Cambridge A Level Biology 9700 — 2016 May/June Paper 3 · Variant 4

This document consists of 11 printed pages and 1 blank page. DC (ST/SW) 105819/3 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 2 6 1 5 4 6 2 0 8 0 * BIOLOGY 9700/34 Paper 3 Advanced Practical Skills 2 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, paperclips, 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/M/J/16 © UCLES 2016 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 The enzyme, E, catalyses the hydrolysis (breakdown) of starch into glucose. You are required to investigate the progress of this enzyme-catalysed reaction by both • testing for the disappearance of starch • testing for the appearance of glucose by finding the time taken for the decolourisation of potassium manganate(VII) solution. To follow the progress of this reaction you will need to take samples from the reaction mixture at different times. (a) (i) Decide how often you will take these samples including removing the last sample at 20 minutes. State the times when you will remove the samples. …[1] (ii) Decide how you will test a sample to show that the starch has disappeared. State the reagent you will use … Describe how you will test each sample to show that the starch has disappeared and state the colour of any results you might collect. test … … colour …[1] To test for the production of glucose, the change in the colour of potassium manganate(VII) solution is: purple colourless Test-tube Z shows the colourless end-point.

3 9700/34/M/J/16 © UCLES 2016 [Turn over You are provided with: labelled contents hazard volume / cm3 E amylase solution harmful irritant 10 S starch solution none 40 A sulfuric acid irritant 20 P potassium manganate(VII) solution harmful 20 You are advised to wear suitable eye protection, especially when using the amylase solution, E and the sulfuric acid, A. If either E or A come into contact with your skin, wash off with cold water. P may stain your skin. (b) 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] Proceed as follows: 1. Label the test-tubes with the sampling times that you stated in (a)(i). 2. Put 2.5 cm3 of A into each test-tube. 3. Put 1 cm3 of P into each test-tube and gently shake to mix with A. (c) Temperature may affect the rate of an enzyme-catalysed reaction. (i) Use the thermometer to measure the temperature of the room. State the temperature of the room. … [1] Read step 4 to step 9 and note that the timer should not be stopped until you have the last end- point recorded. The reaction will start as soon as E is added to S. 4. Put 30 cm3 of S into a beaker. 5. Put 4 cm3 of E into the beaker containing S. 6. Immediately stir the mixture in the beaker and start the timer.

4 9700/34/M/J/16 © UCLES 2016 7. At each of your sampling times: • test for the disappearance of starch as described in (a)(ii) • test for the appearance of glucose by removing 3 cm3 of the mixture and putting it into the appropriately labelled test-tube, mixing well. 8. Record, in (c)(ii), the time shown on the timer when the colourless end-point is reached (raw result). Do not stop the timer. 9. Repeat step 7 and step 8 for each of the times decided in (a)(i) until you have recorded the end-point for the last sample, removed at 20 minutes. 10. Calculate the time taken to reach each end-point (processed results). (ii) Prepare the space below to record your results for: • the test for starch • the raw results for the appearance of glucose • your processed results for the appearance of glucose. [5] (iii) Now measure the temperature of the room once again. State the temperature of the room. … State the difference between this temperature and the temperature of the room you recorded in (c)(i). … State whether temperature was a significant error in this investigation. …[1]

5 9700/34/M/J/16 © UCLES 2016 [Turn over (iv) Explain how a temperature rise of 30 °C might have affected the mixture of starch and amylase. … … … … … … …[3] (v) This procedure investigated the progress of the hydrolysis of starch by amylase. To modify this procedure for investigating a different variable, the time for the hydrolysis would be standardised. Consider how you could modify this procedure to investigate the effect of pH on the activity of amylase. Describe how the independent variable, pH, could be investigated. … … … … Describe how the dependent variable could be measured. … … …[3]

6 9700/34/M/J/16 © UCLES 2016 (d) A student investigated the effect of starch concentration on the initial rate of reaction of amylase. Table 1.1 shows the results for this investigation. Table 1.1 percentage concentration of starch initial rate of reaction of amylase / arbitrary units 0.00 0 0.50 100 1.25 215 1.75 285 2.50 340 3.25 340 You are required to use a sharp pencil for graphs. (i) Plot a graph of the data shown in Table 1.1. [4]

7 9700/34/M/J/16 © UCLES 2016 [Turn over (ii) Use the graph to estimate the Michaelis-Menten constant (Km). Show your working on the graph and in the space below. Km …[3] [Total: 23]

8 9700/34/M/J/16 © UCLES 2016 2 N1 is a slide of a stained transverse section through a plant stem. You are not expected to be familiar with this specimen. You are required to use a sharp pencil for drawings. (a) (i) Select a field of view so that you can observe the epidermis and the vascular bundles. Draw a large plan diagram of the different tissues in the field of view to show • two of the large vascular bundles • the epidermis • any other observable tissues. Use one ruled label line and label to identify the xylem. You are expected to draw the correct shape and proportions of the different tissues. [5]

9 9700/34/M/J/16 © UCLES 2016 [Turn over (ii) Observe the cells in the centre of the stem (pith) in N1. These cells are not identical. Select one group of four adjacent (touching) cells which show some of the differences between these cells. Each cell of the group must touch at least two of the other cells. Make a large drawing of this group of four cells. Use one ruled label line and label to identify the cell wall of one cell. [5]

10 9700/34/M/J/16 © UCLES 2016 (b) Fig. 2.1 is a photomicrograph of a stained transverse section through a root from a different type of plant. You are not expected to be familiar with this specimen. 610 +m cell X Fig. 2.1 (i) In Fig. 2.1 a line is drawn across the diameter of a cell, X. Use this line and the scale bar to find the actual diameter of cell X in μm. You may lose marks if you do not show your working or if you do not use appropriate units. actual diameter … μm [3]

11 9700/34/M/J/16 © UCLES 2016 (ii) Prepare the space below so that it is suitable for you to record the observable differences between the stem on N1 and the root in Fig. 2.1. Record your observations in the space you have prepared. [4] [Total: 17]

12 9700/34/M/J/16 © UCLES 2016 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. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. 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.

® 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 9700/34 Paper 3 Advanced Practical Skills 2 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 34 © 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 34 © Cambridge International Examinations 2016 1 (a) (i) (decides sampling times) (0) 5 + 10 + 15 + or every 5 + minutes ; [1] (ii) (decides on reagent and method to test for starch) iodine solution or I + add to sample + orange / yellow / brown if starch absent or (blue-)black if starch present ; [1] (b) (risk assessment) (acid / amylase / potassium manganate(VII)) harmful or irritant + medium or high ; [1] (c) (i) (collects room temperature) records whole number or to 1 decimal place + °C ; [1] (ii) (recording results) 1. table drawn + heading (sample time) + minutes ; 2. appropriate heading for raw results ; 3. appropriate colours recorded for starch test for at least four times including 20 minutes ; 4. correct pattern of results ; 5. processed times recorded as whole seconds ; [5] (iii) (interpretation of significant error) correct calculation of difference + not significant ; A significant if difference 5 °C or more [1] (iv) (conclusions) 1. (more heat energy / higher temperature) idea of (more / increase in) kinetic / movement energy ; 2. (more heat energy / higher temperature) idea of more successful collisions between S and E or more active sites bind / join with substrate or more enzyme substrate complexes / ESCs ; 3. (at high temperature or increasing by 30 °C or above the optimum) idea of denatured or active site changes shape (so fewer ESCs) ; [3] (v) (modifications) 1. at least five pH or five examples ; 2. use of buffers ; 3. remove sample after set time / example of time or test with iodine and idea of looking for a colour change or test with potassium manganate(VII) and time taken to decolourise ; [3] (d) (i) (line graph) 1. (x-axis) percentage concentration of starch + (y-axis) initial rate of reaction of amylase / arbitrary units ; 2. (scale on x-axis) 1.0 to 2 cm + labelled at least every 2 cm + (scale on y-axis) 100.0 to 2 cm + labelled at least each 2 cm ; 3. correct plotting of six points with a small cross or dot in circle ; 4. six plots + thin line drawn ; [4]

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 34 © Cambridge International Examinations 2016 (ii) (display of calculations) 1. shows on the graph Vmax line at top of curve to the y-axis from the maximum rate of reaction ; 2. shows on the graph how Km is read off at half Vmax ; 3. correct answer for Km from candidate’s graph ; [3] [Total: 23] 2 (a) (i) (plan diagram) 1. plan diagram of appropriate size + no shading ; 2. no cells + only two whole vascular bundles + epidermis drawn ; 3. epidermis shown by two lines in the correct proportions ; 4. all vascular bundles divided into at least three regions ; 5. uses one label line + one label to xylem in any on vascular bundle ; [5] (ii) (drawing) 1. quality of line for outer wall of cells + size at least 40 mm across largest cell ; 2. draws only four whole cells + each cell of the group must touch at least two other cells ; 3. at least one intercellular space ; 4. cell walls drawn as two lines close together ; 5. uses one label line + one label to cell wall ; [5] (b) (i) (calculation) 1. collects correct measurement of length of scale bar + length of line drawn across cell X + correct units ; 2. displays correct method for calculation ; 3. correct answer to calculation ; [3] (ii) (observable difference between stem on N1 and root in Fig. 2.1) organises comparison into three columns with one column for features, one headed N1 and one headed Fig. 2.1 ; any three observable differences of comparison ;;; e.g. N1 has smaller xylem vessels than Fig 2.1 [4] [Total: 17]