Cambridge IGCSE Biology (BES) 0438 — 2012 Oct/Nov Paper 3 · Variant 1

This document consists of 22 printed pages and 2 blank pages. IB12 11_0438_31/2RP © UCLES 2012 [Turn over *2652394698* For Examiner's Use 1 2 3 4 5 6 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education BIOLOGY (US) 0438/31 Paper 3 Extended October/November 2012 1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Center number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. 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. You may lose marks if you do not show your work 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.

2 © UCLES 2012 0438/31/O/N/12 Question 1 begins on page 3.

3 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use 1 Arachnids, crustaceans, insects and myriapods are all classified as arthropods. Scorpions, such as Heterometrus swammerdami shown in Fig. 1.1, are arachnids. abdomen tail cephalothorax eyes pedipalp jaw Fig. 1.1 (a) State three features, shown by H. swammerdami and visible in Fig. 1.1, that arachnids share with other arthropods. 1 2 3 [3]

4 © UCLES 2012 0438/31/O/N/12 For Examiner's Use (b) Fig. 1.2 shows seven species of arachnid. A D G C E B F not to scale Fig. 1.2

5 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use Use the key to identify each species. Write the letter of each species (A to G) in the correct box beside the key. One has been done for you. Key [4] [Total: 7] 1 (a) Abdomen with a tail Abaliella dicranotarsalis E (b) Abdomen without a tail go to 2 2 (a) Legs much longer than abdomen and cephalothorax go to 3 (b) Legs not much longer than abdomen and cephalothorax go to 4 3 (a) Hairs on the legs Tegenaria domestica (b) No hairs on the legs Odielus spinosus 4 (a) Cephalothorax or abdomen segmented Chelifer tuberculatus (b) Cephalothorax and abdomen not segmented go to 5 5 (a) Abdomen and cephalothorax about the same size Poecilotheria regalis (b) Abdomen larger than cephalothorax go to 6 6 (a) Body covered in long hairs Tyroglyphus longior (b) Body not covered in hairs Ixodes hexagonus

6 © UCLES 2012 0438/31/O/N/12 For Examiner's Use 2 Blood flows through the hepatic portal vein from some organs to the liver. Fig. 2.1 shows the hepatic portal vein and these organs. liver spleen hepatic portal vein Fig. 2.1 (a) Blood in the hepatic portal vein is deoxygenated. Explain why the blood in the hepatic portal vein is deoxygenated rather than oxygenated. [2]

7 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use (b) Name four organs, other than the spleen, that are shown in Fig. 2.1 and from which blood flows into the hepatic portal vein. 1 2 3 4 [4] (c) Describe the role of the hepatic portal vein in the transport of absorbed nutrients. [3] (d) Explain how the liver is involved in regulating the composition of the blood and in protecting the body against toxic substances. [5]

8 © UCLES 2012 0438/31/O/N/12 For Examiner's Use (e) The spleen contains lymphatic tissue which is full of phagocytes and lymphocytes. Describe how phagocytes and lymphocytes protect the body against the spread of disease-causing organisms. phagocytes lymphocytes [4] [Total: 18]

9 © UCLES 2012 0438/31/O/N/12 [Turn over Question 3 begins on page 10.

10 © UCLES 2012 0438/31/O/N/12 For Examiner's Use 3 The ribcage and diaphragm are involved in the breathing mechanism to ventilate the lungs. Fig. 3.1 is a flow chart that shows the changes that take place when breathing in. air enters the … which are the site of gaseous exchange atmospheric pressure is … than air pressure in the lungs pressure of air in the lungs … air moves … the lungs volume of thorax … diaphragm is … ribcage is raised diaphragm muscles contract external intercostal muscles contract Fig. 3.1 (a) Complete Fig. 3.1 by writing appropriate words in the spaces provided. [6]

11 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use (b) Fig. 3.2 shows part of the epithelium that lines the trachea. A B Fig. 3.2 Explain how the cells labeled A and B in Fig. 3.2 protect the gas exchange system. A B [4] [Total: 10]

12 © UCLES 2012 0438/31/O/N/12 Question 4 begins on page 13.

13 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use 4 (a) Complete the balanced chemical equation for photosynthesis. light + + [3] chlorophyll A student investigated the effect of increasing the concentration of carbon dioxide on the rate of photosynthesis of Cabomba, an aquatic plant. Fig. 4.1 shows the apparatus that the student used. gas bubble syringe lamp ruler plastic tubing meniscus capillary tubing sodium hydrogencarbonate (NaHCO3) solution Cabomba Fig. 4.1 The concentration of carbon dioxide in the water surrounding the plant was changed by adding different concentrations of sodium hydrogencarbonate solution to the water. The student recorded the time taken for the meniscus to travel 50 mm down the tubing. The rate of photosynthesis was calculated as: rate of photosynthesis = 1000 t where t = time taken in seconds for the meniscus to travel 50 mm.

14 © UCLES 2012 0438/31/O/N/12 For Examiner's Use The student’s results are shown in Table 4.1. Table 4.1 concentration of sodium hydrogencarbonate solution / mol per dm3 t, time taken for meniscus to travel 50 mm / s rate of photosynthesis (1000/t) 0.00 4998 0.20 0.01 2500 0.40 0.02 1175 0.85 0.05 350 2.86 0.07 201 0.10 199 5.03 (b) Calculate the rate of photosynthesis for the concentration of sodium hydrogencarbonate solution of 0.07 mol per dm3. Write your answer in Table 4.1. [1] (c) (i) Explain why the lamp must be kept at a fixed distance from the syringe. [2] (ii) Explain what caused the meniscus to move down the capillary tubing. [2]

15 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use (d) Fig. 4.2 is a partially completed graph of the student’s results. Complete the graph by labeling the axes, adding the missing point and drawing a suitable line. 6.0 5.0 4.0 3.0 2.0 1.0 0.0 0.04 0.06 0.08 0.10 … … … 0.00 0.02 Fig. 4.2 [3]

16 © UCLES 2012 0438/31/O/N/12 For Examiner's Use (e) Explain, using the term limiting factors, the effect of carbon dioxide concentration on the rate of photosynthesis as shown by the student’s results. You will gain credit for using the data in the table and the graph to answer the question. [5] [Total: 16]

17 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use 5 Table 5.1 shows some information about air pollution. Table 5.1 pollutant source of air pollutant effect of pollutant on the environment ……………. combustion of fossil fuels increased greenhouse effect and global warming methane ……………………………… ……………………………… increased greenhouse effect and global warming sulfur dioxide combustion of high sulfur fuels acid rain nitrogen oxides fertilizers acid rain (a) Complete Table 5.1 by writing answers in the spaces indicated. [2] (b) Explain how the increased greenhouse effect is thought to lead to global warming. [3]

18 © UCLES 2012 0438/31/O/N/12 For Examiner's Use (c) Fig. 5.1 shows changes in the emissions of sulfur dioxide in Europe between 1880 and 2004. 60 50 40 30 20 10 0 emissions of sulfur dioxide / millions of tonnes per year 1880 1890 1900 1910 1920 1930 1940 year 1950 1960 1970 1980 1990 2000 2010 Fig. 5.1 (i) Use the information in Fig. 5.1 to describe the changes in the emissions of sulfur dioxide in Europe between 1880 and 2004. [4]

19 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use (ii) Describe the effects of acid rain on the environment. [3] (iii) Outline the methods that have been used to reduce the emissions of sulfur dioxide. [3] [Total: 15] 6 The flowers of pea plants, Pisum sativum, are produced for sexual reproduction. The flowers are naturally self-pollinating, but they can be cross-pollinated by insects. (a) Explain the difference between self-pollination and cross-pollination. [2]

20 © UCLES 2012 0438/31/O/N/12 For Examiner's Use (b) Explain the disadvantages for plants, such as P. sativum, of reproducing sexually. [4] Pea seeds develop inside pea pods after fertilization. They contain starch. A gene controls the production of an enzyme involved in the synthesis of starch grains. The allele, R, codes for an enzyme that produces normal starch grains. This results in seeds that are round. The allele, r, does not code for the enzyme. The starch grains are not formed normally. This results in seeds that are wrinkled. Fig. 6.1 shows round and wrinkled pea seeds. round pea seed wrinkled pea seed Fig. 6.1 Pure bred plants are homozygous for the gene concerned. A plant breeder had some pure bred pea plants that had grown from round seeds and some pure bred plants that had grown from wrinkled seeds. (c) State the genotypes of the pure bred plants that had grown from round and from wrinkled seeds. round wrinkled [1]

21 © UCLES 2012 0438/31/O/N/12 [Turn over For Examiner's Use These pure bred plants were cross-pollinated (cross 1) and the seeds collected. All the seeds were round. These round seeds were germinated, grown into adult plants (offspring 1) and self-pollinated (cross 2). The pods on the offspring 1 plants contained both round and wrinkled seeds. Further crosses (3 and 4) were carried out as shown in Table 6.1. Table 6.1 phenotype of seeds in the seed pods cross round seeds wrinkled seeds ratio of round to wrinkled seeds 1 pure bred for round seeds x pure bred for wrinkled seeds
 1:0 2 offspring 1 self-pollinated

3 offspring 1 x pure bred for round seeds 4 offspring 1 x pure bred for wrinkled seeds (d) Complete Table 6.1 by indicating • the type of seeds present in the pods with a check (
) or a cross () • the ratio of round to wrinkled seeds. You may use the space below and on page 22 for any rough work. [3]

22 © UCLES 2012 0438/31/O/N/12 For Examiner's Use (e) Seed shape in peas is an example of discontinuous variation. Suggest one reason why seed shape is an example of discontinuous variation. [1] Plants have methods to disperse their seeds over a wide area. (f) Explain the advantages of having seeds that are dispersed over a wide area, [3] [Total: 14]

23 © UCLES 2012 0438/31/O/N/12 BLANK PAGE

24 Copyright Acknowledgements: Question 3 Figure 3.2 © Reference A18K2A – Electronmicrograph Peter Arnold, Inc. / Alamy 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. © UCLES 2012 0438/31/O/N/12 BLANK PAGE

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the October/November 2012 series 0438 BIOLOGY (US) 0438/31 Paper 3 (Extended Theory), maximum raw mark 80 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 2012 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

Page 2 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 Question Expected Answers Marks Additional Guidance 1 (a) segmented body / segmentation ; jointed, limbs / legs ; exoskeleton / outer skeleton ; 3 (b) 5 / 6 RIGHT = 4 4 RIGHT = 3 3 RIGHT = 2 1 / 2 RIGHT =1 0 RIGHT = 0 Abaliella dicranotarsalis E go to 2 go to 3 go to 4 Tegenaria domestica A Odielus spinosus G Chelifer tuberculatus D go to 5 Poecilotheria regalis F go to 6 Tyroglyphus longior C Ixodes hexagonus B 4 [Total: 7]

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 Question Expected Answers Marks Additional Guidance 2 (a) (has been through) capillaries (in organs/named organ(s)) ; (has been through) an organ / named organ (beforehand) ; lost oxygen to, (named respiring) tissues / (named) organs / cells / AW ; 2 (b) oesophagus ; stomach ; gall bladder ; duodenum ; ileum ; pancreas ; colon / large intestine / rectum ; 4 Accept small intestine as alternative to duodenum and ileum (c) glucose, amino acids ; (named) vitamin(s) / (named) mineral(s) ; in solution / soluble / in the plasma ; transported from, small intestine / duodenum / ileum site of absorption ; to liver ; max 3 (d) to max 4 (when a) high glucose concentration , glucose converted to glycogen ; low glucose concentration , glycogen converted to glucose ; ref to correct role of, insulin / glucagon ; makes plasma proteins ; excess amino acids , deaminated / described ; to max 3 alcohol, broken down / respired / metabolised ; named toxin, broken down ; R toxin unqualified max 5

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 (e) 1 2 3 4 5 6 7 8 phagocytes to max 3 ingest / engulf , bacteria / pathogens / viruses ; R ‘eat’ digest / destroy (bacteria / pathogens / viruses) ; using enzymes ; any further detail ; lymphocytes to max 3 make / produce / secrete / release, antibodies ; idea of specificity / lymphocytes respond to particular pathogen or antigen ; effect of antibodies described; AVP ; max 4 AVP for either cell type, could be additional point about antibodies [Total: 18]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 Question Expected Answers Marks Additional Guidance 3 (a) lowered / flattened / AW ; increases / AW ; decreases / AW ; higher / greater / more ; into / inside; alveoli ; 6 (b) (A / goblet cell) secretes / produces, mucus ; sticky ; collects / traps, particles (in the air) ; cilia, move / beat / waft; mucus moves / removes, away from alveoli / out of trachea / towards larynx / towards mouth / AW ; max 4 ignore hairs direction needed [Total: 10]

Page 6 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 Question Expected Answers Marks Additional Guidance 4 (a) CO2 + H2O;
C6H12O6 + O2 ; 6O2, 6CO2, 6H2O ; 3 marks for: correct formulae for carbon dioxide and water correct formulae for glucose and oxygen balancing the equation ignore word equation (b) 4.98 ; 1 (c) (i) constant light intensity / ora; idea that light intensity is not the factor that is varied / not the independent variable / only carbon dioxide is varied / it is a control(led) variable ; 2 accept: if changed, would change rate of photosynthesis itself / AW R simply ‘makes results invalid’ (ii) gas / oxygen / air, collects at top of syringe / from plant or photosynthesis ; creates pressure to force water down the tube ; 2 R CO2 A push (d) concentration of (sodium) hydrogen carbonate / mol per dm3 + rate of photosynthesis (1000 / t) ; point plotted correctly ; line of best fit ; 3 A ecf from (b)

Page 7 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 (e) rate of photosynthesis increases as concentration of carbon dioxide increases (up to 0.07 mol per dm3 ); data quote ; carbon dioxide (concentration) is limiting factor ; after 0.07 mol per dm3 :- rate of photosynthesis remains (near) constant ; data quote ; carbon dioxide (concentration) is not the limiting factor ; light intensity / temperature, is limiting factor ; max 5 A increases very little [Total: 16]

Page 8 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 Question Expected Answers Marks Additional Guidance 5 (a) carbon dioxide CO2 ; rice fields / cattle / land fill / rotting rubbish / oil extraction / coal mines / gas fracking sites / AW ; 2 (b) (named) greenhouse gases ; trap / absorb, heat / (infra red / IR) radiation ; radiated back towards the Earth’s surface / heat kept near surface / prevents heat escaping (to space) / AW ; ref to long wavelength cannot ‘escape’ Earth’s atmosphere / AW ; max 3 R UV radiation (c) (i) 1 2 3 4 5 6 7 increases until 1975 ; decreases from 1980 ; to levels in 1930s / less than 1940; idea that slow rate of increase to 1940 ; faster rate of increase from 1945 ; decrease between 1940–1945 ; comparative data quotes ; max 4 Accept reaches a peak in 1975-1980 year and emission must be given for each point, units mentioned once (ii) 1 2 3 4 5 lowers pH of, soil / water; kills / damages, leaves / plants / trees ; salts / minerals / ions, lost from soils ; toxic to / kills, fish / animals in waters / lakes / rivers ; damages, limestone buildings / bronze statues ; max 3 A acidifies lakes A marble, gravestones, etc.

Page 9 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 (iii) use, alternative / renewable / green / AW , sources of energy ; A example(s) use low sulfur fuels / ORA; reduce use of coal ; flue gas desulfurisation / ‘use scrubbers’ / chimney electrostatic precipitators / neutralise waste gases with lime ; catalytic converters ; (named) international treaty for reducing emissions ; AVP ; e.g. any method to reduce demand for energy max 3 car sharing / more public transport / cycle paths / AW [Total: 15]

Page 10 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 Question Expected Answers Marks Additional Guidance 6 (a) self-pollination, occurs within same flower / between flowers of same plant ; cross-pollination, occurs between flowers on different plants ; 2 (b) wastage of pollen ; wastage of energy ; explanation ; depends on presence of pollinator ; need a pollinating / other, plant (nearby) ; long time for next generation to develop ; seeds scattered to places where they cannot grow ; variation leads to plants that are not adapted to place where parents grow / seeds end up ; max 4 A idea of pollen does not reach a stigma (c) round RR wrinkled rr ; 1

Page 11 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 31 © Cambridge International Examinations 2012 (d) phenotype of seeds in the seed pods cross round seeds wrinkled seeds ratio of round to wrinkled seeds 1 pure bred for round seeds x pure bred for wrinkled seeds
 1:0 2 offspring of cross 1 self pollinated

3:1 ; 3 offspring of cross 1 x pure bred for round seeds
 1:0 ; 4 offspring of cross 1 x pure bred for wrinkled seeds

1:1 ; 3 (e) controlled by (a) gene alone ; limited number / two, (pheno)types ; no intermediates ; max 1 A (just) two types / round & wrinkled (f) 1 colonisation / spread to new areas ; 2 where might be able to grow better ; 3 better (named) condition(s) ; 4 less competition ; 5 less (chance of) disease ; 6 idea that allows breeding with wider variety of plants; 7 AVP ; max 3 light / water / minerals / CO2 / space e.g. bigger gene pool / more alleles / AW e.g. Some survive a localized disaster / AW [Total: 14]