;

This question in 9693/21 Oct/Nov 2022

6 A report was made to scientists that an invasive tree species, Nypa fruticans, had become established within an area of mangrove forest on the west coast of Africa. An invasive species is an organism that is not native to an area and that easily spreads to cause ecological damage in the new habitat. The scientists investigated this using the hypothesis: The presence of an invasive species reduces biodiversity. Scientists studied two areas of mangrove of equal size. The invasive Nypa species was present in area Y, but not in area X. Large mangrove plant species were identified and the number of each species of plant in each transect was recorded. The results are shown in Table 6.1. (a) Calculate the total number of all species in mangrove area X and record it in Table. 6.1. Table 6.1 number of individuals number of individuals species name in mangrove area X in mangrove area Y Acrostichum aureum 24 3 Avicennia germinans 19 14 Drepanocarpus lanatus 24 4 Nypa fruticans 0 53 Rhizophora harrisonii 3 0 Rhizophora racemosa 50 35 Total number of all species 109 … [1] (b) Simpson’s index of diversity is used to calculate the species diversity of each habitat. Table 6.2 shows the data calculated for mangrove area X. The equation for Simpson’s index of diversity is: n D = 1 – (Σ( N) 2) where: D = Simpson’s index of diversity Σ = sum of (total) n = number of individuals of each different species N = the total number of individuals of all species Use the formula and the data from Table 6.1 to complete Table 6.2 and calculate the Simpson’s index of diversity for mangrove area Y. Table 6.2 mangrove mangrove mangrove mangrove species name area X area X area Y area Y n / N (n / N)2 n / N (n / N )2 Acrostichum aureum 0.20 0.0400 0.03 0.0009 Avicennia germinans 0.16 0.0256 0.13 0.0169 Drepanocarpus lanatus 0.20 0.0400 0.04 0.0016 Nypa fruticans 0 0 … … Rhizophora harrisonii 0.03 0.0009 … … Rhizophora racemosa 0.42 0.1764 … … Σ 0.2829 … Simpson’s index of diversity for mangrove area X = 1 – 0.2829 = 0.7171 Simpson’s index of diversity for mangrove area Y = … [5] (c) Discuss the extent to which the hypothesis is proven. … … … … … … [3] [Total: 9] 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.

9 marks

Mark scheme: 6(a) 120 ; 1 6(b) 5 mangrove area Y mangrove area Y n / N (n / N)2 Nypa fruticans 0.49 0.2401 ; / (A range of 0.2334–0.2364) Rhizophora harrisonii 0 0 ; Rhizophora racemosa 0.32 0.1024 ; (A 0.1031)  0.3619 ; (A range 0.3555–0.3589) 1 – 0.3619 = 0.6381 ; (0.6411 – 0.6445) 6(c) any 3 from: 3 inconclusive ; diversity index lower for mangrove area Y by 0.079 (A ECF from 6(b)) / ORA ; (but) not by a large amount / need to do (named) significance test ; but species richness is unchanged ; (looking at raw data) 2 species (Acrosichum aureum and Drepanocarpus lanatus) reduced by a large amount (in area Y) ; one species (Rhizophora harrisonii) disappeared but numbers low in mangrove area X ; dominant species in mangrove area X (Rhizophora racemosa) is no longer the dominant species ; need to test in more areas / more data needs to be collected ; AVP ;

This question in 9693/22 Oct/Nov 2022

6 A report was made to scientists that an invasive tree species, Nypa fruticans, had become established within an area of mangrove forest on the west coast of Africa. An invasive species is an organism that is not native to an area and that easily spreads to cause ecological damage in the new habitat. The scientists investigated this using the hypothesis: The presence of an invasive species reduces biodiversity. Scientists studied two areas of mangrove of equal size. The invasive Nypa species was present in area Y, but not in area X. Large mangrove plant species were identified and the number of each species of plant in each transect was recorded. The results are shown in Table 6.1. (a) Calculate the total number of all species in mangrove area X and record it in Table. 6.1. Table 6.1 number of individuals number of individuals species name in mangrove area X in mangrove area Y Acrostichum aureum 24 3 Avicennia germinans 19 14 Drepanocarpus lanatus 24 4 Nypa fruticans 0 53 Rhizophora harrisonii 3 0 Rhizophora racemosa 50 35 Total number of all species 109 … [1] (b) Simpson’s index of diversity is used to calculate the species diversity of each habitat. Table 6.2 shows the data calculated for mangrove area X. The equation for Simpson’s index of diversity is: n D = 1 – (Σ( N) 2) where: D = Simpson’s index of diversity Σ = sum of (total) n = number of individuals of each different species N = the total number of individuals of all species Use the formula and the data from Table 6.1 to complete Table 6.2 and calculate the Simpson’s index of diversity for mangrove area Y. Table 6.2 mangrove mangrove mangrove mangrove species name area X area X area Y area Y n / N (n / N)2 n / N (n / N )2 Acrostichum aureum 0.20 0.0400 0.03 0.0009 Avicennia germinans 0.16 0.0256 0.13 0.0169 Drepanocarpus lanatus 0.20 0.0400 0.04 0.0016 Nypa fruticans 0 0 … … Rhizophora harrisonii 0.03 0.0009 … … Rhizophora racemosa 0.42 0.1764 … … Σ 0.2829 … Simpson’s index of diversity for mangrove area X = 1 – 0.2829 = 0.7171 Simpson’s index of diversity for mangrove area Y = … [5] (c) Discuss the extent to which the hypothesis is proven. … … … … … … [3] [Total: 9] 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.

9 marks

Mark scheme: 6(a) 120 ; 1 6(b) 5 mangrove area Y mangrove area Y n / N (n / N)2 Nypa fruticans 0.49 0.2401 ; / (A range of 0.2334–0.2364) Rhizophora harrisonii 0 0 ; Rhizophora racemosa 0.32 0.1024 ; (A 0.1031)  0.3619 ; (A range 0.3555–0.3589) 1 – 0.3619 = 0.6381 ; (0.6411 – 0.6445) 6(c) any 3 from: 3 inconclusive ; diversity index lower for mangrove area Y by 0.079 (A ECF from 6(b)) / ORA ; (but) not by a large amount / need to do (named) significance test ; but species richness is unchanged ; (looking at raw data) 2 species (Acrosichum aureum and Drepanocarpus lanatus) reduced by a large amount (in area Y) ; one species (Rhizophora harrisonii) disappeared but numbers low in mangrove area X ; dominant species in mangrove area X (Rhizophora racemosa) is no longer the dominant species ; need to test in more areas / more data needs to be collected ; AVP ;

This question in 9693/23 Oct/Nov 2022

4 Sandy shore ecosystems often have low biodiversity. Scientists investigated abiotic factors that affect biodiversity on sandy shores. (a) State the meaning of the term abiotic factor. … … [1] (b) The scientists investigated the relationship between the gradient of the shore, particle size and biodiversity on 12 sandy shores, A–L, at low tide. The gradient of each shore was recorded as a percentage: the higher the percentage, the steeper the gradient. The mean number of species per m2 on each shore was estimated using sampling techniques. Describe a method that could be used to sample the mean number of species per m2 present on each shore. … … … … … … … … … … [5] (c) Table 4.1 shows the data collected from the investigation. Table 4.1 shore gradient mean particle mean number of shore percentage size / μm species per m2 A 10.7 538 4.5 B 8.8 959 1.2 C 4.2 319 8.0 D 11.4 895 2.9 E 3.5 253 9.4 F 6.5 474 5.7 G 6.2 311 7.5 H 6.4 316 5.3 I 4.5 313 7.9 J 6.9 449 4.7 K 4.2 264 5.6 L 9.6 460 4.6 Fig. 4.1 is a scatter diagram showing the relationship between the mean number of species per m2 and shore gradient percentage. 10 8 mean number 6 of species per m2 4 2 3 4 5 6 7 8 9 10 11 12 shore gradient percentage Fig. 4.1 (i) Scientists used Spearman’s rank correlation (rs) to decide if there was a correlation between the mean number of species per m2 and shore gradient percentage. The calculation for Spearman’s rank correlation (rs) uses the following equation: 6 × ΣD 2 rs = 1 – ( n3 – n ) where, Σ = sum of (total) n = number of pairs of items in the sample D = difference in rank between each pair of measurements A value of 539.5 was calculated for ΣD 2. Use this value and the information in Table 4.1 to calculate the value for rs. Give your answer to two significant figures. Show your working. rs = … [3] (ii) Use your calculated value for rs in (c)(i) to describe the correlation between mean number of species per m2 and shore gradient percentage. Explain your answer. … … … … [2] (iii) Fig. 4.2 is a scatter diagram showing the relationship between mean number of species per m2 and mean particle size. 100 80 60 mean number of species per m2 40 20 0 0 100 200 300 400 500 600 700 800 900 1000 mean particle size / μm Fig. 4.2 Spearman’s rank correlation was performed again for this data and an rs value of – 0.80 was calculated. Use this value and the one calculated in part (c)(i) to discuss the effect of shore gradient percentage and particle size on the biodiversity of sandy shores. … … … … … … [3] (d) Suggest why particle size and shore gradient percentage may have an effect on the number of species per m2 found on each shore. … … … … … … … … [4] (e) Simpson’s index of diversity could be used to assess the biodiversity on each shore. Suggest why this would be a better measure of biodiversity than data used in this investigation. … … [1] [Total: 19]

19 marks

Mark scheme: 4(a) abiotic factors are non-living (factors) ; 1 4(b) any 5 of: 1 correctly linking a described method as systematic or random ; 2 transect or grid ; 3 (use of 1 m2) quadrats ; 4 place quadrat at, stated / even, intervals along the transect OR random distance apart along the transect OR random placement within a grid ; 5 ref. method of generating random locations / coordinates ; 6 remove and examine sediment / sieve sediment to obtain samples / take a core sample to examine for species ; 7 suitable reference to depth of sediment taken ; 8 counting the species / record the number of species, found in each quadrat ; 9 correct description of calculating the mean number of species per m2 ; 10 repeat same method on each, shore / coastline ; 11 reference to ethical treatment of organisms ; 12 ref. to a relevant and sensible health and safety ; 5 4(c)(i) substitution of numbers into equation ; correct answer only to any number of sig. figs. from –0.8863636363636363 to –0.89 (any rounding must be correct) ; reasonable answer expressed to 2 significant figures ; 3 Question Answer Marks 4(c)(ii) it is an, inverse / negative, (correlation) ; as the value is negative ; OR it is a strong correlation ; as value is close to (-)1 ; 2 4(c)(iii) any 3 of: the greater the slope gradient the lower the biodiversity ORA ; the greater the particle size the lower the biodiversity ORA ; awareness of correlation not meaning causation ; ref. to data only showing species number not abundance ; 3 4(d) particle size may affect: 1 ability to burrow / move ; 2 ability to, ingest food / pass food through body ; 3 moisture content of substrate OR risk of (organisms) drying out ; slope may affect: 4 drainage of water / slope affects risk of (sediment / organism) drying out ; 5 how easily, detritus / food sources, deposited ; 6 area of shore in tidal range ; 7 size / impact of wave action ; 4 4(e) takes into account number of individuals / population size (as well as number of species) / takes into account abundance (as well as number of species) ; 1

This question in 9693/21 May/June 2023

3 Fig. 3.1 shows a red snapper, a fish commonly harvested for human food from coral reefs. Fig. 3.1 (a) Make a large drawing of the red snapper in Fig. 3.1. Do not include the scales. [4] (b) On your diagram label the following features: • operculum • pectoral fin. [2] (c) (i) Describe one method that could be used to estimate the population of red snapper on a coral reef. … … … … … … … … [4] (ii) Scientists investigated the population of red snapper on a coral reef every month for six months. Draw a results table for this investigation. Include full headings in the results table, but do not write in any results. [1] (iii) State two biotic factors that affect the population of red snapper on a coral reef. 1 … 2 … [2] (d) Scientists investigated the effect of an artificial reef on the populations of six fish species. The area did not contain any natural reefs. They collected data using fish traps from an artificial reef and from an area 150 m away from the artificial reef, which had no reef. The number of fish caught in each area over 8 hours was recorded. Table 3.1 shows the results. Table 3.1 number of fish caught fish species artificial reef no reef P 2 1 Q 6 1 R 137 8 S 45 0 T 129 2 U 0 1 The scientists made the statement: ‘The artificial reef has increased the biodiversity of the area.’ (i) Discuss the extent to which the data supports this statement. … … … … … … [3] (ii) The artificial reef was built 750 m offshore. Discuss the possible effects of the artificial reef on the shore. … … … … … … [3] [Total: 19]

19 marks

Mark scheme: 3(a) outline (neat lines, no shading) ; 4 size (larger than the original) ; proportion (operculum positioned at around ⅓ of the body length (not including caudal fin) and correct body shape, pectoral fin reaching to approximately the middle of the body) ; detail (all fins included, eye, mouth, caudal peduncle) ; 3(b) 2 operculum Pectoral fin 3(c)(i) any 4 from: 4 catch (a selection of the species at the reef) AND count / stated number caught AND tag (all fish) and release ; return (stated time) later and catch a sample of the species ; count the number of fish tagged AND the total caught the second time ; apply the Lincoln index ; AVP ; 3(c)(ii) 1 Date / month Total number (of red snapper) caught Number (red snapper) tagged Number (red snapper) untagged 3(c)(iii) any 2 from: 2 competition ; disease / parasites ; predation ; AVP ; 3(d)(i) any 3 from: 3 5 species of fish / same no. of species / five out of six species / same species richness, in each area; (but there may be) other species affected they did not monitor / data not collected on, all species / species other than fish ; (on the reef area) there is a large increase in numbers, of 2 species / R and T, OR there is a small increase in, 2 species / Q and P, OR a new species / S, is attracted to artificial reef ; (but) there is a reduction in numbers of 1 species / U (in the artificial reef) / (the species that reduced / U) had only a small number of fish in the area with no reef ; no data for the areas before the reef was built ; fish may have, moved / migrated, from the area without a reef to the area of reef ; data only includes species biodiversity / data does not include genetic or environmental biodiversity ; data manipulation ; AVP ; 3(d)(ii) any 3 from: 3 reduces storm surges ; as they absorb (some of) the energy (of the waves) ; waves break before the shore ; reduces shoreline erosion ; shore profile may change / sand deposited / deeper substrate ; because currents are lower behind the reef ; protects, seagrass beds / other habitats, between reef and shore ; AVP ;

This question in 9693/21 Oct/Nov 2023

3 Fig. 3.1 shows a red snapper, a fish commonly harvested for human food from coral reefs. Fig. 3.1 (a) Make a large drawing of the red snapper in Fig. 3.1. Do not include the scales. [4] (b) On your diagram label the following features: • operculum • pectoral fin. [2] (c) (i) Describe one method that could be used to estimate the population of red snapper on a coral reef. … … … … … … … … [4] (ii) Scientists investigated the population of red snapper on a coral reef every month for six months. Draw a results table for this investigation. Include full headings in the results table, but do not write in any results. [1] (iii) State two biotic factors that affect the population of red snapper on a coral reef. 1 … 2 … [2] (d) Scientists investigated the effect of an artificial reef on the populations of six fish species. The area did not contain any natural reefs. They collected data using fish traps from an artificial reef and from an area 150 m away from the artificial reef, which had no reef. The number of fish caught in each area over 8 hours was recorded. Table 3.1 shows the results. Table 3.1 number of fish caught fish species artificial reef no reef P 2 1 Q 6 1 R 137 8 S 45 0 T 129 2 U 0 1 The scientists made the statement: ‘The artificial reef has increased the biodiversity of the area.’ (i) Discuss the extent to which the data supports this statement. … … … … … … [3] (ii) The artificial reef was built 750 m offshore. Discuss the possible effects of the artificial reef on the shore. … … … … … … [3] [Total: 19]

19 marks

Mark scheme: 3(a) outline (neat lines, no shading) ; 4 size (larger than the original) ; proportion (operculum positioned at around ⅓ of the body length (not including caudal fin) and correct body shape, pectoral fin reaching to approximately the middle of the body) ; detail (all fins included, eye, mouth, caudal peduncle) ; 3(b) 2 operculum Pectoral fin 3(c)(i) any 4 from: 4 catch (a selection of the species at the reef) AND count / stated number caught AND tag (all fish) and release ; return (stated time) later and catch a sample of the species ; count the number of fish tagged AND the total caught the second time ; apply the Lincoln index ; AVP ; 3(c)(ii) 1 Date / month Total number (of red snapper) caught Number (red snapper) tagged Number (red snapper) untagged 3(c)(iii) any 2 from: 2 competition ; disease / parasites ; predation ; AVP ; 3(d)(i) any 3 from: 3 5 species of fish / same no. of species / five out of six species / same species richness, in each area; (but there may be) other species affected they did not monitor / data not collected on, all species / species other than fish ; (on the reef area) there is a large increase in numbers, of 2 species / R and T, OR there is a small increase in, 2 species / Q and P, OR a new species / S, is attracted to artificial reef ; (but) there is a reduction in numbers of 1 species / U (in the artificial reef) / (the species that reduced / U) had only a small number of fish in the area with no reef ; no data for the areas before the reef was built ; fish may have, moved / migrated, from the area without a reef to the area of reef ; data only includes species biodiversity / data does not include genetic or environmental biodiversity ; data manipulation ; AVP ; 3(d)(ii) any 3 from: 3 reduces storm surges ; as they absorb (some of) the energy (of the waves) ; waves break before the shore ; reduces shoreline erosion ; shore profile may change / sand deposited / deeper substrate ; because currents are lower behind the reef ; protects, seagrass beds / other habitats, between reef and shore ; AVP ;

This question in 9693/22 Oct/Nov 2023

3 Fig. 3.1 shows a red snapper, a fish commonly harvested for human food from coral reefs. Fig. 3.1 (a) Make a large drawing of the red snapper in Fig. 3.1. Do not include the scales. [4] (b) On your diagram label the following features: • operculum • pectoral fin. [2] (c) (i) Describe one method that could be used to estimate the population of red snapper on a coral reef. … … … … … … … … [4] (ii) Scientists investigated the population of red snapper on a coral reef every month for six months. Draw a results table for this investigation. Include full headings in the results table, but do not write in any results. [1] (iii) State two biotic factors that affect the population of red snapper on a coral reef. 1 … 2 … [2] (d) Scientists investigated the effect of an artificial reef on the populations of six fish species. The area did not contain any natural reefs. They collected data using fish traps from an artificial reef and from an area 150 m away from the artificial reef, which had no reef. The number of fish caught in each area over 8 hours was recorded. Table 3.1 shows the results. Table 3.1 number of fish caught fish species artificial reef no reef P 2 1 Q 6 1 R 137 8 S 45 0 T 129 2 U 0 1 The scientists made the statement: ‘The artificial reef has increased the biodiversity of the area.’ (i) Discuss the extent to which the data supports this statement. … … … … … … [3] (ii) The artificial reef was built 750 m offshore. Discuss the possible effects of the artificial reef on the shore. … … … … … … [3] [Total: 19]

19 marks

Mark scheme: 3(a) outline (neat lines, no shading) ; 4 size (larger than the original) ; proportion (operculum positioned at around ⅓ of the body length (not including caudal fin) and correct body shape, pectoral fin reaching to approximately the middle of the body) ; detail (all fins included, eye, mouth, caudal peduncle) ; 3(b) 2 operculum Pectoral fin 3(c)(i) any 4 from: 4 catch (a selection of the species at the reef) AND count / stated number caught AND tag (all fish) and release ; return (stated time) later and catch a sample of the species ; count the number of fish tagged AND the total caught the second time ; apply the Lincoln index ; AVP ; 3(c)(ii) 1 Date / month Total number (of red snapper) caught Number (red snapper) tagged Number (red snapper) untagged 3(c)(iii) any 2 from: 2 competition ; disease / parasites ; predation ; AVP ; 3(d)(i) any 3 from: 3 5 species of fish / same no. of species / five out of six species / same species richness, in each area; (but there may be) other species affected they did not monitor / data not collected on, all species / species other than fish ; (on the reef area) there is a large increase in numbers, of 2 species / R and T, OR there is a small increase in, 2 species / Q and P, OR a new species / S, is attracted to artificial reef ; (but) there is a reduction in numbers of 1 species / U (in the artificial reef) / (the species that reduced / U) had only a small number of fish in the area with no reef ; no data for the areas before the reef was built ; fish may have, moved / migrated, from the area without a reef to the area of reef ; data only includes species biodiversity / data does not include genetic or environmental biodiversity ; data manipulation ; AVP ; 3(d)(ii) any 3 from: 3 reduces storm surges ; as they absorb (some of) the energy (of the waves) ; waves break before the shore ; reduces shoreline erosion ; shore profile may change / sand deposited / deeper substrate ; because currents are lower behind the reef ; protects, seagrass beds / other habitats, between reef and shore ; AVP ;

This question in 9693/23 Oct/Nov 2023

1 Zooplankton is composed of a variety of organisms, including copepods. (a) Fig. 1.1 shows a copepod found in zooplankton. Fig. 1.1 Make a large drawing of the copepod in Fig. 1.1. Do not include the internal structure of the copepod. Do not label your drawing. [4] (b) Describe the roles of zooplankton in marine ecosystems. … … … … [2] (c) Sea water samples were taken from different depths in the Arctic Ocean. Fig. 1.2 shows the percentage composition of eight species of copepod zooplankton found in the samples. Not all species occurred at each depth. Key 100 species A species B 80 species C species D 60 percentage species E composition of copepod species F zooplankton 40 species G species H 20 0 0 – 200 201 – 500 501 – 1000 sampling depth / m Fig. 1.2 (i) State how many of the eight species of copepod zooplankton are found in all three depth ranges. … [1] (ii) Use Fig. 1.2 to compare the changes in percentage composition of species A and species H. … … … … … … [3] (iii) Suggest why the percentage compositions of the copepod zooplankton species change with increasing depth. … … … … … … [3] (d) A student compared the copepod zooplankton communities by calculating the biodiversity at different depths. Table 1.1 shows the number of individuals per dm3 of sea water for the six species present at depths 0 – 200 m. Table 1.1 species of copepod zooplankton number of individuals / dm3 A 58 B 95 E 380 F 133 G 228 H 56 total number of individuals of all 950 the species (N) Simpson’s index of diversity (D) can be used to calculate biodiversity. n 2 D = 1 / N -c ` j m / = sum of (total) n = number of individuals of each different species N = the total number of individuals of all the species (i) Using the data in Table 1.1, complete Table 1.2 for species G. Table 1.2 species of copepod n / N (n / N)2 zooplankton A 0.061 0.004 B 0.100 0.010 E 0.400 0.160 F 0.140 0.020 G … … H 0.059 0.004 [1] (ii) Use Table 1.2 and the equation to calculate D for the biodiversity of copepod zooplankton between 0 – 200 m. State your answer to three significant figures. Show your working. D = … [3] (iii) The student calculated the value for D for the depth range 201 – 500 m to be 0.699. Use this value for D and your answer to (d)(ii) to describe the change in the biodiversity of copepod zooplankton as the depth increases. Justify your answer. … … … … [2] [Total: 19]

19 marks

Mark scheme: 1(a) clear outline with thin lines with no shading, no gaps ; suitable size ; in proportion ; detail ; 4 1(b) (primary / secondary) consumers / eat phytoplankton / eat plants ; provide food / make energy available / source of energy OR increase biomass, for higher trophic levels OR zooplankton are prey for / fed on by, other animals / other (marine) organisms OR source of food for other organisms ; 2 1(c)(i) 3 ; 1 1(c)(ii) any 3 from: 1 both species / A and H, have the similar (percentage) composition between 0–200 m ; 2 (percentage composition of) both species increase with depth ORA ; 3 idea of greater increase (in percentage composition) for species H ORA ; 4 ref. to greatest increase for both species between 0–200 m and 201–500 m / ORA ; 5 correct manipulation of data to support answers ; 3 Question Answer Marks 1(c)(iii) 1 idea of (presence or absence of) adaptations to different conditions e.g. different species adapted to different (environmental) conditions / some species lack adaptations to survive (and need sunlight) / composition of species H increases with depth, so H is suited to deeper areas of the ocean ; plus any 2 from: 2 (differing / changing amounts of) predation ; 3 (differing / changing) abundance of food ; 4 (differing / changing) salinity / pH ; 5 (differing / changing) oxygen (concentration) ; 6 (differing / changing) density / pressure ; 7 (differing / changing) competition ; 8 (differing / changing)(water) temperature ; 9 (differing / changing) light intensity / brightness / light penetration ; 3 1(d)(i) 0.24(0) AND 0.058 / 0.0576 ; 1 1(d)(ii)  (n / N)2 = 0.256 or 0.2556 ; 1 – 0.256 = 0.744 or 1 – 0.2556 = 0.744(4) ; calculated answer given to 3 sig figs ; 3 1(d)(iii) links change in biodiversity to change in depth e.g. biodiversity is decreasing OR the deeper, the lower biodiversity of copepod zooplankton there is OR biodiversity declines with depth ORA ; value closer to 1 indicates higher biodiversity ; 2

This question in 9693/21 May/June 2024

5 Latitude describes a north or south position of a point on the Earth’s surface. Fig. 5.1 shows the equator is at zero degrees latitude, while the north pole is at 90° north, and the south pole is at 90° south. 90° N 60° N 30° N equator 0° 90° S Fig. 5.1 Razor clams are benthic, bivalve molluscs, living on the continental shelf. There are many species of razor clam across the globe. A scientist investigated if the species diversity of razor clams was affected by latitude. Fig. 5.2 shows the results. 40 30 number 20 of species 10 0 55 45 35 25 15 5 5 15 25 35 45 55 north equator south latitude / degrees Fig. 5.2 (a) Use Fig. 5.2 to outline the effect of latitude on species diversity of razor clams. … … … … … … [3] (b) A variety of other factors were measured. Spearman’s rank correlation was used to calculate the correlation, rs, between each factor and the species diversity of razor clams. The results are shown in Table 5.1. Table 5.1 Spearman’s rank correlation factor northern hemisphere southern hemisphere mean sea surface temperature / °C 0.87 0.61 range of sea surface temperature / °C –0.83 0.39 primary productivity / mg carbon m–2 day–1 –0.54 0.03 ocean area / km2 0.60 0.46 coastline length / km –0.37 0.27 continental shelf area / km2 –0.11 0.41 (i) State the variable in the southern hemisphere which shows the strongest Spearman’s rank correlation. … [1] (ii) State the variable in the northern hemisphere which shows the weakest Spearman’s rank correlation. … [1] (iii) Describe the relationship between the range of sea surface temperatures in the northern hemisphere and razor clam species diversity. … … [1] (iv) Evaluate if the correlation data for razor clam species diversity and primary productivity show a causal relationship. … … … … [2] [Total: 8] 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.

8 marks

Mark scheme: 5(a) any 3 from: 1 low in high latitudes / none at 55 °N and °S ; 2 (then) decreases close to the equator ; 3 in the N, number increases to 10° then decreases ORA ; 4 in the S, the number fluctuates but peaks at 25° and then decreases ; 5 greater diversity in the Northern hemisphere ; 6 AVP ; 5(b)(i) mean sea surface temp. ; 1 5(b)(ii) continental shelf area ; 1 5(b)(iii) (strong) negative (correlation) ; 1 5(b)(iv) any 2 from: correlation in N hemisphere is negative ; in S hemisphere weakly positive ; overall (very) low correlation so unlikely to be causation ; AVP ; 2

This question in 9693/22 May/June 2024

5 Latitude describes a north or south position of a point on the Earth’s surface. Fig. 5.1 shows the equator is at zero degrees latitude, while the north pole is at 90° north, and the south pole is at 90° south. 90° N 60° N 30° N equator 0° 90° S Fig. 5.1 Razor clams are benthic, bivalve molluscs, living on the continental shelf. There are many species of razor clam across the globe. A scientist investigated if the species diversity of razor clams was affected by latitude. Fig. 5.2 shows the results. 40 30 number 20 of species 10 0 55 45 35 25 15 5 5 15 25 35 45 55 north equator south latitude / degrees Fig. 5.2 (a) Use Fig. 5.2 to outline the effect of latitude on species diversity of razor clams. … … … … … … [3] (b) A variety of other factors were measured. Spearman’s rank correlation was used to calculate the correlation, rs, between each factor and the species diversity of razor clams. The results are shown in Table 5.1. Table 5.1 Spearman’s rank correlation factor northern hemisphere southern hemisphere mean sea surface temperature / °C 0.87 0.61 range of sea surface temperature / °C –0.83 0.39 primary productivity / mg carbon m–2 day–1 –0.54 0.03 ocean area / km2 0.60 0.46 coastline length / km –0.37 0.27 continental shelf area / km2 –0.11 0.41 (i) State the variable in the southern hemisphere which shows the strongest Spearman’s rank correlation. … [1] (ii) State the variable in the northern hemisphere which shows the weakest Spearman’s rank correlation. … [1] (iii) Describe the relationship between the range of sea surface temperatures in the northern hemisphere and razor clam species diversity. … … [1] (iv) Evaluate if the correlation data for razor clam species diversity and primary productivity show a causal relationship. … … … … [2] [Total: 8] 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.

8 marks

Mark scheme: 5(a) any 3 from: 1 low in high latitudes / none at 55 °N and °S ; 2 (then) decreases close to the equator ; 3 in the N, number increases to 10° then decreases ORA ; 4 in the S, the number fluctuates but peaks at 25° and then decreases ; 5 greater diversity in the Northern hemisphere ; 6 AVP ; 5(b)(i) mean sea surface temp. ; 1 5(b)(ii) continental shelf area ; 1 5(b)(iii) (strong) negative (correlation) ; 1 5(b)(iv) any 2 from: correlation in N hemisphere is negative ; in S hemisphere weakly positive ; overall (very) low correlation so unlikely to be causation ; AVP ; 2

This question in 9693/23 May/June 2024

2 Fig. 2.1 shows a great white shark, Carcharodon carcharias. Fig. 2.1 (a) (i) On Fig. 2.1 label the following features: • gill slits • caudal fin • pectoral fin. [2] (ii) State the genus for the great white shark. … [1] (b) Fig. 2.2 shows five other species of shark. species A species B species C species D species E NOT TO SCALE Fig. 2.2 Use the key to identify the binomial name of species A. 1 Dark coloured upper body go to 2 Light coloured upper body go to 3 2 Tail similar length to body length Alopias vulpinus Tail shorter than body length go to 4 3 T-shaped head Sphyrna mokarran Pointed head Galeocerdo cuvier 4 Light-coloured spots on dark stripes on upper body Rhincodon typus No light-coloured spots Carcharhinus leucas Binomial name of species A is … [1] (c) A scientist studied sharks accidentally caught from commercial fishing. The sharks were analysed to identify parasites living both internally and externally. (i) Suggest why scientists used sharks that had already been accidentally caught instead of hunting sharks especially for their research. … … … … [2] (ii) Suggest advantages and disadvantages to shark parasites of living internally instead of living externally. advantages … … … … disadvantages … … … … [4] (iii) Some parasites of sharks are crustaceans. State two features of a typical adult crustacean. 1 … 2 … [2] (d) Scientists analysed the data from two different species of shark to compare the biodiversity of the parasites living in each species. Simpson’s index of diversity was used to calculate the species diversity of parasites in the two different species of shark, F and G. The equation used to calculate Simpson’s index of diversity is shown. n 2 D = 1 – 1Σ 1 N2 2 Where: D = Simpson’s index of diversity Σ = sum of (total) n = number of individuals of each different species N = the total number of individuals of all the species. Table 2.1 shows the data calculated from the two types of shark. Table 2.1 shark species F shark species G parasite 2 2 n n n n n n N 1 N2 N 1 N2 H. tergestinus 3 0.188 0.035 12 0.162 0.026 S. viridis 2 0.125 0.016 0 0.000 0.000 A. physeteris 0 0.000 0.000 43 … … L. galei 7 0.438 0.191 17 0.230 0.053 D. betencourti 4 0.250 0.063 2 0.027 0.001 N 16 74 Σ 0.305 Σ … (i) Complete Table 2.1 for shark species G using the data provided. Give your answers to three significant figures. [4] (ii) Calculate Simpson’s index of diversity for the parasites in shark species F and G. Space for working. shark species F: … shark species G: … [1] (iii) Use the Simpson’s index of diversity values you have calculated in 2(d)(ii) to compare the relative biodiversity of parasites in the two species of shark. … … [1] [Total: 18]

18 marks

Mark scheme: 2(a)(i) 2 gill slits caudal fin pectoral (fin) 2(a)(ii) Carcharodon ; 1 2(b) Rhincodon typus ; 1 2(c)(i) idea that the sharks need to be killed to identify parasites inside ; 2 idea that these sharks have already died (as a result of being caught accidentally) / no need to deliberately kill sharks to carry out the research ; 2(c)(ii) advantages: 4 more difficult to be removed from the shark ORA ; more difficult to be removed by other organisms (e.g. cleaner fish) ORA ; protected habitat / environment for parasite to reproduce ORA ; easier access to (high value) nutrient sources e.g. blood ORA ; disadvantages: more difficult for parasite to get inside the body / more difficult for parasite to find a new host ORA ; idea that the parasite needs to evade shark’s internal body defences / immune system ORA ; hard to find a mate / isolated population / reduces genetic variation ORA ; 2(c)(iii) any two from: 2 segmented, abdomen / body ; jointed legs ; two pairs of antennae ; carapace ; 2(d)(i) 4 shark type G n n 2  n  N    N  43 0.581 ; 0.338 ; 74  0.418 ; all three values correct to 3 sig. figs ; 2(d)(ii) shark species F: 0.695 AND shark species G: 0.582 ; 1 2(d)(iii) (shark) species F has a, higher / more, biodiversity (of parasites) (as shark species F has a higher Simpson’s value) ORA ; 1

This question in 9693/22 May/June 2025

2 Fig. 2.1 shows a great white shark, Carcharodon carcharias. Fig. 2.1 (a) (i) On Fig. 2.1 label the following features: • gill slits • caudal fin • pectoral fin. [2] (ii) State the genus for the great white shark. … [1] (b) Fig. 2.2 shows five other species of shark. species A species B species C species D species E NOT TO SCALE Fig. 2.2 Use the key to identify the binomial name of species A. 1 Dark coloured upper body go to 2 Light coloured upper body go to 3 2 Tail similar length to body length Alopias vulpinus Tail shorter than body length go to 4 3 T-shaped head Sphyrna mokarran Pointed head Galeocerdo cuvier 4 Light-coloured spots on dark stripes on upper body Rhincodon typus No light-coloured spots Carcharhinus leucas Binomial name of species A is … [1] (c) A scientist studied sharks accidentally caught from commercial fishing. The sharks were analysed to identify parasites living both internally and externally. (i) Suggest why scientists used sharks that had already been accidentally caught instead of hunting sharks especially for their research. … … … … [2] (ii) Suggest advantages and disadvantages to shark parasites of living internally instead of living externally. advantages … … … … disadvantages … … … … [4] (iii) Some parasites of sharks are crustaceans. State two features of a typical adult crustacean. 1 … 2 … [2] (d) Scientists analysed the data from two different species of shark to compare the biodiversity of the parasites living in each species. Simpson’s index of diversity was used to calculate the species diversity of parasites in the two different species of shark, F and G. The equation used to calculate Simpson’s index of diversity is shown. n 2 D = 1 – 1Σ 1 N2 2 Where: D = Simpson’s index of diversity Σ = sum of (total) n = number of individuals of each different species N = the total number of individuals of all the species. Table 2.1 shows the data calculated from the two types of shark. Table 2.1 shark species F shark species G parasite 2 2 n n n n n n N 1 N2 N 1 N2 H. tergestinus 3 0.188 0.035 12 0.162 0.026 S. viridis 2 0.125 0.016 0 0.000 0.000 A. physeteris 0 0.000 0.000 43 … … L. galei 7 0.438 0.191 17 0.230 0.053 D. betencourti 4 0.250 0.063 2 0.027 0.001 N 16 74 Σ 0.305 Σ … (i) Complete Table 2.1 for shark species G using the data provided. Give your answers to three significant figures. [4] (ii) Calculate Simpson’s index of diversity for the parasites in shark species F and G. Space for working. shark species F: … shark species G: … [1] (iii) Use the Simpson’s index of diversity values you have calculated in 2(d)(ii) to compare the relative biodiversity of parasites in the two species of shark. … … [1] [Total: 18]

18 marks

Mark scheme: 2(a)(i) 2 gill slits caudal fin pectoral (fin) 2(a)(ii) Carcharodon ; 1 2(b) Rhincodon typus ; 1 2(c)(i) idea that the sharks need to be killed to identify parasites inside ; 2 idea that these sharks have already died (as a result of being caught accidentally) / no need to deliberately kill sharks to carry out the research ; 2(c)(ii) advantages: 4 more difficult to be removed from the shark ORA ; more difficult to be removed by other organisms (e.g. cleaner fish) ORA ; protected habitat / environment for parasite to reproduce ORA ; easier access to (high value) nutrient sources e.g. blood ORA ; disadvantages: more difficult for parasite to get inside the body / more difficult for parasite to find a new host ORA ; idea that the parasite needs to evade shark’s internal body defences / immune system ORA ; hard to find a mate / isolated population / reduces genetic variation ORA ; 2(c)(iii) any two from: 2 segmented, abdomen / body ; jointed legs ; two pairs of antennae ; carapace ; 2(d)(i) 4 shark type G n n 2  n  N    N  43 0.581 ; 0.338 ; 74  0.418 ; all three values correct to 3 sig. figs ; 2(d)(ii) shark species F: 0.695 AND shark species G: 0.582 ; 1 2(d)(iii) (shark) species F has a, higher / more, biodiversity (of parasites) (as shark species F has a higher Simpson’s value) ORA ; 1

This question in 9693/23 May/June 2025

3 Organisms are classified in a taxonomic hierarchy. (a) Complete the taxonomic hierarchy to show the correct position of the levels of classification. Use the words from the box. class family genus kingdom phylum taxonomic hierarchy domain order species [1] (b) Fig. 3.1 shows a jellyfish which is in the phylum cnidaria. Fig. 3.1 Make a large drawing of the jellyfish shown in Fig. 3.1. Do not include the markings. Do not label your drawing. [4] (c) Scientists investigated the biodiversity of jellyfish in the ocean. They recorded the number of species of jellyfish found at different depths. Fig. 3.2 shows the results. number of species of jellyfish 0 10 20 30 40 50 60 0–500 501–1000 1001–1500 1501–2000 2001–2500 depth / m 2501–3000 3001–3500 3501– 4000 4001– 4500 4501–5000 Fig. 3.2 (i) Use Fig. 3.2 to describe the change in species diversity of jellyfish as depth increases. … … … … [2] (ii) Explain the distribution of jellyfish species at depths between 0 m and 1500 m of the ocean. … … … … … … [3] (iii) The thermocline in the ocean at the time the results were recorded was at a depth of approximately 30 m. Describe how a thermocline forms. … … … … [2] (iv) The scientists only counted the number of jellyfish species present. State what other measurement is needed to improve the measurement of species diversity. … … [1] (v) Species diversity is one measure of biodiversity. Describe two other levels of measuring biodiversity. … … … … … … … … [4] [Total: 17]

17 marks

Mark scheme: 3(a) 1 taxonomic hierarchy domain kingdom phylum class order family genus species 3(b) outline: unbroken lines in pencil and no shading ; 4 size: most of the space provided and at least as big as original picture ; in proportion ; detail – 3 (or 4) tentacles with the upper tentacles overlapping and tentacles going into the bell ; 3(c)(i) (as depth increases) species richness / number of species, decreases ; 2 plus any one from: (species richness) declines fastest in the first 1500 m / levels off below 1500 m ; correct manipulation of data ; 3(c)(ii) any three from: 3 1 food chains begin with phytoplankton found in surface layer ; 2 phytoplankton need light for photosynthesis ; 3 jellyfish, are consumers / eat animals, (that feed on phytoplankton) ; 4 limited motility / drift in currents so can’t move great distances to obtain food ; 5 vertical migrations / found below 500 m , to reduce being predated in light ; 6 ref. to decrease in temperature with increasing depth ; 7 AVP ; 3(c)(iii) any two from: 2 water at the surface heated (by energy form the sun) ; decreases the density of surface water ; reduced mixing with cooler, denser water below ; 3(c)(iv) idea of population (of each species) ; 1 3(c)(v) genetic diversity ; 4 (genetic diversity) variation in the genes of a species ; ecological diversity ; (ecological diversity) variation in ecosystems (on a regional and global level) ;

This question in 9693/21 Oct/Nov 2025

5 Scientists studied the biodiversity at eight locations in the Arabian Sea. The scientists used a net to catch species in the benthic zone. (a) Describe what is meant by the benthic zone. … … [1] At each location the nets were pulled at a constant speed for one hour. Four of the locations sampled were at a depth of 200 m. The other four locations sampled were at a depth of 1000 m. Table 5.1 shows the depth and total catch at each location. Table 5.1 location depth / m total catch / kg number 1 200 169 2 200 122 3 200 34 4 200 582 5 1000 75 6 1000 453 7 1000 256 8 1000 120 (b) Use the data shown in Table 5.1 to describe if there is a relationship between depth and total catch. … … … … [2] (c) The scientists identified the species present in each catch and the number of individuals of each species. They used this data to calculate Simpson’s index of diversity using the equation: 2 D = 1 – (Σ(nN) ) = sum of (total) Σ n = number of individuals of each different species N = the total number of individuals of all the species (i) Use the data provided to complete Table 5.2 for location 1. Give your answers to three significant figures. Table 5.2 location 1 species 2 n n n N ( N) P 27 0.278 0.077 Q 23 … … R 18 0.186 0.034 S 16 0.165 0.027 T 13 0.134 0.018 N 97 Σ … [4] (ii) Use your answer to (c)(i) to calculate Simpson’s index of diversity for location 1. … [1] (d) Table 5.3 shows the Simpson’s index of diversity calculated for each other location sampled. Table 5.3 Simpson’s location depth / m total catch / kg index of number diversity 1 200 169 2 200 122 0.88 3 200 34 0.92 4 200 582 0.68 5 1000 75 0.91 6 1000 453 0.71 7 1000 256 0.78 8 1000 120 0.91 Compare the biodiversity for the catches shown in Table 5.3. … … … … … … [3] [Total: 11]

11 marks

Mark scheme: 5(a) the lowest part of the ocean (sediments / water) ; 1 5(b) any two from: 2 no, correlation / relationship, + no, trend / pattern / consistency, in results ; more data required to establish a relationship ; possible anomalies at site 3 / 4 and 5 ; relevant use of data to support ; 5(c)(i) 4 location 1 species 2 n n  n    N  N  Q 23 0.237 ; 0.056(0) ; N 97  0.212 ; n values for AND  to 3 sig. fig ; N 5(c)(ii) 0.788 ; 1 5(d) any three from: 3 higher Simpson’s index, value / number, indicates a, greater / higher, biodiversity ORA ; results suggest smaller catches have a higher biodiversity ORA ; results suggest no significant difference between biodiversity at different depths ; use of at least 2 data to support answer ;

This question in 9693/21 Oct/Nov 2025

4 Living walls are used to help increase diversity on human made structures. Fig. 4.1 shows several different designs used to create living walls. Fig. 4.1 Scientists investigated how three different designs of living wall, design A, design B and design C, affect diversity. Ten of each design were attached to a sea wall at the mean low water mark. The scientists recorded the total number of individuals of all species found on each design and on a control area after 12 months. Simpson’s index of diversity was used to calculate the diversity of each design. The equation for Simpson’s index of diversity is given below: n 2 D = 1 -c / ` j m N ∑ = sum of (total) n = number of individuals of each different species N = the total number of individuals of all species The results for design C are shown in Table 4.1. Table 4.1 number of individuals of n n 2 species ` j each different species (n) N N 1 34 0.168 0.028 2 7 0.035 0.001 3 21 0.104 0.011 4 6 0.030 0.001 5 37 0.183 0.033 6 12 0.059 0.003 7 59 0.292 0.085 8 19 0.094 0.009 9 7 0.035 0.001 total number of individuals 202 of all species (N) (a) Suggest what the scientists used for the control area. … … … … [2] (b) (i) Use the information in Table 4.1 to calculate D for design C. D = … [2] (ii) Table 4.2 shows the values for Simpson’s index of diversity (D) in design A, design B and in the control area. Table 4.2 design A design B control area Simpson’s index of diversity (D) 0.674 0.818 0.143 Compare the effectiveness of designs A and B for increasing diversity. Use the values for D from Table 4.2 to support your answer. … … … … … … [3] (iii) Evaluate the extent to which the results from this investigation support the idea that living walls increase diversity on human made structures. … … … … … … [3] (c) Suggest reasons why the different designs shown in Fig. 4.1 affect the diversity of the sea wall. … … … … … … [3] (d) State three examples of the benefits that marine biodiversity provides. 1 … … 2 … … 3 … … [3] [Total: 16]

16 marks

Mark scheme: 4(a) bare, sea wall / human-made surface ; 2 of same size area / at same depth ; 4(b)(i) 0.172 ; 2 1 – 0.172 = 0.828 ; 4(b)(ii) reference to value closer to 1 indicating greater biodiversity ; 3 both designs have greater biodiversity than control area ; design B has greater biodiversity than A ; 4(b)(iii) any three from: 3 supported as all designs show increased diversity compared to control ; (however) only one human-made structure investigated ; (however) only one, sea area / coast investigated ; (however) relatively small sample size ; (however) investigation only lasted 12 months ; investigation only performed once ; AVP ; 4(c) any three from: 3 may provide different surface for secure attachment by organisms ; different shapes may have different degrees of shading at low tide ; different shapes may hold different volumes of water at low tide ; may be made of different materials ; size of hollows / crevices may affect how many, individuals / species, can occupy them ; larger surface area ; idea of not being a uniform habitat ; AVP ; 4(d) any three from: 3 maintaining stable ecosystems ; protection of the physical environment ; providing food sources / increased opportunity for harvesting ; as a source of pharmaceuticals /medicines ; climate control / reduces global warming ;

This question in 9693/22 Oct/Nov 2025

4 Living walls are used to help increase diversity on human made structures. Fig. 4.1 shows several different designs used to create living walls. Fig. 4.1 Scientists investigated how three different designs of living wall, design A, design B and design C, affect diversity. Ten of each design were attached to a sea wall at the mean low water mark. The scientists recorded the total number of individuals of all species found on each design and on a control area after 12 months. Simpson’s index of diversity was used to calculate the diversity of each design. The equation for Simpson’s index of diversity is given below: n 2 D = 1 -c / ` j m N ∑ = sum of (total) n = number of individuals of each different species N = the total number of individuals of all species The results for design C are shown in Table 4.1. Table 4.1 number of individuals of n n 2 species ` j each different species (n) N N 1 34 0.168 0.028 2 7 0.035 0.001 3 21 0.104 0.011 4 6 0.030 0.001 5 37 0.183 0.033 6 12 0.059 0.003 7 59 0.292 0.085 8 19 0.094 0.009 9 7 0.035 0.001 total number of individuals 202 of all species (N) (a) Suggest what the scientists used for the control area. … … … … [2] (b) (i) Use the information in Table 4.1 to calculate D for design C. D = … [2] (ii) Table 4.2 shows the values for Simpson’s index of diversity (D) in design A, design B and in the control area. Table 4.2 design A design B control area Simpson’s index of diversity (D) 0.674 0.818 0.143 Compare the effectiveness of designs A and B for increasing diversity. Use the values for D from Table 4.2 to support your answer. … … … … … … [3] (iii) Evaluate the extent to which the results from this investigation support the idea that living walls increase diversity on human made structures. … … … … … … [3] (c) Suggest reasons why the different designs shown in Fig. 4.1 affect the diversity of the sea wall. … … … … … … [3] (d) State three examples of the benefits that marine biodiversity provides. 1 … … 2 … … 3 … … [3] [Total: 16]

16 marks

Mark scheme: 4(a) bare, sea wall / human-made surface ; 2 of same size area / at same depth ; 4(b)(i) 0.172 ; 2 1 – 0.172 = 0.828 ; 4(b)(ii) reference to value closer to 1 indicating greater biodiversity ; 3 both designs have greater biodiversity than control area ; design B has greater biodiversity than A ; 4(b)(iii) any three from: 3 supported as all designs show increased diversity compared to control ; (however) only one human-made structure investigated ; (however) only one, sea area / coast investigated ; (however) relatively small sample size ; (however) investigation only lasted 12 months ; investigation only performed once ; AVP ; 4(c) any three from: 3 may provide different surface for secure attachment by organisms ; different shapes may have different degrees of shading at low tide ; different shapes may hold different volumes of water at low tide ; may be made of different materials ; size of hollows / crevices may affect how many, individuals / species, can occupy them ; larger surface area ; idea of not being a uniform habitat ; AVP ; 4(d) any three from: 3 maintaining stable ecosystems ; protection of the physical environment ; providing food sources / increased opportunity for harvesting ; as a source of pharmaceuticals /medicines ; climate control / reduces global warming ;

This question in 9693/23 Oct/Nov 2025