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

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*0485738200*

BIOLOGY Paper two Structured Queries AS Prospects answer on the Question Paper. Additional Supplies: Electronic calculator Ruler (cm/mm)

9700/21

October/November 2009 one hour 15 minutes

BROWSE THESE INSTRUCTIONS FIRST Compose your Middle number, applicant number and name inside the spaces supplied at the top of this site. Write in dark blue or black pen. You could use a very soft pencil for just about any diagrams, graphs or difficult working. Tend not to use favorites, paper fasteners, highlighters, stuff or correction fluid. TEND NOT TO WRITE IN DIFFERENT BARCODES. Answer all questions. Towards the end of the exam, fasten all your work safely together. The amount of marks is given in brackets [ ] at the end of each and every question or part issue.

For Examiner's Use you 2 a few 4 5 6 Total

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

[Turn over

two Answer the questions.

For Examiner's Use

you

During an immune response, plasma skin cells secrete antibody molecules. Fig. 1 . you is a picture of an antibody molecule. The diagram is usually not complete.

Fig. 1 ) 1 (a) (i) (ii) (iii) Bring a group around a varying region. Attract and packaging the position of the disulfide bonds in the molecule. [1] [1]

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

В© UCLES 2009

9700/21/O/N/09

three or more (b) Identify how antibodies provide protection against pathogens............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. [4] (c) Various other proteins are simply in cellular surface walls. Describe 3 roles in the proteins in cell area membranes. 1 ................................................................................................................................................................................................................................................................................. 2 ...

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