Cambridge A Level Marine Science 9693 — 2021 Oct/Nov Paper 4 · Variant 0

This document has 16 pages. Any blank pages are indicated. DC (RW/FC) 207523/3 © UCLES 2021 [Turn over * 3 2 6 3 7 8 2 4 9 2 * MARINE SCIENCE 9693/04 Paper 4 A2 Data-Handling and Free-Response October/November 2021 1 hour 15 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use a calculator. ● You should show all your working and use appropriate units. INFORMATION ● The total mark for this paper is 50. ● The number of marks for each question or part question is shown in brackets [ ]. Cambridge International AS & A Level

2 9693/04/O/N/21 © UCLES 2021 Section A Answer both questions in this section. 1 The effect of different wavelengths of light on the rate of photosynthesis of two species of marine algae, A and B, was investigated. Fig. 1.1 shows the apparatus used. alga 1 m ruler light filter lamp Fig. 1.1 Pieces of alga A were placed into a beaker of sea water and exposed to light of wavelength 450 nm for ten minutes. This was repeated four times and the mean rate of bubbles produced per minute was calculated. This was repeated with light of different wavelengths using different coloured light filters. The experiment was then repeated with alga B. The results are shown in Table 1.1. Table 1.1 wavelength of light / nm mean rate of bubbles produced by algae / bubbles per minute A B 450 20 17 490 29 22 520 16 17 575 2 12 610 15 15 710 26 21

3 9693/04/O/N/21 © UCLES 2021 [Turn over (a) The age, mass and surface areas of the algae were kept constant. Suggest an explanation for keeping one other named variable constant. named variable … explanation … … … [2] (b) Draw a line graph to show the effect of light wavelength on the rate of photosynthesis by both algae. [5]

4 9693/04/O/N/21 © UCLES 2021 (c) Fig. 1.2 shows the colours of light of different wavelengths. 700 650 600 550 500 450 Violet Blue Green Yellow Orange Red 400 Wavelength, λ (nm) Fig. 1.2 One of the species of alga lives in surface waters. The other species lives in deeper water. Use the information in Table 1.1, Fig. 1.2 and your graph to explain how the two species of algae are adapted to live at different depths. … … … … … … … … … … [4] [Total: 11]

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6 9693/04/O/N/21 © UCLES 2021 2 Tributyltin (TBT) was often added to antifouling paint and used extensively in the 20th century. It affects the development of larvae of molluscs such as oysters. The effect of different concentrations of TBT on the development of the larvae of two species of mollusc, A and B, was investigated. Larvae were exposed to different concentrations of TBT and the percentage of larvae that developed normally was determined after 48 hours. The results are shown in Fig. 2.1. 0.0 0 10 20 30 40 50 60 70 80 percentage of larvae that developed normally 90 100 0.2 0.4 0.6 0.8 concentration of TBT / μg dm–3 1.0 1.2 1.4 1.6 species B species A species B species A Fig. 2.1

7 9693/04/O/N/21 © UCLES 2021 [Turn over (a) (i) A total of 500 larvae of each species were used. Use Fig. 2.1 to determine the number of larvae from species A that developed normally after exposure to 0.6 μg dm–3 of TBT. … [2] (ii) Compare the effect of increasing concentrations of TBT on the percentage of larvae that develop normally for species A and species B. … … … … … … [2]

8 9693/04/O/N/21 © UCLES 2021 (b) Tannin is a plant extract that is being tested for use as an ‘environmentally friendly’ antifouling agent. It can be added to paints before being placed onto metal surfaces. Barnacles often attach to the underside of boats. Fig. 2.2 shows barnacles growing on metal. Fig. 2.2 Describe a method for a laboratory‑based investigation to determine whether tannin prevents the growth of barnacles on the surface of metal. … … … … … … … … … … … … [5] [Total: 9]

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10 9693/04/O/N/21 © UCLES 2021 Section B Answer both questions in this section. 3 (a) (i) Discuss how the size and shape of marine organisms affect the need for specialised gaseous exchange organs. … … … … … … … … [4] Fig. 3.1 shows the transport systems of a whale and a species of fish. gill fish heart heart lung whale muscles muscles Fig. 3.1 Whales are large, active, air-breathing animals. This species of fish is smaller and less active than whales.

11 9693/04/O/N/21 © UCLES 2021 [Turn over (ii) Use Fig. 3.1, and your own knowledge, to explain the differences in the transport systems of this whale and this species of fish. … … … … … … … … [4] (b) Describe the life cycle of oysters. In your answer, include the principal habitats and the advantages of these habitats. … … … … … … … … … … … … … … [7] [Total: 15]

12 9693/04/O/N/21 © UCLES 2021 4 (a) Discuss the sociological impacts of placing restrictions on fishing. … … … … … … … … … … … … [5] (b) Describe how energy conservation methods in ecotourist resorts are beneficial to conservation. … … … … … … … … [4]

13 9693/04/O/N/21 © UCLES 2021 (c) Explain the negative effects of dredging on the marine environment. … … … … … … … … … … … … … … … … [6] [Total: 15]

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16 9693/04/O/N/21 © UCLES 2021 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge. BLANK PAGE