Biology Practice Paper

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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level

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*0485738200*

BIOLOGY Paper 2 Structured Questions AS Candidates answer on the Question Paper. Additional Materials: Electronic calculator Ruler (cm/mm)

9700/21
October/November 2009 1 hour 15 minutes

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.

For Examiner’s Use 1 2 3 4 5 6 Total

This document consists of 13 printed pages and 3 blank pages. DC (CW/CGW) 13011/4 © UCLES 2009

[Turn over

2 Answer all the questions.
For Examiner’s Use

1

During an immune response, plasma cells secrete antibody molecules. Fig.1.1 is a diagram of an antibody molecule. The diagram is not complete.

Fig. 1.1 (a) (i) (ii) (iii) Draw a circle around a variable region. Draw in and label the position of the disulfide bonds in the molecule. [1] [1]

Explain the importance of disulfide bonds in protein molecules, such as antibodies. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [3]

© UCLES 2009

9700/21/O/N/09

3 (b) Describe how antibodies provide protection against pathogens. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [4] (c) Other proteins are found in cell surface membranes. Describe three roles of the proteins in cell surface membranes. 1 ....................................................................................................................................... .......................................................................................................................................... 2...
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