Cambridge A Level Biology 9700 — 2013 Oct/Nov Paper 3 · Variant 1

This document consists of 11 printed pages and 1 blank page. DC (LEO/CGW) 57938/6 © UCLES 2013 [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. 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. * 9 2 3 6 5 5 8 6 9 0 * BIOLOGY 9700/31 Advanced Practical Skills 1 October/November 2013 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. For Examiner’s Use 1 2 Total

2 © UCLES 2013 9700/31/O/N/13 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 Agar pieces can be used to investigate diffusion. You are required to investigate the effect of ascorbic acid (independent variable) diffusing into stained agar pieces. As ascorbic acid, A, diffuses into the stained agar piece it causes the piece to decolourise (lose its blue colour). You are provided with: labelled contents hazard volume / cm3 A 0.10% ascorbic acid irritant 100 W distilled water none 100 labelled contents hazard size U agar block containing a blue stain none at least 60 mm × 40 mm Read steps 1–6 before proceeding. Proceed as follows: 1. You are required to dilute the 0.10% ascorbic acid, A, to provide a range of known concentrations using simple dilution.

3 [Turn over © UCLES 2013 9700/31/O/N/13 For Examiner’s Use (a) (i) Decide which concentrations of ascorbic acid to make, then complete Table 1.1. • The difference between each concentration should be 0.02%. • You will need to make up 20 cm3 of each concentration. Table 1.1 volume of ascorbic acid / cm3 volume of distilled water / cm3 percentage concentration of ascorbic acid 20 0 0.10 [3] 2. Prepare all the concentrations of ascorbic acid as in Table 1.1 in the beakers or containers provided.

4 © UCLES 2013 9700/31/O/N/13 For Examiner’s Use You will need to cut the agar block, U, into smaller pieces as shown in Fig. 1.1. To avoid staining your skin, try not to touch the agar. You may use the blunt forceps and paper towels to handle the agar. end without stain cut this end only if longer than 5 mm agar piece stain 5 mm 5 mm 5 mm Fig. 1.1 3. Place the agar block onto a damp paper towel and cut the block into identical pieces of 5 mm × 5 mm × 5 mm as shown in Fig. 1.1. You will need to consider the number of pieces needed for each concentration of ascorbic acid you have stated in Table 1.1 on page 3. Fig. 1.1 shows the measurement of the agar pieces that you need. 4. Put the prepared agar pieces into each of the concentrations of ascorbic acid. Immediately start timing. 5. Gently stir the contents of each beaker or container at regular intervals. 6. Record the time taken for the pieces to decolourise. After 15 minutes, if any agar piece has not decolourised, stop timing, and record ‘more than 900’.

5 [Turn over © UCLES 2013 9700/31/O/N/13 For Examiner’s Use (ii) Prepare the space below and record your results. [5] (iii) Identify two significant sources of error in this investigation. … … … … …[2] (iv) Describe three modifications to this investigation which would improve the confidence in your results. … … … … … … …[3]

6 © UCLES 2013 9700/31/O/N/13 For Examiner’s Use A student investigated measuring the concentration of ascorbic acid in different solutions by using a colour change with an indicator. The greater the volume of indicator added the greater the concentration of ascorbic acid in the solution. The student’s results are shown in Table 1. 3. Table 1.3 percentage concentration of ascorbic acid volume of indicator / cm3 0.10 0.25 0.30 0.75 0.60 1.45 0.70 1.75 1.00 2.50 (b) (i) Plot a graph of the data shown in Table 1.3. [4] (ii) Use your graph to estimate the concentration of ascorbic acid present in a solution that required 0.875 cm3 of indicator. Show clearly on your graph how you obtained the ascorbic acid concentration. concentration of ascorbic acid …[2] [Total: 19]

7 [Turn over © UCLES 2013 9700/31/O/N/13 For Examiner’s Use 2 J1 is a slide of a transverse section through a tubular organ which is involved in transport. (a) (i) Draw a large plan diagram of the part of the tube on J1 indicated by the shaded sector in Fig. 2.1. draw this sector Fig. 2.1 On your diagram, use a label line and label to show the muscle tissue. [5] (ii) State one observable feature of the tube on J1 which supports the conclusion that the tube is involved in transport. Explain how this feature supports the conclusion. … … … … …[2]

8 © UCLES 2013 9700/31/O/N/13 For Examiner’s Use Fig. 2.2 is a photomicrograph of blood cells in a field of view. r magnification x 200 Fig. 2.2 Fig. 2.2 shows many blood cells. There are too many red blood cells to count, so the technique of sampling may be used to estimate the number of red blood cells in the field of view. A sample should be counted in a known smaller area and then the result multiplied to obtain an estimate of the number of red blood cells in the whole field of view. For example, if the number of red blood cells is counted in an eighth of the area of the field of view then this number would be multiplied by 8 to obtain the total number in the area of the field of view. (b) (i) Count and record the sample number of red blood cells in the eighth of the area of the field of view. • Mark clearly on Fig. 2.2 each of the red blood cells counted. • Estimate the number of red blood cells in the whole field of view. You will lose marks if you do not show your working. number of red blood cells in the field of view … [2]

9 [Turn over © UCLES 2013 9700/31/O/N/13 For Examiner’s Use To find the area of the field of view you need to calculate the actual length of line r, the radius of the circle, in mm. (ii) Use the magnification on Fig. 2.2 to calculate the actual length of line r in mm. actual length … mm Use the actual length of line r to calculate the area of the field of view using the formula for the area of a circle: area of a circle πr2 π = 3.14 r = radius of field of view area of field of view … mm2 [2] (iii) Calculate the number of red blood cells per mm2 using your answers in (b)(i) and (b)(ii). You will lose marks if you do not show your working. number of red blood cells … mm–2 [2]

10 © UCLES 2013 9700/31/O/N/13 For Examiner’s Use A group of people climbed a mountain. They started at sea level (0.0 km) and reached a height of 6 km above sea level in 60 days. The average number of red blood cells per cm3 of blood was calculated for the group of people at the start of the climb and at 20 day intervals. The data is shown in Table 2.1. Table 2.1 days height above sea level / km average number of red blood cells for the group / millions per cm3 0 0.0 4.7 20 3.0 5.5 40 4.5 6.3 60 6.0 6.5 (iv) Describe the trend in the average number of red blood cells with height above sea level and explain the advantages of this trend. … … … … … … …[3]

11 © UCLES 2013 9700/31/O/N/13 For Examiner’s Use Fig. 2.3 is a photomicrograph of blood from a different organism. Fig. 2.3 (c) Make a drawing of white blood cells as observed in Fig. 2.3 made up of: • two cells of one type of white blood cell • two cells of a different type of white blood cell. The drawings should show any differences in size (linear magnification) observed between each type of cell. On your drawing, use a label line and label to show one nucleus. [5] [Total: 21]

12 9700/31/O/N/13 © UCLES 2013 Copyright Acknowledgements: Question 2 Fig. 2.3 © BIOPHOTO ASSOCIATES/SCIENCE PHOTO LIBRARY. 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. BLANK PAGE

CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2013 series 9700 BIOLOGY 9700/31 Paper 3 (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 October/November 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 – October/November 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

Page 3 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 31 © Cambridge International Examinations 2013 1 (a) (i) at least three further concentrations made according to instructions 0.08 + 0.06 + 0.04 + (0.02 ); correct volumes of ascorbic acid (0.08) 16 + (0.06) 12 + (0.04) 8 + (0.02 ) 4; total volumes made up 20; [3] (ii) organised into table; heading (column to left of data or top row) percent(age) or % concentration of ascorbic acid / A + (any column/row headed) time (/) s or sec(onds); records results according to instructions i.e. for 0.10 + three further concentrations; correct pattern of results records shortest time to end-point for highest concentration of A recorded; records all results to whole numbers of seconds; [5] (iii) cause of error + idea of error: (independent) range of concentrations + too narrow / not enough; (dependent) colour disappearance + not same or difficult to judge or varies or different; timing + inaccurate as timing started when last piece put in; (standardised) size of agar piece / cutting + not same or varies or different; agitating pieces of agar / ascorbic acid + not same or varies or different; pieces of agar with stained side down or stick together + ascorbic acid not reaching indicator; [max 2]

Page 4 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 31 © Cambridge International Examinations 2013 (iv) (independent variable) more or wider or different or larger or at least five different concentrations or gives five examples; A if no units R if incorrect units (dependent variable) use help or two people to record colour or video; stagger start or do individually to prevent timing error; (standardised variables) cut agar block on graph paper or alternative method; use electric or automatic shaker; [max 3] (b) (i) line graph: label on x-axis percent(age) ascorbic acid conc(entration /) % + label on y-axis vol(ume of) indicator (/) cm3; scale x-axis 0.2 to 2 cm labelled each 2cm + y-axis 0.5 to 2 cm labelled each 2 cm; correct plotting of five points as small cross or dot in circle; ruled line of best fit through at least four plotted points + line less than 1 mm thick; [4] (ii) shows clearly on graph with line or point on line; estimate correct with reading at 0.86 cm3 to 2 decimal places with %; [2] [Total: 19]

Page 5 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 31 © Cambridge International Examinations 2013 2 (a) (i) drawing and quality; do not give mark for • any shading • any ruled lines • smaller than 50 mm across widest dimension of largest enclosed area • less than 3 lines or any line • is too thick • has any feathery or dashed lines or gap in line • has any overlaps; no cells + correct quarter drawn; layers of differing widths; inner line drawn with indentations; uses label line with label to muscle tissue; [5] (ii) lumen; + presence of blood cells or AW or to ease flow or allow free movement of blood or less resistance; thick (muscle) wall; + wall to withstand pressure or hold blood; inner surface folded or crinkled or irregular + to allow tube to expand or widen or dilate; [max 2] (b) (i) marks on blood cells counted in correct eighth; shows number of whole cells counted multiplied by 8; [2] (ii) correct measurement of line r + units mm; correct answer for area to correct number of significant figures; (measurement divided by 200)2 × 3.14) [2] (iii) shows number of blood cells ((b)(i)) divided by area (from (b)(ii)); rounded to whole number for answer; [2] (iv) as altitude / height increases (ascends) average number of red blood cells / rbc increases or rbc produced at faster rate; as ascend / at altitude air is thin or less oxygen; extra red blood cells help to supply enough oxygen to tissues or idea more oxygen carried; [3]

Page 6 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 31 © Cambridge International Examinations 2013 (c) drawing and quality; do not give mark • any shading • any ruled lines • smaller than 20 mm across widest dimension of largest cell • less than 4 enclosed areas or any line • is too thick • has any feathery or dashed lines or gap in line • has any overlaps; draws only four whole cells + two of each type; cells shown with correct relevant sizes; (details of) nucleus different between two cells of one type of wbc (lobed nucleus in the two cells); uses label line with label to one nucleus; [5] [Total: 21]