Cambridge A Level Biology 9700 — 2010 May/June Paper 5 · Variant 2

This document consists of 7 printed pages and 1 blank page. DC (SHW) 00479 5/09 16010/4 © UCLES 2010 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education 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 pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer both questions. 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. * 3 7 1 3 7 5 3 5 2 3 * BIOLOGY 9700/52 Paper 5 Planning, Analysis and Evaluation May/June 2010 1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. For Examiner’s Use 1 2 Total

9700/52/M/J/10 © UCLES 2010 For Examiner’s Use 1 Fig. 1.1 shows one type of potometer used by a student to investigate transpiration. rubber bung beaker of water leafy shoot syringe used to push water into capillary graduated capillary tube to measure water movement Fig. 1.1 (a) (i) Suggest a hypothesis the student could test about the transpiration of a mesophyte (a plant adapted to a moist environment) and a xerophyte (a plant adapted to a dry environment). … … [1] (ii) Using this potometer, outline a procedure that the student could use to test this hypothesis. … … … … … … … … … … … 2

3 9700/52/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use … … … … … … … … … … … … [8] (iii) The capillary tube measures the distance moved by the water. Explain how the actual volume of water lost can be calculated. … … … [2] (b) Sketch a graph to predict the expected results of the investigation. [2]

4 9700/52/M/J/10 © UCLES 2010 For Examiner’s Use (c) (i) The student then measured the surface area of the leaves by tracing the outline on a grid and counting the number of squares covered by the leaves. This area was doubled. Mesophyte: surface area of leaves = 36 cm2 water loss in 30 minutes = 0.018 cm3 Calculate the rate of water loss in cm3 m–2 min–1. Show all the steps in your calculation. [3] (ii) State a statistical test that the student could use to find out if the difference in water loss between the two types of leaf is significant. State a reason for your choice. … … [2] (d) In a further investigation the student measured the loss in mass of each type of leaf. Fig. 1.2 shows the experimental set-up. upper surface covered with wax lower surface covered with wax spring balance Fig. 1.2

5 9700/52/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use Table 1.1 shows the results of this investigation. Table 1.1 loss in mass / g per day day upper side covered lower side covered mesophyte xerophyte mesophyte xerophyte 1 4.25 0.55 1.15 0.05 2 3.20 0.35 1.00 0.05 3 1.55 0.20 0.75 0.00 4 0.50 0.10 0.95 0.05 5 0.05 0.04 1.00 0.00 total loss in mass / g 9.55 1.24 4.85 0.15 State three conclusions that can be drawn from these results. 1. … … 2. … … 3. … … [3] [Total: 21]

6 9700/52/M/J/10 © UCLES 2010 For Examiner’s Use 2 The effects of the concentration of two amino acids was tested on the growth of fibroblast cells from mice. The following procedure was used: • a culture of 2000–3000 cells was added to a growth medium containing all the required nutrients other than the amino acids being tested • a total of ten cultures were used for each concentration of amino acid • the cells in the culture were fed every two days with fresh amino acid solution • after 6 days five cell samples from each of the cultures were counted • the proportional increase in cell number was calculated for each culture. Table 2.1 shows the results of this investigation. Table 2.1 mean proportional increase in cell number concentration of amino acid added / mmol dm–3 0.0 0.1 0.2 0.5 1.0 2.5 5.0 10.0 20.0 40.0 glutamine 0.5 1.0 5.2 7.6 8.7 6.3 1.2 1.3 0.0 0.0 glutamic acid 0.4 0.2 0.1 0.3 0.4 0.4 0.4 0.6 0.8 0.3 (a) State two variables that should be controlled in this investigation. For each, suggest a method by which it might be controlled. 1. … … … … 2. … … … … [4] (b) Explain how the proportional increase in cell number is calculated. … … [1]

7 9700/52/M/J/10 © UCLES 2010 For Examiner’s Use (c) The hypothesis tested was Growth of fibroblasts is stimulated by glutamine and inhibited by glutamic acid. Assess how far the results support the hypothesis. … … … … … … … … … … [4] [Total: 9]

8 9700/52/M/J/10 © UCLES 2010 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.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2010 question paper for the guidance of teachers 9700 BIOLOGY 9700/52 Paper 5 (Planning, Analysis and Evaluation), maximum raw mark 30 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 must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 52 © UCLES 2010 Mark schemes abbreviations:
; separates marking points
/ alternative answers for the same point
R reject
A accept (for answers correctly cued by the question, or guidance for examiners)
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

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 52 © UCLES 2010 Question Expected answer Extra guidance Mark AO 1 (a) (i) a mesophytic plant loses more water than a xerophytic plant; Allow: any variation on the basic idea, but it must include a plant and water loss. Do not allow: loss in xerophyte greater than mesophyte Ignore: any ref. to external conditions / water uptake [1] P (ii) 8 of: independent variable: 1. ref. to shoots / leaves of different types of plant / xerophyte and mesophyte / type of plant used; 2. ref. to similar surface area; dependent variable 3. ref. to measuring / recording the movement (of water) along the capillary; 4. ref. to time (of water movement) / description of measuring time; control variables (max 3) 5. ref. to same (environmental) conditions; 6. ref. to inserting / cutting shoot under water / cutting shoot at an angle; 7. ref. to drying leaves before measuring; 8. ref. to airtight seal (around shoot) / airtight apparatus / no air locks; procedure 9. ref. to using syringe to set (water level) in capillary; 10. ref. to leaving until steady rate / equilibrate; reliability 11. ref. to repeats / replicates – min 3 and mean value; safety: 12. ref. to a low risk experiment; 1. Allow: named examples of xerophyte / mesophyte 2. Ignore: mass Allow: same / similar number of leaves 3. Do not allow: upwards movement Ignore: dye 4. Do not allow: if an inappropriate time is specified e.g. seconds 5. Allow: for any example, light / humidity / temperature 8. Ignore: watertight 9. Ignore: ref. to indicator 11. Allow: to remove anomalies 12. Allow: example of appropriate safety e.g. care in cutting shoots / pushing capillary through a bung [8] M

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 52 © UCLES 2010 Question Expected answer Extra guidance Mark AO (iii) ref. to finding surface area of the capillary; ref. to multiplying (surface area (πr2)) by distance moved; OR use syringe to push water back to original position; measure volume from the syringe: OR idea that the capillary is pre-calibrated; (and) find the volume from the distance moved / read from scale; Allow: both marks if formula for volume of cylinder is shown – any of these is acceptable πr2 l / d / h π 4 d2 l / d / h; π       2 d2 l / d / h; [2] D (b) 2 of: axes correct orientation and labelled appropriately for type of graph; mesophyte shown as having higher water loss / rate of water loss; Allow: marks on a horizontal bar chart Line Graphs and Bar Charts: y axis – rate / water loss / distance moved (by water or meniscus) / rate of transpiration Line Graph x axis – time Allow: lines that start at 0 Bar Charts x axis – type of leaf If the x axis is incorrect but y axis is related to water movement Allow: mark for the difference in water loss If axes reversed on a line graph, Allow: the mark for the lines if shown correctly Allow: marks on two graphs units are not required [2] P rate type of leaf meso xero water loss time meso xero rate type of leaf xero meso

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 52 © UCLES 2010 Question Expected answer Extra guidance Mark AO (c) (i) area = 4 10 / 000 10 36 / 0.0036 / 3.6 × 10-3 / 36 × 10-4 (m2); water loss = 30 0.018 / 0.0006 / 6 × 10-4 (cm3 min-1); rate = 3 - -4 10 3.6 / 0.0036 10 6 / 0.0006 × × ) (m 10 36 min cm 2 4 - -1 3 × = 0.167 cm3 m-2 min-1; Watch for area being halved or doubled 72 or 18 Allow: ecf for the calculation Look for the correct figures in the answer. This may be in a combined formula. Allow: 0.17 / 6 1 0.& cm3 m-2 min-1 Allow: any other valid method of calculating rate Do not allow: fractions [3] D (ii) t- test; the data has a normal distribution / continuous / not discrete / comparing two means / averages; Allow: correct reason for t-test even if the name is incorrect Do not allow: to compare 2 sets of data [2] D (d) 3 of: 1. mesophyte has greater mass loss / water loss / transpiration (than a xerophyte); 2. less mass / less water is lost / less transpiration over time by (both) leaves / lower side of leaves / upper side of leaves covered; 3. both leaves / xerophyte / mesophyte lose more mass / more water / transpire more from the lower side of the leaf / when the upper surface is covered; 4. xerophyte loses almost no water from the upper side / loses most of its water from the lower side of the leaf; Allow: reverse arguments for points 1–4 Allow: use of figures for points 1–4 1. Allow: if refer to upper and lower surface of leaves Allow: 5. there are more stomata on the lower surface (of both leaves); 6. xerophyte has fewer stomata on lower side than the mesophyte / mesophyte has more stomata on lower side than a xerophyte; 7. mesophyte has stomata on both sides of the leaf; 8. xerophyte may not have any stomata on upper side; 9. xerophyte has thicker cuticle than mesophyte; Do not allow: guard cells [3] C Total: [21]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 52 © UCLES 2010 Question Expected answer Extra guidance Mark AO 2 (a) 2 of: ref. to culture medium / growth medium / nutrient; ref. to constant volume / concentration; ref. to amino acid; ref. to constant volume (of both types) added; ref. temperature; ref. to suitable method of providing constant temp. ref. to aeration; ref. to a method of supplying oxygen / air; ref. to pH; ref. to buffers / named buffers; Do not allow: amount for any quantitative answer. Do not allow: ref. to cell numbers or time Allow: ref. to fermenter features – water jacket (+ monitor) water bath must refer to a constant / stated temperature Allow: ref. to fermenter features – sparger / air lift [2] [2] P M (b) Increase in number of cells (after 6 days); number of cells at beginning / previous Allow: ratio of increase in cells to the initial number of cells. Ignore: percentages [1] D

Page 7 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 52 © UCLES 2010 Question Expected answer Extra guidance Mark AO (c) glutamine: Support 1. stimulates / shows an increase and ref to any figure or range between 0.1–10 (mmol dm-3); Not support 2. does not stimulate / inhibits / shows decrease at 20 / 40 (mmol dm-3); glutamic acid: Support 3. does not stimulate / inhibits / shows a decrease at 0.1 / 0.2 / 0.5 / 40 (mmol dm-3); Not support 4. shows little effect on growth / too inconsistent / does not show any trend (to draw any conclusion); Not support 5. at 10 (mmol dm-3) / 20 (mmol dm-3) appears to increase growth; anywhere in answer: Support 6. results should be reliable as means of 50 counts (per culture) / large number used; Not support 7. cell counting procedures are estimates / prone to error; Cause and effect must be correct – watch for cell increase and amino acids concentrations being reversed. Allow: glutamate for glutamic acid 2. Allow: no cells / no growth / no changes Do not allow: cells are dead / no cells 5. Allow: may be anomalous results at these concentrations For comparisons between figs. of glutamine and glutamic acid: for appropriate use of figures max 2. mark points 6 and 7 can also be awarded. Support 8. more growth with glutamine than glutamic acid between 0–10 (mmol dm-3); Not support 9. more growth with glutamic acid than glutamine at 20 (mm dm-3) and 40 (mmol dm-3); [4] E Total: [9]