Cambridge A Level Biology 9700 — 2004 Oct/Nov Paper 5 · Variant 1

This document consists of 7 printed pages and 1 blank page. (NH) S67012/2 © UCLES 2004 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Level BIOLOGY 9700/05 Paper 5 Practical Test A2 October/November 2004 1 hour 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in Instructions to Supervisors. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name in the spaces provided at the top of this page. Write in dark blue or black pen in the spaces provided on the Question Paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You are advised to spend 60 minutes on Question 1 and 30 minutes on Question 2. Centre Number Candidate Number Name If you have been given a label, look at the details. If any details are incorrect or missing, please fill in your correct details in the space given at the top of this page. Stick your personal label here, if provided. For Examiner’s Use 1 2 Total

2 © UCLES 2004 9700/05 O/N/04 1 Starch is a storage product found in many plant cells. It contains a carbohydrate called amylose that stains blue/black in the presence of iodine in potassium iodide solution. Iodine is also a powerful enzyme inhibitor. You are provided with a solution of the enzyme amylase, labelled A. The enzyme amylase hydrolyses starch. You are also provided with a suspension of starch, labelled S. You are required to plan, devise and carry out a method to investigate the effect of the enzyme solution on the suspension of starch. In order to ensure that your results are reliable, you will need to consider: • the identification of a consistent end point. • a calculation of a mean time taken for complete hydrolysis. • the volume of solutions A and S which you have available. (a) (i) Describe how you carried out your investigation. … … … … … … … … … … … … …[7] For Examiner’s Use

3 © UCLES 2004 9700/05 O/N/04 [Turn over (ii) Record your observations by making and completing a table in the space below. [4] For Examiner’s Use

4 © UCLES 2004 9700/05 O/N/04 (b) A student carried out a similar investigation and obtained the following data. (i) Calculate the rate of reaction for an amylase concentration of four arbitrary units and complete the table. [1] rate = 1/t t = time in minutes (ii) Plot the results from the table on the grid to show rate of reaction against amylase concentration. [3] For Examiner’s Use amylase concentration / arbitrary units mean time taken for complete hydrolysis / min rate of reaction / min–1 1 5.02 0.20 2 2.45 0.41 3 1.69 0.59 4 1.24 5 0.98 1.02

5 © UCLES 2004 9700/05 O/N/04 [Turn over (iii) Explain these results as fully as possible. … … … … … … …[3] (c) The data that you have been given were obtained in a laboratory with a variable air temperature of about 20 °C. Suggest how the laboratory procedure could have been improved. … … … …[2] [Total: 20] For Examiner’s Use

6 © UCLES 2004 9700/05 O/N/04 2 K1 is a stained, transverse section through the pancreas of a small mammal. (a) Examine K1 using both low-power and high-power objectives of your microscope. Move the slide around so that you see the different structures present. The organ consists of tissue, within which are scattered large numbers of islets of Langerhans. (i) State three visible features of K1 that allow you to distinguish islets from the surrounding tissue. 1. … … 2. … … 3. … …[3] (ii) State any differences in structure between different islets that you have observed. …[1] (iii) Suggest two explanations for any differences that you state in (a) (ii). … … …[2] For Examiner’s Use

7 For Examiner’s Use © UCLES 2004 9700/05 O/N/04 (b) Look at a range of islets and choose one that shows a number of adjacent cells clearly. Draw a large, labelled high-power drawing of five cells from that islet. [4] [Total: 10]

8 9700/05 O/N/04 BLANK PAGE University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Level MARK SCHEME for the November 2004 question paper 9700 BIOLOGY 9700/05 Paper 5 (Practical Test A2), maximum raw mark 30 This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. This shows the basis on which Examiners were initially instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began. Any substantial changes to the mark scheme that arose from these discussions will be recorded in the published Report on the Examination. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes must be read in conjunction with the question papers and the Report on the Examination. • CIE will not enter into discussion or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the November 2004 question papers for most IGCSE and GCE Advanced Level syllabuses.

Grade thresholds taken for Syllabus 9700 (Biology) in the November 2004 examination. minimum mark required for grade: maximum mark available A B E Component 5 30 23 18 12 The threshold (minimum mark) for B is set halfway between those for Grades A and C. The threshold (minimum mark) for D is set halfway between those for Grades C and E. The threshold (minimum mark) for G is set as many marks below the F threshold as the E threshold is above it. Grade A* does not exist at the level of an individual component.

November 2004 GCE A LEVEL MARK SCHEME MAXIMUM MARK: 30 SYLLABUS/COMPONENT: 9700/05 BIOLOGY Paper 5 (Practical Test A2)

Page 1 Mark Scheme Syllabus Paper A LEVEL – NOVEMBER 2004 9700 5 © University of Cambridge International Examinations 2005 Qn Expected Answers Marks Additional Guidance 1 a i ii b i ii iii c 1 volume of amylase; 2 volume of substrate; 3 idea of mixing; 4 drops of iodine on tile/test tube; 5 (add drops of mixture) at set time; 6 until no colour change; 7 replication; 8 other specific detail e.g. wash pipette etc; 9 control qualified e.g. boiled enzyme /use water; boxes with data in e.g. time or colour; qualification of data e.g. time taken for starch to disappear; units in headings (secs); mean included; 0.81; axis correct orientation, units and scale correct; plots correct; straight line of best fit; reference to number/more enzyme molecules; reference to number/more active sites; reference to number of collisions; reference to why linear i.e. excess substrate/enzyme limiting; using water bath; for stable temperature/thermostatic/ fixed temperature given between 20 – 60 oC; max 7 1 1 1 1 1 1 1 1 max 3 1 1 20 use equal volumes = 1 mark accept put drops of sample on tile; add iodine solution to it; max 2 if do not use time ignore rate no significant figures points clearly lie close to a straight line, so a line of best fit is clearly the most appropriate way to plot the graph if candidate only refers to enzyme substrate complex allow 1 mark. more enzyme substrate complexes = 2 AVP

Page 2 Mark Scheme Syllabus Paper A LEVEL – NOVEMBER 2004 9700 5 © University of Cambridge International Examinations 2005 Qn Expected Answers Marks Additional Guidance 2 a i ii iii b different colour/lighter/less densely stained; islets have larger nuclei; islets larger than other structures; islets have irregular shape; more spaces/loosely packed; different sizes/shapes/more or less cells; vary in size and shape; sectioned at different levels; sectioned at different orientations; nuclei represented in most cells; nuclei labelled; fine lines joined up with no gaps to show edge of one cell membrane; three (of five) cells touching; max 3 1 max 2 1 1 1 1 10 allow blood vessels in spaces Paper total 30