GCSE Additional Applied Sc Jan 2008 Scientific Detection Paper B

INSTRUCTIONS TO CANDIDATES • Write your name in capital letters, your Centre Number and Candidate Number in the boxes above. • Use blue or black ink. Pencil may be used for graphs and diagrams only. • Read each question carefully and make sure that you know what you have to do before starting your answer. • Answer all the questions. • Do not write in the bar codes. • Do not write outside the box bordering each page. • Write your answer to each question in the space provided. INFORMATION FOR CANDIDATES • The number of marks for each question is given in brackets [ ] at the end of each question or part question. • The total number of marks for this paper is 36. FOR EXAMINER’S USE Qu. Max. Mark 1 5 2 5 3 10 4 11 5 5 TOTAL 36 GENERAL CERTIFICATE OF SECONDARY EDUCATION A325/02 TWENTY FIRST CENTURY SCIENCE ADDITIONAL APPLIED SCIENCE A Scientific Detection (Higher Tier) MONDAY 21 JANUARY 2008 Afternoon Time: 45 minutes Candidates answer on the question paper. Additional materials: Calculator Pencil Ruler (cm/mm) H * C U P /T 4 3 5 6 1 * This document consists of 11 printed pages and 1 blank page. SP (MML 15405 1/07) T43561/4 © OCR 2008 [M/103/3781] OCR is an exempt Charity [Turn over2 © OCR 2008 Answer all the questions. 1 A burglar breaks into a house. He takes off his shoes and wears gloves so as not to leave any clues. However, he leaves a footprint behind. (a) Identify two important features of the image that the police may want to record. You may label the diagram above if you wish. .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................ [2] (b) The police take measurements of the footprint. second toe scale 1 division = 4 cm Estimate the width of the burglar’s second toe print. ........................................ [1]3 [Turn over © OCR 2008 (c) Give four examples of ways in which the police may record information from the scene of the crime. .................................................................................................................................................. .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................ [2] [Total: 5]4 © OCR 2008 2 Petra works in a laboratory. She uses this standard procedure to set up a light microscope. step 1 Prepare the microscope slide. step 2 Switch on the lamp. step 3 Place the slide on the stage under the clips. step 4 Select and position an objective lens. step 5 Lower the objective lens close to the slide, then raise slowly until the image is in focus. step 6 Take photographs of the image. (a) Why did Petra switch on the lamp? ............................................................................................................................................ [1] (b) Why did Petra place the slide under the clips? ............................................................................................................................................ [1] (c) Why did Petra need to select an objective lens? ............................................................................................................................................ [1] (d) Petra lowers the objective lens before looking through the microscope and then raises it. Explain why. .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................ [2] [Total: 5]5 [Turn over © OCR 2008 3 Scientists sometimes use light microscopes when collecting evidence. (a) How does the microscope help you to see more detail? Put a tick (✓) in the box next to the best answer. magnification resolution increases decreases no change increases increases increases decreases decreases increases no change decreases increases [1]6 © OCR 2008 (b) A forensic scientist looks at a human hair through a microscope. She takes three different photographs. A B C (i) Which photograph, A, B or C, has the greatest magnification? ......................................... [1] (ii) Which photograph, A, B or C, has the greatest resolution? ......................................... [1] (c) Look at the diagram showing a human hair growing in skin. gland shaft pore sweat gland blood capillaries muscle follicle root Use information from the diagram to label two features on the following photograph. [2] © Steve Gschmeissner /Science Photo Library © Steve Gschmeissner /Science Photo Library7 [Turn over © OCR 2008 (d) For a photograph of a human hair, the scientist uses an eyepiece lens of ×5 and an objective lens of ×15. Calculate the magnification of the image. Show your working. magnification = × ......................................................... [2] (e) Even greater detail can be obtained using an electron microscope. Look at the diagram of an atom. (i) Put a ring around an electron. [1] (ii) Explain fully why it is called an electron microscope. .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [2] [Total: 10]8 © OCR 2008 4 A student uses paper chromatography to identify unknown sweeteners found in five different drinks. solvent front Rf value with chosen solvent sweetener ABCD 0.6 0.2 0.8 0.4 start line X 1 2 3 drinks 4 5 (a) The chromatogram above is drawn actual size. (i) Use your ruler to measure the distance moved by the solvent. .....................................................cm [1] (ii) Use your ruler to measure the distance moved by sweetener X. .....................................................cm [1] (b) The Rf value of the sweetener X can be calculated using the following formula. Rf = distance moved by sweetener distance moved by solvent (i) Use the equation to find the Rf value of sweetener X. Rf of sweetener X = ......................................................... [1]9 [Turn over © OCR 2008 (ii) Which of the sweeteners, A, B, C or D, is sweetener X? .......................................................... [1] (c) State which two drinks contain a mixture of sweeteners. .................................................................. and .................................................................. [1] (d) State which drink contains sweeteners not listed in the table at the beginning of the question. .......................................................... [1] (e) Explain why some sweeteners travel further up the paper than others. .................................................................................................................................................. ............................................................................................................................................ [1] (f) The same drinks were tested by a food scientist. (i) The food scientist included the known sweeteners on her chromatogram. Explain why. .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [2] (ii) The food scientist used thin layer rather than paper chromatography. Explain the advantages of using thin layer chromatography. .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [2] [Total: 11]10 © OCR 2008 5 Public laboratories have a system of accreditation to ensure reliability. (a) To gain accreditation, laboratories have to carry out proficiency tests. Explain the purpose of a proficiency test. .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................ [1] (b) What can be done to ensure that different laboratories produce comparable results? .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................ [1] (c) Public laboratories also try to use good laboratory practice. State how each of the following improves laboratory practice. (i) maintaining and checking equipment .......................................................................................................................................... .................................................................................................................................... [1] (ii) training staff .......................................................................................................................................... .................................................................................................................................... [1] (iii) keeping to Health & Safety regulations .......................................................................................................................................... .................................................................................................................................... [1] [Total: 5] END OF QUESTION PAPER11 © OCR 2008 BLANK PAGE PLEASE DO NOT WRITE ON THIS PAGE12 © OCR 2008 PLEASE DO NOT WRITE ON THIS PAGE Copyright Acknowledgements: Q.3 image © Steve Gschmeissner /Science Photo Library Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (OCR) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. OCR is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.