Cambridge A Level Biology 9700 — 2013 May/June Paper 3 · Variant 1

This document consists of 12 printed pages. DC (SM/SW) 52066/5 © UCLES 2013 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level * 7 3 2 5 3 1 0 7 8 8 * BIOLOGY 9700/31 Advanced Practical Skills 1 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, paper clips, 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 9700/31/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 You are provided with solutions S1, S2, S3, S4 and S5 which represent extracts from different tissues of a plant, including the xylem. You are required to identify which biological molecule may be present in each of the plant extracts. Four of the solutions contain one type of biological molecule, which could be: • glucose • protein • starch • sucrose. Each solution contains one type of biological molecule, but the same type of biological molecule may be present in more than one of S1, S2, S3, S4 and S5. For example, glucose may be present in S1 AND S2. The solution from the xylem does not contain any of these biological molecules. You are provided with: labelled hazard volume / cm3 S1, S2, S3, S4 and S5 none 25 Proceed as follows: (a) (i) As you carry out each test to identify the presence or absence of the biological molecule in S1, S2, S3, S4 and S5, complete the following:

3 [Turn over © UCLES 2013 9700/31/M/J/13 For Examiner’s Use Decide which biological molecule to identify in the first test. First test: Test for … Describe how you used the reagents to carry out this test. … … … Carry out the first test and record your observations. solutions tested observations of colour Use these observations to complete the sentence. Solution(s) … contain(s) the biological molecule … . Decide which biological molecule to identify in the second test. Second test: Test for … Describe how you used the reagents to carry out this test. … … … Carry out the second test and record your observations. solutions tested observations of colour Use these observations to complete the sentence. Solution(s) … contain(s) the biological molecule … .

4 9700/31/M/J/13 © UCLES 2013 For Examiner’s Use Decide which biological molecule to identify in the third test. Third test: Test for … Describe how you used the reagents to carry out this test. … … … Carry out the third test and record your observations. solutions tested observations of colour Use these observations to complete the sentence. Solution(s) … contain(s) the biological molecule … .

5 [Turn over © UCLES 2013 9700/31/M/J/13 For Examiner’s Use Decide which biological molecule to identify in the fourth test. Fourth test: Test for … Describe how you used the reagents to carry out this test. … … … Carry out the fourth test and record your observations. solutions tested observations of colour Use these observations to complete the sentence. Solution(s) … contain(s) the biological molecule … . From these observations, the remaining solution … contains … . [15] (ii) Identify which of the solutions S1, S2, S3, S4 and S5 is most likely to be the plant extract from the phloem. …[1]

6 9700/31/M/J/13 © UCLES 2013 For Examiner’s Use A student identified the presence of reducing sugars in two plant extracts and was then required to find the concentration of reducing sugars in the two plant extracts. (b) Describe how the student would find the concentration of reducing sugars in each plant extract. … … … … … … …[3] [Total: 19]

7 9700/31/M/J/13 © UCLES 2013 [Turn over Question 2 starts on page 8

8 9700/31/M/J/13 © UCLES 2013 For Examiner’s Use 2 Fig. 2.1 shows a photomicrograph of a transverse section through part of a plant stem showing the eyepiece graticule scale as seen using a microscope. P N M K L R Fig. 2.1 An eyepiece graticule scale can be used to measure the layers of tissues and to help draw a plan diagram with the correct shape and proportions of the tissues, without needing to calibrate the eyepiece graticule scale. (a) (i) The length of the vascular bundle (from K to R) in Fig. 2.1 was measured using the eyepiece graticule scale and recorded in Table 2.1. Table 2.1 layer L M N P length from K to R number of eyepiece graticule scale divisions 30 Complete Table 2.1 by finding the thickness of each of the different layers, L, M, N and P using the line between K and R and the eyepiece graticule scale. [2]

9 [Turn over © UCLES 2013 9700/31/M/J/13 For Examiner’s Use The length (from K to R) of the vascular bundle in eyepiece graticule divisions was used to make a scale drawing of the outline of the vascular bundle as shown in Fig. 2.2. K R Fig. 2.2 (ii) Complete the plan diagram of the vascular bundle to show the proportion and shape of each of the tissues. Use the values in Table 2.1 to help you. [3] (iii) Using Fig. 2.2, count the total number of 1 cm by 1 cm squares occupied by the vascular bundle and count the total number of 1 cm by 1 cm squares occupied by the xylem. Count any ‘half square’ or ‘more than half’ as one square. State the ratio of the area occupied by the vascular bundle to that of the xylem. You will lose marks if you do not show all the steps in finding the ratio, including indicating counted squares on Fig. 2.2. ratio …[2]

10 9700/31/M/J/13 © UCLES 2013 For Examiner’s Use Some scientists investigated the rate of transpiration during part of a day. The results are shown in Table 2.2. Table 2.2 time of day / hours rate of transpiration / g cm–2 hr–1 06.00 0.6 08.00 1.9 10.00 2.2 12.30 2.2 15.00 1.5 18.30 0.4 (b) (i) Plot a graph of the data shown in Table 2.2. [4] (ii) From your graph, state the rate of transpiration at 14.30 hours. Show on your graph where you obtained the rate of transpiration. …[1]

11 [Turn over © UCLES 2013 9700/31/M/J/13 For Examiner’s Use J1 is a slide of a transverse section through another plant stem. This plant grows mainly in Europe and Asia. This stem shows a layer of stained cells close to the epidermis and just beneath these cells is another tissue close to the vascular bundles. (c) Make a large drawing of one group of three whole adjacent (touching) cells • from the layer of stained cells close to the epidermis, as observed on the specimen J1. Make a large drawing of one group of three whole adjacent (touching) cells • from the cells between the layer of stained cells and the vascular bundles, as observed on the specimen J1. The drawings should show any difference in size (linear magnification) observed between each group of cells. layer of stained cells cells between the layer of stained cells and the vascular bundles [4] Question 2 continues on page 12

12 9700/31/M/J/13 © UCLES 2013 For Examiner’s Use 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. Fig. 2.3 shows a photomicrograph of a transverse section through part of a different plant stem. Fig. 2.3 (d) Prepare the space below so that it is suitable for you to record the observable differences between the specimen on slide J1 and in Fig. 2.3 to include: • the vascular tissue • at least two other tissues. [5] [Total: 21]

© Cambridge International Examinations 2013 CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2013 series 9700 BIOLOGY 9700/31 Paper 31 (Advanced Practical Skills 1), 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 31 © 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 ACE Analysis, Conclusions and Evaluation (skills) MMO Manipulations, Measurement and Observation (skills) PDO Presentation of Data and Observations (skills)

Page 3 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 31 © Cambridge International Examinations 2013 Expected Answers 1 (a) (i) [max 15] mp1 (MMO Decision) test for glucose/reducing sugar before sucrose/non-reducing sugar; mp2 (MMO Decision) tests (gets a result for) only remaining solutions in next test so test 1 S1, S2, S3, S4, S5 AND test 2 S1, S2, S3, S4, S5 minus solution(s) identified in test 1 AND test 3 S1, S2, S3, S4, S5 minus solution(s) identified in test 1 and test 2 AND test 4 S1, S2, S3, S4, S5 minus solution(s) identified in test 1, test 2 and test 3; mp3 (MMO Decision) cm3 or ml(s) once AND volume of only Benedict’s (solution) or sum of volumes of Fehling’s A and B equal to or more than volume of sample; mp4 (PDO Recording) draws in all the row lines in test 1 results table only; starch test glucose test sucrose test Decision on method M only starch, glucose, sucrose tests ignore protein test ✓ or X ✓ or X ✓ or X R and I only awarded in correct context of molecule being tested and reagent and for sucrose only if after glucose (mp1 awarded) test 1 test 2 test 3 test 4 collection records R ✓ or X ✓ or X ✓ or X ✓ or X conclusion identification I ✓ or X ✓ or X ✓ or X ✓ or X

Page 4 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 31 © Cambridge International Examinations 2013 M,R and I are same marking points but can only be awarded in correct contexts of molecule tested and reagent for as shown below: M decision on (starch) Idea of uses iodine or Lugol’s; do not give mark if heated (glucose (ignore reducing/non-reducing ) or reducing sugar only) Benedict’s AND boil or heat to degrees or oC AND any whole number 80 to and including 100 or range within 80 to 100 e.g. 80 to 100; (sucrose (ignore reducing/non-reducing ) or non-reducing sugar only add acid/ HCl/ named acid AND heat/ warm AND neutralise/adds base/alkali/ named alkali; (protein) ignore method R Records (starch + iodine) only one positive result blue/black or black or navy blue or dark blue; (glucose/reducing sugar + Benedict’s) only one positive result green or yellow or orange or red or brown or any combination; (sucrose/non-reducing sugar + Benedict’s) only one positive result green or yellow or orange or red or brown or any combination; ignore brick only award if test done after glucose test. do not give mark if S2 and S5 tested (protein + Biuret or KOH/NaOH and copper sulphate or Biuret A and B) only one positive result biuret only accept lilac or purple or mauve or violet; the first test must have recorded results for all five solutions. Tests 2 and 3 must have recorded results for at least two solutions I Conclusion (starch + iodine) (S)4 and starch; (glucose/reducing sugar + Benedicts) (S)5 and glucose; (sucrose/non-reducing test + Benedicts) (S)2 and sucrose; only award if test done after glucose test (protein + biuret or KOH/NaOH and copper sulphate or biuret A and B); (S)3 and protein Test 4 I is only awarded for (S)1 and contains no biological molecules/ none; [max 15]

Page 5 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 31 © Cambridge International Examinations 2013 (ii) [1] ACE interpretation 1 S2; (b) [3] ACE improvements 2 mp1 (independent variable) (using reducing sugars or named reducing sugar/glucose/standard solutions) at least 5 sugar concentrations or at least five examples of concentrations; mp2 serial dilution or simple dilution or described method for making different concentrations; ACE improvements 1 mp3 (dependent variable) compare results/colour of plant extracts/samples/unknown with known (standard) solutions; [Total: 19]

Page 6 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 31 © Cambridge International Examinations 2013 2 (a) (i) [2] do not give either mark if include units other than ep(g)u(nits) MMO collection 2 mp1 L M N P any numbers which add up to 11or 11.5 or 12 ignore 15 or 15.5 or 16 or 16.5 or 17; mp1 any 4 values which add up to 30; (ii) [3] PDO layout 1 mp1 suitable plan diagram do not give mark if • any line outside the drawn line given • any line off the grid • any shading • any ruled line AND clear, sharp, unbroken lines; do not give mark if • less than 3 enclosed areas (ignore cells) • any part of line 1mm or thicker (use grid) • any feathery or broken or dashed line or gap • any tail or overlap PDO recording 1 mp2 3 bands (3 lines) which dip downwards AND (completed outline at base as) an enclosed area from ends of lines provided AND two converging lines to R; MMO decision 1 mp3 (draws correct proportion and shape of layers) 3 lines in the top half AND both of the top 2 bands are wider than 3rd band; (iii) [2] PDO display 2 mp1 (inside the drawn outline) shows counting of all complete 1 cm by 1 cm squares AND those squares which are half or more than half; mp1 number clearly linked to bundle AND number clearly linked to xylem AND larger whole number to smaller whole number to lowest denominator OR as fraction larger number over smaller number to lowest denominator;

Page 7 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 31 © Cambridge International Examinations 2013 (b) (i) [4] if draw a chart then only give mp1 PDO layout 4 mp1 x-axis time of day(/) hours AND y-axis rate of transpiration (/) g cm–2 hr–1 ; mp2 scale as x-axis 5:00 hours to 2 cm, labelled each 2 cm AND y-axis 0.5 to 2 cm labelled each 2 cm ; mp3 correct plotting of all points as small cross or dot(in circle) or cross in circle; mp4 six plots with ruled lines exactly point to point AND (quality) smooth line less than 1 mm thick; (ii) [1] ACE interpretation 1 correct reading from graph with g cm–2 hr–1;

Page 8 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 31 © Cambridge International Examinations 2013 (c) [4] PDO layout 1 mp1 suitable drawing; do not give mark if • any shading • draw over the print of the question • any ruled lines • less than 40 mm at widest distance across largest cell • less than six enclosed areas or if any outer lines (of enclosure) • are thicker than 1 mm • are feathery or broken/dashed or have a gap • have any tail or overlap MMO collection 1 mp2 only 6 complete cells drawn AND as two groups of 3 touching cells; PDO recording 1 mp3 7 or fewer cells (cells between the layer of stained cells and the vascular bundles) widest dimension of the biggest cell is at least twice the narrowest dimension of the smallest cell (from the layer of stained cells); MMO decision 1 mp4 in one group of three cells, all cells must be drawn with double lines all the way round AND where two pairs of cells touch there must be three lines (representing the middle lamella);

Page 9 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9700 31 © Cambridge International Examinations 2013 (d) [max 5] PDO recording 1 mp1 organise as a table with only three columns or rows separated by lines AND headed J1 and Fig. 2.3 AND third column headed feature or AW or contains at least one feature; MMO collection 1 mp1 collected only differences; ACE interpretation MAX 3 max 3 mp feature J1 Fig. 2.3 mp1 vascular bundle or xylem position not in a ring or separate or irregular or scattered or further away from epidermis than others in a ring or in line or regular or continuous or altogether or near epidermis any ref to size (either way but must be comparative) variation in sizes (small and large) Ignore thickness number (either way but must be comparative) Idea of few(er) with more or numerous shape star-shaped or egg- shaped/AW or pointed at one end rounded or circular; mp2 continuous layer/cambium absent or has not or no(ne) present or has or yes; mp3 trichome or hairs NOT root hair Accept spike/thorn or hairs etc on cuticle absent or has not or no(ne) small(er) or few(er) present or has or yes large(r) or more; mp4 hollow or gap or pith or centre or parenchyma (cells) present or has or yes absent or has not or no(ne) absent or has not or no(ne) present or has or yes; mp5 thickened cells/layer/ collenchyma/ sclerenchyma present or has or yes absent or has not or no(ne); mp6 layer under epidermis might be called cortex thin(ner) thick(er); [Total: 21]