Cambridge A Level Biology 9700 — 2016 May/June Paper 3 · Variant 3

This document consists of 10 printed pages and 2 blank pages. DC (ST/SW) 105814/4 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 8 6 8 1 2 3 2 6 4 0 * BIOLOGY 9700/33 Paper 3 Advanced Practical Skills 1 May/June 2016 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

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3 9700/33/M/J/16 © UCLES 2016 [Turn over 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 Plant cells contain an enzyme, catalase, which catalyses the hydrolysis (breakdown) of hydrogen peroxide into oxygen and water. An extract of plant tissue contains catalase. You are required to investigate the effect of temperature (independent variable) on catalase in a plant extract solution. You are provided with: labelled contents hazard volume / cm3 P plant extract solution none 100 H hydrogen peroxide solution harmful irritant 100 You are advised to wear suitable eye protection, especially when using the hydrogen peroxide solution, H. If H comes into contact with your skin, wash off with cold water. (a) When carrying out a practical procedure the hazards of using the solutions need to be considered. Then the level of risk needs to be assessed as low or medium or high. State the hazard with the greatest level of risk when using the solutions then state the level of risk of the procedure: low or medium or high. hazard … level of risk …[1] (b) You are required to keep a sample of 10 cm3 of the solution in P to test at the temperature of the room. Then heat the remaining solution in P and remove 10 cm3 samples of the solution at different temperatures including a sample at the maximum temperature of 70 °C. (i) Use the thermometer to measure the temperature of the room. temperature …[1] (ii) You will need to test a sample of the solution in P which has been heated to 70 °C. State the other temperatures at which you will remove each sample. … …[2]

4 9700/33/M/J/16 © UCLES 2016 Proceed as follows: 1. Put 10 cm3 of the solution in P into a petri dish labelled with the temperature of the room you recorded in (b)(i). 2. Gently heat the beaker labelled P, containing the remaining solution. 3. When the temperature of the solution in P reaches the lowest temperature stated in (b)(ii), remove the Bunsen burner. 4. Remove 10 cm3 of the solution in P and put it into a labelled petri dish. 5. Replace the Bunsen burner. 6. Repeat step 2 to step 5 for each of the temperatures stated in (b)(ii). 7. When the solution reaches 70 °C, remove the last sample and put it into a labelled petri dish. 8. Turn off the Bunsen burner. 9. Leave the solutions to cool while you cut squares of filter paper, 1 cm × 1 cm. You will need to decide how many squares to cut to give you confidence in your results. 10. Put a mark on the test-tube 2 cm from the top. 11. Put H into the test-tube up to this mark. 12. Use forceps to pick up one square of filter paper and dip the whole square into the solution in the petri dish that is labelled with the temperature of the room. 13. Wipe the square against the petri dish to remove excess solution from both sides of the square. 14. Hold the square just below the surface of H so that the top of the square is level with the surface of H as shown in Fig. 1.1. forceps surface of H level with mark on test-tube Fig. 1.1 15. Immediately release the square (you may need to shake the forceps) and start timing. 16. Measure the time taken for the square to return to the surface. Record the time in (b)(iii). If the time is more than 120 seconds, stop timing and record ‘more than 120’.

5 9700/33/M/J/16 © UCLES 2016 [Turn over 17. Remove the square from the test-tube. Note: if the square remains at the bottom of the test-tube, pour off H into the container labelled H. Use water in the beaker labelled ‘for washing’ to rinse out the square from the test-tube. Then repeat step 11. 18. Repeat step 12 to step 17 with each of the samples removed at the different temperatures. (iii) Prepare the space below and record your results. [6] (iv) Identify two significant sources of error in this investigation. … … … … …[2]

6 9700/33/M/J/16 © UCLES 2016 (v) Explain how the enzyme catalase was affected by the change in temperature. … … … … …[2] (vi) This procedure investigated the effect of temperature on the activity of catalase in the plant extract. To modify this procedure for investigating another variable, the independent variable (temperature) would need to be standardised. Describe how the temperature could be standardised. … … Now consider how you could modify this procedure to investigate the effect of the concentration of catalase in the plant extract on the breakdown of hydrogen peroxide. Describe how this independent variable, concentration of catalase, could be investigated. … … … … …[3]

7 9700/33/M/J/16 © UCLES 2016 [Turn over (c) A student investigated the activity of catalase in plant extracts from different species of plants, R, S, T, U and V, by measuring the initial rate of activity. Table 1.1 shows the results for this investigation. Table 1.1 different plant species initial rate of activity of catalase / s–1 R 0.0750 S 0.1275 T 0.0900 U 0.0325 V 0.0625 You are required to use a sharp pencil for charts. Plot a chart of the data shown in Table 1.1. [4] [Total: 21]

8 9700/33/M/J/16 © UCLES 2016 2 K1 is a slide of a stained transverse section through a plant leaf. You are not expected to be familiar with this specimen. You are required to use a sharp pencil for drawings. (a) (i) Draw a large plan diagram of the part of the leaf as shown by the shaded area in Fig. 2.1, to include observable features and two vascular bundles. draw this area Fig. 2.1 You are expected to draw the correct shape and proportions of the different tissues. [4]

9 9700/33/M/J/16 © UCLES 2016 [Turn over (ii) Observe the epidermis in K1. These cells are not identical. Select one group of four adjacent (touching) cells which show some of the differences between these cells. Make a large drawing of this group of four cells. Each cell of the group must touch at least one other cell. Use one ruled label line and label to identify the cell wall of one cell. [5]

10 9700/33/M/J/16 © UCLES 2016 (b) Fig. 2.2 is a photomicrograph of a stained transverse section through part of a leaf from a different type of plant. You are not expected to be familiar with this specimen. X Y Fig. 2.2 (i) Use the line X–Y to determine the simplest ratio of the depth of the midrib to the diameter of the vascular bundle. You may lose marks if you do not show your working. simplest ratio …[5] (ii) Suggest a habitat where this plant might grow and one observable feature, shown in Fig. 2.2, which adapts it to this habitat. habitat … feature …[1]

11 9700/33/M/J/16 © UCLES 2016 (c) Prepare the space below so that it is suitable for you to record observable differences between the leaf on K1 and the leaf in Fig. 2.2. Record your observations in the space you have prepared. [4] [Total: 19]

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® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 4 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level BIOLOGY 9700/33 Paper 3 (Advanced Practical Skills 1) May/June 2016 MARK SCHEME Maximum Mark: 40 Published 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 2016 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 – May/June 2016 9700 33 © Cambridge International Examinations 2016 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 – May/June 2016 9700 33 © Cambridge International Examinations 2016 1 (a) (i) (risk assessment) (hydrogen peroxide) harmful or irritant + medium or high ; [1] (b) (i) (measures room temperature) whole number or to half a degree + °C ; [1] (ii) (decides on interval for temperature) at least three additional temperatures + whole numbers + even intervals ; °C ; [2] (iii) (recording results) 1. table drawn + heading, temperature + °C ; 2. heading, time + seconds ; 3. records results for at least five temperatures ; 4. correct pattern of results ; 5. times recorded as whole seconds ; 6. records results for repeats + means calculated ; [6] (iv) (source of error with reason) appropriate error with reason ; e.g. concentration of hydrogen peroxide decreases appropriate error with reason ; e.g. different volumes of extract on each square of filter paper [2] (v) (conclusions) (as temperature increases, activity increases) more successful collisions or more enzyme-substrate-complexes / ESCs ; (decreased / no activity) denatures or changed shape of active site ; [2] (vi) (modification to investigate another variable) 1. (to standardise temperature) stated temperature + thermostatically controlled water-bath ; 2. (independent variable) at least five concentrations of catalase ; 3. (method) simple dilution / proportional dilution / serial dilution ; [3] (c) (chart) 1. (x-axis) different plant species + (y-axis) initial rate of activity of catalase / s–1 ; 2. (scale on x-axis) even width of bars + (scale on y-axis) 0.05 to 2 cm, labelled at least each 2 cm ; 3. correct plotting of five bars ; 4. five bars labelled with each horizontal line drawn as a thin line + each column labelled ; [4] [Total: 21]

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 33 © Cambridge International Examinations 2016 2 (a) (i) (plan diagram) 1. plan diagram of appropriate size + no shading ; 2. no cells + at least two vascular bundles + correct section drawn ; 3. epidermis drawn as two lines drawn closely together ; 4. line drawn to show area of cells located at tip of leaf ; [4] (ii) (drawing) 1. quality of line for outer wall of cells + size at least 50 mm across largest cell ; 2. only four cells drawn, each cell touching at least one other cell ; 3. cell walls drawn as two lines close together ; 4. one cell which shows a difference from other cells ; e.g. cell contains an inclusion 5. uses one label line + one label to cell wall ; [5] (b) (i) (ratio) 1. measures depth of midrib + diameter of the vascular bundle ; 2. records whole numbers or to 0.5 for both measurements ; 3. decides to use same units for both measurements ; 4. displays, in final ratio, larger number to smaller number ; 5. final answer as simplest ratio ; [5] (ii) (conclusion) (habitat) water + (feature) large air spaces or more air spaces or AVP ; [1] (c) (observable difference between leaf on K1 and leaf in Fig. 2.2) organises comparisons into three columns with one column for features, one headed K1 and one headed Fig. 2.2 ; any three observable differences of comparison ;;; e.g. K1 has more vascular bundles than Fig. 2.2 [4] [Total: 19]