Cambridge A Level Biology 9700 — 2013 May/June Paper 3 · Variant 4

This document consists of 15 printed pages and 1 blank page. DC (NH/SW) 52072/6 © UCLES 2013 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level * 6 1 9 3 6 8 6 6 7 6 * BIOLOGY 9700/34 Advanced Practical Skills 2 May/June 2013 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 ink. You may use a pencil for any diagrams, graphs or rough working. Do not use red ink, staples, paperclips, highlighters, 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 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use You are reminded that you have only one hour for each question in the practical examination. You should: • read carefully through the whole of Question 1 and Question 2 • then 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 Yeast cells use enzymes as part of their metabolic reactions. Some of these reactions release carbon dioxide. You are required to investigate the hypothesis that: The rate of release of carbon dioxide from yeast cells will decrease with time. Carbon dioxide reacts with water to form a weak acid. The indicator, P, can be used to show the change in pH. The pink indicator, P, will become colourless when carbon dioxide is added. This is the end-point as shown in Fig. 1.1. colour of indicator at start (no darker than this) test-tube E with indicator showing the colourless end-point Fig. 1.1

3 9700/34/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use You are provided with: labelled contents hazard volume / cm3 Y yeast cell suspension none 20 P indicator solution flammable 10 A alkali solution irritant 20 W distilled water none 100 You will need to standardise the pink colour before you start the readings. Proceed as follows: 1. Put 5 cm3 of W into a test-tube. For steps 2 and 3, you must use one pipette to add the drops of P and a different pipette to add the drops of A. 2. Put 2 drops of P into the same test-tube. The solution should remain colourless. Insert the bung and with your finger holding the bung in place, mix the solution. 3. You are required to put drops of A into the solution until it becomes a pink colour. The colour should not be darker than the pink colour shown in Fig. 1.1. (a) (i) Decide how you will use this test-tube to standardise the five other test-tubes you require. State the variables which you will standardise when setting up these test-tubes to take the readings. … …[1] 4. Set up the five test-tubes as you have described in (i). (ii) Describe how you standardised the colour in these five test-tubes. … …[1]

4 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use Fig. 1.2 shows how to use the apparatus provided. nozzle of syringe holding barrel of syringe upright tubing fitted to nozzle position of tubing in the indicator Fig. 1.2 The tubing from the syringe needs to reach into the test-tube so that it is below the surface of the indicator solution as shown in Fig. 1.2. (iii) Decide how you will standardise the position of the tubing in each test-tube, without cutting the tubing. You may find Fig. 1.2 helpful. Describe how you standardised the position of the tubing. …[1]

5 9700/34/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use You are required to: • take five readings as shown in Fig. 1.3 • leave Y in the syringe for 10 minutes • take another five readings as shown in Fig. 1.3. time to end-point (1st) (pink to colourless) step 11 step 10 start timing (1st) step 12 move tubing repeat steps 11 and 12 with each test-tube 1st reading 2nd reading 3rd reading 4th reading 5th reading air nozzle tubing barrel Y Fig. 1.3 The tubing must be transferred from one test-tube to the next as quickly as possible, after reaching the end-point. Read up to the end of step 17 before proceeding. To avoid the time delay in stopping and starting the timing, you must not stop the timer at any of the end-points, just record the time. From your readings you will be required to calculate the time taken to reach the end-point in each test-tube. (iv) Consider the units of the values recorded on your timer or clock. State the: • smallest value which your timer shows … • smallest unit of time you have decided to record … . [1]

6 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use (v) Complete Table 1.1 with the raw data, recording the time when the tubing is put into the indicator and the time when the end-point is reached. Repeat for each test-tube. After 10 minutes, complete Table 1.2 with the second set of raw data. Table 1.1 – first five readings time time time time time start of reading 1st 2nd 3rd 4th 5th end-point 1st 2nd 3rd 4th 5th space for any processing of the results Table 1.2 – readings after 10 minutes time time time time time start of reading 1st 2nd 3rd 4th 5th end-point 1st 2nd 3rd 4th 5th space for any processing of the results [3]

7 9700/34/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use 5. Remove the tubing from the syringe nozzle. 6. Use this syringe to take up 5 cm3 of Y from below the froth. 7. Clean the outside of the syringe to remove any of Y. 8. Holding the barrel of the syringe with the nozzle pointing upwards, pull out the plunger to the 10 cm3 mark. There is now 5 cm3 of air in the syringe. The syringe should be kept upright to avoid Y from entering the tubing. Do not press the plunger. 9. Holding the barrel of the syringe upright, fit the tubing onto the nozzle of the syringe. 10. As shown in Fig. 1.2 and Fig. 1.3, put the end of the tubing into P in the first test-tube and start timing. Both the syringe and the test-tube contents need to be gently mixed by shaking until the end-point is reached. 11. Record in Table 1.1 the time shown on the timer when the end-point is reached. The colourless end-point can be compared with the contents of E. Do not stop the timer. 12. Immediately, transfer the tubing into P in the next test-tube and record in Table 1.1 the start time shown on the timer (start of second reading). Both the syringe and the test-tube contents need to be gently mixed by shaking until the end-point is reached. 13. Repeat steps 11 and 12 with the remaining three test-tubes. 14. After the 5th reading, stop timing. Remove the syringe with the tubing from the test-tube. 15. Leave Y in the syringe for 10 minutes. (The syringe should be kept upright so that Y is not able to enter the tubing). 16. During the 10 minutes, repeat step 4. You are provided with a container labelled, ‘for waste’ and a container labelled ‘for washing’, so you can re-use your test-tubes. 17. After 10 minutes, repeat steps 10 to 14 and record the results in Table 1.2.

8 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use Depending on the timer or clock which you have used you may find the following examples helpful, so that you can process your results to find the time taken to reach the end-point. Example 1: using stop clock or stopwatch start time end-point time minutes:seconds 1:54 2:18 = 114 seconds = 138 seconds time taken to reach end-point = 24 seconds Example 2: using clock times start time end-point time hours:minutes:seconds 9:10:50 9:11:14 difference in time 24 seconds time taken to reach end-point = 24 seconds (vi) Using your results from Table 1.1, complete Table 1.3 below to show the calculation to find the time taken to reach the end-point in your first test-tube. Table 1.3 1st start time 1st end-point time time taken to reach end-point = [1]

9 9700/34/M/J/13 © UCLES 2013 [Turn over Question 1 continues on page 10

10 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use (vii) Combining the processed results from Table 1.1 and Table 1.2, prepare the space below to record only the processed results. This will enable the trend to be observed. [4] (b) Identify three significant sources of error in this investigation. … … … … … … …[3]

11 9700/34/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use (c) Describe three modifications to this investigation which would improve the confidence in your results. … … … … … … …[3] The original hypothesis was: The rate of release of carbon dioxide from yeast cells will decrease with time. (d) State whether your results support this hypothesis. Use your results to explain your answer. … … … … … … …[2] [Total: 20]

12 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use 2 N1 is a slide of a transverse section through a plant leaf. This plant grows mainly in Spain. (a) Draw a large plan diagram of the whole section of the plant leaf on N1. On your diagram, use a ruled label line and label to show the epidermis. [5]

13 9700/34/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use The vascular bundle is surrounded by a ring of large cells. (b) Make a large drawing of one group of adjacent (touching) cells, as observed on the specimen on N1, made up of four whole cells from this ring of large cells. [4] (c) Use the eyepiece graticule scale to measure the: • diameter of the vascular bundle including the ring of cells • width of the xylem tissue. State the ratio of the diameter of the vascular bundle to the width of the xylem. Note: You are not required to calibrate the eyepiece graticule scale with a stage micrometer. You will lose marks if you do not show all the steps in finding the ratio. [2]

14 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use Fig. 2.1 shows a photomicrograph of a transverse section through a leaf from a different species. This plant grows mainly in China. magnification ×100 Fig. 2.1 (d) Prepare the space below so that it is suitable for you to record observable differences between the specimens on slide N1 and in Fig. 2.1. [4]

15 9700/34/M/J/13 © UCLES 2013 For Examiner’s Use Both the specimen on N1 and Fig. 2.1 are from plants which are adapted to survive in dry conditions. Some scientists investigated the water potential in the leaf cells of a tree living in dry conditions over a period of 22 hours. The results are shown in Table 2.1. Table 2.1 time of day / hours water potential in the leaf cells / MPa 00:00 –1.0 02:00 –1.1 06:00 –1.5 08:00 –2.0 12:00 –3.0 18:00 –1.7 22:00 –1.4 (e) (i) Plot a graph of the data shown in Table 2.1. [4] (ii) Suggest how transpiration may explain the difference in the water potential in the leaf cells between 12:00 hours and 22:00 hours. … … …[1] [Total: 20]

16 9700/34/M/J/13 © UCLES 2013 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.

CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2013 series 9700 BIOLOGY 9700/34 Paper 34 (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 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

Page 2 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 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 AVP Alternative valid point (examples given as guidance)

Page 3 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 1 (a) (i) [1] MMO decision 1 1 volume of W/water AND (number of) drops of (P/indicator); (for W/water) R amount (ii) [1] MMO decision 1 1 add drops of A/alkali (solution) (not amount) or add same number of drops/stated number of drops of A/alkali (solution) AND same colour as/matches (Fig. 1.1) first (test-tube)/all tubes; A (use the original 5 cm3) putting 1 cm3 into the other test-tubes; (a) (iii) [1] MMO decision 1 1 mark (draw a line on each/all test-tube(s) or tubing) or position the tubing at bottom of test-tube; R measuring distance above bottom/below surface without ref. to marking (a) (iv) [1] MMO decision 1 1 seconds or s;

Page 4 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 (v) [3] MMO collection 1 mp1 records times for ‘start of reading’ and ‘end-point’ in Table 1.1; MMO decision 1 mp2 records end time for before (less than) the start time of the next reading; PDO recording 1 mp3 records times for all readings to same precision; (vi) [1] ACE interpretation 1 1 time taken to reach end-point with whole numbers and correct units seconds/s; Table 1.3 1 st start time 0:00 0 1 st end-point time 1:45 105 time taken to reach end-point = 105 seconds

Page 5 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 (vii) [4] PDO recording 2 mp1 table with all cells drawn AND heading (top or left) test-tube or reading or number of test or sample; Do not give mark if ‘heading’ in cells of headed/rows mp2 (heading) time (taken to end-point) (/) s or seconds in any one column; Do not give mark if • units in cells of this column/row • minutes • additional method information either headings for columns/rows or in cells e.g. volumes MMO collection 2 mp3 for all 10 (processed/end-point) times records only processed results as whole numbers; Must have • whole seconds only Do not give mark if • raw results mp4 [comparing Table 1.1 (first five readings) with Table 1.2 (readings after 10 minutes)] for results showing same trend; Must have • processed data Do not give if • raw results (start and end times) (b) [max 3] ACE interpretation max 3 cause of error with idea of error mp1 any reference to colour/end-point difficult to judge/distinguish//identify/ is subjective/varies may be different; mp2 quantity/amount of A/alkali different or varies; mp3 Y/yeast (enters tubing) so goes cloudy/ different amount of yeast for subsequent test-tubes; mp4 position of tubing changes (as shake); mp5 shaking different/varies/not same;

Page 6 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 (c) [max 3] ACE improvement max 3 max 3 mp1 (standardised variables) (start colour) mix W/water and P/indicator and A/alkali in one beaker and then put into test-tubes; mp2 (instead of using one syringe containing yeast) have one syringe(with yeast) per reading/end-point or idea of individual timing/set each one up separately/fixed time between each transfer or another person to help record time or identify end-point or gather data/use ‘laptime’ on timer; mp3 (dependent variable) use a colorimeter; Do not give mark for • use of white tile • calorimeter mp4 (to obtain at least three sets of data) repeat more than once; mp5 machine to standardise shaking; mp6 (from alkali to neutral/acid) use pH meter to detect change; (d) [2] ACE conclusion 2 mp1 (for 10 figures processed results) supports/’yes’ as all data consistent or cannot tell/‘no’ if data not consistent; mp2 (for 10 figures processed results) (supports/‘yes’) in line with some trend in their results end-point times become longer or quotes correctly any selective comparative data; OR (for 10 figures processed results) (rejects/’no’/cannot tell) in line with some trend in results no consistent pattern/end-point times become shorter or quotes correctly any selective comparative data; [Total: 20]

Page 7 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 2 (a) [5] PDO layout 1 mp1 suitable plan diagram; Do not give mark if • any shading • drawn over the print of the question • any ruled line Do not give mark if • less than 60mm at widest point (across mid-rib upper to lower epidermis) AND clear, sharp, unbroken lines for outermost line; Do not give mark if • less than 3 enclosed areas • open-ended in epidermis lines • any part of the line 1mm or thicker (use grid) • any feathery or broken or dashed line or gap • any ’tail’ or overlap in line MMO collection 3 mp2 no cells AND drawn whole section mp3 draws vascular bundle (in central area) with interior subdivided into at least three enclosed areas or at least 3 stomata; mp4 at least one circle at end OR clear double line for outside of vascular bundle; MMO mp5 labels the epidermis with label line ending either within three lines of epidermis; Do not give mark if • any label within drawn area

Page 8 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 (b) [4] PDO layout 1 mp1 suitable plan diagram; Do not give mark if • any shading • drawn over the print of the question • any ruled lines Do not give mark if • less than 40 mm at widest distance across largest cell Do not give mark if • less than four enclosed areas or if any outer lines (of enclosures) • any feathery or broken/dashed line or have gaps • have tails or overlaps MMO collection 2 mp2 only 4 complete cells drawn AND adjacent (touching) cells as a group; mp3 the 2 end cells should touch only one other cell; Do not give mark if • more than 4 cells MMO decision 1 mp4 the cells must be drawn with double lines all the way round AND where two pairs of cells touch there must be 3 lines (representing the middle lamella); Do not give mark if • organelles e.g. mitochondria, Golgi, etc. (c) [2] PDO display 2 mp1 shows measurement of diameter (with reference to vascular bundle) AND shows measurement of width (with reference to xylem) AND shows both measurements as whole numbers or 0.5 only AND units; mp2 (in context of measurements) answer as larger whole number to/: smaller whole number (no units in final ratio) or as fraction as larger whole number over smaller whole number (no units in final ratio); Must have • to lowest denominator Do not give if • if no measurements shown anywhere

Page 9 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 (d) [max 4] PDO recording 1 mp1 organise as a table with only three columns or rows separated by lines AND headed N1 and Fig. 2.1 AND third column contains features; MMO decision 1 mp2 only differences; Do not give mark if • any similarities recorded • any functions • any non-observable differences ACE interpretation max 2 max 2 feature N1 Fig. 2.1 mp3 cuticle/epidermis any comparative comment any comparative comment; mp4 number of stomata many/more/present few(er)/less/none; mp5 air space/ spongy mesophyll arrangement of air space/ spongy mesophyll few(er)/less small(er) many/more/ larg(er); mp6 packing of palisade cells /layer below epidermis position of palisade cells /layer below epidermis shape of palisade cells loose/less compact all around leaf rectangular or long(er) compact upper part of leaf round(er) or short(er); mp7 shape of vascular bundle ring of cells around vascular bundle circular present/has/yes oval absent/none/no; mp8 extra circles/canals yes/has/present no(ne)/absent; mp9 any (overall) comparative shape rounded ends or midrib as ‘bump’ pointed ends or has pointy midrib; mp10 any reference to size (whether overall shape or internally) big(ger) small(er);

Page 10 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 34 © Cambridge International Examinations 2013 (e) (i) [4] PDO layout 4 mp1 x-axis time of day (/) hours AND y-axis water potential in leaf (cells)/MPa; mp2 scale as x-axis 5.00 or 5:00 to 2 cm labelled each 2 cm AND y-axis -1.0 to 2 cm labelled each 2 cm; mp3 must be negative scale • check presence of seven points • all seven as small cross or dot(in circle) or cross in circle; • correct plotting mp4 seven plots with ruled lines exactly point to point AND (quality) smooth sharp line; ecf from incorrect plots Do not give mark if • any feathery line • irregular thickness (e) (ii) [1] ACE conclusion 1 1 time 12:00 hours (day) 22:00 hours (night) between 12:00 hours and 22:00 hours AND (rate of) transpiration high low decreases AND water potential low most negative high least negative increases/becomes less negative