Cambridge IGCSE Biology (BES) 0438 — 2013 Oct/Nov Paper 2 · Variant 1

This document consists of 19 printed pages and 1 blank page. IB13 11_0438_21/RP © UCLES 2013 [Turn over *4266016397* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education BIOLOGY (US) 0438/21 Paper 2 Core October/November 2013 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 working 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 2013 0438/21/O/N/13 For Examiner's Use 1 Fig. 1.1 shows a woodlouse. Fig. 1.1 The woodlouse is a crustacean, one of the four groups of arthropod. It is a herbivore that lives on land and eats decaying plant materials. It breathes with gills that must be kept moist. (a) Name two other groups of arthropod. For each group state one feature found only in animals of that group. 1 group feature 2 group feature [4] (b) Some students were sent to find woodlice for an investigation. Suggest and explain two reasons why populations of woodlice are usually found under stones, decaying wood and leaves. 1 reason explanation 2 reason explanation [4] [Total: 8]

3 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use 2 Inspired air has a different composition to expired air. Complete Table 2.1 to show how inspired air is different from expired air. Table 2.1 substance how inspired air is different from expired air carbon dioxide dust particles oxygen water vapour [4] [Total: 4]

4 © UCLES 2013 0438/21/O/N/13 For Examiner's Use 3 Fig. 3.1 shows a poster that a student made for a biology lesson. BLOOD A plasma that makes antibodies B red blood cell that transports oxygen C white blood cells that transport glucose Fig. 3.1 The teacher told the class that the student had made a number of mistakes. (a) For each of the three labels, correct the mistakes by giving the name and function of each component. A name function B name function C name function [6]

5 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use (b) Name one other component of the blood that is not labeled on the poster. State its function. component function [2] [Total: 8]

6 © UCLES 2013 0438/21/O/N/13 For Examiner's Use 4 (a) Table 4.1 shows some of the top ten causes of death in parts of the world during 2010. Table 4.1 cause of death percentage of the deaths of adult males percentage of the deaths of adult females cancer (lung, alimentary canal, breast, prostate and others) 17 12 coronary heart disease 7 14 stroke (blood clot in brain) 17 10 Fig. 4.1 shows the data for the adult males. cancers coronary heart disease stroke 20 10 0 percentage of deaths males females males females males females Fig. 4.1 (i) Draw the bars for the adult females on Fig. 4.1. [1] (ii) Calculate the percentage of males dying from causes other than those in Table 4.1. Show your working. % [2] (iii) State the type of cancer, listed in Table 4.1, that occurs only in males. [1]

7 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use (b) The lifestyles of people can affect their risk of dying from some diseases. (i) Suggest three actions that humans could take to lower their risk of dying from coronary heart disease. 1 2 3 [3] (ii) In 2010 2% of adult male deaths were due to liver disease. Suggest one aspect of their life style that could have caused this. [1] [Total: 8]

8 © UCLES 2013 0438/21/O/N/13 For Examiner's Use 5 (a) Wheat is a type of grass that has been grown by humans for about 9000 years. The earliest variety is called emmer. Fig. 5.1 shows emmer wheat and a modern type of wheat. ear of modern wheat ear of emmer wheat ear ear awn grain Fig. 5.1 (i) Use Fig. 5.1 to describe two ways in which emmer wheat is different from modern wheat. 1 2 [2] (ii) Over hundreds of years farmers improved the yield of wheat crops. They kept grains from the highest yielding ears to grow the next crop. Name this farming practice. [1]

9 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use (b) There is evidence that emmer wheat was pollinated by pollen from other grasses. This produced new varieties. Fig. 5.2 shows a section through a flower of wheat. Fig. 5.2 Suggest the method of pollination in this wheat flower. Give two reasons for your answer. method reasons [3]

10 © UCLES 2013 0438/21/O/N/13 For Examiner's Use (c) 3000 years ago some farmers stored wheat in pits in the ground. Fig. 5.3 shows a pit full of grain. chalk rock chalk rock waterproof, airtight cap of clay layer of wheat grains that germinate wheat grains that do not germinate or decay ground level Fig. 5.3 Wheat grains near the edge of the pit germinate. The germinating grains use up all of one gas from the air in the pit and produce a different gas. The germinating grains also release heat that causes the temperature in the pit to rise to 80 °C. (i) Name the chemical reaction that uses up and produces the gases. [1] (ii) Name the gas used up during this chemical reaction. [1] (iii) Name the gas released during this chemical reaction. [1]

11 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use (iv) Suggest and explain three reasons why most of the grains in the pit did not germinate or decay. 1 2 3 [3] [Total: 12]

12 © UCLES 2013 0438/21/O/N/13 For Examiner's Use 6 Complete the sentences about the contents of a nucleus by writing the most appropriate word in each space. Use only words from the box. alleles chromosomes diploid DNA gametes genes haploid muscles Chromosomes are long threads of made up of many . Two or more alternative forms of a gene, are called . A nucleus contains a single set of unpaired . These nuclei are found in . [Total: 6]

13 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use 7 (a) Fig. 7.1 shows a carbon cycle. carbon dioxide in the air carbon compounds in fossil fuels carbohydrate, fat and protein in green plants carbohydrate, fat and protein in soil carbohydrate, fat and protein in animals death death death feeding feeding feeding death death death A B C D E F Fig. 7.1 (i) Write the letter of an arrow, A, B, C, D, E, or F as shown in Fig. 7.1, that represents each of the following processes. combustion photosynthesis respiration [3] (ii) Many of the world’s governments are concerned that the carbon dioxide concentration in the atmosphere keeps rising. Explain why they are concerned about the rise in carbon dioxide concentration. [3]

14 © UCLES 2013 0438/21/O/N/13 For Examiner's Use (b) Gazelles are herbivores that eat grass. Oxpecker birds feed on ticks that live on the skin of gazelles. Ticks suck blood from the gazelles. (i) Draw a food chain to represent these feeding relationships. [2] (ii) State what the arrows represent in a food chain. [1] (iii) Explain why a food chain is not considered to be a cycle like the carbon cycle. [3] [Total: 12]

15 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use 8 Throughout the world there are almost equal numbers of female and male babies born. The sex of a baby is determined by the sex chromosomes. (a) State the sex chromosomes present in a female and a male. Use X and Y to represent the sex chromosomes. female male [2] (b) Complete the genetic diagram to show the inheritance of sex in humans. parent parental chromosomes gametes offspring chromosomes offspring male … … … … … female … … … … … [3] [Total: 5]

16 © UCLES 2013 0438/21/O/N/13 For Examiner's Use 9 The enzyme lactase digests lactose into simple sugars. (a) Define the term enzyme. [2] (b) Describe how you could test for the presence of reducing sugars. State what you would observe if the result was positive. [3]

17 © UCLES 2013 0438/21/O/N/13 [Turn over For Examiner's Use (c) Fig. 9.1 shows the results of an investigation into the effect of pH on the activity of the enzyme lactase. 0 7 pH 14 activity of lactase 1 2 3 4 5 6 8 9 10 11 12 13 Fig. 9.1 (i) Use Fig. 9.1 to determine the optimum pH of lactase. [1] (ii) Describe the effect of the changes in pH on the activity of lactase. [3]

18 © UCLES 2013 0438/21/O/N/13 For Examiner's Use (d) Enzymes are involved in chemical digestion. Explain the role of teeth in physical digestion. [2] [Total: 11]

19 © UCLES 2013 0438/21/O/N/13 For Examiner's Use 10 Photosynthesis takes place in the leaves of plants. (a) (i) Leaves absorb light energy and this is converted into chemical energy. State where in leaves this energy change takes place. [1] (ii) Complete the word equation for photosynthesis. water + … oxygen + … [2] (b) Describe how water enters a plant from the soil. [3] [Total: 6]

20 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 2013 0438/21/O/N/13 BLANK PAGE

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the October/November 2013 series 0438 BIOLOGY (US) 0438/21 Paper 2 (Core 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 2013 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 2013 0438 21 © Cambridge International Examinations 2013 Mark schemes will use these abbreviations • ; separates marking points • / alternatives • R reject • A accept (for answers correctly cued by the question) • I ignore as irrelevant or inadequate • ecf error carried forward • AW alternative wording (where responses vary more than usual) • AVP alternative valid point • ORA or reverse argument • OWTTE or words to that effect • underline actual word given must be used by candidate (grammatical variants excepted) • ( ) the word / phrase in brackets is not required but sets the context • D, L, T, Q quality of: drawing / labelling / table / detail as indicated • max indicates the maximum number of marks

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 Answer Marks Guidance for Examiners 1 (a) insects; 3 pairs of / six legs / 3 regions to body / wings; arachnids; 4 pairs of / eight legs; myriapods; 1 or two pairs of identical legs on each segment; Any two pairs – 2 marks each [max 4] A – head, thorax, abdomen named I – Refs to individual organisms but if in an arthropod group allow correct feature for the group (b) 1 to be out of sight; to avoid predators / less likely to be eaten; 2 it is damper; to avoid drying out / keep gills moist; 3 it is cooler; avoids drying out; 4 to be out of the sun; avoids UV light; 5 is herbivore / eats plants / source of food; (feeds on) decaying vegetation; Any two pairs – 2 marks each [max 4] A – desiccation A – temperature changes less A – metabolism more constant A – rotting [Total: 8]

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 2 substance how inspired air is different from expired air carbon dioxide less in inspired air; dust particles more in inspired air; oxygen more in inspired air; water vapour less in inspired air; [4] A – ORA if specify reverse comparison No credit for absolutes for oxygen, carbon dioxide, water vapour [Total: 4] 3 (a) label A plasma; transports / carries food materials; label B white blood cell; engulfs bacteria / pathogens / produces antibodies; label C red blood cell; transports / carries oxygen; [6] A – transports carbon dioxide, urea, hormones, blood cells, named food materials A – leucocytes, phagocytes, lymphocytes (b) platelets; help to form clots / prevent bleeding; [2] A – plaquettes [Total: 8]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 4 (a) (i) three bars plotted correctly; [1] (ii) working - add totals; deduct from 100; [max 2] 17 + 7 + 17 = 41 100 – 41 = 59% Correct answer but no working shown = 2 marks (iii) prostate (cancer); [1] (b) (i) 1 exercise (regularly); 2 reduce / stop smoking; 3 reduce (animal / saturated) fat / cholesterol in diet; 4 lose weight / avoid obesity; 5 reduce salt intake; 6 reduce alcohol intake; 7 avoid stress situations; 8 correct ref to medication; [max 3] I – refs to balanced diet (ii) drinking a lot of alcohol / binge drinking / drug abuse; [1] A – heroin use [Total: 8]

Page 6 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 5 (a) (i) 1 (emmer) has smaller ears (than modern wheat); 2 (emmer) grains are smaller (than modern wheat); 3 (emmer) has fewer grains per ear (than modern wheat); 4 (emmer) grains have an awn (but not modern wheat); [max 2] Assume answer refers to emmer unless specifically stated otherwise A – description of awn as bristle, hair etc. (ii) (artificial) selection / selective breeding; [1] (b) wind (pollination); has exposed anthers / stamens / OWTTE; has feathery / exposed stigma / OWTTE; [3] (c) (i) (aerobic) respiration; [1] R – anaerobic A – oxidation (ii) oxygen; [1] (iii) carbon dioxide; [1] (iv) 1 high temperature kills grains / embryo; 2 high temperature denatures enzymes; 3 lack of oxygen kills grains / embryo; 4 accumulation of carbon dioxide kills / poisons grains / embryo; 5 high temperature kills bacteria / fungi (so no decay); 6 lack of water (prevents germination / decay); [max 3] A – ref to 80 °C A – lack of air [Total: 12]

Page 7 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 6 DNA; genes; alleles; haploid; chromosomes; gametes; [6] [Total: 6]

Page 8 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 7 (a) (i) combustion – E; photosynthesis – C; respiration – A / B / D; [3] (ii) 1 it could cause a rise in world temperatures / global warming; 2 heat energy becomes trapped; 3 causing ice caps to melt; 4 sea levels to rise; 5 flooding (of low lying land); 6 could cause climate change / alter rainfall; 7 affects agriculture / have to grow different crops; 8 affects ecosystems / distribution of plants / animals; 9 affects water supply; [max 3] 1 A – greenhouse effect 3 A – glaciers, poles 6 A – extreme weather conditions (b) (i) four organisms in suitable sequence; joined by arrows in correct direction; [2] grass, gazelle, ticks, oxpecker bird grass
gazelle
ticks
oxpecker bird (ii) the flow of energy (between organisms); (iii) 1 the energy in the food chain is lost; 2 as heat; 3 it cannot be reused (by living organisms); 4 carbon (dioxide) can be reused (in photosynthesis); [max 3] A – energy cannot be reused / not returned to start of chain again [Total: 12]

Page 9 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 8 (a) female – XX; male – XY; [2] (b) parent female male parent XX XY chromosomes gametes X X X Y; offspring XX XY XX XY; chromosomes offspring female male female male; [3] NO MARK for parent chromosomes Gametes ECF from parent chromosomes. Continue marking in logical sequence [Total: 5]

Page 10 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 9 (a) 1 enzymes are proteins; 2 act as (biological) catalysts; 3 speed up / alter the speed of chemical reactions; 4 not changed by the reaction; [max 2] 4 A – can be used over and over again (b) 1 Benedict’s reagent / solution; 2 ref to crushing food to be tested 3 heat food / material with reagent; 4 to at least 70 °C; 5 if colour changes from blue to red reducing sugar present; [max 3] 4 A – boiling 5 A – green, yellow, orange (c) (i) 8.6 +/– 0.2; [1] (ii) 1 increasing the pH increase lactase / enzyme activity (up to a peak); 2 (beyond peak) as pH rises further the lactase activity decreases; 3 no activity below pH 4 / above pH 13 / only active between pH 4 and 13; [3] (d) 1 break food up into small pieces (that can be swallowed); 2 increase surface area of food particles; 3 for enzyme activity; [max 2] 1 I – molecules 3 A – named digestive enzyme [Total: 11]

Page 11 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 21 © Cambridge International Examinations 2013 10 (a) (i) in palisade cells / in chloroplasts; [1] A – chlorophyll / (upper / spongy) mesophyll (ii) (water +) carbon dioxide; (oxygen +) sugar / glucose; [2] mark is for carbon dioxide mark is for sugar / glucose A – starch (b) 1 water enters root hairs (cells); 2 by osmosis; 3 through partially permeable cell membrane; 4 from high (water) concentration to low concentration / down (water) concentration gradient; [max 3] 2 A – by diffusion [Total: 6]