Cambridge A Level Biology 9700 — 2015 Oct/Nov Paper 3 · Variant 4

This document consists of 13 printed pages and 3 blank pages. DC (RW/SW) 118931/4 R © UCLES 2015 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 3 6 5 5 4 2 0 0 5 5 * BIOLOGY 9700/34 Advanced Practical Skills 2 October/November 2015 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 pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, 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/O/N/15 © UCLES 2015 Before you proceed, read carefully through the whole of Question 1 and Question 2. Plan the use of the two hours to make sure that you finish all the work that you would like to do. If you have enough time, consider how you can improve the accuracy of your results, for example by obtaining and recording one or more additional measurements. You will gain marks for recording your results according to the instructions. 1 When plant tissue is soaked in methylene blue solution, the stain enters the tissue and colours it blue. When the stained plant tissue is placed into a salt solution, methylene blue is released. You are required to investigate the effect of different surface areas (independent variable) on the release of methylene blue from pieces of stained plant tissue. You are provided with: labelled contents hazard volume / cm3 S salt solution (sodium chloride) none 250 labelled contents hazard details quantity P plant tissue stained with methylene blue methylene blue will stain your skin same cross- sectional area, stained with methylene blue and washed 4 pieces If any methylene blue comes into contact with your skin wash off immediately with water. It is recommended that you wear safety glasses/goggles. When carrying out a practical procedure, the hazards of the use of all the apparatus and solutions need to be considered. Then the level of risk needs to be assessed as low or medium or high. (a) State the hazard with the greatest level of risk when carrying out step 1 on page 4. State the level of risk of the procedure: low or medium or high. hazard … … level of risk … [1]

3 9700/34/O/N/15 © UCLES 2015 [Turn over You are required to prepare pieces of plant tissue with different surface areas. (b) Each piece of plant tissue has the same cross-sectional area. The largest piece needs to be cut to a length of 4 cm by removing each end. (i) Complete Fig. 1.1 to show how you will cut further pieces which reduce the length by half between each piece of plant tissue. Fig. 1.1 is not drawn to scale. piece A use in step 10 use in step 11 halve piece B Fig. 1.1 [1] (ii) Complete the table to show for each piece in (b)(i): • the dimensions of the piece of plant tissue • the surface area of each piece. piece dimensions / mm surface area / mm2 A 5 × 5 × 40 850 [2]

4 9700/34/O/N/15 © UCLES 2015 Proceed as follows: Always use blunt forceps when handling the plant tissue to avoid contact with the methylene blue solution. 1. Remove the pieces of plant tissue from the container, labelled P, and place them onto a white tile. 2. Prepare the pieces of plant tissue as stated in (b)(ii). 3. Any pieces of plant tissue which you do not need should be put into the beaker labelled ‘For waste’. You will need to prepare a number of pieces of plant tissue to enable you to have confidence in your results. 4. Empty the coloured water from the container labelled P. 5. Put the pieces of plant tissue into the empty container labelled P and cover with water from the beaker labelled ‘Tap Water’. 6. Change the tap water five times, either using a syringe or by pouring off the water. Fig. 1.2 shows how you will set up the apparatus for each piece of plant tissue. S piece of plant tissue Fig. 1.2 (iii) Describe how you will standardise the volume of S for each piece of plant tissue. … … …[1]

5 9700/34/O/N/15 © UCLES 2015 [Turn over 7. Label one test-tube as 850 (surface area in mm2 of piece A). 8. Repeat step 7 for each of the other surface areas as in (b)(ii). 9. Put the volume of S into each of the test-tubes as described in (b)(iii). 10. Put piece A into the test-tube labelled 850. 11. Repeat for the other pieces of plant tissue, matching the surface area to the label on the test-tube. 12. Leave for 5 minutes. While you are waiting continue with Question 1. After 5 minutes you will need to remove the plant tissue from each test-tube so that the colour of each solution can be recorded. 13. After 5 minutes, pour the solution and the piece of plant tissue from one of the test-tubes into the beaker labelled R. 14. Put the piece of plant tissue into the container labelled ‘For waste’. Put the solution back into the test-tube. 15. Rinse beaker R with tap water. 16. Repeat step 13 to step 15 with each of the remaining test-tubes. 17. Put the test-tubes into the test-tube rack in the order of the intensity (quantity) of blue colour from lowest intensity to highest intensity. 18. Observe the colour in the test-tubes and use the number scale below to match each test-tube to an intensity of colour. 0 2 4 6 8 10 darkest blue colourless highest intensity lowest intensity 19. Record the results in (b)(iv) on page 6.

6 9700/34/O/N/15 © UCLES 2015 (iv) Prepare the space below and record your results. [6] (v) A student suggested: ‘The ruler used to measure the pieces of plant tissue resulted in both systematic error and random error.‛ State which type of error, systematic or random, could affect the trend in the results. Give a reason for your answer. type of error … reason …[2] (vi) Explain how the methylene blue solution was released from the stained plant tissue. … … …[1]

7 9700/34/O/N/15 © UCLES 2015 [Turn over (vii) This procedure investigated the effect of different surface areas of stained plant tissue when placed into a salt solution. To modify this procedure for investigating another variable, the independent variable (surface area) would need to be standardised. Describe how the independent variable (surface area) would be standardised. … … Consider how you would modify this procedure to investigate the effect of temperature on the stained plant tissue. Describe how the independent variable, temperature, will be investigated. … … … …[3] [Total: 17] Check that you have finished the whole of Question 1.

8 9700/34/O/N/15 © UCLES 2015 2 Some plant cells, for example in roots, store starch as grains. Fig. 2.1 shows some different shapes of starch grains and patterns in the surface of the starch grains. J K L M Fig. 2.1 You are required to: • observe and draw the starch grains from potato cells • observe the effect of iodine stain on starch grains. You are provided with a piece of peeled potato tuber in a dish, labelled T, water in a container, labelled W, and iodine solution in a container labelled I. 1. Put one clean and dry microscope slide on a piece of black card with a paper towel underneath as shown in Fig. 2.2. smear of potato cells paper towel W black card slide Fig. 2.2 2. Using a sharp blade or scalpel, cut the piece of potato to show a fresh surface. 3. Scrape the fresh surface of the piece of potato to remove a small quantity of tissue. 4. Put this tissue onto the slide and use the flat surface of the blade to squash this tissue. 5. Use forceps to remove any larger bits of tissue so that a smear of cells can be seen on the slide. 6. Put a few drops of W onto the smear of cells. 7. Cover the cells with a coverslip and use a paper towel to remove any excess liquid that is outside the coverslip.

9 9700/34/O/N/15 © UCLES 2015 [Turn over 8. View the slide to observe the starch grains using the microscope. Select an area of starch grains on the slide. You may need to reduce the amount of light entering the microscope to observe cells clearly. You must adjust the fine focus to observe the patterns in the starch grains. You are required to use a sharp pencil for drawings. (a) Select 6 starch grains which show the different sizes and features of the grains. (i) Make a large drawing of these 6 starch grains. [5] (ii) Use Fig. 2.1 to suggest which of the starch grains, J, K, L or M matches some of the grains observed on the slide. answer …[1] 9. Remove the slide from the microscope and place it on a paper towel. You will now add solution I to the water on the slide without removing the coverslip. 10. Put a drop of solution I onto the slide so that the drop touches the edge of the coverslip. Wait a few seconds while the solution I moves under the coverslip. Use the paper towel to remove any excess liquid from the top of the coverslip. 11. Immediately use the microscope to observe the starch grains where there is solution I on the slide. (iii) Suggest why using solution I as a stain may lead to inaccurate recording of the features of starch grains. … …[1]

10 9700/34/O/N/15 © UCLES 2015 (b) Scientists investigated the mean size of starch grains in cells from five different types of maize D, E, F, G and H. The results are shown in Table 2.1. Table 2.1 type of maize size of starch grain / μm mean size of starch grains / μm 1 2 3 4 5 D 16.240 16.255 16.525 16.260 16.245 E 16.725 16.730 16.715 16.730 16.725 16.725 F 17.195 17.205 17.200 17.198 17.202 17.200 G 16.975 16.980 16.970 16.976 16.974 16.975 H 17.945 17.950 17.955 17.940 17.960 17.950 (i) Circle the anomalous result in Table 2.1. [1] (ii) Complete the table by calculating the missing mean value. [1] You are required to use a sharp pencil for charts. (iii) Plot a chart of the data in Table 2.1. Note: To plot the data clearly, the scale should not have 0 at the origin. [4]

11 9700/34/O/N/15 © UCLES 2015 [Turn over (iv) Suggest one reason which might explain the differences in the mean size of starch grains between different types of maize. … … …[1] (c) A student calibrated the eyepiece graticule in a light microscope using a stage micrometer scale so that they could find the actual length of specimens observed using a light microscope. The calibration was: one eyepiece graticule division equal to 0.023 mm. The use of this unit (mm) is not the most appropriate unit for use with a light microscope. (i) State which unit is the most appropriate for use with a light microscope and show how the value 0.023 mm is converted to this unit. You may lose marks if you do not show your working. [2]

12 9700/34/O/N/15 © UCLES 2015 (ii) Fig. 2.3 is a photomicrograph showing a stained transverse section through a root with a root nodule. Y draw this sector in (d) Fig. 2.3 Fig. 2.3 was produced using the same microscope with the same lenses as the student. Use the calibration of the eyepiece graticule division from (c)(i) and line Y shown on Fig. 2.3 to calculate the actual total width as shown by line Y. You may lose marks if you do not show your working or if you do not use appropriate units. actual total width …[2]

13 9700/34/O/N/15 © UCLES 2015 You are required to use a sharp pencil for drawings. (d) Draw a large plan diagram of the sector as shown on Fig. 2.3. You are not expected to be familiar with this specimen. Use one ruled label line and label to identify the vascular bundle. [5] [Total: 23]

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® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International Advanced Subsidiary and Advanced Level MARK SCHEME for the October/November 2015 series 9700 BIOLOGY 9700/34 Paper 3 (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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2015 9700 34 © Cambridge International Examinations 2015 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 accepted) 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 Cambridge International AS/A Level – October/November 2015 9700 34 © Cambridge International Examinations 2015 1 (a) low ; [1] (b) (i) shows at least 2 more sizes cut using previous size ; [1] (ii) (dimension) 5 × 5 × 20 (surface area) 450 ; dimension) 5 × 5 × 10 (surface area) 250 + (dimension) 5 × 5 × 5 (surface area) 150 ; [2] (iii) use syringe to measure same volume for all test-tubes or mark the level on first test-tube and then use this to mark other test-tubes ; [1] (iv) mp1 table drawn + heading for surface area + mm2 ; mp2 heading for number ; mp3 records values for at least 4 different size pieces ; mp4 records results as whole numbers ; mp5 records the highest surface area as having the highest intensity ; mp6 repeats ; [6] (v) random ; correct error described e.g. ends not vertical or idea of problems cutting the potato to the correct dimensions ; [2] (vi) diffusion ; [1] (vii) (standardise surface area) same size / measurements ; (change temperature) 5 temperatures or examples of temperatures ; use a thermostatically controlled water-bath ; [3] [Total: 17]

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2015 9700 34 © Cambridge International Examinations 2015 2 (a) (i) at least 6 starch grains + size at least 30 mm across the largest starch grain + sharp continuous lines ; draws only 6 whole starch grains + no shading ; correct shape ; shows different sizes ; shows correct pattern of lines inside at least 3 starch grains ; [5] (ii) L ; [1] (iii) idea of patterns not visible as iodine stains the starch grains blue / black ; [1] (b) (i) circled only 16.525 ; [1] (ii) correct mean 16.250 ; [1] (iii) mp1 (x-axis) type of maize + (y-axis) mean size of starch grains ( / ) µm ; mp2 (x-axis) even bar widths + equal spaces between bars + (y-axis) 0.5 to 2 cm labelled each 2 cm with origin at 16 ; mp3 correct plotting of each bar in order in table + with horizontal line ruled within half a square ; mp4 clear sharp lines + labelling of bars D, E, F, G and H ; [4] (iv) genetic or DNA or different enzymes or age or sample size too small to show a valid difference ; [1] (c) (i) shows 0.023 multiplied by 1000 or 103 ; 23µm ; [2] (ii) correct number of eyepiece graticule units ; shows eyepiece graticule units multiplied by the answer to (c)(i) ; [2] (d) mp 1 size at least 90 mm + no shading ; mp 2 no cells + at least 4 lines + one enclosed area drawn + correct section drawn ; mp 3 draws vascular bundle inside bulge ; mp 4 draws vascular bundle with central enclosed area within an outer enclosed area ; mp 5 correct label with label line to the vascular bundle ; [5] [Total: 23]