Cambridge A Level Biology 9700 — 2003 Oct/Nov Paper 2 · Variant 1

This document consists of 11 printed pages and 1 blank page. SPA (BR/PW) S56410/2 © UCLES 2003 [Turn over CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level BIOLOGY 9700/02 Paper 2 Structured Questions AS October/November 2003 1 hour Candidates answer on the Question Paper. No Additional Materials are required. 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 in the spaces provided on the Question Paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. Centre Number Candidate Number Name If you have been given a label, look at the details. If any details are incorrect or missing, please fill in your correct details in the space given at the top of this page. Stick your personal label here, if provided. FOR EXAMINER’S USE 1 2 3 4 5 6 TOTAL

2 9700/02/O/N/03 Answer all the questions. Write your answers in the spaces provided. 1 Fig. 1.1 is a photomicrograph of a transverse section of an artery and a vein from a mammal. Fig. 1.1 (a) State three ways, visible in Fig. 1.1, in which the artery differs from the vein. 1 … … 2 … … 3 … …[3] For Examiner’s Use

3 9700/02/O/N/03 [Turn over (b) The lungs contain arteries, veins and capillaries. Explain the role of capillaries in the lungs. … … … … …[3] (c) Describe the effect of tar from cigarettes on the lining of the gaseous exchange system. … … … … … …[3] [Total: 9] For Examiner’s Use

4 9700/02/O/N/03 2 Fig. 2.1 shows the flow of energy through an ecosystem. All the figures are in kJ m–2 year–1. Fig. 2.1 light energy absorbed by producers 1.71 x 106 producers energy trapped by producers and converted into biomass = 87 403 food primary consumers food 3 610 secondary consumers food 135 tertiary consumers decomposers detritus heat loss in respiration 50 303 22 953 19 210 For Examiner’s Use

5 9700/02/O/N/03 [Turn over (a) Calculate how much energy is available to the primary consumers in this ecosystem. …[1] (b) The efficiency of energy transfer between trophic levels is calculated by comparing the energy available to a trophic level with the energy available to the next trophic level. Between secondary and tertiary consumers, this is calculated as follows. energy available to tertiary consumers ––––––––––––––––––––––––––––––––– × 100 % energy available to secondary consumers Use the formula above to calculate the efficiency of energy transfer between the secondary consumers and the tertiary consumers in this ecosystem. … … …[1] (c) In some food webs, individual consumer species feed at different trophic levels. With reference to Fig. 2.1, explain an advantage of this for these consumer species. … … …[2] (d) Explain the role of decomposers in the cycling of carbon and nitrogen in ecosystems. … … … … … …[4] [Total: 8] For Examiner’s Use

6 9700/02/O/N/03 3 Complete the following passage on cholera. Cholera is an acute intestinal infection caused by the bacterium … . It has a short incubation period, from less than one day to five days, and produces a toxin that causes symptoms, such as … that can quickly lead to severe dehydration and death if not treated promptly. Cholera bacteria are transmitted by contaminated … . In highly endemic areas, it is mainly a disease of young children, although breastfeeding infants are rarely affected. Limited stocks of two oral cholera vaccines that provide high-level protection for several months against one strain of cholera have recently become available in a few countries. The vaccine stimulates an … … , involving the lymphocytes in the lining of the gut. The B lymphocytes produce … that act against the cholera bacteria, which tend to remain in the intestines during an infection. [Total: 5] For Examiner’s Use

4 Starch, glycogen and cellulose are all polysaccharides. They are made from monomers that are joined by covalent bonds. (a) Complete the table below to show which of the statements apply to each of the polysaccharides. Fill in each box using a tick (✓) to show that the statement applies and a cross (✗) if it does not. [5] A solution of the enzyme amylase was added to a solution of starch and kept at 25 °C. The starch was broken down by hydrolysis. (b) Explain how you would determine the rate of hydrolysis. … … … … … …[4] [Total: 9] 7 9700/02/O/N/03 [Turn over For Examiner’s Use statement starch glycogen cellulose glycosidic bonds between monomers monomer is β glucose stored within chloroplasts stored in muscle cells exists in two forms – branched and unbranched chains

8 9700/02/O/N/03 5 (a) State the roles of glycoproteins, carrier proteins and cholesterol in the cell surface membrane of an animal cell. glycoproteins … … … carrier proteins … … … cholesterol … … …[4] (b) Fig. 5.1 is a diagram of an animal cell showing the concentrations and direction of movement of an ion (A) and a non-polar molecule (B) on either side of the cell surface membrane. Fig. 5.1 A B key high concentration low concentration nucleus For Examiner’s Use

9 9700/02/O/N/03 [Turn over With reference to Fig. 5.1, explain how A and B cross the cell surface membrane of the cell. A … … … B … … …[4] (c) Describe how particles, such as bacteria, are taken up by phagocytes. … … …[2] (d) Phagocytes contain many lysosomes. State the function of lysosomes in phagocytes. … …[1] [Total: 11] For Examiner’s Use

10 9700/02/O/N/03 6 An athlete exercised for eight minutes. The athlete’s oxygen consumption was measured before, during and after the exercise. The results are shown in Fig. 6.1. Fig. 6.1 (a) Explain why the athlete’s oxygen consumption increased between two minutes and six minutes. … … … …[2] 20 18 16 14 12 10 8 6 4 2 00 2 4 6 8 10 12 14 oxygen uptake/ arbitrary units Period of exercise For Examiner’s Use

11 9700/02/O/N/03 (b) Explain why the athlete’s oxygen consumption took more than four minutes to decrease to resting values after the end of exercise. … … … … … …[4] (c) Heart transplants and coronary by-pass surgery are used in the treatment of heart disease. State two reasons why heart transplants are much less common than coronary by-pass surgery in the treatment of heart disease. 1 … … 2 … …[2] [Total: 8] For Examiner’s Use