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GCE JUN 2010 : (AS 1) Molecules and Cells - Revised

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Sp N ec e i w ca tio n Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education 2010 Biology assessing Module 1: Molecules and Cells AB111 Assessment Unit AS 1 [AB111] THURSDAY 3 JUNE, 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 1.4 for use with Question 4 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. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question. 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. For Examiner s use only Question Marks Number 1 2 3 4 5 6 7 8 Total Marks 5456 Section A Examiner Only Marks 1 Remark The cell surface membrane is mainly composed of phospholipids and proteins. (a) The symbol below represents a phospholipid molecule. In the space below, and using the symbol above, draw a diagram to show how phospholipids are arranged in a cell surface (plasma) membrane. [2] (b) Describe two roles for proteins in the cell surface membrane. 1. ______________________________________________________ ________________________________________________________ 2. ______________________________________________________ _____________________________________________________ [2] (c) Name one other component of the cell surface membrane. _____________________________________ 5456 2 [1] [Turn over 2 The diagrams below represent some important stages (labelled A to D) during mitotic cell cycle in an animal cell. A B C Examiner Only Marks Remark D (a) Identify stage B. _____________________________________________________ [1] (b) The diagrams are not in the correct sequence. Rearrange the letters to illustrate the correct sequence of the stages. _____________________________________________________ [1] (c) Give one piece of evidence which suggests that the diagrams represent animal cells and not plant cells. _____________________________________________________ [1] (d) Give two pieces of evidence from the diagrams which suggest that the stages take place during mitosis and not meiosis. 1. ______________________________________________________ ________________________________________________________ 2. ______________________________________________________ _____________________________________________________ [2] 5456 3 [Turn over 3 The diagram below shows the tissues present in a mesophytic leaf. Examiner Only Marks Remark Biology GCSE Edition by G & M Jones, published by Cambridge University Press, 1987, ISBN 0521338697 The leaf is an organ with adaptations for maximising photosynthesis while minimising transpiration. Describe these adaptations for maximising photosynthesis _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ _____________________________________________________ [3] minimising transpiration _______________________________________________________ _______________________________________________________ _______________________________________________________ _____________________________________________________ [2] 5456 4 [Turn over 4 Photograph 1.4 is an electron micrograph of part of a mammalian liver cell. Examiner Only Marks Remark (a) Identify the structures labelled A to C. A _____________________________________________________ B _____________________________________________________ C ___________________________________________________ [3] (b) Using the scale bar on the photograph, calculate the magnification of the electron micrograph. (Show your working.) Answer _____________________ [3] The storage polysaccharide glycogen is labelled on the electron micrograph. (c) Apart from liver cells, in which other mammalian tissue would glycogen stores be located? _____________________________________________________ [1] (d) Describe two ways in which glycogen is adapted to its function as a storage polysaccharide. 1. _____________________________________________________ _______________________________________________________ 2. _____________________________________________________ _____________________________________________________ [2] (e) Name the equivalent storage polysaccharide in plant cells. _____________________________________________________ [1] 5456 5 [Turn over 5 The diagram below summarises the polymerase chain reaction (PCR). Copies of sample DNA removed Step 4 Step 1 Heat to 94 C Sample DNA double-stranded AGTGC TCACG C GA Primers TC A G TCAC TTGAC DNA polymerase starts copying AGTGC TTGAC AACTG Step 2 Cool to 46 65 C TCA AGT G AACTG TGAC TCACG T Step 3 C TTG AC AACTG GAC TCACG DNA polymerase plus C TC A Nucleotides TGA Examiner Only (a) (i) Explain the role of heating the sample DNA to 94 C in step 1. Marks Remark ___________________________________________________ ___________________________________________________ ___________________________________________________ _________________________________________________ [2] (ii) State one function of the primers added in step 2. ___________________________________________________ _________________________________________________ [1] (iii) Explain why the DNA sample is cooled during the addition of the primers in step 2. ___________________________________________________ _________________________________________________ [1] 5456 6 [Turn over (b) Describe the structure of the nucleotides added in step 3. Examiner Only Marks Remark _______________________________________________________ _______________________________________________________ _______________________________________________________ _____________________________________________________ [2] (c) Restriction endonuclease enzyme cuts DNA into fragments. The restriction endonuclease enzyme EcoR1 recognises the sequence of bases GAATTC (from the 59 end to the 39 end) in a DNA molecule and cuts the DNA between G and A bases. (i) Show the position of the cuts in the seqence of bases in the diagram below. 59 39 GGCCT TGCTGGAAT TCAA :::::::::::::::::: CCGGAACGACCT T AAGT T 39 59 [1] (ii) State the type of end that is produced. _________________________________________________ [1] (d) Outline how a DNA probe is used to locate a specific DNA fragment. _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ _____________________________________________________ [3] 5456 7 [Turn over BLANK PAGE 5456 8 [Turn over 6 In an investigation into the effect of temperature on the movement of pigment through cell membranes, small cylinders were cut from fresh beetroot. In beetroot cells the red anthocyanin pigment occurs within the vacuoles. Each vacuole is surrounded by a tonoplast membrane and, outside this membrane, the cytoplasm is surrounded by the cell surface (plasma) membrane. Examiner Only Marks Remark After cutting and rinsing six beetroot cylinders, each small cylinder was placed in a test tube containing water. Each of the six test tubes had been maintained at a particular temperature. Each cylinder was left for one minute during which some pigment leaked out. After cooling, samples from each test tube were placed in cuvettes and the percentage transmission of light through each sample was measured using a colorimeter. (a) (i) Explain why a blue filter was selected for use in the colorimeter. ___________________________________________________ ___________________________________________________ ___________________________________________________ _________________________________________________ [2] (ii) State one precaution required, when using a colorimeter, to ensure that an accurate meter reading is obtained. ___________________________________________________ _________________________________________________ [1] (iii) Explain precisely how the colorimeter is used to measure the amount of red pigment in each sample. ___________________________________________________ ___________________________________________________ ___________________________________________________ _________________________________________________ [2] 5456 9 [Turn over The results of the investigation are shown in the table below. Examiner Only Marks Temperature/ C Percentage transmission/% 40 90 50 90 55 80 58 25 60 20 70 Remark 15 (b) Plot the above results, using an appropriate graphical technique. (Use the graph paper opposite.) [5] (c) (i) Identify the trends evident in the results. ___________________________________________________ ___________________________________________________ ___________________________________________________ _________________________________________________ [2] (ii) Suggest explanations for the trends identified in (i) above. ___________________________________________________ ___________________________________________________ ___________________________________________________ _________________________________________________ [2] 5456 10 [Turn over 5456 11 [Turn over 7 In an experiment to determine the solute potential ( s) of leaf tissues by means of the incipient plasmolysis method, tissues from two plants were immersed in a series of sucrose solutions of different concentrations. Samples of the tissue were observed under a microscope, the total number of cells counted and the number of plasmolysed cells recorded for each sample. Examiner Only Marks Remark The two leaf tissues were onion bulb leaves and leaves from the pondweed, Elodea. The onion leaf cells are modified for storage of sugars. The Elodea is a common freshwater aquatic plant, found in many ponds and lakes. It was predicted that the onion cells would have a lower solute potential than the Elodea cells. (a) (i) Unstained onion cells can be difficult to see under a microscope unless the light is reduced. Describe one method of reducing the light passing through the onion tissue. ___________________________________________________ _________________________________________________ [1] (ii) Describe how you would recognise a plasmolysed onion cell under a microscope. ___________________________________________________ _________________________________________________ [1] (b) Plasmolysed Elodea cells were identified by a clumping of chloroplasts in the centre of the cell. Explain why the chloroplasts clumped in the centre of a plasmolysed cell. _______________________________________________________ _____________________________________________________ [1] 5456 12 [Turn over The results of the experiment are presented in the graph below. Examiner Only Marks Remark 100 80 60 onion Elodea 40 Percentage plasmolysed cells in sample/% 20 0 4000 3000 2000 1000 Solute potential of immersing solution/kPa (c) (i) Use the graph to determine the solute potentials of the onion and Elodea cells. Onion cells ____________________ kPa Elodea cells ____________________ kPa [2] (ii) Explain the basis of the method used to determine the solute potential of the tissues. ___________________________________________________ ___________________________________________________ ___________________________________________________ _________________________________________________ [2] (iii) Suggest one reason for the difference in the solute potentials determined in (i) above. ___________________________________________________ ___________________________________________________ _________________________________________________ [2] 5456 13 [Turn over (d) Explain why the pondweed, Elodea, cannot survive in seawater which has a high concentration of salts. Examiner Only Marks Remark _______________________________________________________ _____________________________________________________ [1] 5456 14 [Turn over Section B Examiner Only Marks Remark Quality of written communication is awarded a maximum of two marks in this section. [2] 8 Enzymes are sensitive to a number of factors. The three graphs in this question illustrate the influence of three independent variables on the activity of an enzyme. For each of the three graphs identify the independent variable describe trends evident in the graph explain the trends described [13] Enzyme activity Independent variable __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ 5456 15 [Turn over identify the independent variable describe trends evident in the graph explain the trends described Examiner Only Marks Remark Enzyme activity Independent variable __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ 5456 16 [Turn over identify the independent variable describe trends evident in the graph explain the trends described Examiner Only Marks Enzyme activity Independent variable __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ THIS IS THE END OF THE QUESTION PAPER 5456 17 Remark 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. 5456 GCE Biology Advanced Subsidiary (AS) Assessment Unit AS 1 Module 1: Cell Biology Summer 2010 Photograph 1.4 (for use with Question 4) B A George McCartney 2 m glycogen 5456.02 C AB111INS1

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Additional Info : Gce Biology June 2009 Assessment Unit AS 1 Molecules and Cells
Tags : General Certificate of Education, A Level and AS Level, uk, council for the curriculum examinations and assessment, gce exam papers, gce a level and as level exam papers , gce past questions and answer, gce past question papers, ccea gce past papers, gce ccea past papers

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