Cambridge A Level Biology 9700 — 2002 Oct/Nov Paper 2 · Variant 1

This question paper consists of 11 printed pages and 1 blank page. SP (SM/JB) S26225/3 © CIE 2002 [Turn over CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level BIOLOGY 9700/2 PAPER 2 OCTOBER/NOVEMBER SESSION 2002 1 hour Candidates answer on the question paper. No additional materials are required. TIME 1 hour INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page. Answer all questions. Write your answers in the spaces on the question paper. All working for numerical answers must be shown. INFORMATION FOR CANDIDATES The intended number of marks is given in brackets [ ] at the end of each question or part question. Candidate Centre Number Number Candidate Name FOR EXAMINER’S USE 3 2 1 4 TOTAL 6 5

2 9700/2/O/N/02 Answer all the questions. Write your answers in the spaces provided. 1 Fig. 1.1 is a drawing made from an electron micrograph showing a cross-section of an alveolus and two adjacent capillaries. Fig. 1.1 (a) Calculate the magnification of Fig. 1.1. Show your working and express your answer to the nearest whole number. … …[2] (b) With reference to Fig. 1.1, describe the process of gaseous exchange in the alveolus. … … … … …[4] 10 m fibre-secreting cell alveolar air space For Examiner’s Use

3 9700/2/O/N/02 [Turn over Allergies, such as asthma, are the result of an over reaction by the immune system to a harmless antigen. When people suffer from an asthma attack, their immune systems respond to the presence of a specific antigen by producing antibodies. These antibodies attach to the surface of mast cells in the airways causing these cells to release histamine. This hormone-like chemical stimulates inflammation in the lining of the airways, which then makes breathing very difficult. (c) State the name of the cells of the immune system that secrete antibodies. …[1] (d) Describe the changes that occur in airways, such as the bronchioles, during an asthma attack that make breathing difficult. … … … … …[3] [Total : 10] For Examiner’s Use

4 9700/2/O/N/02 2 Fig. 2.1 shows the reaction to form triglycerides. Fig. 2.1 (a) With reference to Fig. 2.1, (i) name the molecules A and B; A … B …[2] (ii) state the name of the reaction shown. …[1] (b) Animals and plants store triglycerides as energy reserves. Explain the advantages of storing triglycerides as energy reserves rather than carbohydrates, such as starch. … … …[2] CH2OH (CH2)n CH3 HO C O CH OH CH2OH (CH2)n CH3 HO C O (CH2)n CH3 HO C O (CH2)n CH2 CH2 CH CH3 O C O (CH2)n CH3 O C O (CH2)n CH3 O C O + B A + 3 H2O For Examiner’s Use

5 9700/2/O/N/02 [Turn over Overconsumption of fat in the diet may lead to obesity. (c) State how it is determined whether a person is sufficiently overweight to be classed as obese. … … …[1] (d) Outline two risks to health of being obese. 1. … 2. …[2] [Total : 8] For Examiner’s Use

6 9700/2/O/N/02 3 (a) Explain why transpiration is the inevitable consequence of gaseous exchange in land plants. … … … … …[3] Fig. 3.1 shows some of the cells from the lower part and under surface of a leaf. The water potentials of three cells, A, B and C, are shown. Fig. 3.1 (b) Explain how water moves from the xylem vessel to cell B. … … … …[3] (c) Draw labelled arrows on Fig. 3.1 to show the direction in which (i) water flows between the cells A, B and C; [2] (ii) water vapour diffuses. [1] B A –1000 kPa –800 kPa C –1200 kPa xylem vessel For Examiner’s Use

7 9700/2/O/N/02 [Turn over (d) State two features of xerophytic plants that help to reduce the loss of water by transpiration from their leaves. 1. … … 2. … …[2] [Total : 11] For Examiner’s Use

8 9700/2/O/N/02 4 Enzymes are globular proteins that catalyse specific reactions. (a) Explain how enzymes catalyse specific reactions. … … … … … …[3] (b) Restriction enzymes cut DNA into fragments. They cut at specific sites determined by the sequence of bases. Fig. 4.1 shows the base sequences cut by three restriction enzymes and a section of DNA cut by one of these enzymes. restriction enzyme DNA sequence HindIII A AGCTT EcoRI G AATTC BamHI G GATCC section of DNA TACGAATTCGTAA ATGCTTAAGCATT TACG AATTCGTAA ATGCTTAA GCATT Fig. 4.1 (i) Identify the restriction enzyme that has cut the section of DNA shown in Fig. 4.1. …[1] (ii) State the name given to the unpaired base sequences that remain after DNA has been cut by the three restriction enzymes shown in Fig. 4.1. …[1] For Examiner’s Use

9 9700/2/O/N/02 [Turn over (c) Human genes may be cloned by inserting lengths of DNA into bacteria. This may be carried out by inserting the DNA into a plasmid. Explain how lengths of DNA, cut by restriction enzymes, are inserted into plasmids. … … … … … …[3] [Total : 8] For Examiner’s Use

10 9700/2/O/N/02 5 (a) Describe how the malarial parasite is normally transmitted from an infected person to an uninfected person. … … … …[2] Fig. 5.1 is drawn from an electron micrograph of a red blood cell taken from a person suffering from malaria. Fig. 5.1 (b) State two features, visible in Fig. 5.1, that indicate that the malarial parasite is eukaryotic. 1. … 2. …[2] (c) Outline the likely effects on the body of the presence of malarial parasites in red blood cells. … … … …[3] [Total : 7] red blood cell cytoplasm malarial parasite For Examiner’s Use

11 9700/2/O/N/02 6 Complete the following passage. During strenuous exercise, muscles often do not receive sufficient oxygen to support aerobic respiration. As a result, muscles carry out … respiration and produce … , which diffuses into the blood. Most is then absorbed by the … , which respires it to form carbon dioxide and water or uses it to form glucose. The volume of oxygen absorbed by the lungs does not return to normal immediately after strenuous exercise because the body has to repay an oxygen … . Exercise that uses the cardiovascular and gaseous exchange systems is termed … exercise. Improvements in fitness of the cardiovascular system can be followed by measuring the decrease in the … pulse rate. [6] [Total : 6] For Examiner’s Use

CAMBRIDGE INTERNATIONAL EXAMINATIONS NOVEMBER 2002 GCE Advanced Subsidiary Level UNIVERSITY of CAMBRIDGE Local Examinations Syndicate

rc Page 1 Mark Scheme Sylabus | Paper AS Level Examinations — November 2002 9700 ~[ 2 Question 1(@) (b) ©) C)) Expected Answers , * Marks correct measurement of scale bar used as basis for finding magnification with appropriate working; A. 1.7- 1.9 cm for length of scale bar e.g. xxmm x 1 000 10 = Xxxxx, A. any fig. between x 1700 - 1900 2 N.B. award one mark if correct answer given without any working shown movement of air / oxygen into alveoli; concentration gradient (between alveolar air and blood) / AW (for either oxygen or carbon dioxide); . oxygen dissolves in film of liquid / surfactant fluid; diffusion; oxygen and carbon dioxide exchanged (idea of); squamous / alveolar / pavement epithelium; } A. alveolar/capillary endothelium (of capillary); } wall once ted blood cell; ref to short diffusion distance into capillary / one cell thick / 2-3 um; R. thin wall 4 max B lymphocyte / B cell / plasma cell; 1 secretion of mucus by, goblet cells / glands; fluid leaks from capillaries; R. capillaries permeable contraction of (smooth) muscle / muscle spasm; congestion / blocking / narrowing / AW, of airways / bronchioles; increased resistance to air flow / air flow restricted; 3 max [Total: 10]

Page 2 Mark Scheme : -_| Syllabus | Paper | I AS Level Examinations — November 2002 9700 2 Question Expected Answers : Marks 2 (a) (@ A glycerol; B fatty acid; 2 (ii) condensation / esterification / ester bond formation; 1 (b) more energy released / stored per gram / unit / given mass; R. per mole . 37k} v17kJ; A. (37-40 kJ) v(15-17kJ) A. equivalent calorific values if calculated fats are highly reduced; more hydrogens / fewer oxygens / higher carbon to hydrogen tatio / more CH bonds; release / yield more energy when respired / oxidised; 2 max (ce) 20% or more above the recommended weight / mass for height 7 BMI / Body Mass Index/ masskg _ greater than 30; (height in m)? A. within range (30-40) 1 (d) diabetes; coronary heart disease / atherosclerosis / cardiovascular disease / stroke / AW; hypertension / high blood pressure; cancer; arthritis / joint problems; hernia; varicose veins; gallstones; increased risk during surgical operations; 2 max [Total: 8]

Page 3 | Mark Scheme -_| Syllabus |. Paper AS Level Examinations — November 2002 9700 Question 3 (a) (b) © (@) @ (ii) Expected Answers ; . Marks stomata (are open) for gas exchange / CO: / O> uptake / release (for photosynthesis and respiration); large surface area / many cell surfaces; in spongy mesophyll; (so) evaporation from (damp) walls (into air spaces); (and) diffusion / loss down a conc. gradient, of water vapour; to air / atmosphere via stomata; 3 max ref cohesion / tension ( in context of xylem); hydrogen bonds; : through (freely permeable) cell wall / apoplast pathway; through partially permeable membrane / AW (in context of cell B); osmosis; down water potential gradient / high / less negative to low / more negative water potential / AW; 3 max Bto Aand C; AtoC; 2 from cell surfaces through air through stomata; 1 small leaves / small surface area / reduction of leaf surfaces / needle shaped leaves; R. spines rolled / curled leaves; R. folded shed leaves; sunken stomata / stomata in pits / crypts / grooves; stomata surrounded by hairs / hairy leaves; waxy / impermeable / thick, cuticle / thick leaves qualified; 2 max [Total: 11]

Page 4 Mark Scheme : __| Syllabus | Paper AS Level Examinations — November 2002 9700 | 2 Question 4@ (b) @ (c) (ii) Expected Answers , . Marks active site; specific shape / configuration / conformation (in ref to active site); complementary to substrate / exact / perfect fit (between substrate and active site); combine to form enzyme-substrate / ES complex; mould around substrate / substrate alters shape of active site (induced fit); R. induced fit unqualified ref to temporary bonds / named bond; 3 max EcoR1; . 1 sticky ends; 1 plasmid DNA cut with same restriction enzyme / endonuclease; DNA and plasmid mixed together / AW; R. inserted tef complementary / base pairing / C and G on sticky ends pair up; tef to hydrogen bonding; ligase forms bonds between sugar and phosphate / phosphodiester bonds; 3 max _[Total: 8]

Page 5 Mark Scheme __| Syllabus | Pa AS Level Examinations —- November 2002 9700 2 Question 5 @ (b) (©) Question 6 (a) Expected Answers ‘ - Marks female, Anopheles, mosquito sucks blood from (infected) person; R. bites parasites / plasmodia / pathogens reproduce / multiply / form gametes (in mosquito); injects / inserts / pumps in / (saliva) with parasites / transmits / transfers parasite as feeds / in saliva (into uninfected person); . 2 max malarial parasite has nucleus / nuclear membrane / nuclear envelope; mitochondria; . membranous organelles; R. ribosomes R. nucleolus 2 max fewer red blood cells / number of r.b.cs. reduced; due to bursting / rupturing of r.b.c. / parasite destroys r.b.cs.; less haemoglobin; less oxygen transported / reduced ability to carry oxygen; waste excreted / toxins released (by parasite); symptom; A. one from - anaemia / fatigue / tiredness / muscular pain / headaches / nausea / fever / high temp. and sweating / inability to control temp. / shivering 3 max [Total: 7] Expected Answers Marks anaerobic; R. inaerobic, R. unaerobic lactate / lactic acid; liver; debt; R. deficit aerobic; resting; 6 [Total: 6] Total mark for paper = 50