Cambridge A Level Biology 9700 — 2002 May/June Paper 3 · Variant 1

This question paper consists of 5 printed pages, 2 blank pages and a Report Form. SP (SM/JB) S23298/2 © CIE 2002 [Turn over CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level BIOLOGY 9700/3 PAPER 3 Practical Test AS MAY/JUNE SESSION 2002 1 hour 15 minutes Candidates answer on the question paper. Additional materials: As listed in Instructions to Supervisors TIME 1 hour 15 minutes INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page. Answer all questions. Write your answers in the spaces provided on the question paper. INFORMATION FOR CANDIDATES The intended number of marks is given in brackets [ ] at the end of each question or part question. You are advised to spend 45 minutes on Question 1 and 30 minutes on Question 2. Candidate Centre Number Number Candidate Name FOR EXAMINER’S USE 2 1 TOTAL

For Examiner’s Use 2 Question 1 [45 minutes] You are provided with five different concentrations of sucrose solution in Petri dishes, labelled W1, W2, W3, W4 and W5. The concentration of the sucrose solution does not correspond to the order of the labelling. You are also provided with ten potato strips, labelled W6. Using a scalpel or a sharp knife, carefully trim each strip to a length of 50 mm. It is very important that you perform this task as accurately as possible. Place two strips of potato into each Petri dish and leave for at least twenty minutes. While you are waiting, you should start Question 2. After twenty minutes, remove the strips from each Petri dish, blot carefully with a paper towel and accurately re-measure their lengths. (a) (i) Record the lengths of the strips in Table 1.1 and calculate the mean strip length and mean change in strip length, for each solution. Table 1.1 [4] (ii) The concentration of each solution is given in Table 1.2. From your results, decide which labelled solution corresponds to the concentration indicated and enter W1, W2, W3, W4 and W5 in the table. Table 1.2 [3] 9700/3/M/J/02 length of strip 1 length of strip 2 mean length mean change in length W1 W2 W3 W4 W5 solution name solution concentration mol / dm3 1.0 0.8 0.6 0.4 0.2

For Examiner’s Use 3 (iii) On the grid, plot a graph of the mean change in length against the molar concentration. [3] (iv) Use the graph to determine the molar concentration that is equal to the solute potential of the potato cell sap. …[1] (v) State what is happening to the osmotic movement of water, through the cell membrane, at this concentration. … …[1] 9700/3/M/J/02 [Turn over

For Examiner’s Use 4 (b) Suggest three ways in which you could improve this experiment to make your results more reliable. 1. … … 2. … … 3. … …[3] [Total : 15] 9700/3/M/J/02

5 Question 2 [30 minutes] K7 is a stained, transverse section of an aorta. Examine K7, using a hand lens and a microscope. (a) Make a large, labelled, accurate plan drawing of K7. [4] (b) State the magnification of your drawing and your method of calculating it. … …[2] (c) Explain the significance of the thickness of the wall and the appearance of the inner lining of the aorta. wall … … … inner lining … … …[4] [Total : 10] 9700/3/M/J/02 For Examiner’s Use

8 REPORT FORM The teacher responsible for this subject is asked to answer the following questions. (a) Was the candidate physically handicapped in drawing or in using a microscope or is the candidate colourblind? If so, give brief details. (b) Was the candidate handicapped by deficient material or apparatus? If so, give brief details. (c) Was it necessary to make any substitutions for the materials sent from Cambridge? If so, give brief details of the circumstances. (d) Any comments. Signed ……………………………………………… N.B. Information that applies to all candidates need be given on the first candidate’s answer book only. 9700/3/M/J/02

CAMBRIDGE INTERNATIONAL EXAMINATIONS JUNE 2002 GGE Advanced Subsidiary Leve! MAXIMUM MARK : 25 SYLLABUS/COMPONENT :9700 /3 BIOLOGY (PRACTICAL (AS)) Eq Universiry of CAMBRIDGE #9 Local Examinations Syndicate

Page 1 Mark Scheme Syllabus Paper AS Level Examinations — June 2002 9700 dai Any four from: + &- readings; All five averages in correct relative order ie W2 W4 W5 W1 WS ‘tongest to shortest; Units in mm in ail ceils of left column; 3 out 5 mean lengths calculated correctly; 3 out Of 5 mean change in fengths correct. W4 to laftof W2 } WS to left of W4 } = max 3 marks W1 toleftof W5 } WS to left of Wt} ~1 mark for each error (max3) Any three from: Axis correct orientation; scale and labels correct; Plotting correct; Line of best fit ie straight line close to picts. Correct reading from graph & units correct Water entering equals water feaving / no net movement. Any three from: Ensure widths of strips are ali same / SA; Use bigger range of solutions (between 0-4 untess all + then allow >1); Larger number of strips / repeat expt; Temperature control; Even drying with paper towel; All strips from same potato; Leave > 20 min; Leave for same time; Increase length of each strip; Cover Petri dish; Weigh. max 3 Total 15 Expected Answers | Marks | Additional Guidance } Based on candidates results. } Allow extrapolation. OWTTE 2a 2b Quality of diagram ie 3 concentric elipses. Outer only can be broken. No cells, shading or stiples. Allow fat line. Ignore blood contents; 2 layers of comparable thickness; wall width : overall width 1:4 - 1:8 Tunica media / elastic, labelled; Tunica adventia / connective, labeiled, Diameter of aorta 1 - 5 mm divided into diagram size, t Calculation correct; 1 Four from Wail is thick; To withstand pressure; Wall crinkted / elastic tissue in wall; To stretch / recoil Inner lining crinkled; Allow fat label Accept cm if used for both. Accept written explanation of method. Bold answer allowed if within parameters. Accept prevents bursting OWTTE