Cambridge IGCSE Biology (BES) 0438 — 2012 Oct/Nov Paper 2 · Variant 1

This document consists of 17 printed pages and 3 blank pages. IB12 11_0438_21/2RP © UCLES 2012 [Turn over *6666698289* For Examiner's Use 1 2 3 4 5 6 7 8 9 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education BIOLOGY (US) 0438/21 Paper 2 Core 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 0438/21/O/N/12 For Examiner's Use 1 Vertebrate animals are grouped into a number of classes. Complete the sentences by naming each of the vertebrate classes that are described. (a) A vertebrate with scaly skin and no legs could be either a or a [2] (b) A vertebrate with lungs and hair is a but if it has feathers instead of hair it is a [2] [Total: 4]

3 © UCLES 2012 0438/21/O/N/12 [Turn over For Examiner's Use 2 Fig. 2.1 shows a section through the eye of a small mammal as viewed with a microscope. Z X Y Fig. 2.1 (a) Name the structures labeled X, Y and Z. X Y Z [3] (b) A student looks at a clock at the far end of an examination room and then looks at a diagram on her examination paper. Describe the changes that take place in her eyes so that she can focus on the diagram. [4]

4 © UCLES 2012 0438/21/O/N/12 For Examiner's Use (c) The shortest distance from the eye at which a clear focus is possible is known as the near point. As a person gets older this distance changes. Table 2.1 shows the near point for people of different ages who have normal vision. Table 2.1 age / years distance of near point / cm 10 7.0 15 8.5 20 10.0 25 12.5 40 22.0 50 40.0 60 80.0

5 © UCLES 2012 0438/21/O/N/12 [Turn over For Examiner's Use (i) Plot the data in Table 2.1 on the grid. [4] (ii) Use the graph to estimate the distance of the near point for a 30 year old person. [1] (iii) Use the graph to estimate the age of a person whose near point is 32.0 cm. [1] [Total: 13]

6 © UCLES 2012 0438/21/O/N/12 For Examiner's Use 3 Fig. 3.1 shows an external view of the heart. coronary artery X shaded area Fig. 3.1 (a) A blood clot is stuck at X. Explain what will happen to the heart muscle cells in the shaded area on Fig. 3.1. [3] (b) List three actions people can take to reduce the risk of having a blood clot in the coronary arteries. 1 2 3 [3] [Total: 6]

7 © UCLES 2012 0438/21/O/N/12 [Turn over For Examiner's Use 4 Fig. 4.1 shows a section along a pea pod, the fruit of a pea plant. D A B C Fig. 4.1 (a) (i) Name the parts of the original pea flower from which structures A and B have developed. A B [2] (ii) Parts C and D are the remains of parts of the pea flower. Suggest which part C was and which part D was in the original flower. C D [2] Fig. 4.2 shows a section through a pea seed. Fig. 4.2 (b) Label, with a label and line on Fig. 4.2 the plumule, the radicle and the testa of this seed. Put your labels on Fig. 4.2. [3] (c) State two ways in which seeds are dispersed. 1 2 [2]

8 © UCLES 2012 0438/21/O/N/12 For Examiner's Use (d) Name three factors that are essential for all seeds to germinate. 1 2 3 [3] [Total: 12]

9 © UCLES 2012 0438/21/O/N/12 [Turn over For Examiner's Use 5 Fig. 5.1 shows a carbon cycle. carbon compounds in dead organic matter carbon compounds in animals carbon dioxide in the air carbon compounds in fossil fuels, e.g. oil and coal carbon compounds in green plants F E C D B G A death death death death death death Fig. 5.1 (a) (i) Name the process represented by arrow A. [1] (ii) Name the process represented by arrow E. [1] (b) (i) Name one group of organisms responsible for process B. [1] (ii) List two environmental conditions needed for process B to occur. 1 2 [2] (c) (i) Which arrow represents photosynthesis? [1] (ii) Complete the word equation for photosynthesis. +
oxygen + [2] (iii) This process needs a supply of energy. Name the form of energy needed. [1]

10 © UCLES 2012 0438/21/O/N/12 For Examiner's Use (d) In an ecosystem the flow of carbon can be drawn as a cycle but the flow of energy cannot be drawn as a cycle. Explain this difference. [3] [Total: 12]

11 © UCLES 2012 0438/21/O/N/12 [Turn over For Examiner's Use 6 Fig. 6.1 shows the body temperature of a student over a 32 hour period. 4 8 12 midnight pm am pm 4 8 time of day 12 noon day 1 day 2 4 8 12 midnight 39 38 37 36 35 body temperature / °C Fig. 6.1 (a) Between 2.30pm and 4.15pm on day 2 the student was involved in gymnastics training. Explain why the body temperature increased during the training. [2] (b) The student had a normal body temperature of 36.8 °C. If the body temperature rises above normal, homeostasis takes place. (i) Define homeostasis. [2]

12 © UCLES 2012 0438/21/O/N/12 For Examiner's Use (ii) Explain how sweating can help to change body temperature. [3] [Total: 7]

13 © UCLES 2012 0438/21/O/N/12 [Turn over For Examiner's Use 7 Complete the sentences by writing the most appropriate word in each space. Use only words from the box. allele diploid fertilization gametes gene half haploid implantation meiosis mitosis same In animals, new cells replace damaged cells. These new cells are formed from existing cells by division. When this happens the nucleus also has to divide. During the process of the nucleus divides into two new nuclei. These new nuclei contain the two sets of chromosomes, which is the number of chromosomes as the original nucleus. They are described as being . During the process of a nucleus normally divides into four new nuclei that are not genetically identical. These nuclei contain the number of chromosomes of the original nucleus and are described as . This type of division produces . At the original number of chromosomes is restored. [8] [Total: 8]

14 © UCLES 2012 0438/21/O/N/12 For Examiner's Use 8 Fig. 8.1 shows a cell from the palisade layer of a leaf. 3 2 1 4 5 6 Fig. 8.1 (a) In Table 8.1 check () the numbers that label the three features of the palisade cell which are also found in animal cells. Table 8.1 label number present in both animal and plant cells 1 2 3 4 5 6 [3]

15 © UCLES 2012 0438/21/O/N/12 [Turn over For Examiner's Use (b) State and describe the function of two features of the palisade cell that are only found in plant cells. feature function feature function [4] (c) Fig. 8.2 shows some red blood cells, which are animal cells. Fig. 8.2 (i) Which feature normally present in an animal cell is absent from a red blood cell? [1] (ii) State the function of a red blood cell and describe one way in which the red blood cell is adapted to carry out its function. [2] [Total: 10]

16 © UCLES 2012 0438/21/O/N/12 For Examiner's Use 9 Fig. 9.1 shows a food web. squirrels and other small rodents rabbits snakes lizards bats badgers eagles coyotes mountain lions insects sagebrush bushes prickly pear cactus desert flowers deer and other grazers Fig. 9.1 (a) Explain the difference between a food web and a food chain. [2]

17 © UCLES 2012 0438/21/O/N/12 For Examiner's Use (b) From the food web name: (i) a carnivore; (ii) a producer; (iii) a consumer from the 2nd trophic level. [3] (c) In some regions, mountain lions have been hunted and face extinction. Suggest how the coyotes might be affected if the mountain lion became extinct. [3] [Total: 8]

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20 Copyright Acknowledgements: Question 8 Fig. 8.2 © Red Blood Cells; Science Photo Library C0088462 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 0438/21/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) 0438/21 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 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 21 © Cambridge International Examinations 2012 Question Mark Scheme Mark Guidance 1 (a) fish; reptile; [2] 1st or 2nd space 1st or 2nd space (b) mammal; bird; [2] 2nd space A – scientific names for the classes R – named examples e.g. shark, dog, etc. [Total: 4]

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 21 © Cambridge International Examinations 2012 Question Mark Scheme Mark Guidance 2 (a) X – iris; Y – retina; Z – optic nerve; [3] (b) 1 ciliary muscles contract; 2 tension on (suspensory) ligaments less; 3 lens no longer stretched; 4 becomes more convex / curved; 5 refracts / bends light (rays) more; 6 (brings focus) on to the retina / fovea; any four – 1 mark each [4] 1 R – wrong muscle 1 Ig – muscle unqualified 2 A – ligaments less taut / slackened 3 A – under less tension / no tension 4 A – rounded / fatter / wider 5 A – reduces focal length 6 A – yellow spot (c) (i) 1 axes correctly labelled with units; 2 suitable scales used and uses at least half of the grid; 3 five points plotted correctly; 4 points joined; [4] Ig – orientation A – ± half a square R – line extrapolated to 0.0 (ii) distance as shown by candidate’s graph ± 1; [1] likely to be 15 (cm) (iii) age as shown by candidate’s graph ± 1 [1] likely to be 47 (years) [Total: 13]

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 21 © Cambridge International Examinations 2012 3 (a) 1 blood unable to reach muscle (in shaded region); 2 less / no oxygen / glucose reaches muscle; 3 less / no respiration; 4 less / no energy release; 5 (muscle) cells die; 6 causes a heart attack; any three – 1 mark each [3] Ig – nutrients (b) 1 exercise (regularly); 2 reduce / stop smoking (tobacco); 3 reduce (animal / saturated) fat / cholesterol in diet; 4 lose weight; 5 reduce salt intake; 6 avoid stressful lifestyles; 7 use of medication qualified; any three – 1 mark each [3] A – examples of exercise Ig – refs to balanced diet Ig – refs to visits to doctor [Total: 6]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 21 © Cambridge International Examinations 2012 4 (a) (i) A – ovary; B – ovule; [2] R – ovum (ii) C – style/stigma; D – sepals; [2] A – calyx (b) plumule correctly labelled; radicle correctly labelled; testa correctly labelled; [3] (c) by animals / mammals / birds; by wind; by water; by explosive mechanisms; any two – 1 mark each [2] A – agents or methods (d) oxygen; water / moisture; suitable temperature / warmth; food store; any three – 1 mark each [3] Ig – refs to light Ig – refs to humidity Ig – refs to heat / temperature unqualified A – named example [Total: 12]

Page 6 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 21 © Cambridge International Examinations 2012 5 (a) (i) respiration; [1] (ii) combustion; [1] A – burning (b) (i) fungi/bacteria; [1] A – decomposers (ii) moisture / water; warmth / suitable temperature; oxygen; any two – 1 mark each [2] A – dampness, humidity Ig – refs to light Ig – refs to heat unqualified Ig – air (c) (i) C; [1] (ii) water and carbon dioxide; glucose / sugar; [2] both for the mark Ig – refs to carbohydrates / starch (iii) light / sunlight; [1] Ig – sun / radiation / solar energy (d) 1 carbon dioxide trapped in plant / used in photosynthesis; 2 released (as carbon dioxide) during decay / in burning / in respiration; 3 carbon is recycled / reused; 4 light energy trapped (in plant) by Photosynthesis; 5 (light energy) changed to chemical energy; 6 (energy) lost (as heat) to environment / not released as light energy / light cannot be recycled; three – 1 mark each [max. 3] A – carbon not lost [Total: 12]

Page 7 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 21 © Cambridge International Examinations 2012 6 (a) 1 increased muscle activity; 2 increased / faster release of energy / heat; 3 from increased respiration; any two – 1 mark each [2] A – muscle movement, contraction only need ref to increase once A – use more energy (b) (i) maintenance of a constant internal environment; [2] A – ref to keeping within narrow limits A – in context of named examples (ii) 1 sweat secreted (onto surface of skin / body); 2 water evaporates; 3 this process needs heat / energy; 4 ref to latent heat (of vaporisation); 5 body temperature falls; any three – 1 mark each [3] A – released A – water and salts Ig – refs to sweat A – vapour takes energy / heat with it A – cools the body [Total: 7] 7 (a) mitosis; same; diploid; meiosis; half; haploid; gametes; fertilisation; [8] Must be in correct position in sentences [Total: 8]

Page 8 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 21 © Cambridge International Examinations 2012 8 (a) label number present in both animal and plant cells 1 2 3
4 5
6
correct ticks – 1 mark each [3] Ig – any crosses Four ticks MAX 2 if two are correct Five ticks MAX 1 Six ticks MAX 0 (b) 1 chloroplast / 1; 2 carry out photosynthesis / absorb light 3 cell wall / 4; 4 give shape / provides support / protected cell; 5 vacuole / 2; 6 reserve / store of water / salts / provides support; any two pairs – 2 marks each [4] correct feature must be stated to award function mark (c) (i) nucleus; [1] (ii) carrying / transporting oxygen; contains haemoglobin / large surface area; [2] A – ref to no nucleus qualified by idea can contain more haemoglobin / carry more oxygen [Total: 10]

Page 9 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0438 21 © Cambridge International Examinations 2012 9 (a) food chain shows energy transfer from one organism to next organism; food web shows energy transfer through an ecosystem; [2] A – only one organism at each (trophic) level A – can have more than one organism at (trophic) levels A – food web is a network of linked food chains (b) (i) snake / lizard / bat / badger / eagle / coyote / mountain lion; (ii) producer – sage brush / prickly pear (cactus) / (desert) flowers; A – bushes, cactus (iii) rabbit / insects / deer (and other grazers) / squirrel (and other small rodents); [3] (c) (no mountain lions / extinction) leads to increase in numbers of deer (and other grazers); more food for coyotes; leads to increase in numbers of coyotes; [3] A – alternative routes that lead from mountain lion to coyotes via deer, producers, insects, lizards, etc. A – less competition for food [Total: 8]