Cambridge A Level Biology 9700 — 2013 Oct/Nov Paper 3 · Variant 6

This document consists of 11 printed pages and 1 blank page. DC (SJF/CGW) 57935/6 © 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. * 6 6 1 1 1 7 5 0 3 7 * BIOLOGY 9700/36 Advanced Practical Skills 2 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

© UCLES 2013 9700/36/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 The enzyme amylase catalyses the hydrolysis (breakdown) of starch to a reducing sugar. You are required to: • identify which solution, E1 or E2 contains the highest enzyme concentration by estimating the concentration of reducing sugar produced by the action of E1 and E2 when breaking down starch • prepare known concentrations of reducing sugar solutions to compare with the concentrations of reducing sugars produced by the action of E1 and E2 • compare the concentrations of reducing sugars by using the Benedict’s test. For each of your Benedict’s tests you need to standardise the: • volume of Benedict’s solution • volume of the samples • temperature of the water bath. (a) (i) State the: volume of Benedict’s solution …………………… cm3 volume of each of the samples to be tested …………………… cm3 temperature of water bath …………………… °C. [1] You are provided with: labelled contents hazard volume / cm3 E1 amylase solution harmful irritant 20 E2 amylase solution harmful irritant 20 S starch solution none 50 G 0.4% reducing sugar solution none 50 W distilled water none 100 2

3 [Turn over © UCLES 2013 9700/36/O/N/13 For Examiner’s Use Read steps 1 to 6 before proceeding. Proceed as follows: 1. Put 1 cm3 of E1 and E2 into separate beakers. 2. Put 10 cm3 of S into each of the beakers with E1 and E2. Mix well. 3. Leave the beakers for 15 minutes. During the 15 minutes you are required to: • set up a water bath ready for step 6 (on page 4) • prepare the known concentrations of the reducing sugar solution. 4. Set up the water bath to heat to the temperature as decided in (a)(i). (ii) Decide which concentrations of the reducing sugar solution to make: • using serial dilution • using 20 cm3 of the 0.4% reducing sugar solution, G, to start the serial dilution • reducing the concentration by half between each concentration. Complete Fig. 1.1 to show how you will make three further concentrations. … … … … 20 cm3 of 0.4 % G … … … … … … … … Fig. 1.1 [3]

4 © UCLES 2013 9700/36/O/N/13 For Examiner’s Use 5. Prepare all the concentrations of the reducing sugar solution, as in Fig. 1.1, in the containers provided. 6. You are now required to test for the concentrations of reducing sugars by using the Benedict’s test: • test each sample separately using the volumes decided in (a)(i) • record the time taken for the appearance of any colour change. If there is no colour change after 120 seconds record ‘more than 120’. (iii) Prepare the space below and record only your results for the known concentrations of reducing sugars. [5]

5 [Turn over © UCLES 2013 9700/36/O/N/13 For Examiner’s Use (iv) Using your results for E1 and E2 complete the following. The time taken for the first colour change in E1 was ……………………… . The time taken for the first colour change in E2 was ……………………… . Using these two times, state which of these two solutions has the highest concentration of reducing sugars. … Using the results from (a)(iii) estimate the concentration of reducing sugars in this solution. …[2] (v) Describe how you would modify this investigation to follow the time course of the hydrolysis of starch by enzyme E, without the use of Benedict’s solution. … … … … … … …[3]

6 © UCLES 2013 9700/36/O/N/13 For Examiner’s Use (b) A student investigated the effect of iron sulfate on the rate of amylase activity, using immobilised amylase in alginate beads. The student prepared two types of alginate beads containing amylase: • with iron sulfate • without iron sulfate. The student mixed the two types of beads together in varying proportions, for example 30 beads with iron sulfate and 70 beads without iron sulfate (30% with iron sulfate) as shown in Fig. 1.2. The student put the beads into beakers containing starch solution. alginate beads alginate beads with iron sulfate Key: alginate beads without iron sulfate starch solution Fig. 1.2 Other variables were considered and kept to a standard. The student measured the mass of reducing sugars produced by each mixture of beads in one minute. The student’s results are shown in Table 1.1. Table 1.1 percentage of beads with iron sulfate mass of reducing sugar produced / μmoles min–1 0 60 10 25 20 12 30 5 40 2

7 [Turn over © UCLES 2013 9700/36/O/N/13 For Examiner’s Use (i) Plot a graph of the data shown in Table 1.1. [4] (ii) Describe the trend shown by the data. … …[1] (iii) Explain the reason for the difference in the results between 0 and 10 percentage of beads with iron sulfate. … … … …[2] [Total: 21]

8 © UCLES 2013 9700/36/O/N/13 For Examiner’s Use 2 The eyepiece graticule scale in your microscope may be used to help draw a plan diagram, as in (a), with the correct shape and proportions of the tissue, without needing to calibrate the eyepiece graticule scale. N1 is a slide of a stained transverse section through a tubular organ from an animal. (a) Select a part of the wall of the organ which shows the highest number of different layers of tissues. Draw a large plan diagram of a part of the wall of the organ to show the proportions of the different layers of tissues. On your diagram, use a label line and label to show the lumen. [5]

9 [Turn over © UCLES 2013 9700/36/O/N/13 For Examiner’s Use Fig. 2.1 is a photomicrograph of cells from the same tubular organ as the specimen on slide N1. use this box Fig. 2.1 (b) Make a large drawing of the whole cells shown in the box marked on Fig. 2.1. The drawings should show any difference in size (linear magnification) observed between each cell. On your drawing, use a label line and label to show one nucleus. [5]

10 © UCLES 2013 9700/36/O/N/13 For Examiner’s Use Fig. 2.2 is a photomicrograph of a stained transverse section through a different tubular organ of an animal. Y Z Fig. 2.2 (c) (i) Use the lines Y and Z shown on Fig. 2.2, to calculate the ratio of Y to Z. You will lose marks if you do not show all the steps in finding the ratio. ratio … [3]

11 © UCLES 2013 9700/36/O/N/13 For Examiner’s Use (ii) The tubular specimen shown in Fig. 2.2 transports blood at low pressure. Suggest one observable feature which supports this conclusion. … … …[1] (iii) Prepare the space below so that it is suitable for you to record the observable similarities and differences between the specimen on slide N1 and that in Fig. 2.2. Record your observations in the space you have prepared. [5] [Total: 19]

12 9700/36/O/N/13 © UCLES 2013 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.

CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2013 series 9700 BIOLOGY 9700/36 (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 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 36 © 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 36 © Cambridge International Examinations 2013 1 (a) (i) B volume same as sample or B volume more than sample + temperature 80 °C to 100 °C; [1] (ii) (labels under correct sequence of beakers) (G2) 0.2%, + (G3) 0.1%, + (G4) 0.05%; transfers 10 from second beaker to third, third to fourth + cm3; adds 10 cm3 distilled water / W to each of three beakers; [3] (iii) organised into table; heading (column to left of data or top row) time (/) sec(onds) + (any column / row headed) percentage concentration of reducing sugar; records results according to instructions i.e. for 0.4% and three other concentrations; correct pattern of results: highest concentration shorter time than next concentration; records all results as whole seconds; [5] (iv) correct E has the shortest time; correct % estimate for E; [2] (v) use of iodine solution; sampling at equal time intervals; time until iodine remains same colour; [3] (b) (i) label on x-axis percentage of beads with iron sulfate + label on y-axis mass of (reducing sugar) produced / µ moles min–1; (x-axis) 10 to 2 cm labelled each 2 cm + (y-axis) 20 to 2 cm labelled each 2 cm; correct plotting of five points as small cross or dot in circle; ruled lines through the 5 points; [4] (ii) as % of beads with iron sulfate increases mass of reducing sugar decreases; [1] (iii) iron sulfate inhibits reaction; alters active site or binds to enzyme or fewer Enzyme-Substrate Complexes; [2] [Total: 21]

Page 4 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 36 © Cambridge International Examinations 2013 2 (a) drawing and quality; do not give mark if • any shading • drawn over print of question • any ruled lines • smaller than 50 mm at widest point of wall • less than 4 lines or 3 lines + 1 enclosed area or if any part of line • is too thick • has any feathery or dashed lines or gap in line • has any overlaps no cells + only part of wall; draws at least 6 lines or 5 lines + 1 enclosed area; innermost layer thin + draws at least 6 lines or 5 lines + 1 enclosed area; uses label line + labels lumen; [5] (b) drawing and quality; do not give mark if • any shading • drawn over print of question • any ruled lines • enclosed area smaller than 30 mm at widest point • less than 4 enclosed areas or if any part of line • is too thick • has any feathery or dashed lines or gap in line • has any overlaps at least 4 enclosed areas; draws at least 4 nuclei; draws at least 2 nuclei that are not circular or oval; uses label line + labels nucleus; [5]

Page 5 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 36 © Cambridge International Examinations 2013 (c) (i) correct measurement of Y (in mm 119 or 119.5 or 120 or 120.5 or 121 or cm 11.9(0) or 11.95 or 12(.0) or 12.05 or 12.1(0)) + Z (in mm 16 or 16.5 or 17 or 17.5 or 18) or cm 1.6(0) or 1.65 or 1.7(0) or 1.75 or 1.8(0); correct precision with mm or correct precision with cm; shows ratio correctly; [3] (ii) correct observable feature e.g. large lumen; [1] (iii) mp1 organise as a table with three columns or rows separated by lines + two columns headings N1 / slide and Fig 2.2 in any order + third column or row contains list of features; mp2 includes at least one similarity; mp feature N1 /slide Fig. 2.2 mp3 lumen present large present large; mp4 more than one tissue layer or thickness of wall or innermost layer present or thick or thin present or thick or thin; mp5 (lumen) shape rounded or ‘C’ ‘U’ shape or irregular or folded oval or circular or regular or not folded; mp6 cartilage / chondrocytes present absent; mp7 ref. to layers e.g. number of layers e.g. air spaces more 3 present less 1 absent; mp8 contents or valve or nucleus nothing absent present present present absent; mp9 ref. to thickness of wall e.g. ratio of thickness of any wall to lumen e.g. outer wall (Z) thinner or thicker thicker or thinner; [max 5] [Total: 19]