Cambridge A Level Biology 9700 — 2011 May/June Paper 3 · Variant 4

This document consists of 11 printed pages and 1 blank page. DC (CW/DJ) 31764/6 © 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. * 1 9 1 2 3 8 2 5 2 5 * BIOLOGY 9700/34 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 Total

2 9700/34/M/J/11 © UCLES 2011 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 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 In some countries, certain plants have seasonal growth. During the summer plants transport sucrose from the leaves to store it as starch in the roots. Table 1.1 summarises the changes in the leaves and roots during the year. Table 1.1 season leaves roots summer leaves synthesize sucrose sucrose stored as starch winter no leaves starch stored spring leaves growing starch converted to glucose You are required to identify the source of four plant extracts. These have been taken from • a root in winter • a root in spring • phloem sap in summer • phloem sap in winter (a) (i) Use the information in Table 1.1 to predict which substances you would expect to be present in each of the four plant extracts, then complete Table 1.2. Key: ✓ (tick) substance present in plant extract ✗ (cross) substance absent from plant extract Table 1.2 source of plant extract substances present in each of the plant extracts starch sucrose glucose root in winter root in spring phloem sap in summer phloem sap in winter [2]

3 [Turn over 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use One sample was taken from each of the four plant extracts shown in Table 1.2. You are required to identify from which plant extract each of the four samples S1, S2, S3 and S4 was taken. You are provided with: Table 1.3 labelled contents hazard volume / cm3 Benedict’s solution Benedict’s solution harmful irritant If you require more of any of these reagents, please ask the Invigilator. Biuret copper sulfate sodium hydroxide harmful irritant iodine iodine in potassium iodide solution irritant hydrochloric acid hydrochloric acid irritant sodium hydrogen carbonate sodium hydrogen carbonate none (ii) Describe the tests that show that sucrose is present in a plant extract. … … … … … … … …[2]

4 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use Select the appropriate reagents from those provided in Table 1.3 and carry out tests to identify the samples S1, S2, S3 and S4. (iii) Prepare the space below and record your results. [4] (iv) Complete Table 1.4 to match the samples, S1, S2, S3 and S4, with each plant extract. Table 1.4 source of plant extract sample a root in winter a root in spring phloem sap in summer phloem sap in winter [1]

5 [Turn over 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use A student investigated the effect of different concentrations of sodium chloride solution on root tissues. A separate sample of root tissue was put into a starting volume of each concentration of sodium chloride solution. After a set time the root tissue was removed and the final volume of each solution was recorded. The change in volume for each concentration was calculated. (b) (i) State three variables which the student should keep the same in this investigation. Describe how the student would keep each of these variables the same. … … … … … … …[4]

6 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use The results of the student’s investigation are shown in Table 1.5. Table 1.5 concentration of sodium chloride / mol dm–3 change in volume of solution / cm3 0.00 –6.0 0.25 +1.0 0.50 +4.5 0.80 +5.2 1.00 +5.2 (ii) Plot a graph of the data shown in Table 1.5. [4]

7 [Turn over 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use (iii) Show on your graph the sodium chloride concentration where there is no change in volume of solution. [1] Use this information to estimate the sodium chloride concentration where there is no change in volume of solution. … mol dm–3 [1] (iv) Use your graph to explain the effect of the different concentrations of sodium chloride solution on the root cells. … … … … …[3] [Total: 22]

8 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use 2 Fig. 2.1 is a photomicrograph of a transverse section through part of a stem. magnification × 100 Fig. 2.1 (a) Draw a large plan diagram of the specimen shown in Fig. 2.1. Label the epidermis. [6]

9 [Turn over 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use Fig. 2.2 is a photomicrograph of a transverse section through part of a different plant organ from a different plant species. Y Fig. 2.2 (b) (i) Prepare the space below so that it is suitable for you to record three observable differences between the specimens in Fig. 2.1 and in Fig. 2.2. Record your observations in the space you have prepared. [4]

10 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use (ii) The actual length of line Y is 495 μm. Use this measurement to calculate the magnification of Fig. 2.2. You may lose marks if you do not show your working or if you do not use appropriate units. magnification × … [4] (c) You are provided with a sample of plant material, labelled P. You are required to prepare a slide of the xylem vessels from this plant material. Proceed as follows: 1. Using forceps extract long thin strands of P containing xylem vessels as shown in Fig. 2.3. strand of xylem tissue Fig. 2.3 2. Put the strands onto a microscope slide. 3. Add two drops of water and carefully lower a cover slip onto the strands. 4. Put the paper towel over the cover slip and gently press to separate the xylem vessels from surrounding tissue. 5. Look carefully under high power to find two xylem vessels which show different patterns of thickening in the walls.

11 9700/34/M/J/11 © UCLES 2011 For Examiner’s Use Make large drawings of two different patterns of thickening in the walls of the xylem vessels. Label the part of the vessel where lignin is found. [4] [Total: 18]

12 9700/34/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 9700/34 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 34 © 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 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 34 © University of Cambridge International Examinations 2011 1 (a (i) Use information in Table 1.1 to predict which substances you would expect to be present in each of the four plant extracts, complete Table 1.2. [2] source of plant extract substances present in each of the plant extracts starch sucrose glucose root in winter/S2 ✓ X or gap X or gap root in spring/S4 ✓ (X or ✓ or gap) ✓ phloem sap in summer/S3 X or gap ✓ X or gap phloem sap in winter/S1 X X X 4 ticks only in correct place for first three rows; (phloem sap in winter) all crosses/all gaps if in whole table; MMO decisions 2 [1] [1] Additional guidance Do not give if • hybrid tick / cross • or mixture of gaps and crosses (ii) Describe the tests that show that sucrose is present in a plant extract. [2] Tick where mark awarded. [1] (with Benedict’s / reducing sugar test) negative test or no result / reaction or no change or stays blue; [1] add (hydrochloric) acid and boil/heat AND neutralise OR add sodium hydrogen (bi)carbonate sodium carbonate sodium/potassium hydroxide alkali AND Benedict’s; MMO decisions 2 Additional guidance Do not give mark if • warm or just put in water-bath

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 (iii) Prepare the space below and record your observations. [4] Use vertical line of ticks table with all cells drawn AND heading (top or left) sample(s) ; [1] Additional guidance Ignore • test-tube/additional columns Can have • no outer boundary • solution(s) or extract (heading to show results of tests being recorded) colour or observations or description or result(s) AW; PDO recording 2 [1] Additional guidance Do not give mark if • heading for description of test or test only needs to be what is being recorded • additional columns/rows with volumes of reagents or temperatures • if ‘result’ heading is actually for conclusion/identification shows only tests for starch, reducing sugar and non-reducing sugar AND (for starch and reducing sugar) show have done the test for ALL four samples; [1] Additional guidance Do not give mark if • Biuret or protein test with results anywhere (non-reducing sugar result for S3) (reducing sugar Benedict’s) blue or no change AND (after hydrolysis) any correct colour (green / yellow / orange / brown / red); MMO collection 2 [1] Additional guidance Can have • combination of colours greeny yellow Do not give mark if • just positive and negative or ticks and crosses

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 (iv) Complete Table 1.4 to match the samples, S1, S2, S3 and S4, with each plant extract. [1] ACE interpretation 1 [1] Source of plant extract sample root in winter (S)2 root in spring (S)4 phloem sap in summer (S)3 phloem sap in winter (S)1; all correct only one per box; (b) (i) State three variables which the student should keep the same in this investigation. Describe how the student would keep each of these variables the same. [4] MMO decision 1 [1] three relevant variables selected from below max 3 1. size / dimensions / e.g. of dimensions / length OR (surface) area or / to volume OR mass / weight (of root tissue) OR 2. root or plant use (metre) ruler or Vernier callipers or describes use of knife / blade / scalpel / cork borer to cut discs / cylinders OR use balance to keep mass the same; same plant or species / type or same root or part of root or same age; 3. volume of (sodium chloride) solution or example of volume (10 or more) with units (Ignore amount) uses syringe / measuring cylinder / graduated pipette or graduated test-tube or burette to keep same / example of volume; 4. evaporation (from solutions or test- tubes/ beakers) cover the containers / bungs into test-tubes; 5. temperature use thermostatic(ally-controlled) water-bath or describes method; Give mark for incubator or temperature controlled room Do not give mark if air-conditioned room ACE improvements max 3 6. example of time more than 20 mins; (time only)use stop clock or stopwatch or clock or timer / chronograph / chronometer;

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 (ii) Plot a graph of the data shown in Table 1.1. [4] If CHART then max 2 for O and S x-axis conc(entration) of sodium chloride / NaCl (/) mol dm–3 or mol / dm3 AND y-axis change in / ∆ volume (of solution) (/) cm3 ; Do not give mark if V [1] Additional guidance Must have • units on x-axis and y-axis scale as x-axis 0.20 to 2 cm Must label each 2 cm AND y-axis 2.0 to 2 cm; Must label each 2 cm [1] Additional guidance Do not give mark if • awkward scale e.g. 0.25 to 2 cm x-axis • scale not written on each 2 cm • if numbers to right of y-axis Must have • negative below 0 and positive above 0 correct plotting of each point; [1] Additional guidance 0.00 (–)6.0 0.25 (+)1.0 0.50 (+)4.5 0.80 (+)5.2 1.00 (+)5.2 Can have • small cross or dot in circle or cross in circle • ecf if x-axis not 0 if scale 20 to 2 cm. even 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 – • an additional plotted point at 0.0 volume same as other plotted points PDO layout 4 [1] lines point to point or smooth curve through all points and horizontal line between last two points AND • ruled, clear sharp – • quality – ruled lines thinner than half square;

Page 7 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 Additional guidance Do not give mark if • less than 5 plots • line of best fit • any feathery line • irregular thickness • no extrapolation or meets axes 2 mm or more (iii) Show on graph the sodium chloride concentration where there is no change in volume of solution. [1] Use to estimate the sodium chloride concentration. [1] [1] clearly shows with line(s) or point on line shown at 0 change in volume; estimate correct from graph at 0 change in volume; ACE interpretation 2 [1] Additional guidance Must have • rounding down to two decimal places e.g. 0.20 or with (0.025 scale) e.g. 8.5 x 0.025 = 0.2125 so must be 0.21 Do not give mark if • any estimate if shown on graph if between 0.8 and 1.0 • estimate any scale precision is to half square e.g. 0.2 to 2 cm therefore 2 mm = 0.02 and half square is 0.01 so answers can only be to 2 decimal places. So on the awkward scale of 0.25 to 2 cm therefore 2 mm = 0.025 and half square is 0.0125 therefore can only read to half square values, not in between. (iv) Use your graph to explain the effect of the different concentrations of sodium chloride solution on root cells. [3] ACE conclusions max 3 max 3 1. (water) moves from high / less negative to low / more negative water potential OR from higher / less negative water potential OR to lower / more negative water potential OR down a water potential gradient;

Page 8 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 Additional guidance Can have • even if direction is incorrect from roots to solution Ignore • refs. to hypertonic and hypotonic even if incorrect 2. (in context of water ) by (endo) / (ex) osmosis; Additional guidance Can have • even if direction is incorrect from roots to solution 3. (in correct context of) describes correct direction of movement of water; e.g. (when volume decreases –6 from 0.0 to where it crosses line 0.2+ NaCl) idea of water moving into cells or correct use of endosmosis (into cells) OR (when volume increases all + values from 0.2+ to 1.00 NaCl) idea of water moving out of cells or correct use of exosmosis (out of cells) 4. (in context of zero change in volume ECF from graph) ref. to idea of no net movement of water; [Total: 22]

Page 9 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 2 (a) Draw a large plan diagram of the specimen shown in Fig. 2.1. Label the epidermis. [6] clear, sharp, unbroken lines AND no shading AND larger than 50 mm across bottom of arc to top; PDO layout 1 [1] Additional guidance Must have minimum of • three or more hand-drawn lines and at least two enclosed area/vascular bundles in a semicircle or less Do not give mark if • drawn over the print of question • any line thicker – 1 mm or more • any feathery line or broken or overlaps in the lines [1] no cells drawn AND section drawn with four/five complete vascular bundles; MMO collection 2 [1] (inner layer) drawn irregular (not smooth); PDO recording 1 [1] (stoma) drawn as gap or feature AND at lowest point of epidermis; [1] (vascular bundles observed and drawn the (incomplete) vascular bundle at left hand side; correct label with label line or adjacent to correct layer to epidermis; MMO decision 2 [1] Additional guidance Do not give mark if • lower or upper or cells • labelled top irregular line epidermis • no top or bottom line drawn (no context) • any label which is biologically incorrect e.g. from incorrect organ or animal • any label within drawn area

Page 10 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 (b) (i) Prepare the space below so that it is suitable for you to record the observable differences between the specimens on Fig. 2.1 and that in Fig. 2.2. [4] Mark first four differences only for THREE marks. [1] organise as a table/Venn diagram/ruled boxes AND headed Fig. 2.1 and Fig. 2.2 AND first difference opposite each other; PDO recording 1 Additional guidance (Fig.) 2.1 (Fig.) 2.2 (Fig.) 2.2 (Fig.) 2.1 feature Fig. 2.1. Fig. 2.2 max 3 1. vascular tissue / xylem / phloem bundles / more / separate near middle / pith / edge (no) bundle / one / less; middle / centre; 3. hollow centre / pith present / has / yes absent / none / no 4. OR stele OR endodermis / bundle sheath / Casparian strip / suberised / pericycle absent / none / no absent / none / no present / has / yes present / has / yes; 5. air spaces OR chains of cells shape of cells small(er) / not large / less absent / none / no round / circular large(r) / more present / has / yes long; 6. thickened cell layer / collenchyma or epidermis(layers) absent / none / no thin(ner) or 2 / few layers thick(er) or 2 present / has / yes thick(er) or 3 / more layers thin(ner) or 1 7. epidermis or cuticle cuticle regular / smooth absent / none / no irregular / rough (do not give damaged) present / has / yes; 8. gap / stomata / guard cells present / has / yes / one absent / none / no; 9. cortex / cells present / has / yes / more absent / none / no few(er); 10. one ref. to size of any of features above but not air spaces or specimens small(er) large(r); ACE interpretation max 3

Page 11 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 Additional guidance Ignore • tick and cross without a key • diagrams • 3-D descriptions such as spherical • colours/staining (ii) Actual length of line Y is 495 µm. Use this to calculate the magnification of Fig.2.2. [4] measures line Y in mm; 80 or 80.5 or 81 or 81.5 or 82 mm MMO collection 1 [1] Additional guidance Must have • units somewhere that is clear • Check Fig. For measurement (converts to same units) (mm to µm) X 1000 Or 80 000 or 80 500 or 81 000 or 81 500 or 82 000; OR (converts µm to mm) 495/1000 or 0.495; MMO decision 1 [1] Additional guidance Do not give mark if • metres anywhere or conversion to metres Can have • even if no units mm or cm anywhere • if incorrect measurement shows division of converted measurement in µm by 495 OR division of actual measurement in mm / 0.495; [1] Additional guidance Can have • if no units or incorrect measurement or no or incorrect conversion e.g. metres. PDO display 2 [1] answer as whole number only; 162 or 163 or 164 or 165 or 166

Page 12 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2011 9700 34 © University of Cambridge International Examinations 2011 Additional guidance Mark final answer as given on the line provided. If no answer on the line then accept the final number shown BOD. Do not give mark if • two or more answers • any units given • more significant figs e.g. 0 (iii) Make large drawings of two different patterns of thickening in the walls of the xylem vessels. Label the part of the vessel where lignin is found. [4] PDO layout 1 [1] no shading anywhere everything drawn AND any line longer length is 50 mm or more AND (clear, sharp, unbroken lines) Do not give mark if • any ruled lines • any line too thick (thinner than 1 mm) • drawn over the print of question EITHER only xylem vessels with thickening (same or two types) OR only two different bandings (on any number of vessels); [1] Additional guidance Can have • differences in pattern e.g. rings to spiral or in spacing • bandings circular, spirals or reticulate or shows as pits/circles or walls showing clear extra thickening as in section of bands Do not give mark if • any cell(s) or bundles of lines drawn [1] drawn any one set of bandings as two lines or shaded bands or if no bands then allow circles for pits; correct label with label line to lignin which can be the wall or band; MMO collection 3 [1] Additional guidance Do not give mark if any label • to a middle of a pit • any label which is biologically incorrect e.g. from incorrect organ or animal • label within drawn area Must have • line to touch wall or band [Total: 18]