CIE Nov 2015 v3 Paper 4 Q7

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16 Section B Answer all the questions in the spaces provided. DNA is an important biochemical molecule. PMT (a) DNA has a double helical structure that consists of two strands linked together. Draw a block diagram of DNA showing two repeat units in each strand. Label all the components, showing and labelling the bonds between the strands. [5] (b) Genetic information is stored in DNA. Outline the main steps in the replication of DNA.[2]UCLES 2015 9701/43/O/N/15<br /> PMT 17 (c) DNA fingerprinting is based on the fact that all humans (apart from genetically identical twins) have different DNA base sequences. This is regularly used to help investigate serious crimes. (i) The first stage of DNA fingerprinting requires a sample of DNA to be broken down into shorter fragments. What could be used to carry out this fragmentation?[1] (ii) Name the analytical technique used to separate these short fragments.[1] (iii) After the fragments have been separated, what could the DNA fingerprint be treated with to reveal the position of the bands?[1] (iv) A sample of blood, thought to be from the suspect, was found at a crime scene. The DNA of the blood sample, and that of four possible suspects, was analysed. blood stain suspect suspect suspect suspect Based on this evidence, circle the suspect who should be arrested. suspect 1 suspect 2 suspect 3 suspect 4 [1] [Total: 11]UCLES 2015 9701/43/O/N/15 [Turn over<br />

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