Cambridge A Level Biology 9700 — 2009 Oct/Nov Paper 3 · Variant 2

This document consists of 10 printed pages and 2 blank pages. DC (SHW 00338 7/08) 16163/4 © UCLES 2009 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level 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 a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. 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. * 4 1 4 0 9 4 4 4 2 5 * BIOLOGY 9700/32 Paper 3 Advanced Practical Skills October/November 2009 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions For Examiner’s Use 1 2 3 Total

9700/32/O/N/09 © UCLES 2009 For Examiner’s Use You are reminded that you have TWO hours to complete Questions 1, 2 and 3 in the practical examination. Questions 1 and 3 use apparatus or a microscope. You should start with either Question 1 or 3. It is expected that Question 1 will take you approximately one hour. Question 3 should take you approximately 20 minutes. Question 2 does not require apparatus or the use of a microscope, you should complete this question whenever you have spare time, most likely after you have completed Question 3. You should read carefully through the whole of each question and then plan your use of the time to make sure that you finish all of the work that you would like to do. You will gain marks for recording your results according to the instructions. 1 You are required to identify four samples S1, S2, S3 and S4. One sample contains starch suspension which a person was about to eat. One sample was taken from the mouth two minutes after being eaten. One sample was taken from the stomach ten minutes after being eaten. One sample was taken from the small intestine two hours after being eaten. Starch is hydrolysed to glucose by enzymes in the mouth and small intestine. These enzymes are not active in the stomach. The starch suspension moves from the mouth to the stomach to the small intestine. (a) (i) Suggest what happens to the concentrations of starch and glucose after the starch suspension has been eaten. mouth … … stomach … … small intestine … … [2] 2

3 9700/32/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use Using only the materials provided test the four samples S1, S2, S3 and S4. You will need to consider carefully how you will carry out the tests so that you can determine the relative concentrations of starch and glucose. (ii) Prepare the space below and record: • the tests you used • the quantities of the samples and reagents • and your results. [7]

4 9700/32/O/N/09 © UCLES 2009 For Examiner’s Use (iii) Using the information provided and your results, complete Table 1.1 below to identify the samples. Table 1.1 sample from sample identified starch about to be eaten ……………… mouth ……………… stomach ……………… small intestine ……………… [3] (iv) Explain your answer to (a)(iii). … … … … … … … [3] (b) A student wanted to obtain a quantitative measurement of the glucose concentrations. Suggest how the student could modify this investigation to obtain quantitative measurements of the glucose concentrations. … … … … … … … [3] www.OnlineExamHelp.com

5 9700/32/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use A student investigated the effect of increasing the starch concentration on the time taken for 2 cm3 of a 1% solution of amylase to hydrolyse the starch. The student’s results are shown in Table 1.2. Table 1.2 concentration of starch / g dm–3 mean time taken for 1 cm3 of starch to be hydrolysed / seconds 5 12 15 39 20 53 30 79 (c) (i) Plot a graph of these data shown in Table 1.2. [4] (ii) Use your graph to find the rate of hydrolysis by finding the gradient of the line. Show on your graph where you took the readings to calculate the gradient. [1] Show your working. rate of hydrolysis … g dm–3 s–1 [1] [Total: 24]

6 9700/32/O/N/09 © UCLES 2009 For Examiner’s Use 2 (a) Fig. 2.1 is a photomicrograph of a transverse section through a tubular organ of a mammal. magnification × 100 Fig. 2.1 Draw a large plan diagram of the section shown in Fig 2.1. No labels are required. [4]

7 9700/32/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use (b) Fig. 2.2 is a photomicrograph showing a high-power view of the surface of a leaf. magnification × 400 Fig. 2.2 (i) Make a large, labelled drawing to show two guard cells and the complete cells that surround them. Do not draw more than six cells in total. Show on Fig. 2.2 the cells that you have drawn. [5]

8 9700/32/O/N/09 © UCLES 2009 For Examiner’s Use (ii) Calculate the actual length in micrometres (m) of one of the guard cells. Show all the steps in your calculation. … m [2] [Total: 11] www.OnlineExamHelp.com

9 9700/32/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use 3 You are provided with two samples of plant material. A suspension of leaf cells in a dish, labelled L. A piece of peeled potato tuber in a dish, labelled P. 1. Label four slides, two with L and two with P. 2. Using a pipette, place one drop of L on each of the two slides labelled L. [H] 3. Add one drop of iodine solution to one of the slides labelled L. 4. Using a sharp blade or scalpel, cut the potato piece to show a fresh surface. 5. Carefully scrape off some potato cells from the fresh surface and smear them onto the middle of each of the two slides labelled P. [H] 6. Add one drop of iodine solution to one of the slides labelled P. 7. Add a coverslip to each slide and use a paper towel to absorb the excess liquid. 8. Use your microscope to search each slide carefully and record the observations of the cells you can find. (a) Prepare the space below and record all your observations. [3]

10 9700/32/O/N/09 © UCLES 2009 For Examiner’s Use (b) Explain your observations. … … … … [2] [Total: 5]

12 9700/32/O/N/09 BLANK PAGE 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. University of 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. www.OnlineExamHelp.com

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2009 question paper for the guidance of teachers 9700 BIOLOGY 9700/32 Paper 32 (Advanced Practical 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 must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the October/November 2009 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9700 32 © UCLES 2009 Question Expected Answers Marks Additional Guidance 1 (a) (i) Suggest what happens to the concentrations of starch and glucose after the starch suspension has been eaten. (starch) (glucose/reducing sugar) MMO decisions 2 (stomach) stays same/no change; [1] (mouth) AND (small intestine) less/decreases, AND no/little/less/decreases AND some/little/increases all/lots/more/increases; [1] (ii) Prepare the space below and record: the tests you used, the quantities of the samples and reagents and your results. all cells drawn AND sample/S1, S2, S3, S4 as heading for top or left column ; [1] Mark both of separate results tables for mark points 1 and 2. PDO recording 2 observations/colour/result/s ; Check heading where colours recorded and credit this heading. [1] MMO collection 3 all samples tested for starch AND Ignore actual colours S2 (iodine) blue/black AND Reject purple. (with Benedict’s) blue/no test done; Reject colourless [1] S4 (Benedict’s only) (brick) red ; [1] S1 and S3 (Benedict’s) either same colour or both colours, less than S4; [1] MMO decisions 2 same volume for each sample AND same or excess volume for Benedict’s; [1] Reject if just amounts or drops. (Benedict’s) heats to more than 80o C /boils AND same time 10 minutes or less ; [1]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9700 32 © UCLES 2009 Question Expected Answers Marks Additional Guidance (iii) Using the information provided and your results, complete Table 1.1 below to identify the samples. ACE interpretation 3 sample sample identified starch about to be eaten S2; mouth S1 and/or S3 ; stomach S1 and/or S3 ; small intestine S4; [max 3] (iv) Explain your answer to (a) (iii). hydrolysis/ed, used in correct context; [1] In correct context (starch eaten or S2/sample identified) no (hydrolysis/breakdown)/only contains starch/no glucose/ description of results; (stomach or sample identified)idea of no/(enzyme action/ breakdown) OR (mouth or sample identified) little (enzyme action/breakdown); ACE conclusions 3 (small intestine or S4/sample identified) more/increased/most (enzyme action/breakdown); [max 2] Allow results only for starch eaten. (b) Suggest how the student could modify this investigation to obtain quantitative measurements of the glucose concentration. use known/range of concentrations of glucose; [1] serial dilution/description of dilutions/examples of 3 concentrations; [1] use colorimeter/colour chart/mass of precipitate/time for colour to change/diastix/glucose test strip; [1] Reject calorimeter’ draw graph/calibration curve; [1] ACE improvements 3 compare unknowns/samples to standards/AW; [max 3]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9700 32 © UCLES 2009 Question Expected Answers Marks Additional Guidance (c) (i) Plot a graph of these data shown in Table 1.2. PDO layout 4 O x-axis conc/concentration, g dm-3 Reject g/dm-3 Allow g/dm3 AND y-axis time, seconds/secs/s ; [1] S scale as 5 to 2 cm (allow no 0) or 5 at origin and 20 to 2 cm allow 10 at origin; [1] If O is incorrect, allow suitable scale more than half grid on both axes. P plotting crosses or dot in circle ONLY AND plots correct; No cross larger than X or o. If plot additional point with same symbol used to show calculation/gradient then reject plotting. [1] Do not credit blobs in or out of circles. Credit x s in circles. L ruled/straight line to 3 points; Allow point to point if not plotted correctly. [1] Allow extrapolation to 0 within 3 mm. Reject if origin not 0,0. Do not credit if any extrapolation beyond 30 or beyond y-axis. (ii) Use your graph to find the rate of hydrolysis by finding the gradient of the line. MMO collection 1 shows how on graph ; [1] ACE interpretation 1 correct answer (from their correctly plotted graph); Allow any answer between 0.3500 and 0.4255 Reject as fraction OR 2.350 and 2.900/allow 2 with a fraction; [1] Allow 1 to 4 significant figures. If graph incorrectly plotted then check readings and calculation. Total [24] www.OnlineExamHelp.com

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9700 32 © UCLES 2009 Question Fig 2.1 Expected Answers Marks Additional Guidance 2 (a) Draw a large plan diagram of the section shown in Fig. 2.1. PDO layout 1 clear, sharp, AND unbroken lines no shading AND larger than the diagonal across 6 cm grid from apex of drawing [1] MMO collection 1 no cells AND only whole section drawn; Reject if draw more than whole section labelled. [1] PDO recording 1 inner layer shown by two/three lines closer together than next line ; [1] MMO decision 1 drawn 3 large folds as shown in pmg All three folds larger than any of others. OR bulge on side approx. half way between apex and edge ; [1]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9700 32 © UCLES 2009 Question Fig. 2.2 Expected Answers Marks Additional Guidance (b) (i) Make a large, labelled drawing to show TWO guard cells and the COMPLETE cells that surround them. Do not draw more than 6 cells. Show on Fig. 2.2 the cells you have drawn. PDO layout 1 clear, sharp, AND unbroken lines no shading AND does not fit inside the 6 cm grid; [1] collection 1 shows on Fig 2.2 at least 2 cells AND 2 guard cells only AND up to 4 complete cells drawn; [1] MMO 1 length of surrounding cell more than width; [1] MMO decision 1 outline of (surrounding cells) wavy/not straight AND no air spaces between adjacent cells; [1] 1 cell wall labelled correctly; Reject if ultrastructure labelled. [1] cell wall (ii) Calculate the actual length in micrometres of one of the guard cells. Show all the steps in your calculation. PDO display 2 (length in mm (5 to 32) × 1000/103; OR (length in cm (0.5 to 3.2) × 10000/104; Reject any metre conversions and measurements outside the range given. [1] divided by 400; Must show division by 400. [1] Total [11]

Page 7 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9700 32 © UCLES 2009 Question Expected Answers Marks Additional Guidance 3 (a) Prepare the space below and record all your observations. PDO recording 1 table/divided space into four with lines and clearly leaf/L stained/LI AND unstained/L AND potato/P stained/PI AND unstained/P; [1] MMO collection 1 (leaf cells/L) at least TWO different types of cells observed; Allow drawn or named from epidermal cells/palisade cells/mesophyll cells/xylem vessels/cells/ guard cells. [1] MMO decision 1 (potato cells/P) black/starch AND granules/grains/sacs/AW (when stained with iodine) AND in cells; Reject blue/black cells [1] (b) Explain your observations. ACE interpretation 2 (iodine) stains/shows starch; [1] (iodine)no effect/little/less starch in LI/leaf; (potato) contains more starch; [1] Allow any comparative statement. Total [5] www.OnlineExamHelp.com