Cambridge A Level Biology 9700 — 2010 May/June Paper 2 · Variant 2

This document consists of 16 printed pages and 4 blank pages. DC (CW/DJ) 25487/3 © UCLES 2010 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name in the spaces provided at the top of this page. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs, or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. 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. * 5 8 3 2 6 2 7 0 7 9 * BIOLOGY 9700/22 Paper 2 Structured Questions AS May/June 2010 1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. For Examiner’s Use 1 2 3 4 5 6 Total

2 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use Answer all the questions. 1 Fig. 1.1 is a diagram of an electron micrograph of a plant cell. Fig. 1.2 is a diagram of an electron micrograph of an animal cell. Both diagrams are incomplete. Fig. 1.1 Fig. 1.2 (a) Explain how Fig. 1.1 can be identified as a plant cell. … … … …[2]

3 9700/22/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (b) Some organelles are missing from Figs 1.1 and 1.2. Information about these organelles is shown in the shaded boxes in Table 1.1. Complete the empty boxes in Table 1.1 by adding the correct information below each column heading. Table 1.1 name of organelle diagram of organelle(s) as seen under the electron microscope (not to scale) one function of organelle cell type(s) in which organelle is located mitochondrion animal and plant assemble microtubules to produce the mitotic spindle rough endoplasmic reticulum protein synthesis Golgi apparatus animal and plant photosynthesis plant only [8] [Total: 10]

4 9700/22/M/J/10 © UCLES 2010 BLANK PAGE

5 9700/22/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use 2 Fig. 2.1 is a diagram of a vertical section through a healthy mammalian heart. Fig. 2.1 (a) (i) Label the two chambers of the heart by writing in the boxes provided on Fig. 2.1. [1] (ii) State two ways in which the composition of blood entering the right atrium is different to blood entering the left atrium. 1. … … 2. … …[2]

6 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use Some people are born with structural defects of the heart and its associated blood vessels. This is known as congenital heart disease. The dotted circles labelled A to G on Fig. 2.2 show some areas that are affected by different types of congenital heart disease. G A B C D F E Fig. 2.2 The structural defects causing four types of congenital heart disease are described below: • patent ductus arteriosus – a link between the pulmonary artery and aorta fails to close after birth • pulmonary stenosis – a narrowing of the semilunar valve of the pulmonary artery • coarctation of the aorta – a localised narrowing of the aorta • ventricular septal defect – a hole in the septum between the ventricles. (b) Match the one correct area from A to G on Fig. 2.2 with each of the congenital heart diseases. The first one has been completed for you. A patent ductus arteriosus … pulmonary stenosis … coarctation of the aorta … ventricular septal defect … [3]

7 9700/22/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (c) Suggest and explain how the flow of blood in a person with patent ductus arteriosus differs from that of a person with a healthy heart. … … … … … …[3] [Total: 9]

8 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use 3 The HIV/AIDS pandemic has had a very large impact on life expectancy in many African countries. Table 3.1 shows estimated data for seven African countries for • the average life expectancy of an individual born in 2002 • the percentage of the population testing positive for HIV in 2002 • the average life expectancy of an individual born in 2002 if there was no HIV/AIDS pandemic. Table 3.1 country life expectancy / years percentage of population testing positive for HIV without HIV/AIDS with HIV/AIDS Botswana 72.4 33.9 35.8 Côte d’Ivoire 55.6 42.8 10.8 Kenya 65.6 45.5 14.0 Malawi 56.3 38.5 16.0 South Africa 66.3 48.8 19.9 Zambia 55.4 35.3 20.0 Zimbabwe 69.0 40.2 25.1 (a) Using the ‘without HIV/AIDS’ and ‘with HIV/AIDS’ data shown in Table 3.1, calculate the percentage decrease in life expectancy for Botswana. Show your working and give your answer to the nearest whole number. Answer = … % [2]

9 9700/22/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (b) Suggest two reasons for the differences shown in estimated life expectancy without HIV/AIDS between the different African countries. 1. … … … 2. … … …[2] (c) After studying the data in Table 3.1, a student concluded that: “There is a correlation between the percentage of the population testing positive for HIV and the decrease in estimated life expectancy with HIV/ AIDS.” (i) With reference to Table 3.1, explain why the data do not fully support the student’s conclusion. … … … … … …[2] (ii) List two factors in the prevention and control of HIV/AIDS that would help to improve average life expectancy in the African countries shown in Table 3.1. 1. … … 2. … …[2]

10 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use (d) A person who is confirmed as HIV-positive has tested positive for the presence of antibodies to HIV. Outline the events that occur in a newly-infected person, which lead to the production of antibodies to HIV. … … … … … … … … … …[5] [Total: 13]

11 9700/22/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use 4 Fig. 4.1 shows the primary structure of a lysozyme molecule, an enzyme found in tears, saliva and in lysosomes. S S S S S S S S 30 40 50 60 80 70 100 90 129 110 1 10 20 120 N H H amino end carboxyl end C OH O Fig. 4.1 (a) (i) Explain what is meant by the term primary structure. … … …[1]

12 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use (ii) The molecular structure of the first two amino acids of lysozyme, lysine and valine, is shown below. Use the space to show how these amino acids become linked in a condensation reaction. NH2 C C OH O N H H (CH2)4 H lysine H3C CH3 C C OH O N H H CH H valine [3] (b) Proteins, such as the enzyme lysozyme, have a secondary structure and a tertiary structure. (i) Describe the secondary and tertiary structure of an enzymatic protein, such as lysozyme. secondary … … … … tertiary … … … … … … …[5]

13 9700/22/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (ii) State why it is important for enzymes, such as lysozyme, to possess a tertiary structure. … …[1] (c) Some people have a rare disease caused by a single change in the DNA nucleotide sequence of the gene coding for lysozyme. The change leads to the formation of an insoluble protein that has a different structure to the normal soluble lysozyme molecule. Suggest how a change in the gene can lead to the differences observed between the normal lysozyme and the changed lysozyme. … … … … … …[3] [Total: 13]

14 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use 5 Fig. 5.1 is a diagram of part of the human gas exchange system. A B C D Fig. 5.1

15 9700/22/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (a) Complete the table to show the distribution of the structural features within the parts of the gas exchange system, A to D, shown in Fig. 5.1. Use a tick (✓) if the feature is present and a cross (✗) if the feature is absent. Some of the boxes have been completed for you. structure features cartilage ciliated epithelium elastic fibres goblet cells smooth muscle A ✓ ✓ B ✓ C ✓ ✓ D ✗ ✗ [4] (b) Explain the role of goblet cells and cilia in the maintenance of a healthy gas exchange system. goblet cells … … … … … cilia … … … … …[4] [Total: 8]

16 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use 6 When investigating ecosystems, food chains and food webs are constructed. Read the passage below about trophic relationships on one of the Galapagos Islands. Marine iguanas feed on kelp, which grows attached to rocks in shallow waters. Kelp is a photosynthetic organism. Further inland, xerophytes are grazed upon by land iguanas. A great diversity of herbivorous insects, including many species of short-horned grasshoppers, feed on the xerophytes. An analysis of the gut contents of lava lizards reveals that these insects are prey for the lizards. The lizards are preyed upon by Galapagos snakes. The snakes also hunt grasshoppers and newly hatched iguanas. The Galapagos hawk has a varied diet and catches animals such as Galapagos snakes, short-horned grasshoppers, small lava lizards and newly hatched iguanas. (a) Complete Fig. 6.1 to make a food web by: • filling in the blank boxes with the names of the organisms • adding arrows to show the direction of energy flow between all the different links in the food web. [4]

17 9700/22/M/J/10 © UCLES 2010 For Examiner’s Use galapagos hawk xerophyte kelp land iguana marine iguana Fig. 6.1 (b) State which of the organisms in Fig. 6.1 are the producers. Explain your choice. … … … … …[3] [Total: 7]

18 9700/22/M/J/10 © UCLES 2010 BLANK PAGE

19 9700/22/M/J/10 © UCLES 2010 BLANK PAGE

20 9700/22/M/J/10 © UCLES 2010 BLANK PAGE 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.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2010 question paper for the guidance of teachers 9700 BIOLOGY 9700/22 Paper 2 (AS Structured Questions), maximum raw mark 60 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 must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 22 © UCLES 2010 1 (a) plant cell because presence of cell wall ; A cellulose cell wall R incorrect cell wall materials plasmodesma ; A plasmodesmata tonoplast ; A vacuolar membrane large/central, vacuole ; ignore permanent [2 max] (b) name of organelle diagram of organelle(s) as seen under the electron microscope (not to scale) one function of organelle cell type(s) in which organelle is located all 3 for one mark oval/circular shape and two membranes close together and inner membrane infolded as two or more cristae ; aerobic respiration/ATP, production/synthesis ; A oxidative phosphorylation A ref. β oxidation fats A ref. urea/ornithine cycle R any answer that refers to synthesis/production, of energy centrioles ; A centriole A centrosome animal ; both for one mark two membranes and ribosomes on external surface ; R if ribosomes are excessively large animal and plant/both ; processing/modification/AW/ packaging, of, proteins/ molecules ; A description of modification e.g. glycosylation A production of, secretory/ Golgi, vesicles A production of lysosomes R protein synthesis chloroplast ; [8] [Total: 10]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 22 © UCLES 2010 2 (a) (i) right, atrium/auricle and left ventricle ; correctly labelled left hand side box right hand side box [1] (ii) right atrium has (ora for left atrium) lower, concentration/partial pressure/AW, of, oxygen ; R no oxygen A (right) deoxygenated blood (versus oxygenated blood) A higher saturation of haemoglobin with oxygen higher concentration/AW of, hydrogen carbonate ions/carbon dioxide ; A more carbaminohaemoglobin higher concentration of water molecules/high(er) water potential/less negative water potential ; higher concentration/AW, of glucose ; [2 max] (b) reject if more than one letter for each disease pulmonary stenosis = G ; coarctation of the aorta = D ; ventricular septal defect = F ; [3] (c) accept ora where relevant suggest 1 blood flows from aorta to pulmonary artery ; 2 increased volume of / more, blood to lungs ; A blood to lungs at higher pressure 3 oxygenated and deoxygenated mix ; 4 oxygenated blood / blood from aorta, to lungs ; explain (why blood flows from aorta to pulmonary artery) 5 left ventricle thicker wall (than right ventricle) ; 6 (so) contraction generates greater force (than right ventricle)/AW ; 7 higher pressure in aorta (than pulmonary artery) ; [3 max] [Total: 9] 3 (a) 53 % ;; 2 marks for correct answer max 1 mark for correct calculation but, no/incorrect, answer or not to nearest whole number 72.4 – 33.9 = 38.5 (38.5 / 72.4) x 100 = 53.18 / 53.2 [2]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 22 © UCLES 2010 (b) R greater wealth unless linked to points below any two valid reasons e.g. accept answers written as ora 1 more educated population ; in context of health 2 better/greater access to, health care/AW ; 3 higher level of preventive medicine ; e.g. immunisation programmes 4 better diet ; A ref. to less malnourished A ref. to access to food supplies 5 greater access to, therapeutic medicines/drugs ; A antibiotics 6 better/less overcrowded, housing/living conditions ; 7 better, sanitation/sewage treatment ; 8 greater access to uncontaminated drinking water ; R clean water unqualified 9 fewer, fatal diseases/AW ; 10 ref. to effects of, civil war/war ; 11 ref. to natural disaster ; [2 max] (c) (i) rank of % positive (of countries) is different to rank of difference in decrease in life expectancy ; data quote to support ; e.g. Kenya 6th highest % positive but 3rd highest decrease in life expectancy S. Africa 4th highest % positive but 6th highest decrease in life expectancy countries with, similar/same, decrease (in life expectancy) have different % positive ; data quote to support ; e.g. Malawi 17.8 years decrease, 16%, cf South Africa 17.5 years, 19.9% Kenya 20.1 years, 14%, cf Zambia 20.1 years, 20% ; with ref. to decrease in life expectancy and % positive Kenya, does not fit general trend/AW ; South Africa, does not fit general trend/AW ; data quote to support ; e.g. Kenya larger decrease than, Malawi/South Africa, but lower % positive Kenya 20.1 years decrease but only 14.0 %, compared to, Malawi 17.8 with 16.0%/ South Africa 17.5 with 19.9 % ; [2 max] (ii) any two relevant factors e.g. 1 anti HIV drug therapy/AW ; 2 ref. to treatment of AIDS-related diseases ; 3 ref. to education to prevent, transmission/spread ; 4 use/provide free, condoms/femidoms ; A dental dams 5 avoid promiscuity ; A one sexual partner 6 HIV mothers avoid breast feeding ; 7 heat treat/screen, blood (for transfusion) ; 8 needle-exchange schemes/AW ; A ref. to sterile syringes 9 use of sterile equipment, qualified e.g. in surgery/tattooing/piercing ; 10 testing for HIV status/contact tracing ; 11 ref. to vaccine development ; [2 max]

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 22 © UCLES 2010 (d) 1 primary/immune, response ; 2 ref. specificity; in correct context 3 (HIV/virus) antigens ; 4 antigen presentation/antigen presenting cell/APC/described ; 5 clonal selection/described ; e.g. recognition of/binding to, antigen by, B-lymphocyte 6 sensitisation/activation/described ; e.g. cell growth or cellular changes 7 clonal proliferation/formation of clone/mitosis/cell division/AW ; 8 B-lymphocytes/B-cells/plasma cells, synthesise/produce/secrete/release, antibody ; 9 T(helper)-lymphocyte response described ; e.g. cytokine production ignore ref. to T killer cells [5 max] [Total: 13] 4 (a) (i) (describes the) sequence of amino acids (in a polypeptide chain) ; A order/arrangement [1] (ii) H2O/water, released ; (correct) bond formation between (lysine) carboxyl group and (valine) amino group ; dipeptide (of lysine and valine) and formed with correct structural formula ; [3] (b) (i) secondary 1 regular order/pattern, based on H-bonds ; 2 between CO– group of one amino acid and NH– group of another ; 3 alpha-helix and β-pleated sheet ; tertiary to max 4 1 folding coiling ; 2 interactions between, R groups side chains ; 3 two correctly named bonds ; e.g. hydrogen bonds, disulfide, bonds/bridges, ionic bonds, hydrophobic interactions 4 further description of bonds ; e.g. disulfide between cysteine (S–H) groups hydrogen between polar groups (NH– and CO–) ionic between ionised amine and carboxylic acid groups hydrophobic interactions between non-polar side chains 5 ref. active site, specific/precise, shape ; 6 ref. globular/AW, shape ; A spherical/ball 7 ref. amino acids with, hydrophilic/polar, R groups facing to outside ; ora [5 max] (ii) enables (protein to) function/AW ; A enables antimicrobial action/AW A biological catalyst, qualified provides active site ; qualified ref. to specificity ; [1 max] (c) altered, (mRNA) codon(s)/triplet(s) ; A named type of mutation changed/AW, amino acid(s) ; ref. to effects of stop codon ; e.g. shortened polypeptide chain different, primary structure/described ; A ref. to differences in, transcription/translation ref. to different properties of, R group/side chain (of normal v replaced amino acid) ; altered tertiary structure/AW ; A different R group interactions A change/loss of, active site idea of globular to fibrous change/hydrophilic R groups no longer to outside ; [3 max] [Total: 13]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 22 © UCLES 2010 5 (a) one mark for each correct row ; ; ; ; cartilage ciliated epithelium elastic fibres goblet cells smooth muscle A ✓ ✓ ✓ B ✓ ✓ ✓ ✓ C  ✓ ✓ D  ✓  [4] (b) goblet cells to max 3 synthesise/produce/secrete/release, mucus ; mucus, sticky/AW ; (mucus) traps/AW, pathogens/AW , dust/particles/AW, pollen ; A named organism types/microorganisms R cilia traps increased secretion when, inflamed / infection ; qualified ref. to role of mucus ; e.g. increases distance (e.g. of pathogen) to reach (epithelial) cells acts as barrier/prevents, entry/attachment to, cells prevent, infections/pathogens reaching alveoli allow once only in either section cilia to max 3 waft/move/AW, mucus ; synchronous/metachronal, rhythm ; AW movement towards back of throat for, swallowing/coughing out ; qualified ref. to role of cilia in health ; e.g. ref. to, normal air flow/ventilation/keeping airways clear [4 max] [Total: 8]

Page 7 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9700 22 © UCLES 2010 6 (a) Galalapagos hawk land iguana marine iguana xerophyte kelp animals in correct boxes ; all five animals to hawk ; all animals except hawk to snake ; (only) short-horned grasshopper to lava lizard xerophyte to short-horned grasshopper and land iguana ; kelp to marine iguana max 3 if all correct but one arrow head missing max 2 if arrow heads, mixed in incorrect direction/missing [4] (b) kelp and xerophytes ; allow ecf for next two mps if only one organism both, photosynthetic/autotrophic/fix carbon/AW ; A both have chlorophyll both are, at the start of the food web/at the first trophic level/the source of energy to rest of food web/AW ; [3] [Total: 7] Galapagos snake lava lizard short-horned grasshopper