Cambridge A Level Biology 9700 — 2013 Oct/Nov Paper 5 · Variant 3

This document consists of 7 printed pages and 1 blank page. DC (AC/SW) 63044/3 © UCLES 2013 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Level * 1 5 3 1 3 9 6 0 0 2 * BIOLOGY 9700/53 Paper 5 Planning, Analysis and Evaluation October/November 2013 1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. 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 staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. 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.

2 9700/53/O/N/13 © UCLES 2013 For Examiner’s Use 1 (a) Fig. 1.1 shows a simple respirometer that can be used to measure the rate of respiration by measuring oxygen uptake. organism plastic mesh carbon dioxide absorbent plastic syringe plastic tubing capillary tube coloured dye Fig. 1.1 A student used this apparatus to test the hypothesis: The rate of respiration will double for every 10 °C rise in temperature. (i) Identify the independent and dependent variables in this investigation. independent variable … … dependent variable … … [2] (ii) Sketch a graph to show the expected results if the student’s hypothesis is correct. [2]

3 9700/53/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use (iii) Describe how the student could use the apparatus in Fig. 1.1 to test this hypothesis using germinating seeds. Your method should be detailed enough for another person to use. … … … … … … … … … … … … … … … … … … … … … … … … [8]

4 9700/53/O/N/13 © UCLES 2013 For Examiner’s Use (b) The student calculated the rate of respiration as volume of oxygen taken up per unit mass of the germinating seeds. Explain how this rate of respiration was calculated. … … … … …[3] (c) Outline how the student could use the apparatus in Fig. 1.1 to find the optimum temperature for respiration in the germinating seeds. … … … … …[2] (d) In a different investigation the student measured the effect of external temperature on the oxygen uptake of a small mammal. Careful attention was paid to the welfare of the mammal during the investigation. Table 1.1 shows the results of this investigation. Table 1.1 environmental temperature / °C oxygen uptake / arbitrary units trial 1 trial 2 trial 3 trial 4 mean 5 52 36 48 45 45.3 10 42 32 35 36 36.3 15 35 25 29 24 28.3 20 28 15 17 22 20.5 25 17 10 11 9 11.8 30 14 11 13 10 12.0 35 12 10 11 11 11.0

5 9700/53/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use (i) State why the student decided that the results from trial 1 were anomalous. … …[1] (ii) Suggest a reason for the cause of these anomalous results in trial 1. … …[1] (iii) Suggest an explanation for the higher rates of oxygen uptake of the small mammal at the low temperatures. … … … … … …[2] [Total: 21]

6 9700/53/O/N/13 © UCLES 2013 For Examiner’s Use 2 (a) In plants the growth regulator, auxin, is synthesised in the stem tip and moves away from the tip. The movement of auxin through plant tissues was investigated using bean seedlings as shown in Fig. 2.1. The following procedure was used. • Stems were cut into 60 mm lengths. • Agar blocks containing radioactive auxin were placed on the apical surfaces of two groups of stem lengths. • The basal ends of the stem lengths were placed on agar blocks without any auxin to provide support. 60 mm agar block containing radioactive auxin agar support basal end (end closest to root) apical end (end closest to stem tip) stem tip location of tissue used main root Fig. 2.1 • After 10 minutes the agar blocks at the apical ends were removed. • One group of stem lengths was placed in air and the other group in an atmosphere of nitrogen. • Both groups were left in light for 30 minutes after removing the agar blocks. • The position of the radioactivity was located. Fig. 2.2 shows the results of the investigation. 25 mm 2 mm mean distance moved in air mean distance moved in nitrogen atmosphere position of radioactivity when agar removed position of radioactivity after 30 minutes in light stem lengths Fig. 2.2 (i) Identify one variable that should be standardised during this investigation. …[1] (ii) Suggest one conclusion that can be made from these results. … …[1]

7 9700/53/O/N/13 © UCLES 2013 For Examiner’s Use (iii) Calculate the rate in mm h−1 of movement of auxin in air. … …[1] (b) A similar investigation was carried out to test the hypothesis: The rate of movement of auxin will be faster in plants grown in the light than plants grown in the dark. Table 2.1 shows the results of this investigation. Table 2.1 plants grown in light plants grown in the dark sample number sample number 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 rate of movement mm h−1 56 61 66 52 50 68 76 51 55 64 45 52 42 35 55 38 32 37 45 51 mean ± standard deviation (s) = 59.9 ± 8.5 mean ± standard deviation (s) = 43.2 ± 7.7 (i) State two pieces of evidence from Table 2.1 that support the hypothesis. … … … …[2] (ii) A t-test was carried out to see if the difference in the rates of movement of auxin in plants grown in the light and plants grown in the dark was significant. Suggest a null hypothesis for this statistical test. … …[1] (iii) Explain how the student should use the value for t to find out if the difference in the rates of movement of auxin is significant. … … … …[3] [Total: 9]

8 9700/53/O/N/13 © UCLES 2013 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. BLANK PAGE

CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2013 series 9700 BIOLOGY 9700/53 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 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 53 © Cambridge International Examinations 2013 Mark schemes abbreviations: ; separates marking points / alternatives answers for the same point R reject A accept (for answers correctly cued by the question, or guidance for examiners) I ignore (for responses that are irrelevant to the answer given) 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 ecf error carried forward mp marking point (with relevant number)

Page 3 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark 1 (a) (i) independent: temperature ; dependent: distance moved by, dye / air (along capillary / AW, in a specific time); I volume of oxygen taken in / rate of respiration A distance moved / movement of, dye / air [2] (ii) axes correct orientation and labelled ; line, exponential / increases with temperature; units not required A for y-axis, volume of oxygen / amount of oxygen / oxygen uptake / distance moved / distance along capillary / movement of dye or air line does not need to start at origin if axes not labelled assume they are correct way round and award plot mark if possible if axes inverted, look for appropriate curve [2] temperature rate of respiration rate of respiration temperature

Page 4 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark (iii) 8 of: independent variable: 1. use, same mass / known (stated) mass, of (germinating) seeds ; 2. ref. to suitable number and range of temperatures ; dependent variable : 3. ref. to method of measuring distance moved ; 4. ref. to measurements of distance at, specific / known / stated, time intervals ; 5. ref. to some idea of a method of placing dye into capillary or ref. to use of syringe to, set / reset, dye ; controlled variables (max 3) 6. ref. to ensuring apparatus is airtight / method described ; 1. I amount. A stated number of seeds but ignore 1 seed R organisms / named organisms other than seeds 2. minimum of 4 temperatures giving minimum of three 10°C rises 3. e.g. use a ruler or grid on tube / mark start and end and use a ruler / use a graduated tube / callipers R metre rule if first on list mp3 and mp4 can be stated as same distance and measure time or same time and measure distance either time or distance must be fixed A any specified time 5. A pull dye into capillary / dye sucked in / idea of dropping pipette to insert dye / tube dipped into dye 6. I watertight A vaseline / plasticine / tight connections / AW, as method

Page 5 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark 7. ref. to method of keeping constant temperature ; 8. idea of: equilibration / acclimatisation / AW, of respirometer containing seeds before measuring ; 9. idea of: replacing, air / oxygen, between measurements ; 10. ref. to control / comparison, with inert material (of same mass) ; 11. ref. to using, same / stated, mass of absorbent or replacing, each time / from time to time / when saturated / AW ; 7 e.g. in water bath / incubator / temp controlled room I air conditioning R ref. to thermometers if used to control temperature A thermostatically controlled device 8. I stated times - looking for acclimatisation / AW A ‘to get a steady rate’ 9. A refresh air at intervals 10. e.g. glass beads / boiled seeds / stones / AW 11. A idea of enough absorbent to ensure all carbon dioxide absorbed / excess absorbent. I amount / volume A same number of pellets

Page 6 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark safety: 12. ref. to suitable hazard and precaution ; reliability: 13. ref. to replicates, and mean / to identify or eliminate anomalies ; 12. A carbon dioxide absorbent being, corrosive / an irritant / harmful / toxic / poisonous / AW, and gloves / eye protection / AW A ref. to allergic risk from seeds or absorbent and precaution (gloves / mask / AW) A 70 °C or above water and suitable handling like tongs A low risk R no risk 13. must be a minimum of 3 A as original and 2 more / several A repeats A average for mean A outliers for anomalies I mean of readings along the capillary at timed intervals i.e. mean of distances measured 1–2 min, 2–3 min, 3–4 min [max 8]

Page 7 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark (b) allow answers that describe the main stages of the calculation in words or as a formula look for the elements of the calculation which may be shown separately 3 of: 1. ref. to valid method calculating volume of oxygen ; 2. ref. to dividing by the mass ; 3. ref. to dividing by time ; 4. ref. to correct units either cm3 g–1 s–1 or cm3 g–1 min–1 ; or ref. to valid method calculating volume of oxygen ; total volume of oxygen (cm3) (= y) total time (s) x mass (g) ; ; (y )= cm3 s–1 g–1 or cm3 g–1 min–1 ; 1. A any valid method, e.g. distance (d) / length (l) / height (h) × π r2 / π (D ÷ 2)2 / D2 ÷ 4, pre- calibrated tube. d / l / h do not need to be explained. I surface area × d / l / h 4. A cm3 / g / s or cm3 / g / min I actual value of y if an example is used A cm3 / g / s or cm3 / g / min or per in words [max 3]

Page 8 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark (c) 2 of: 1. idea of finding range at which the, oxygen uptake / dye movement / respiration rate, was greatest ; 2. ref. to repeating the measurements (in this range) at smaller temperature intervals ; 3. one with max, oxygen uptake / dye movement / respiration rate = optimum temperature ; 2. A do smaller intervals across whole range 3. A in context of plotting a graph to find optimum A general ref. to do at various temps and find one with highest value [max 2] (d) (i) idea that: (most / all, of) the results are, higher / larger (than those measured at the same temperature in the other trials) ; A results, furthest from / large distance from / AW, means A some results are significantly higher R does not follow the trend of others / trend different but A same trend but higher I just quoting one or two temps are out, e.g 20 I ref. to standard deviation [1] (ii) 1 of: idea that mammal, moving around / more energetic / not at rest / has higher metabolic rate ; mammal, under stress / frightened / shocked / nervous / AW ; idea of have not given enough time for the mammal to adapt to the apparatus ; I ref. to faulty, apparatus / technique A different, gender / size / species / type, of mammal, (in, each trial / first trial) A idea of food intake before (first) trial I contaminated with microorganisms A mammal not, acclimatised / accustomed / used / AW, to conditions [max 1]

Page 9 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark (iii) 2 of : 1. higher oxygen uptake means, higher rate of / more, respiration ; ora 2. (at, lower temperatures / this temperature,) mammal is losing more heat (to the environment) / AW ; 3. ref. to (at lower temperatures) mammal is respiring more / using more oxygen, to, release more heat / maintain (body) temperature / keep (body) temperature constant ; A metabolism / ATP production, as alternative terms for respiration A thermal energy for heat I energy unqualified 1. look for a link between the higher uptake and higher rate. not just ‘needs more oxygen to respire’ 2. A faster temperature drop / looses heat more easily / AW 3. Ignore ref. to keeping warm [max 2] [Total: 21]

Page 10 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark 2 (a) (i) 1 of: temperature ; light intensity ; concentration of (radioactive) auxin ; composition / type, of the agar ; mark first in list but I amount throughout I light unqualified A mass / weight R volume A same agar / same concentration of agar [max 1] (ii) 1 of: oxygen / air, is required for the movement of auxin ; energy / ATP / respiration, is required for the movement of auxin ; movement of auxin involves active transport ; A in terms of ‘most movement’ A idea that movement is, greater / faster / better / more / AW, in, air / oxygen (than in nitrogen) ora but must mention air / oxygen I ‘air is an opt medium for movement’ I ‘rate of movement is affected by surrounding air / atmosphere’ I ref. to N being inhibitory / AW [max 1] (iii) 50 (mm h–1) ; R if units wrong A mm/h or mm per hour [1]

Page 11 Mark Scheme Syllabus Paper GCE AS/A LEVEL – October/November 2013 9700 53 © Cambridge International Examinations 2013 Question Expected answer Extra guidance Mark (b) (i) mean in dark is lower / mean rate in dark is slower ; ora no overlap in terms of using the values for s / confidence intervals ; A idea that lower rates overall for plants grown in the dark ora A raw figures I ref. to standard deviation being lower I ref. to error bars [2] (ii) idea of: there is no significant difference in the rate of movement (of auxin) for, plants grown in light and (plants grown) in dark / the 2 treatments; A the difference in the rate of movement (of auxin) for plants grown in light and plants grown in dark is not significant I differences in movement in light and dark are due to chance. [1] (iii) 3 of: 1. general idea of, finding / using, degrees of freedom 2. ref. to using 0.05 / 5% probability to find critical value / AW (for t) ; 3. idea of: compare the (calculated) t –value with the critical value / AW ; 4. if value of t is higher than critical value it is significant / not due to chance) / reject null hypothesis / accept alternative hypothesis ; ora 1. A using 18 degrees of freedom ; I any wrong number calculated and award mark if degrees of freedom cited I any formula e.g. (10 –1) +( 10–1) 2. A 0.01 / 1% probability A significance levels for probability 3. A see if value of t is, higher / lower, than critical value A if refer to ‘the right or left of the critical value’ or ‘above or below’. A for mp2 and mp3 alternatives to critical value, e.g.‘table value / chart value / the value looked up’ 4. I ref. to ‘insignificant’ / ‘more significant’ / ‘less significant’ [3] [Total: 9]