Cambridge A Level Biology 9700 — 2011 May/June Paper 3 · Variant 2

This document consists of 10 printed pages and 2 blank pages. DC (CW/DJ) 31757/6 © UCLES 2011 [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 ink. You may use a pencil for any diagrams, graphs or rough working. Do not use red ink, staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. 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. * 5 6 9 7 3 2 7 8 7 4 * BIOLOGY 9700/32 Advanced Practical Skills 2 May/June 2011 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. For Examiner’s Use 1 2 3 Total

2 9700/32/M/J/11 © UCLES 2011 For Examiner’s Use You are reminded that you have two hours to complete questions 1, 2 and 3. It is expected that each question will take you approximately 40 minutes. Question 2 does not require any apparatus or the use of a microscope. You should plan your work so that you complete this question whenever you have spare time. You may start with either Question 1 or Question 3, which require the use of apparatus or a microscope. At the start of the second hour, you should begin the work for the other question, either Question 1 or Question 3. You should: • Read carefully through the whole of each question. • Plan your use of the time to make sure that you finish all the work that you would like to do. You will gain marks for recording your results according to the instructions. 1 Doctors use the analysis of urine to help diagnose some medical conditions. One such medical condition is diabetes which results in glucose being released in urine if the condition is untreated. You are provided with: labelled contents hazard concentration / % volume / cm3 G glucose solution none 4 30 S1 unknown glucose concentration representing urine none – 15 S2 unknown glucose concentration representing urine none – 15 W distilled water none – 100 Benedict’s solution Benedict’s solution harmful irritant – 50 You are required to find the glucose concentrations of solutions S1 and S2. You are required to carry out a serial dilution of glucose solution, G, to reduce the concentration of the glucose solution by half between each successive dilution.

3 9700/32/M/J/11 © UCLES 2011 [Turn over For Examiner’s Use Fig. 1.1 shows how to make the first concentration of 2% glucose solution. … … … 20 cm3 of 4% glucose solution, G 2% glucose solution 10 cm3 of distilled water, W 10 cm3 of 4% glucose solution, G Fig. 1.1 (a) (i) Complete Fig. 1.1 to show how you will make three further concentrations of glucose solution, G. [3] (ii) Complete Table 1.1 to show the volumes of solutions you intend to use in your investigation. Table 1.1 solution volume / cm3 Benedict’s each concentration of G S1 S2 [2]

4 9700/32/M/J/11 © UCLES 2011 For Examiner’s Use Proceed as follows: 1. Prepare the dilutions of G as shown in Fig. 1.1 in the containers provided. 2. Label test-tubes with the concentrations of G. 3. Label test-tubes S1 and S2. 4. Set up a water-bath and, testing each test-tube separately, test all the concentrations of G and the solutions S1 and S2 for the presence of glucose. Start timing when the test- tube is placed into the hot water-bath. If there is no colour change after 300 seconds, record ‘more than 300’ as your result (for step 5). 5. Observe the test-tube very carefully for the first sign of a colour change. This is the end- point of the reaction. As soon as you see this colour change, record the time taken for the reaction to reach the end-point. (b) (i) State one variable, other than the volume of each solution, which needs to be kept the same in this investigation. Describe how you will keep this variable the same. … … … [1] (ii) Prepare the space below and record your results. [4]

5 9700/32/M/J/11 © UCLES 2011 [Turn over For Examiner’s Use (c) (i) Estimate the concentration of glucose in solutions S1 and in S2. S1 … S2 … [1] (ii) State which solution, S1 or S2, is most likely to be from an untreated diabetic. untreated diabetic … [1] [Total: 12]

6 9700/32/M/J/11 © UCLES 2011 BLANK PAGE Question 2 starts on page 7

7 9700/32/M/J/11 © UCLES 2011 [Turn over For Examiner’s Use 2 The diameter of a tube, which carries urine in a mammal, was measured at different distances along its length. The diameter of the tube was found to vary along its length. The results are shown in Table 2.1. Table 2.1 distance along the tube / cm diameter of the tube / mm 0.5 1.8 4.5 2.4 12.5 3.8 20.0 5.1 24.0 5.8 (a) (i) Plot a graph of the data shown in Table 2.1. [4]

8 9700/32/M/J/11 © UCLES 2011 For Examiner’s Use Fig. 2.1 is a photomicrograph of the transverse section through this tube. lumen X connective tissue muscle tissue fold epithelial tissue Fig. 2.1 magnification × 22 (b) (i) Calculate the actual diameter of the tube shown by line X in Fig. 2.1. You may lose marks if you do not show your working or if you do not use appropriate units. [4] (ii) Use the actual diameter of the tube calculated in (ii) and your graph in (a)(i) to estimate the distance along the length of the tube, where the section was cut. …[1] (iii) Describe how you would find the mean diameter of the tube shown in Fig. 2.1. … … …[2]

9 9700/32/M/J/11 © UCLES 2011 [Turn over For Examiner’s Use Fig. 2.2 is a photomicrograph of a transverse section of a different tube from a mammal. lumen connective tissue muscle tissue epithelial tissue magnification × 90 Fig. 2.2 (iv) Prepare the space below so that it is suitable for you to record the observable differences between the specimens in Fig. 2.1 and in Fig. 2.2. Record your observations in the space you have prepared. [5] [Total: 16]

10 9700/32/M/J/11 © UCLES 2011 For Examiner’s Use 3 L1 is a slide of a stained transverse section through a stem. (a) (i) Draw a large plan diagram of the whole of the transverse section. Label the epidermis and xylem. [5] (ii) Calculate the ratio of the total diameter of the stem to the diameter of the central pith. You may lose marks if you do not show your working or if you do not use appropriate units. [1]

11 9700/32/M/J/11 © UCLES 2011 For Examiner’s Use (b) (i) State one observable feature of the epidermis that supports the conclusion that this is a stem from a plant growing in a dry habitat. Explain how this feature reduces water loss. feature … explanation … … …[1] (ii) Make a large drawing of three adjacent (touching) cells from the central pith. Label the cell wall. [5] [Total: 12]

12 9700/32/M/J/11 © UCLES 2011 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.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2011 question paper for the guidance of teachers 9700 BIOLOGY 9700/32 Paper 32 (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 must be read in conjunction with the question papers and the report on the examination. • Cambridge will not enter into discussions or correspondence in connection with these mark schemes. Cambridge is publishing the mark schemes for the May/June 2011 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 AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 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 excepted) 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 BOD Benefit of Doubt given ACE Analysis, Conclusions and Evaluation (skills) PDO Presentation of Data and Observations (skills) MMO Manipulations, Measurement and Observation (skills)

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 1 (a) (i) Complete Fig. 1.1 to show how you will make a serial dilution to reduce the concentration by half between each concentration. [3] (labels under correct sequence of beakers) 1(.0) AND 0.5 AND 0.2(5); MMO decisions 1 [1] Additional guidance Must have • % once (uses serial dilution) (adds previous concentration of G to each of three beakers and same volume) volume of 2(%) or shown by arrow with volume AND the same volume transferred from first beaker to second and from second beaker to third beaker); [1] Additional guidance Must have • cm3 once (adds of (distilled) water/W to each of three beakers) 10 cm3; MMO decisions 2 [1] Additional guidance Must have • cm3 once

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (ii) Complete Table 1.1 to show the volumes of solutions you intend to use in your investigation. [2] MMO decisions 2 [1] [1] solution volume / cm3 all same volume; G and S1 and S2 Additional guidance Must have • volume 2 cm3 or more AND 15 cm3 or less • whole number Do not give mark for • drops Benedict’s (whole number) same as G and S1 and S2 OR more than G and S1 and S2 OR same or more than the largest volume from G / S1 / S2; Additional guidance Do not give mark if • for a combined volume of solution plus Benedict’s of 21 or more cm3 • if any value missing for G / S1 / S2

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (b) (i) State one variable, other than volume, which needs to be kept the same in this investigation. Describe how you will keep this variable the same. [1] Do not give credit if answer gives a choice. [1] temperature AND (idea of how kept the water-bath the same) heat or described Or add hot or cold water AND boil Or to temperature 80(°C) to 100 Or checking or monitoring with thermometer BOD temperature probe/gauge; ACE improvement 1 Additional guidance Do not give mark if • ref to thermostatically controlled or electronic etc. how will you • heating with thermometer • temperatures below 80

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (ii) Prepare the space below and record your results. Allow G as 4%. [4] table with all cells drawn AND heading (top or left) percent(age) conc(entration); [1] Additional guidance Can have • no outer boundary • % Do not give mark if • test-tube or beaker • other units e.g. mol dm–3 (heading for any column/row including mean) time with s or sec(onds); PDO recording 2 [1] Additional guidance Do not give mark if • units in cells of this column/row • min(utes) • additional columns/rows for method e.g. volumes of glucose or water or temp • t or T records whole seconds (numbers) less than 301 for ANY 5 concentrations and S1 and S2 (7); [1] Additional guidance Must have • whole seconds only • no value over 300 highest concentration recorded is shorter time than next concentration; MMO collection 2 [1] Additional guidance Can have • minimum two recorded times

Page 7 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (c) (i) Estimate the concentration of glucose in solutions S1 and S2. [1] correct estimate with their results for both S1 and S2 AND percentage or % once; ACE conclusion 1 [1] Additional guidance Do not give mark if • calculate value between concentrations Can have • ‘lower than’ or quote lower value • ‘higher than’ or quote higher value • ‘between … and ….’ Or e.g. 2–4% (ii) State which solution, S1 or S2 is most likely to be from an untreated diabetic. [1] (from (c)(i) – MUST have values for both S1 and S2) correct with their estimate from (c)(i) i.e. the highest concentration estimate; ACE conclusion 1 [1] Additional guidance ECF if estimates the same value then can have ‘S1 and S2’ Or ‘S1 or S2’ Or ‘both’ Must have • estimate in (c)(i) for both S1 and S2 [Total: 12]

Page 8 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 2 (a) Plot a graph of the data shown in Table 2.1. [4] x-axis distance (along tube (/) cm AND y-axis diameter (of tube) (/) mm; [1] Additional guidance Must have • units on x-axis and y-axis scale as x-axis 5.0 to 2 cm Must label each 2 cm AND y-axis 1.0 to 2 cm; Must label each 2 cm [1] Additional guidance Do not give mark if • awkward scale • scale not written on each 2 cm correct plotting of each point; [1] Additional guidance 0.5 1.8 4.5 2.4 12.5 3.8 20.0 5.1 24.0 5.8 Can have • small cross or dot in circle or cross in circle • ECF if x-axis not 0 if scale 20 to 2 cm. Do not give mark if • awkward y-axis scale • blobs or dots alone • cross too large with any part of line touching 4 mm by 4 mm square – lines point to point or line of best fit AND • ruled, clear sharp – • quality – ruled lines thinner than half square; PDO layout 4 [1] Additional guidance Can have • extrapolation to edges of grid if line of best fit Do not give mark if • less than 5 plots • any feathery line • irregular thickness • extrapolated when point to point line (not line of best fit)

Page 9 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (b) (i) Calculate the actual diameter of the tube shown by line x in fig. 2.1 [4] measures line X correctly in mm; 95 or 95.5 or 96 or 96.5 or 97 mm MMO collection 1 [1] Additional guidance Must have • units shows measurement divided by 22; [1] Additional guidance Can show • alternative division signs • incorrect measurement rounds any answer of division by 22 to two or three significant figures; PDO display 2 [1] Additional guidance Do not give if • in metres correct answer one of following only in mm; 4.32 or 4.34 or 4.36 or 4.39 or 4.41 or 4.3 or 4.4 mm. ACE interpretation 1 [1] Additional guidance Do not give mark if 0.43/0.44 cm or micrometres (ii) Use the actual diameter of the tube calculated in (b)(i) and your graph in (a)(i) to estimate the distance along length of the tube. [1] ACE interpretation 1 [1] correct answer using their answer from (b)(i) and graph and cm;

Page 10 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (iii) Describe how you would find the mean diameter of the tube shown in Fig. 2.1. [2] assume in context of the tube – Do not give mark if • Idea of different tubes • Just ‘take readings’ [1] Idea of more or e.g. 2 or higher take/find measure make readings/measurements of OR Uses/adds diameters (from graph) measurements 5 actual figures from data or 5 points from graph – Or all diameters or values-or readings ACE improvements 2 [1] add/sigma/sum of (measurements can be from graph) and divide by the number of measurements (ecf) OR alternative description;

Page 11 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (iv) Prepare the space below so that it is suitable for you to record the observable differences between the specimens in Fig. 2.1 and in Fig. 2.2. [5] [1] organise as a table/Venn diagram/ruled boxes AND headed Fig. 2.1 and Fig. 2.2 AND first difference opposite each other; Additional guidance Fig. 2.1 Fig. 2.2 OR Fig. 2.2 Fig. 2.1 PDO recording 2 [1] observable differences only; can be incorrect Do not give mark if any similarities or function differences or features in overlapping part of Venn diagram ACE interpretation max 3 max 3 feature Fig. 2.1 Fig. 2.2 1. lumen shape or epithelial less / few / four folds / thick cross(-shape) or drawn more / five / six folds / thin star or drawn 2. lumen size large(r) small(er); 3. epithelial tissue thick(er) thin(er); 4. connective tissue goes less into folds thick(er) or thin(ner) goes more into folds thin(ner) or thick(er); 5. muscle tissue more / thick or less / thin striated / skeletal / voluntary less / thin or more / thick smooth / involuntary; 6. cells or nuclei visible / present / seen not visible / absent / not seen; 7. (Overall) shape Extra layer between connective tissue and muscle squashed / no extra layer absent round / extra ‘arm’ present / has / described [Total: 16]

Page 12 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 3 (a) (i) Draw a large plan diagram of the whole of the transverse section. Label the epidermis and xylem. [5] clear, sharp, unbroken lines AND no shading AND larger than 60 mm across widest point top to bottom; PDO layout 1 [1] Additional guidance ‘tail’ or overlap or gap has to be more than 1 mm Must have • three or more enclosed areas Do not give mark if • drawn over the print of question • any line thicker – 1 mm or more • any feathery line or broken in enclosed area [1] no cells drawn AND complete section drawn; draws outline with at least four larger bulges; MMO collection 2 [1] Additional guidance Can have • different bulge attached or additional structure outside main outline inner region below bulges has at least three lines (two layers); [1] Additional guidance Do not give mark if • vascular bundle(s) drawn correct label with label lines to epidermis (outer two lines or touches outermost line not into area past a single line) and xylem (any inner region outside centre and under bulges); blob tick MMO decisions 2 [1] Additional guidance Do not give mark if • any label which is biologically incorrect e.g. from incorrect organ or animal • any label within drawn area except if showing ratio • upper or lower Can have • labels to additional bulges

Page 13 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (ii) Calculate the ratio of the total diameter of the stem to the diameter of the pith. [1] last answer as larger whole number to /: smaller whole number; ACE interpretation 1 [1] Additional guidance Must have • to smallest denominator Can have • as a fraction to smallest denominator Do not give mark if • any units/epg in answer • if give more than one answer (b) (i) State one observable feature of the epidermis that supports the conclusion that this is a stem from a plant growing in a dry habitat. Explain how this feature reduces water loss. [1] Read whole answer for feature. [1] cuticle stomata with no or BOD few or sunken epidermis with folded grooved fleshy AND reduces or prevents storage of water evaporation or water escaping or diffusing or transpiration; ACE conclusions 1 Additional guidance Do not give mark if • features not linked to epidermis • ref. to leaf Ignore • ref. to surface area

Page 14 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 32 © University of Cambridge International Examinations 2011 (ii) Make a large drawing of three adjacent cells from the central pith. Label the cell wall. [5] clear, sharp, unbroken lines AND no shading AND longer than 30 mm across widest point of largest cell; PDO layout 1 [1] Additional guidance Must have • at least three enclosed areas Do not give mark if • drawn over the print of question • any thicker line – than 1 mm • any feathery line [1] only three cells drawn AND as a group or as line; no gaps between two pairs of touching cell walls; [1] Additional guidance Must have • be in contact for whole length where adjacent MMO collection 3 [1] cell walls drawn as double lines with middle lamella between adjacent walls of any two cells; correct label with label line to cell wall; MMO decision 1 [1] Additional guidance Do not give mark if • any label is biologically incorrect e.g. from incorrect organ or animal or EM organelles or chloroplasts • label within drawn area [Total: 12]