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GCE JAN 2009 : (AS 1) Cell Biology - Revised

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Sp ec Ne i w ca tio n Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education January 2009 Biology assessing Module 1: Cell Biology AB111 Assessment Unit AS1 [AB111] WEDNESDAY 14 JANUARY, AFTERNOON TIME 1 hour 30 minutes. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number in the spaces provided at the top of this page. Write your answers in the spaces provided in this question paper. Answer all eight questions. You are provided with Photograph 1.3 for use with Question 3 in this paper. Do not write your answers on this photograph. INFORMATION FOR CANDIDATES The total mark for this paper is 75. Section A carries 60 marks. Section B carries 15 marks. You are reminded of the need for good English and clear presentation in your answers. Use accurate scientific terminology in all answers. You should spend approximately 20 minutes on Section B. You are expected to answer Section B in continuous prose. Quality of written communication will be assessed in Section B, and awarded a maximum of 2 marks. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question. 4943 For Examiner s use only Question Marks Number 1 2 3 4 5 6 7 8 Total Marks BLANK PAGE 4943 2 [Turn over Section A Examiner Only Marks 1 Remark A lysosome and other cellular structures are shown in the diagram below. The lysosome may contain over 40 different hydrolytic enzymes. lysosome Describe the sequence of events which occur from the initial synthesis of the enzymes until their encapsulation within the lysosome. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ ____________________________________________________ ___________ [3] 4943 3 [Turn over 2 The diagram below shows the amino acids in each of the two polypeptides of human insulin. S A chain S asp-cys-tyr-asp-glu-leu-glu-tyr-leu-ser-cys-val-ser-ala-cys-cys-glu-glu-val-ile-gly S B chain S S S ala-lys-pro-thr-tyr-phe-phe-gly-arg-glu-gly-cys-val-leu-tyr-leu-ala-glu-val-leu-his-ser-gly-cys-leu-his-glu-asn-val-phe Reproduced with the permission of Nelson Thornes Ltd from Nelson Advance Science 3rd Ed - Molecules and Cells - John Adds, Erica Larkcom, Ruth Miller and Martin Furness-Smith - ISBN 978 0 7487 7484 5 first published in 2003 Examiner Only (a) Explain what is meant by the primary structure of a protein. Marks Remark ______________________________________________________________ ___________________________________________________________ [1] (b) Explain the role of the sulphur-containing amino acid, cysteine (cys), in the formation of the tertiary and quaternary structure of the insulin molecule. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ___________________________________________________________ [4] (c) In which part of the cysteine molecule would you expect to find sulphur? ___________________________________________________________ [1] 4943 4 [Turn over 3 (a) Photographs 1.3 A to D show light micrographs of bluebell cells at different stages of mitosis. Examiner Only Marks Remark (i) Identify the stage of mitosis shown by each of the cells A to D. A ________________________________________________________ B ________________________________________________________ C ________________________________________________________ D _____________________________________________________ [4] (ii) Arrange the letters A to D to give the correct sequence of stages during mitosis. _______________________________________________________ [1] (b) The diagram below shows an homologous pair of chromosomes (bivalent) during prophase I of meiosis. E F (i) Name the features labelled E and F in the diagram. E _______________________________________________________ F _____________________________________________________ [2] (ii) Explain how feature E results in genetic variation. __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] 4943 5 [Turn over 4 Cylinders of potato tissue were immersed in sucrose solutions, differing in their solute potential, for 24 hours and the percentage change in length determined. The results are shown in the graph below. 10 8 4 2 Solute potential/kPa 0 2000 1600 1200 800 400 2 4 Percentage change in length/% 6 6 8 10 (a) With reference to water potential, explain the change in length that occurred when the cylinder of potato tissue was immersed in a sucrose solution of solute potential 600 kPa. Examiner Only Marks Remark ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ___________________________________________________________ [2] (b) Using the information in the graph, determine the water potential of the potato tissue. ______________________________________________________________ Explain your reasoning. ______________________________________________________________ ___________________________________________________________ [2] 4943 6 [Turn over (c) The initial length of the potato cylinder immersed in a solution of water potential 1600 kPa was 50 mm. Calculate its final length. (Show your working in the space below.) Examiner Only Marks Remark Answer _______________ [2] (d) Draw a potato cell as it might appear when immersed (for 24 hours) in a sucrose solution of solute potential 1200 kPa. [1] 4943 7 [Turn over 5 (a) Describe the structure and function of mitochondria. Examiner Only Marks Remark ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ___________________________________________________________ [2] (b) In a culture of actively dividing animal cells, the cell volume and number of mitochondria were measured. The results are shown in the table below. Cell volume/ m3 Number of mitochondria 760 118 650 90 560 65 870 141 920 153 1030 146 1140 152 (i) Plot the above results, using an appropriate graphical technique. (Use the graph paper opposite.) [6] (ii) Identify the major trends evident in the results. __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] (iii) Using your understanding of the events in the cell cycle, suggest explanations for the changes shown in the graph. __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] 4943 8 [Turn over 4943 9 [Turn over (c) Bacteria are prokaryotic cells and, as such, lack mitochondria and other membrane-bound organelles. State two other differences between prokaryotic cells and eukaryotic cells. Examiner Only Marks Remark 1. ___________________________________________________________ _____________________________________________________________ 2. ___________________________________________________________ __________________________________________________________ [2] 4943 10 [Turn over BLANK PAGE (Questions continue overleaf) 4943 11 [Turn over 6 The enzyme amylase catalyses the following reaction. Examiner Only Marks Starch Remark > maltose (a) Starch and maltose are both carbohydrates. (i) Describe how they are similar in their molecular structure. __________________________________________________________ _______________________________________________________ [1] (ii) Describe how they are different in their molecular structure. __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] In an investigation of the above reaction, 0.1% amylase was added to a 1% solution of starch. The amount of starch remaining in solution was determined over time. (b) (i) Describe a method that you would use to determine the amount of starch in solution over time . __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [3] 4943 12 [Turn over (ii) Suggest one possible limitation in your method. Examiner Only Marks Remark __________________________________________________________ _______________________________________________________ [1] The results are shown in the table below. Time/minutes Amount of starch remaining in solution/% 0 1.0 0.5 0.5 1.0 0.25 2.0 0.07 3.0 0.02 4.0 0.01 (c) (i) Describe the pattern of change in the amount of starch remaining in solution over time. __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] (ii) Explain the changes in the amount of starch remaining in solution over time. __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] 4943 13 [Turn over 7 (a) Nucleic acids are composed of nucleotides. Complete the table below to give two ways in which the structure of a DNA nucleotide differs from that of an RNA nucleotide. DNA nucleotide Examiner Only Marks Remark RNA nucleotide 1. 2. [2] (b) The polymerase chain reaction (PCR) enables many copies of DNA to be made from a small sample. The diagram below summarises the procedure. One molecule of DNA Step 1 Step 2 Step 3 Two molecules of DNA KEEP REPEATING THE PROCESS 4943 14 [Turn over (i) Explain what is happening at each of the steps indicated. Examiner Only Marks Step 1 Remark _________________________________________________ __________________________________________________________ Step 2 _________________________________________________ __________________________________________________________ Step 3 _________________________________________________ ___________________________________________________ ____ [3] _ (ii) At the end of the first cycle, there are two molecules of DNA. How many molecules will there be at the end of five cycles? ___________________________________________________ ____ [1] _ (c) Explain, precisely, how restriction endonucleases cut DNA molecules into fragments. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [2] (d) A DNA fragment, consisting of 24 base pairs, was analysed for the number of different bases on each strand. The table below shows some of the results. Determine the missing values and complete the table. Number of bases A G Strand 1 7 8 Strand 2 T C 4 [2] 4943 15 [Turn over Section B Examiner Only Marks 8 Remark Describe the structure of the cell surface membrane, and explain how its structure determines how molecules pass through. [15] Structure of cell surface membrane _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 4943 16 [Turn over _________________________________________________________________ Examiner Only Marks Remark _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Passage of molecules through the membrane _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 4943 17 [Turn over _________________________________________________________________ Examiner Only Marks Remark _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 4943 18 [Turn over Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright holders may have been unsuccessful and CCEA will be happy to rectify any omissions of acknowledgement in future if notified. 935-052-1 GCE Biology Advanced Subsidiary (AS) Assessment Unit AS 1 Module 1: Cell Biology January 2009 Photographs 1.3 A to D (for use with Question 3) A B C D Source: Pr. G. Gimenez-Martin/Science Photo Library 4943.02 AB111INS1

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Additional Info : Gce Biology January 2009 Assessment Unit AS 1 Module 1: Cell Biology - Revised
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