Cambridge IGCSE Biology (BES) 0438 — 2013 May/June Paper 3 · Variant 3

This document consists of 18 printed pages and 2 blank pages. IB13 06_0438_33/RP © UCLES 2013 [Turn over *4101933035* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education BIOLOGY (US) 0438/33 Paper 3 Extended May/June 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 0438/33/M/J/13 For Examiner's Use 1 Fig. 1.1 shows three annelid species and Ascaris lumbricoides, a species of nematode. Chaetopterus variopedatus Nereis diversicolor Lagisca flocculosa Ascaris lumbricoides annelids nematode not drawn to scale Fig. 1.1 (a) State three features shown by the three annelid species that are not shown by the nematode species. 1 2 3 [3]

3 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use (b) Organisms are given two names, e.g. Nereis diversicolor. State what is meant by the first name. [1] (c) N. diversicolor is a filter feeder. It filters plankton from sea water. Annelids like N. diversicolor form an important part of the ecosystems of estuaries. Fish feed on annelids when the sea covers the mud in the estuary. When the tide is out wading birds are the main predators of annelids. Birds of prey are the main predators of the wading birds. (i) Explain the term ecosystem. [3] (ii) Use the space below to draw a food chain for the estuary ecosystem when the tide is out. [2] (iii) Describe the advantages of drawing a food web rather than a food chain for an ecosystem. [2]

4 © UCLES 2013 0438/33/M/J/13 For Examiner's Use (d) The palolo worm is a species of annelid that lives on coral reefs in the Pacific Ocean. At certain times of the year, all the worms in an area leave their burrows to swim to the surface. They all release their gametes into the water at the same time. This is known as mass spawning. Suggest the advantages of having mass spawning occurring only at certain times of the year and not all year round. [3] (e) Meiosis is involved in producing gametes in palolo worms. Describe how meiosis differs from mitosis and explain why meiosis is important for the production of gametes. [4] [Total: 18]

5 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use 2 Fanwort, Cabomba caroliniana, is an aquatic plant often used to provide oxygen in fish tanks. Some students investigated the effect of temperature on the rate of photosynthesis of C. caroliniana. The apparatus that they used is shown in Fig. 2.1. ruler oil droplet capillary tubing water with sodium hydrogencarbonate beaker of water Cabomba caroliniana thermometer bench lamp stopwatch Fig. 2.1 (a) Explain why: (i) the lamp was kept at the same distance from the C. caroliniana throughout the investigation; [2] (ii) the water was enriched with carbon dioxide by adding sodium hydrogencarbonate. [2]

6 © UCLES 2013 0438/33/M/J/13 For Examiner's Use The students determined the rate of photosynthesis by measuring the movement of the oil droplet along the glass tubing. Their results are shown in Table 2.1. Table 2.1 distance traveled by the droplet / mm per minute temperature / °C 1 2 3 mean 17 5 3 3 3.7 21 10 15 11 12.0 23 20 10 15 15.0 25 30 15 15 20.0 30 50 40 30 40.0 45 5 3 5 4.3 50 1 0 1 0.7 (b) Describe the effect of temperature on the rate of photosynthesis of C. caroliniana. [3]

7 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use (c) Photosynthesis is a chemical process catalyzed by enzymes. Explain how the results shown in Table 2.1 support the idea that enzymes are involved in photosynthesis. [4] (d) C. caroliniana originally grew only in Latin America. This plant has escaped into the wild in Australia where its rapid growth has reduced the biodiversity of many streams and rivers. Suggest why the growth of C. caroliniana in Australia is far greater than in Latin America. [2] [Total: 13]

8 © UCLES 2013 0438/33/M/J/13 For Examiner's Use 3 Fig. 3.1 shows a diagram of a cell from the pancreas that secretes the hormone, insulin. A B C Fig. 3.1 (a) State one function of each of the parts of the cell labeled A, B and C. A B C [3] (b) Glucose in the blood is absorbed by liver cells and muscle cells. These cells convert glucose to glycogen for storage. Explain why glucose needs to be converted to glycogen for storage rather than remaining dissolved in the blood. [2]

9 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use (c) Other cells in the pancreas secrete the hormone glucagon. Glucagon stimulates liver cells, but has no effect on muscle cells. (i) State the effect that glucagon has on liver cells. [1] (ii) State how hormones, such as glucagon and insulin, travel around the body. [1] (d) Hormone Growth Promotants (HGPs) are hormones. HGPs are used to improve the production of food from animals. Many of these HGPs are hormones that are secreted naturally by the gonads (ovaries and testes). Name two hormones that are secreted by the gonads. 1 2 [2] (e) The hormones are given to cattle by placing implants behind the ears. These release the hormones slowly during the animal’s life time. The advantages of using HGPs in meat production are: • more meat is produced per animal; • a 15 to 30 % increase in growth rate; • a 5 to 15 % improvement in conversion of feed into meat; • a decrease in greenhouse emissions from cattle. Suggest: (i) the advantages of an increase in the conversion of feed into meat for the farmer; [2]

10 © UCLES 2013 0438/33/M/J/13 For Examiner's Use (ii) how the use of HGPs leads to a decrease in greenhouse emissions from cattle. [2] (f) HGPs are used in animal production systems in North America and Australia. The European Union (EU) has banned the use of HGPs and the import of meat from countries where the hormones are used. Suggest reasons for the ban on the use of HGPs in the EU. [2] [Total: 15]

11 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use 4 Blood is distributed through the body of a mammal in blood vessels. The blood supply to muscles changes considerably at the start and at the end of exercise. Fig. 4.1 shows a cross section of a blood vessel as seen with an electron microscope. cell X liquid Y Z Fig. 4.1 (a) Name: (i) cell X; [1] (ii) liquid Y; [1] (iii) the type of blood vessel shown in Fig. 4.1. [1] (b) State three substances that move across the wall of the blood vessel at Z. 1 2 3 [3]

12 © UCLES 2013 0438/33/M/J/13 For Examiner's Use (c) Table 4.1 shows the distribution of blood to different organs at rest and during exercise. Table 4.1 blood flow / cm3 per minute regions of the body at rest during strenuous exercise percentage change / % heart muscle 250 750 200 kidneys 1 200 600 -50 skeletal muscles 1 000 12 500 skin 400 1 900 375 liver and alimentary canal 1 400 600 -57 brain 750 750 0 others 600 400 -33 total 5 600 17 500 213 (i) Calculate the percentage change in the blood supply to the skeletal muscles. Show your working. Write your answer in Table 4.1. [1]

13 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use (ii) Explain why it is necessary for the blood supply to muscles to increase during exercise. [5] (iii) The volume of blood to different organs varies as shown in Table 4.1. During exercise, blood flow to the skin increases and to the kidneys decreases. Describe the changes that occur in blood vessels to cause blood flow to increase and to decrease. increase blood flow decrease blood flow [4] [Total: 16]

14 © UCLES 2013 0438/33/M/J/13 For Examiner's Use 5 Mammals and flowering plants both have internal fertilization and internal development. (a) Describe what happens after pollination that results in fertilization in flowering plants. [3] (b) Fig. 5.1 shows a fetus developing inside the uterus. umbilical cord placenta amniotic fluid amniotic sac cervix uterus back bone Fig. 5.1

15 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use Describe how the structures named in Fig. 5.1 provide the following needs of the fetus. protection constant temperature nutrients excretion of metabolic waste [8] [Total: 11]

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17 © UCLES 2013 0438/33/M/J/13 [Turn over For Examiner's Use 6 Many biologists study populations of organisms in their natural habitats. (a) Define the term population. [2] Question 6 continues on page 18.

18 © UCLES 2013 0438/33/M/J/13 For Examiner's Use (b) A 10-year study was carried out to investigate the relationship between voles and owls. Voles are small mouse-like mammals and owls are carnivorous birds. The results are shown in Fig. 6.1 and Fig. 6.2. 1 2 3 4 5 time / years 6 7 8 9 10 45 000 40 000 35 000 30 000 25 000 20 000 15 000 10 000 5 000 0 number of voles Fig. 6.1 1 2 3 4 5 time / years 6 7 8 9 10 30 25 20 15 10 5 0 number of owls Fig. 6.2

19 © UCLES 2013 0438/33/M/J/13 For Examiner's Use (i) Suggest three reasons for the decrease in the population of voles between years 5 and 6. 1 2 3 [3] (ii) State the evidence from Fig. 6.1 and Fig. 6.2 that supports the idea that voles form a large part of the food eaten by owls. [2] [Total: 7]

20 Copyright Acknowledgements: Figure 1.1 Figure 4.1 © R Philip Dales; Annelids; Hutchinson University Library; 1967. © A J Grove, G E Newell; Animal Biology; University Tutorial Press; 1961. © Robert D Barnes; Invertebrate Zoology; Saunders; 1968. © EM Image of cross section of a capillary; http://remf.dartmouth.edu/images.mammalianPancreasTEM/source/14.html. 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. 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 0438/33/M/J/13 BLANK PAGE

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2013 series 0438 BIOLOGY (US) 0438/33 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 May/June 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 – May/June 2013 0438 33 © 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 • ecf error carried forward • AW alternative wording (where responses vary more than usual) • AVP alternative valid point • ORA or reverse argument • 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 – May/June 2013 0438 33 © Cambridge International Examinations 2013 Answer Marks Guidance for Examiners 1 (a) segments ; antennae / ‘feelers’ ; projections over whole of the body / AW ; idea of heads / tails ; A not parasitic / free living / AW ; max [3] A ‘sections’ / ‘divisions’ / ‘rings’ / ‘parts’ / ‘sub-parts’ A bristles / chaetae / hairs R feet / legs / AW (b) genus / generic (name) ; [1] A ‘genus part of species name’ (c) (i) (all the) organisms / community ; in a given area / AW ; and non-living factors / abiotic factors AW ; idea of interacting together ; max [3] A place / location / region / habitat R ecosystem i.e. physical factors / named e.g. feeding (ignore feeding on each other) (ii) arrows point from food
feeder ; organisms in correct sequence ; plankton
annelid / named
wading bird(s)
bird of prey = 2 marks [2] (iii) shows complex feeding relationships / AW ; all organisms in the ecosystem ; A (many) more / part of / wide range of each species has more than one food source / AW ; each species has more than one predator / AW ; AVP ; e.g. shows possible chain reaction to an animal’s population change max [2] A all possible connections

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 (d) many, sperm and eggs / gametes, released at the same time ; increases chances of gametes fusing ; (many individuals so more genetic) variation ; may occur at a time when food is available ; for development of, young / offspring ; or when there are currents to disperse young ; smaller proportion of, eggs / zygotes / embryos, eaten by predators ; AVP ; max [3] R fewer predators (e) assume answer is about meiosis unless told otherwise mark differences between meiosis and mitosis to max 3 1 two divisions ; 2 four, cells / nuclei / gametes, produced ; 3 halves chromosome number ; 4 (diploid to) haploid ; 5 variation (between cells / nuclei / gametes) ; 6 gametes have different alleles ; 7 gives (more) variation in offspring ; 8 so chromosome number remains the same in next generation ; max [4] ignore quoted numbers of chromosomes R genes A number does not double with each generation / full pairs of chromosomes when fertilized / AW A ora for mitosis [Total:18]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 2 (a) (i) light intensity ; constant ; A control(led) variable ref to limiting factor ; intensity / amount of light, will affect (rate of) photosynthesis max [2] ignore refs to temperature change (ii) raw material for / ‘is needed for’ / AW, photosynthesis ; maintain suitable concentration ; carbon dioxide, concentration / AW, is / could be / wasn’t a limiting factor ; max [2] A ‘amount’ for concentration, A fixed quantity (b) rate of photosynthesis (‘it’) general description – increases and decreases ; peak / maximum rate, at 30 oC ; optimum temperature is 30 oC ; use of two figures from the table to illustrate, including units ; max [3] ignore droplet movement unqualified (c) if no enzymes then rate should increase as temperature increases ; but rate decreases, above 30 oC / at high temperatures ; enzymes are denatured ; ref to active site destroyed ; substrate no longer fits into active site ; reaction not catalysed / AW ; max [4] A (30 °C) optimum temperature / described (d) ref to fewer limiting factors ; higher temperatures / hot temperatures; higher rates of photosynthesis ; more food for, growth / reproduction ; no, grazers / animals to feed on it ; more suitable habitats / more fertile soils / more nutrients ; no disease ; fewer / no, competitors ; AVP ; max [2] This MP is dependent on making point 3. A no predators R space [Total:13]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 3 (a) A – controls the cell / contains DNA / contains genes ; B – makes protein / makes insulin / respiration / storage / contains the insulin (that will be released) ; C – controls movement of (named) substance(s), in / out, of cell ; [3] A contains code for insulin / controls cell development ignore just … provides protein (b) glucose is soluble, glycogen is insoluble ; glucose in blood would, lower water potential / AW e.g. (cause) hyperglycemia ; water leaves cells ; by osmosis ; much larger quantities can be stored ; can be stored for (much) longer ; glucose would not be reabsorbed in the kidney ; (and would be) excreted / lost, in the urine ; AVP ; max [2] A affect water potential / affect blood glucose concentration / AW A urinated (c) (i) stimulates liver cells to break down glycogen and release glucose ; [1] A glycogen → glucose for breakdown (ii) (in the) blood / plasma / circulatory system ; [1] A via hepatic portal vein (d) oestrogen ; progesterone ; testosterone ; max [2]

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 (e) (i) grow faster so keep animals for shorter time ; can provide less food (for animals); better economic return ; however expressed less waste / described ; fewer problems with waste disposal / described / example ; [2] R more meat (in Q) (ii) cattle produce, methane / carbon dioxide (greenhouse gases) ; (if more food converted to meat), less is excreted / egested / less waste / less carbon dioxide / less methane ; if eat less food, then less emissions ; if growth rate is higher, do not to keep them for as long ; fewer cattle means that less methane is released ; max [2] if ‘less methane’ award mp1 too (f) health risk / hormones may have adverse effect, in humans ; any e.g. ; faster growth rate / early puberty / cancer ref to animal welfare / kill animals ; harm to animals of fast growth rates ; any likely health issue in animals ; AVP ; e.g. protect European farmers max [2] A ill / sickness / increased mass A men’s gender effect R bacteria (that make the hormone) making cattle / humans ill [Total:15]

Page 8 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 4 (a) (i) red blood cell ; [1] (ii) plasma ; [1] (iii) capillary ; [1] (b) oxygen ; carbon dioxide ; water ; glucose ; sodium ions ; amino acids ; urea, (named) hormone(s) ; AVP ;;; e.g. lactic acid max [3] (c) (i) 1150 (%) [1] look in the space for working if answer is not in table (ii) increase in energy demand in muscle ; for contraction (of muscle) ; increase in respiration in muscle ; increase in blood flow supplies more oxygen ; for aerobic respiration ; more glucose ; more, fat / fatty acids ; increase in blood flow removes carbon dioxide ; lactate / lactic acid ; from anaerobic respiration ; max [5] A lot of energy A lot of oxygen A conversion of lactic acid

Page 9 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 (iii) max 3 for increase blood flow vasodilation ; muscle in wall relaxes ; arterioles / arteries ; widen / dilate ; more blood flows to capillaries ; max 3 for decrease blood flow vasoconstriction ; muscle in wall contracts ; arterioles / arteries ; narrow / constrict ; less blood flows to capillaries ; max [4] R ‘blood vessels’ once only allow ecf for ‘blood vessels’ [Total:16] 5 (a) pollen (grain) germinates / pollen (grain) grows pollen tube ; pollen tube grows down the style ; reaches the ovule ; (tip of) pollen tube breaks open ; male gamete(s) travels down the pollen tube ; male gamete(s) / (male) nucleus / nuclei, enter ovule ; (male gamete) fuses with female gamete / ovum ; zygote forms ; max [3] A pollen grain gametes / nucleus A fertilization / fusion, occurs inside the ovule

Page 10 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 (b) protection (amnion / uterus / amniotic fluid) 1 provides protection against, mechanical damage / ‘knocks’ ; 2 provides sterile environment / no entry of pathogens ; 3 backbone provides protection against, jolts / AW ; 4 placenta provides a barrier to (named) pathogen(s) / AW ; 5 placenta prevents mixing of blood between fetus and mother constant temperature 6 ref to blood flow to the, uterus / placenta / amnion ; 7 brings heat from elsewhere in mother’s body ; 8 removes heat from amniotic fluid ; 9 fetus enclosed inside, any named structure / the mother’s body ; 10 named structure(s), acts as insulators / reduces heat loss ; nutrients 11 across placenta / through placenta ; 12 diffusion / active transport ; 13 between mother’s blood and fetal blood / into fetal blood; excretion of metabolic waste 14 across placenta / through placenta ; 15 diffusion of, urea / carbon dioxide ; 16 from fetal blood to mother’s blood / into mother’s blood ; nutrients / excretion A once only 17 umbilical cord transports, nutrients / excretory products ; max [8] max 3 from each section A baby for fetus R amniotic sac as insulator R absorbed by placenta [Total:11]

Page 11 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0438 33 © Cambridge International Examinations 2013 6 (a) group of organisms of the same species ; in the same area / at the same time ; [2] A ‘of a kind’ / a species A same habitat / ecosystem / community (b) (i) greater predation by owls / more predators / more owls; lack of food / starvation / more competition for food ; adverse (named) weather condition (s) ; disease / sickness / illness; emigration ; AVP ; habitat destruction max [3] R climate change (ii) 1 owl population increases, after / AW, vole population increases ; 2 owl population crashes (in year 7) ; 3 immediately after crash in vole population ; 4 vole population crashes / decreases (in year 6) ; 5 when there are most owls ; 6 if owls ate (much) other prey there would not be a close relationship / AW ; 7 ref to numbers of owls from the graph ; max [2] if MP1 and MP2 not given accept the idea that ‘owl population follows changes in vole population’ if answer does not refer to the increase or decrease [Total:7]