Cambridge A Level Biology 9700 — 2015 May/June Paper 3 · Variant 2

This document consists of 12 printed pages. DC (NF/SW) 87481/4 © UCLES 2015 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 0 1 9 5 5 2 0 1 9 8 * BIOLOGY 9700/32 Advanced Practical Skills 2 May/June 2015 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 2 Total

2 9700/32/M/J/15 © UCLES 2015 Before you proceed, read carefully through the whole of Question 1 and Question 2. Plan the use of the two hours to make sure that you finish all the work that you would like to do. If you have enough time, consider how you can improve the accuracy of your results, for example by obtaining and recording one or more additional measurements. You will gain marks for recording your results according to the instructions. 1 Athletes who run long distances need to drink while they are running. Their drinks often contain carbohydrates to provide energy. You are provided with four drinks: D1, D2, D3 and D4. Each drink contains one or more carbohydrates. You are required to identify the carbohydrates in the drinks using the reagents provided. (a) (i) Describe how you will use the reagent(s) to determine whether any of the drinks contain a polysaccharide. … … … [1] Carry out the test you have described in (a)(i) on D1, D2, D3 and D4. (ii) Complete the table by using a tick (✓) to show the presence of a polysaccharide and a cross (✗) to show the absence of a polysaccharide, in any of D1, D2, D3 and D4. drink presence (✓) or absence (✗) of polysaccharide D1 D2 D3 D4 [1] You are required to compare the quantity of reducing and non-reducing sugars in each of the drinks. You will need to record the time taken for the first appearance of any colour change. If no colour change occurs after 180 seconds (3 minutes), stop the experiment and record ‘more than 180’.

3 9700/32/M/J/15 © UCLES 2015 [Turn over (iii) Describe how you will use the reagent(s) to test for reducing and non-reducing sugars. reducing sugar test: … … … … non-reducing sugar test: … … … … … [3] When carrying out a practical procedure, the hazards of the use of all the apparatus and all of the reagents need to be considered, then the level of risk needs to be assessed as low or medium or high. (iv) State the hazard with the greatest level of risk when testing for reducing and non-reducing sugar. State the level of risk of the procedure: low or medium or high. hazard … level of risk … [1]

4 9700/32/M/J/15 © UCLES 2015 Carry out the tests on D1, D2, D3 and D4, as described in (a)(iii), and record your results in (a)(v). (v) Prepare the space below and record your results. [5] The sugars in the drinks are sucrose and glucose. (vi) Suggest which drink, D1, D2, D3 or D4, would provide the athletes with the greatest quantity of glucose, and explain why you selected this drink. … … … [1] (vii) A student wanted to investigate the concentration of reducing sugar in another drink, D5, used by athletes. Describe how the student could estimate the concentration of reducing sugar in drink D5. … … … … … … … [3]

5 9700/32/M/J/15 © UCLES 2015 [Turn over Question 1 continues on page 6

6 9700/32/M/J/15 © UCLES 2015 (b) The London Olympic Games of 2012 included races run over distances ranging from 100 m to 42 200 m (the Marathon). Table 1.1 shows the average speed of the winner of five of these races over different distances. Using log10 of the distance makes the numbers easier to plot on a graph. Table 1.1 log10 distance / m average speed / m s−1 2.0 10.4 2.6 9.1 3.2 7.0 4.0 6.1 4.6 5.5 You are required to use a sharp pencil for graphs. (i) Plot a graph of the data in Table 1.1. [4]

7 9700/32/M/J/15 © UCLES 2015 [Turn over (ii) Estimate the average speed for a race of distance log10 3.5 m. … [1] (iii) Describe the trend shown by the data. … … … [1] (iv) The winner of the Marathon race had trained at high altitude. Explain why this may have resulted in an increased average speed. … … … [1] [Total: 22]

8 9700/32/M/J/15 © UCLES 2015 You are required to use a sharp pencil for drawings. 2 (a) L1 is a slide of a stained transverse section through a plant stem. This plant species is a native of Europe and parts of Asia. You are not expected to be familiar with this specimen. (i) Draw a large plan diagram of the quarter of the stem, as shown in Fig. 2.1. draw this quarter Fig. 2.1 Use one ruled label line and label to identify one vascular bundle. [5]

9 9700/32/M/J/15 © UCLES 2015 [Turn over (ii) Select one group of four cells from near the centre of the stem. Each cell in the group should touch two of the other cells. Make a large drawing of this group of four cells. Use one ruled label line and label to identify one cell wall. [5]

10 9700/32/M/J/15 © UCLES 2015 (b) Fig. 2.2 is a stained transverse section of an organ from a different plant species. This plant species grows in Asia, Europe and North America. You are not expected to be familiar with this specimen. Fig. 2.2 Prepare the space below so that it is suitable for you to record observable differences between the specimen on slide L1 and Fig. 2.2. Record your observations in the space you have prepared. The differences should include: • the vascular tissue • one other tissue. [4]

11 9700/32/M/J/15 © UCLES 2015 [Turn over (c) Fig. 2.3 is a high power view of part of the organ shown in Fig. 2.2. Q Y R magnification × 250 Fig. 2.3 (i) Calculate the actual widest diameter of the cell labelled R as shown by line Y in Fig. 2.3. You may lose marks if you do not show your working or if you do not use appropriate units. actual widest diameter … μm [2] (ii) State one observable feature of cells Q and R shown on Fig. 2.3, and explain how this feature enables the cells to carry out their function. … … … [1]

12 9700/32/M/J/15 © UCLES 2015 (iii) A student observed a different plant of the same species as shown in Fig. 2.3. The student determined the ratio of the diameter of one cell to the diameter of a smaller cell as 360 : 85. However, a ratio may be simplified by dividing each side by the same number to give the smallest possible whole number on each side. In this example, both sides of the ratio 360 : 85 are divisible by 5, so the simplest ratio for the diameters measured by the student is 72 : 17. In Fig. 2.3, cell Q has an actual diameter of 200 μm. Determine the simplest ratio of the diameter of cell Q to the diameter of cell R. ratio …[1] [Total: 18] 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 International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge

® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International Advanced Subsidiary and Advanced Level MARK SCHEME for the May/June 2015 series 9700 BIOLOGY 9700/32 Paper 3 (Advanced Practical Skills 2), maximum raw mark 40 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2015 9700 32 © Cambridge International Examinations 2015 Mark scheme abbreviations: ; separates marking points / alternative answers for the same point R reject A accept (for answers correctly cued by the question, or by extra guidance) AW alternative wording (where responses vary more than usual) underline actual word given must be used by candidate (grammatical variants accepted) max indicates the maximum number of marks that can be given ora or reverse argument mp marking point (with relevant number) ecf error carried forward I ignore

Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2015 9700 32 © Cambridge International Examinations 2015 1 (a) (i) starch test + iodine solution ; [1] (ii) completed table with tick for D1 + cross for each of D2, D3, D4 ; [1] (iii) (reducing sugar test) add Benedict's + heat (80 ºC - 100 ºC) ; (non-reducing sugar test) add acid + heat ; (non-reducing sugar test) neutralise ; [3] (iv) (level of risk) medium or high ; [1] (v) 1 table with heading + drinks ; 2 table with heading + time + seconds ; 3 records results for 4 reducing sugar tests + 4 non-reducing sugar tests ; 4 for D2 records time for reducing sugar test as longer than for non-reducing sugar test ; 5 records time in whole seconds ; [5] (vi) D1 or D2 (breaks down to glucose) or D3 shortest time to show colour change ; [1] (vii) at least 5 known glucose concentrations ; made by simple or serial dilution ; carry out Benedict's test with known glucose concentrations and D5 + compare result for D5 with results for known glucose concentrations ; [3] (b) (i) orientation (x-axis) log10 distance (/) m + (y-axis) average speed (/) m s–1 ; scale (x-axis) 2 cm to 0.5 labelled each 2 cm + must have 2 at the origin + (y-axis) 2 cm to 1 labelled each 2 cm + must have 5 at origin ; plotting correct plotting of 5 points as small cross or dot in circle ± half a square ; line 5 plots with ruled lines exactly point to point + quality smooth line less than 1 mm thick ; [4] (ii) correct estimate from candidate's graph ; [1] (iii) as distance increases the average speed decreases ; [1] (iv) increased number of red blood cells ; [1] [Total: 22]

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2015 9700 32 © Cambridge International Examinations 2015 2 (a) (i) draws at least 2 layers of tissue + size at least 70 mm + no shading ; no cells drawn + correct quarter drawn ; epidermis drawn as 2 lines close together ; draws at least one vascular bundle subdivided into tissue layers ; correct label with label line to vascular bundle ; [5] (ii) thin and continuous lines + size at least 40 mm for at least one cell ; draws only 4 whole cells + each cell touching at least 2 other cells ; intercellular space present for 4 cells; cell walls drawn as double lines ; correct label with label line to cell wall ; [5] (b) organizes table with 3 columns or rows + with appropriate headings + one column or row for features ; records only differences ; at least one observable difference for the vascular tissue ; at least one observable difference for one other tissue ; [4] (c) (i) shows measurement of line Y within range + mm ; shows length of Y divided by 250 + multiplied by 1000 ; [2] (ii) lumen / space / no (cell) contents + transport / idea of less resistance [1] or wall + support to prevent collapse ; (iii) shows the simplest ratio of the diameter of cell Q to the diameter of cell R ; [1] [Total: 18]