Cambridge IGCSE Biology (BES) 0438 — 2013 Oct/Nov Paper 3 · Variant 1

This document consists of 19 printed pages and 1 blank page. IB13 11_0438_31/2RP © UCLES 2013 [Turn over *1282503609* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education BIOLOGY (US) 0438/31 Paper 3 Extended 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 0438/31/O/N/13 For Examiner's Use 1 (a) Table 1.1 shows some features of the five groups of vertebrates. Complete Table 1.1 to compare the five groups of vertebrates using a tick (
) to indicate if the group shows the feature, or a cross () if not. The first row has been completed for you. Table 1.1 group of vertebrates scaly skin external ear (pinna) feathers mammary glands birds

 bony fish amphibians reptiles mammals [4] Fig. 1.1 shows a southern cassowary, Casuarius casuarius, which is a large bird that cannot fly. It lives in rainforests in northern Australia and southern New Guinea. The cassowary feeds on fruits and helps to disperse seeds for many tree species, such as the cassowary plum. Fig. 1.1 (b) Suggest why the cassowary can digest the fruit but not the seeds of rainforest trees. [2]

3 © UCLES 2013 0438/31/O/N/13 [Turn over For Examiner's Use (c) Describe one method of seed dispersal that does not require animals. [2] (d) State two environmental conditions that seeds require so that they can germinate. 1. 2. [2] (e) Cassowaries are an endangered species. Many are killed on the roads and development threatens their rainforest habitat. Cassowaries, as with many other rainforest species, cannot survive in small nature reserves. Suggest why species, such as cassowaries, cannot survive in small nature reserves. [3] [Total: 13]

4 © UCLES 2013 0438/31/O/N/13 For Examiner's Use 2 (a) (i) Explain the term balanced diet. [3] (ii) State three factors that influence a person’s nutritional needs. 1 2 3 [3]

5 © UCLES 2013 0438/31/O/N/13 [Turn over For Examiner's Use (b) Glucose is absorbed in the small intestine and transported in the blood. The kidneys filter the blood and reabsorb the glucose. If the blood contains more than 180 mg of glucose per 100 cm3, the kidney cannot reabsorb it all and some is present in the urine. This figure is called the renal threshold. A doctor suspects that a patient has diabetes because a urine test is positive for glucose. The patient takes a glucose tolerance test by drinking a solution of glucose. The doctor records the patient’s blood glucose concentration at 30 minute intervals for five and a half hours. The results are plotted on Fig. 2.1. 300 250 200 150 100 50 0 0 30 60 90 120 150 180 210 240 270 300 330 blood glucose concentration / mg per 100 cm3 time / minutes glucose drink Fig. 2.1 (i) Draw a horizontal line on Fig. 2.1 to show the renal threshold. [1] (ii) State the time period when the kidney will produce urine containing glucose. [1] (iii) Sketch on Fig. 2.1 the blood glucose concentrations that the doctor might expect if he repeated this test on someone who does not have diabetes. [1]

6 © UCLES 2013 0438/31/O/N/13 For Examiner's Use (c) People who do not have diabetes maintain their blood glucose concentration below 180 mg per 100 cm3. Explain how the body does this. [3] [Total: 12]

7 © UCLES 2013 0438/31/O/N/13 [Turn over For Examiner's Use 3 (a) Starch, glucose and fructose are carbohydrates. Fructose syrup is used as a sweetening agent as an alternative to sucrose. The flow chart in Fig. 3.1 shows how fructose is prepared from maize starch. starch released from the maize grains glucose syrup fructose syrup maize grains grains are crushed pH is adjusted addition of enzyme 1 addition of enzyme 2 Fig. 3.1 (i) Name enzyme 1. [1] (ii) State why it is necessary to adjust the pH before an enzyme is added to the process. [1] (b) Maize grains contain protease enzymes. With reference to the processes shown in Fig. 3.1, suggest why it is important that these enzymes do not contaminate the glucose syrup. [1]

8 © UCLES 2013 0438/31/O/N/13 For Examiner's Use (c) The formation of fructose syrup from glucose syrup is carried out at a temperature of 60 °C. Suggest an important property of enzyme 2 that allows it to be used at temperatures as high as 60 °C. [1] (d) Enzyme 2 is found naturally in many bacteria. Enzymes for use in washing powders are obtained from bacteria. Describe how bacteria are used to produce enzymes for washing powders. [3] (e) Pectinase is an enzyme that breaks down compounds known as pectins. Cell walls of fruits, such as apples and mangoes, contain pectins. Explain the advantages of using pectinase in fruit juice production. [3] [Total: 10]

9 © UCLES 2013 0438/31/O/N/13 [Turn over For Examiner's Use 4 (a) Sickle cell anemia is a genetic disorder that is found among people in certain parts of the world. A sample of blood was taken from a person with sickle cell anemia and examined with an electron microscope. Fig. 4.1 shows some of the red blood cells in the sample. Fig. 4.1 Explain the problems that may occur as these cells circulate in the blood system. [4]

10 © UCLES 2013 0438/31/O/N/13 For Examiner's Use (b) The gene for hemoglobin exists in two alternative forms: HA codes for the normal form of hemoglobin; HS codes for the abnormal form of hemoglobin. (i) State the name for the alternative forms of a gene. [1] (ii) A child has sickle cell anemia. The parents do not have this disorder. Complete the genetic diagram to show how the child inherited the disorder. Use the symbols HA and HS in your answer. parental phenotypes parental genotypes gametes child’s genotype child’s phenotype normal HAHS normal HAHS × × + … sickle cell anemia [2] (iii) The parents are about to have another child. What is the probability that this child will have sickle cell anemia? [1]

11 © UCLES 2013 0438/31/O/N/13 [Turn over For Examiner's Use (c) The maps in Fig. 4.2 show the distribution of sickle cell anemia and malaria in some parts of the world. distribution of malaria distribution of sickle cell anemia northern Australia Indonesia and the Philippines key malaria key sickle cell anemia Fig. 4.2

12 © UCLES 2013 0438/31/O/N/13 For Examiner's Use (i) Explain why sickle cell anemia is common in people who live in areas where malaria occurs. [4] (ii) Suggest why sickle cell anemia is very rare among people who live in Indonesia and northern Australia. [2] [Total: 14]

13 © UCLES 2013 0438/31/O/N/13 [Turn over Question 5 begins on page 14.

14 © UCLES 2013 0438/31/O/N/13 For Examiner's Use 5 (a) Complete Table 5.1 by naming three sense organs and the stimulus which each detects. Table 5.1 sense organ stimulus [3] (b) Reflexes are involuntary actions coordinated by reflex arcs like the one shown in Fig. 5.1. spinal cord spinal nerve motor neurone sensory neurone biceps muscle triceps muscle relay neurone Fig. 5.1

15 © UCLES 2013 0438/31/O/N/13 [Turn over For Examiner's Use (i) Explain what is meant by the term involuntary action. [2] (ii) The arm shown in Fig. 5.1 moves in response to the detection of heat. Explain how the parts of the reflex arc shown in Fig. 5.1 bring about this response. [5] (iii) Describe the advantages of simple reflexes, such as the one shown in Fig. 5.1. [2]

16 © UCLES 2013 0438/31/O/N/13 For Examiner's Use (c) The organs of the human body are coordinated by the nervous system. Outline one other way in which these organs are coordinated. [2] [Total: 14]

17 © UCLES 2013 0438/31/O/N/13 [Turn over For Examiner's Use 6 Nitrogen is one of the most important chemical elements in the biosphere. Nitrogen must be continually recycled if life is to continue on Earth. Savanna grasslands are an important ecosystem in Africa. Fig. 6.1 shows part of the nitrogen cycle in a grassland ecosystem in southern Africa. nitrogen gas (N2) in the atmosphere nitrate ions in the soil ammonia in the soil urea in urine cheetah D E F lightning C impala D B A nitrogen fixation Cassia mimosoides legume that fixes nitrogen Fig. 6.1 (a) Name: (i) a type of nitrogen-containing compound that is made by Cassia mimosoides, eaten by the impala and by the cheetah; [1] (ii) the type of consumer as represented by the cheetah; [1]

18 © UCLES 2013 0438/31/O/N/13 For Examiner's Use (iii) the process by which urea is removed from the body of the animals as shown by D; [1] (iv) process F. [1] (b) Explain the importance of recycling nitrogen in ecosystems, such as the African savanna. [3] (c) The most common plants that grow in the African savanna are grasses. There are very few legume plants, such as C. mimosoides. Suggest reasons why C. mimosoides is a rare plant in the African savanna. [3]

19 © UCLES 2013 0438/31/O/N/13 For Examiner's Use (d) Explain why there are far fewer cheetah than impala. [4] (e) The cheetah is an endangered species. It is important to conserve their food supply and all the species that inhabit their ecosystem. Explain why. [3] [Total: 17]

20 Copyright Acknowledgements: Figure 4.1 © Ref: M108/0009; Sickle cell disease: variation in cell deformity; Omikron / Science Photo. Library. 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 0438/31/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) 0438/31 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 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 31 © 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 • 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 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners 1 (a) group of vertebrates scaly skin external ear (pinna) feathers mammary glands birds

 bony fish
   ; amphibians     ; reptiles
   ; mammals 

; [4] (b) • either fruit is soft or seeds, are hard / thick / have a hard / thick / protective covering or testa ; • no enzymes to digest, testa / seed coat / seed ; [2] I refs to teeth

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners (c) 1 2 3 4 5 6 wind (dispersal) ; ‘hairs’ / wing(s), on seed / fruit, to aid dispersal ; self– (dispersal) ; explosive, pods / fruits ; water (dispersal) ; float / buoyant ; [max 2] A parachute / light I fur I pollination (d) oxygen ; warmth / warm temperature ; water ; [max 2] A suitable quoted warm temp, 15–30 ºC I humidity (e) 1 2 3 4 5 (cassowaries are large birds) so need large, territory / habitat / feeding area / lots of space ; cannot fly so cannot move easily from one area to another ; need many trees to produce enough fruit ; cassowaries are dependent on many (tree) species ; need suitable nesting areas ; [max 3] [Total: 13]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners 2 (a) (i) provides, sufficient energy / energy for needs ; provides, molecules / materials, for metabolism / equivalent ; provides, nutrients / named nutrients i.e. CPFVM H2O fibre ; in correct / right, quantities / proportions / amounts ; [max 3] A substances fibre – accept roughage and non-starch polysaccharide. A minimum of any three named nutrients A contains (all the) food, groups / types / classes R ‘substances’ A adequate / sufficient R ‘equal’ (ii) age ; sex / gender ; activity / exercise; pregnancy / lactation ; growth / body building ; ambient temperature / climate / weather ; disease / medical condition / illness ; allergy / food intolerance ; size / body mass / build ; [max 3] A weight I height (b) (i) horizontal line at 180 mg per 100 cm3 ; [1] A tolerance of half-square up or down (ii) 60 to 300 minutes Units essential [1] A 240 minutes / 4 hours (iii) increases after time when glucose is ingested, decreases, but stays below or touches 180 / line from b(i) throughout ; [1] (c) insulin secreted / produced / released ; by pancreas ; glucose absorbed (by liver / muscles) ; stored as / converted to , glycogen ; [max 3] [Total:12]

Page 6 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners 3 (a) (i) amylase ; [1] (ii) pH is a factor that influences / affects enzyme activity / AW; to give the optimum pH ; extreme pH could denature enzyme / AW ; [max 1] ORA (b) idea that protease , would break down, enzymes / enzyme 2 ; [1] (c) stable at high temperatures / does not denature at 60 °C / optimum temperature near 60 °C ; [1] I bears / tolerates hot temperatures I heat resistant I ref to denatures > 60 ºC (d) 1 2 3 4 5 6 7 (bacteria grown in) fermenters ; (bacteria provided with) substrate / food (substances) / glucose / minerals / whey / waste substances / nutrients / culture medium / AW ; oxygen / aerobic conditions ; A air bubbled through (bacteria) grow / reproduce / increase in number ; enzymes, secreted / released / AW ; enzymes separated from, bacteria / mixture ; A ref to filtration AVP ; e.g. conditions – 26 °C / pH 5–6 [max 3] A extracted by crushing bacteria (e) extracts more juice / speeds up juice extraction ; pectin converted to sugars ; so juice is sweeter ; cell wall material is removed from juice / pectin digested to soluble product(s) ; so the juice is clearer ; AVP; humans don’t produce pectinase i.e. humans can digest the juice. [max 3] I easier……. [Total:10]

Page 7 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners 4 (a) 1 2 3 4 5 6 7 8 9 (red blood cells) get stuck in capillaries / do not flow smoothly / capillaries blocked; reduce , supply of, oxygen / nutrients ( to tissues / cells / muscles) ; reduce , removal of, carbon dioxide / wastes, (from tissues / cells / muscles) ; ref to respiration (in tissues) ; cause sickle cell crises ; pain ; increased chance of, thrombosis / blood clotting ; death of tissues / cells ; AVP ; [max 4] ignore less haemoglobin A carries less oxygen / nutrients… A carries less carbon dioxide… I reduced life expectancy (b) (i) allele(s) ; [1] (ii) HA , HS + HA , HS ; (HAHA , HAHS , HAHS) HSHS ; [2] Could be in Punnett square A just A and S A just S and S (iii) 0.25 / 25 % / ¼ / 1 in 4 ; [1] I ratios

Page 8 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners (c) (i) 1 2 3 4 5 6 7 8 9 10 malaria, is severe disease / may be fatal ; idea that it is the selective agent / ref to natural selection ; HAHA / homozygous dominant, susceptible to malaria ; HAHS / heterozygous, resistant ; A HSHS resistant ; HAHS survive / HAHA more likely to die before have children ; HAHS have children and pass on, the allele / HS ; (if HAHS x HAHS) 1 in 4 chance of, HSHS / homozygous recessive ; 2 in 4 / ½ , have advantage of resistance to malaria ; AVP ; e.g. ref to malarial parasite / AVP ; e.g. ref to transmission of malaria [max 4] A sickle cell trait / carrier for HSHA throughout the answer R immune (ii) 1 2 3 4 5 6 7 8 9 malaria not very serious / not a severe strain of malaria ; people have other genetic protection from malaria ; malaria has only recently spread to these areas / no malaria before; mutation not occurred in populations of these areas ; people with mutation / have sickle cell allele , have not migrated here ; (majority of) population in Australia has not lived there for long ; came from areas where no malaria, is / was, present ; AVP ; AVP ; [max 2] E.g. Thalassemia A mutation described I gene, for allele [Total:14]

Page 9 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners 5 (a) 1 2 3 4 5 6 7 8 eye, light ; ear, sound / noise ; ear, gravity / acceleration / movement ; tongue, taste / chemicals / flavours in food ; nose, smell / chemicals in the air / odours ; skin, touch / pressure ; skin, temperature ; skin, pain ; [max 3] (b) (i) response / reaction , to stimulus ; occurs without having to, think / use the brain / make decision ; [2] I reflex A not conscious of action until it has happened (ii) 1 2 3 4 5 6 7 8 9 receptor(s) / sensory cells / nerve ending , detects heat / stimulus ; (nervous / electrical) impulses ; generated by (skin) receptor ; travels to spinal cord along sensory neurone(s) ; within spinal nerve ; synapse ; relay / connector / inter–, neurone ; motor neurone to effector / biceps / muscle ; biceps contracts ; [max 5] R messages, signals R spinal cord (iii) fast ; automatic ; protective / defensive / avoid injury ; removes (part of) body from source of danger ; [2] (c) hormones / chemical messengers ; secreted into the blood / which travels in blood ; stimulate target , cells / tissues / organs ; [max 2] A endocrines I endocrine system [Total:14]

Page 10 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners 6 (a) (i) amino acid / protein / RNA / DNA / AW; [1] A named protein, both plant and animal (ii) secondary (consumer) / carnivore / predator ; [1] R third / tertiary (iii) excretion ; [1] (iv) nitrification ; [1] A oxidation (b) 1 2 3 4 5 idea that (fixed) nitrogen is in limited supply ; idea that if not recycled is not available for plants to absorb ; needed for many biological compounds ; (required by organisms to make) amino acids / proteins / DNA / chlorophyll ; for growth / for repair / for enzymes / for genes / AW ; [max 3] (c) 1 2 3 4 5 6 7 9 8 not ideal habitat / not well adapted to habitat / conditions not favourable ; any suitable reason ; e.g. too dry / wrong soil / wrong pH / wider leaves / larger leaf surface (area) (seedlings) eaten by impala / herbivores ; much tastier than grass / better nutritional content ; competition with grasses ; for any resource ; e.g. light / nutrients / minerals / water slow growing ; AVP ; e.g. few seeds produced, lack of suitable pollinators, lack of suitable / required symbiont, soil contains plenty of nitrate (so no advantage to being a nitrogen fixer, because of much animal dung) / poor seed dispersal Connection…lightning and nitrogen in soil ; [max 3] I competition with self A lack of light / minerals / water

Page 11 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0438 31 © Cambridge International Examinations 2013 Answers Marks Guidance for Examiners (d) 1 2 3 4 5 6 7 8 9 10 11 12 general idea of energy loss (in food chain) ; cheetahs are at a higher trophic level (than impala) / impala are the primary consumers / prey ; each cheetah eats many impala; large population of cheetahs cannot be sustained / number of impala controls or determines the number of cheetahs ; hunted / poached (for skins) ; killed by local people as they feed on animals ; reference to balanced ecosystem / food chain / food web; cheetahs do not eat, all impalas / all parts of an impala ‘lose energy’, in respiration / as heat to environment ; and in movement / excretion / egestion / reproduction ; offspring killed / die (while growing) by other predators / their prey AVP ; [max 4] (e) 1 2 3 4 5 6 7 8 idea of interdependence ; if one species is lost others may become extinct ; rely indirectly on plants ; impala eat a variety of plants ; cheetahs eat a variety of other prey animals ; idea of conserving habitats ; to ensure species continue for future generations to, enjoy / use ; biodiversity reference; [max 3] A idea of knock-on effect / AW A tourism [Total:17]