Cambridge A Level Biology 9700 — 2010 May/June Paper 3 · Variant 4

This document consists of 11 printed pages and 1 blank page. DC (KN/CGW) 15996/4 © UCLES 2010 [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. You are advised to spend one hour on each question. * 1 9 7 8 9 8 2 8 2 2 * BIOLOGY 9700/34 Paper 32 Advanced Practical Skills May/June 2010 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/10 © UCLES 2010 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 and 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 Plant cells contain an enzyme, catalase, which catalyses the breakdown of hydrogen peroxide into oxygen and water. You are required • to immobilise the catalase in sodium alginate beads • to investigate the independent variable, hydrogen peroxide concentration. When a bead is dropped into hydrogen peroxide it will sink and then the release of oxygen causes the bead to rise. You are provided with • 50 cm3 of 10 % hydrogen peroxide solution, labelled H • 100 cm3 of distilled water, labelled W • 10 cm3 of a plant extract containing catalase, labelled P • 15 cm3 of 2 % sodium alginate solution, labelled S • 30 cm3 of 1.5 % calcium chloride solution, labelled C. Proceed as follows: 1. Put 10 cm3 of C into a large test-tube. 2. Put 5 cm3 of S into a small beaker. 3. Put 3 cm3 of P into the same beaker and mix well. 4. Use a 5 cm3 syringe to collect 2 cm3 of the mixture, S and P. 5. Suspend the 5 cm3 syringe over the large test-tube containing C as shown in Fig. 1.1. calcium chloride solution, C mixture S and P 5 cm3 syringe barrel resting on top of large test-tube gently press down with thumb test-tube Fig. 1.1

3 [Turn over 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use 6. Gently press down on the plunger of the 5 cm3 syringe with your thumb to release a drop into solution C. The drop should form a bead. 7. Repeat step 6 to make the number of beads that you think you will need. 8. Tip the contents of the large test-tube into a Petri dish or shallow container. (a) (i) Decide on the concentrations of hydrogen peroxide you will use in your investigation. You will need to make up 10 cm3 of each hydrogen peroxide concentration. Prepare the space below to show • the concentrations of hydrogen peroxide • the volumes of hydrogen peroxide • the volumes of distilled water. [4] 9. Put 10 cm3 of H into a small test-tube in a test-tube rack. 10. Pick up a bead using blunt forceps. 11. Drop the bead into H and immediately start the stop clock, stop watch or note the time on a clock. 12. Record the time taken for the bead to reach the surface.

4 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use 13. Repeat steps 9 to 12 with each concentration of H that you have chosen to use. (A bead may sink to the bottom of the tube. If it does not rise to the surface after three minutes, stop the experiment and record >3 minutes.) (ii) Prepare the space below to record your results. [5]

5 [Turn over 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use (iii) Identify three significant errors in your investigation. … … … … … … …[3] (iv) Suggest how you would make three improvements to this investigation. … … … … … … … …[3]

6 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use A student investigated the evolution of oxygen during the breakdown of hydrogen peroxide. Immediately the catalase and the hydrogen peroxide were mixed, a stop clock was started and the volume of oxygen released in each minute for five minutes was recorded. The student’s results are shown in Table 1.1. Table 1.1 time / min volume of oxygen collected in each minute / cm3 trial 1 trial 2 trial 3 trial 4 trial 5 mean 1 3.0 2.8 3.0 2.9 2.8 2.9 2 0.6 0.8 0.8 0.7 0.9 0.8 3 0.4 0.5 0.6 0.6 0.7 0.6 4 0.3 0.3 0.4 0.5 0.5 0.4 5 0.1 0.2 0.2 0.1 0.3 0.2 (b) (i) Plot a graph of the data shown in Table 1.1. [4]

7 [Turn over 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use (ii) Describe and explain the results of the student’s investigation. … … … … … … … …[3] [Total: 22]

8 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use 2 N1 is a slide of a stained transverse section through a plant organ. (a) (i) Draw a large plan diagram of a sector to include only three vascular bundles. Draw a circle around one of the vascular bundles on your plan diagram. Label the xylem. [5]

9 [Turn over 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use (ii) Draw three complete cells from the epidermis which are touching. Draw three complete touching cells between the inner edge of a vascular bundle and the centre of the specimen. This drawing should show any difference in size observed between these cells and the two epidermal cells. [4]

10 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use Fig. 2.1 is a photomicrograph of a transverse section of part of an organ from a different plant species. X magnification ×110 Fig. 2.1 (b) (i) Calculate the actual length, in μm, of the structure shown by line X. Show all the steps in your calculation. Answer …μm [2] (ii) Using Fig. 2.1, find the mean actual length of these structures. Prepare the space below and record your results. [3]

11 9700/34/M/J/10 © UCLES 2010 For Examiner’s Use (iii) Draw a large plan diagram of the specimen as shown in Fig. 2.1. [1] (iv) Annotate your plan diagram (make notes with label lines) to show three differences between your diagram and the specimen on slide N1. [3] [Total: 18]

12 9700/34/M/J/10 © UCLES 2010 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 2010 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. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2010 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 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks 1 (a) (i) Prepare the space below to show concentrations of hydrogen peroxide; volumes of hydrogen peroxide; volumes of distilled water. three or more concentrations; [1] includes 10 % as highest; [1] volumes to make up to 10 cm3 or 20 or 30 AND correct; [1] MMO decisions 4 even range or serial dilution; [1] (ii) Prepare the space below to record your results. table with all cells drawn (heading to left or top) AND concentration; [1] PDO recording 2 (heading for one other column or row) time with units; Reject if units in body of table [1] collects times in whole seconds or whole minutes; [1] MMO collection 2 figures for time faster at highest concentration compared with lowest concentration recorded; [1] MMO decision 1 repeats/more than one bead recorded for a concentration or six concentrations; [1]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks (iii) Identify three significant errors in your investigation. Mark for any correct. (beads) not all same or damaged; (test-tube) not vertical (measuring bead to surface); (conditions for enzyme action) temperature not constant; (measuring) beads stuck to sides of tube/stuck together with those already dropped/float up under each other; test-tubes not all the same size; ACE interpretation 3 hydrogen peroxide concentration changes or too high or too low; [max 3]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks (iv) Suggest how you would make three improvements to this investigation. (ref. to beads) describes selection of bead or passes through sieve with same size holes or mechanism to release or allow to drip from syringe or use spoon or method to prevent damage; (ref. to method) (hydrogen peroxide/H) wider range or more concentrations or adjust the concentration or use fresh hydrogen peroxide/H each time or cover hydrogen peroxide or wash and dry beads or use same size of test-tube or use a large test-tube/measuring cylinder; (ref to conditions) thermostatically-controlled waterbath or describes keeping water bath at constant temp; (ref. to measuring) put test-tube in retort stand and make vertical or view at correct angle or use video/camera/light gate to record drop or stain beads or mark line at top; ACE improvements 3 repeats and mean/average; [max 3]

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks (b) (i) Plot a graph of the data shown in Table 1.1. O x-axis time/min y-axis AND vol(ume/) cm3; Must have units [1] S scale as 1 min to 2 cm 0.5 cm3 to 2 cm; Reject S if awkward scale [1] P correct plotting with crosses or dot in circle; Intersection of cross must be clear to show plot Reject P plotting if awkward scale Reject if only blobs or dots or blobs in circles [1] PDO layout 4 L ruled/straight line to all points or smooth curve; Quality – no thicker than on grid, not feathery for the complete line Joining plots – • Ruled lines plot to plot • Curve through all plots Extrapolation • Not beyond x- or y-axis If not correct in context of data then no extrapolation at either end of data [1]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks (ii) Describe and explain the results of the student’s investigation. in first minute or from 2.9 drops to 0.8 or fastest or largest increase or biggest volume; [1] hydrogen peroxide/H or substrate fits into or binds to enzyme or active sites or forms ESCs; [1] ACE conclusion 3 lack of hydrogen peroxide/H or substrate or hydrogen peroxide not high enough; [1] Total [22]

Page 7 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks 2 (a) (i) Draw a large plan diagram of a sector to include three vascular bundles. Draw a circle around one of the vascular bundles on your plan diagram. Label the xylem. PDO layout 1 clear, sharp, (not thicker than grid line for whole line) unbroken lines AND no shading AND larger than 6 cm across widest point on sector drawn; Reject if overlaps the text of question [1] no cells AND only three vascular bundles AND circle round one vascular bundle; [1] any one vascular bundle divided into at least three regions with at least one curved line AND middle region of vascular bundle thicker than the epidermis; [1] MMO collection 3 one vascular bundle from three drawn or circled wider at outer edge than inner edge (apex); Reject if any writing on drawing [1] MMO decision 1 Reject if any label is biologically incorrect. correct label with label line to inner half of vascular bundle xylem; [1]

Page 8 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks (ii) Draw three complete cells from the epidermis which are touching. Draw three complete touching cells between the inner edge of vascular bundle and centre of the specimen. This drawing should show any difference in size observed between these cells and the ‘two’ epidermal cells. PDO layout 1 clear, sharp, AND no shading AND size of bottom group of cells; [1] two groups of only three cells drawn AND each group of 3 cells touching; [1] (epidermis) all cell walls must have two lines AND straight line between any two cells AND one of these cells, cell wall obviously curved or domed; [1] MMO collection 3 (inner cells) all cells rounded AND at least one cell larger than smallest epidermal cell; [1] (b) (i) Calculate the actual length, in µm, of the structure shown by line X. PDO display 2 shows 27.5 or 28 or 28.5 or 29 or 29.5 or 2.75 or 2.8 or 2.85 or 2.9 or 2.95 AND multiplied by × 1000/103 or multiplied by or × 10000/104 divided by 110; [1] any answer correctly rounded to no more than three sig. figs.; [1]

Page 9 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks (ii) Using Fig. 2.1 find the mean actual length of these structures. Prepare the space below and record your results. 5 or more recorded; [1] PDO recording 2 0.0/0.5 mm or 0.00/0.05 cm OR calculated data to same precision, same number of sig. figs.; [1] MMO decision 1 shows addition and division by number of measurements; [1] (iii) Draw a large plan diagram of the specimen as shown in Fig. 2.1. PDO layout 1 no cells AND five areas of thickening touching epidermis; [1]

Page 10 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 34 © UCLES 2010 Question Expected Answers Additional Guidance Marks (c) Annotate your plan diagram to show three differences between your diagram and the specimen on slide N1. Any three annotated labels on plan features labelled: under epidermis patches thickening or present; vascular bundles scattered or not in ring or in centre; vascular bundle thickening or collenchyma on top and bottom/more; vascular bundle shape longer/thinner; pith or centre cells not completely stained cells OR cells relatively much smaller compared to vascular bundle OR no intercellular or air spaces between cells; air space present or large; ACE interpretation 3 whole shape or outer square or not wavy or has straight sides; [max 3] Total [18]