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GCE JUN 2008 : (AS 1) Cell Biology

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Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education 2008 Biology assessing Module 1: Cell Biology ASB11 Assessment Unit AS 1 [ASB11] TUESDAY 3 JUNE, MORNING TIME 1 hour. 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. For Examiner s use only Question Number 1 INFORMATION FOR CANDIDATES The total mark for this paper is 55. Section A carries 43 marks. Section B carries 12 marks. You should spend approximately 15 minutes on Section B. You are expected to answer Section B in continuous prose. Quality of written communication will be assessed in Section B. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question. 2 3 4 5 6 7 8 Total Marks ASB1S8 3309 Marks Section A Examiner Only Marks 1 Remark Identify the word or phrase that is described by each of the following statements. (a) A macromolecule consisting of glycerol bonded to three fatty acids. ______________________________________________________ [1] (b) An organic molecule containing nitrogen in the form of NH2 and a carboxyl group COOH, bonded to the same carbon atom. ______________________________________________________ [1] (c) The level of structure of a polypeptide that occurs when it folds to form an overall globular shape. ______________________________________________________ [1] (d) The region of an enzyme s surface that binds the substrate during the reaction catalysed by the enzyme. ______________________________________________________ [1] ASB1S8 3309 2 [Turn over 2 The diagram below shows the uptake of a bacterium by a phagocytic cell and structures relating to its subsequent digestion. Examiner Only Marks Remark New Perspectives in Advanced Biology by Martin Hanson & Ann Hanson, published by Hodder and Stoughton, 1999, ISBN 0340664436 "Reproduced by permission of Hodder & Stoughton Ltd". (a) Describe the process by which the bacterium is taken up by phagocytosis. _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] (b) Describe the process by which lysosomes are produced. _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] (c) Describe how lysosomes bring about digestion of the bacterium. _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ ASB1S8 3309 3 [Turn over 3 The diagram below shows onion cells which have been immersed in a sugar solution. Examiner Only Marks Remark Source: A-level Biology, W D Phillips and T J Chilton, Oxford University Press, 1989 (a) Explain why the water potential of a cell is always less than zero. _________________________________________________________ ______________________________________________________ [1] (b) (i) Compare the relative water potentials of the cell contents and the immersing (external) sugar solution. ______________________________________________________ ___________________________________________________ [1] (ii) Explain the appearance of the onion cells shown in the diagram above. ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ___________________________________________________ [3] ASB1S8 3309 4 [Turn over 4 Photograph 1.4 is a light micrograph of onion root tip cells undergoing mitotic cell division. Examiner Only Marks Remark (a) Identify the stage of mitosis shown by each of the cells labelled A to D. A ___________________________________ B ___________________________________ C ___________________________________ D ___________________________________ [4] (b) Arrange the letters A to D to give the correct sequence of stages in the cell cycle. ______________________________________________________ [1] (c) Use the scale bar (at the bottom of the photograph) to calculate the magnification of the micrograph. Show your working. Answer ______________ [2] ASB1S8 3309 5 [Turn over 5 An experiment was undertaken to determine the effect of oxygen availability on the uptake of potassium ions by discs of potato tissue. Examiner Only Marks Remark Discs of potato tissue were immersed in a number of solutions containing potassium ions. The solutions were aerated with each receiving a different percentage of oxygen in the air bubbled through it. The absorption of potassium ions (K+) by the potato discs was then measured. The results are shown in the graph below. 500 K+ uptake/mg g 1 plant tissue 400 300 200 100 0 0 10 20 30 40 Percentage of oxygen in aeration mixture 50 (a) State two variables that should be controlled during this experiment (excluding characteristics of the potato tissue). 1. _______________________________________________________ 2. ____________________________________________________ [2] (b) Describe how oxygen availability affects potassium ion uptake. _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] ASB1S8 3309 6 [Turn over (c) Explain how the results provide evidence that potassium ion uptake takes place by active transport. Examiner Only Marks Remark _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] ASB1S8 3309 7 [Turn over 6 Pectinase is an enzyme produced by fungal cells. It is capable of digesting pectins found in the middle lamella of plant cells. This helps the fungi to gain access to the plant cell protoplasm as a potential source of nutrients. Examiner Only Marks Remark (a) (i) What inorganic ion is required for the manufacture of the middle lamella? ___________________________________________________ [1] (ii) State the location of the middle lamella in plant tissue. ___________________________________________________ [1] Pectinases may be used commercially to gain access to the fruit juices within fruit pulp. Traditionally, pectinase enzymes were simply added to fruit pulp in a batch reactor maintained at 40 C. Pectinases were then allowed to digest the pulped fruit which was then squeezed to produce the juice. (b) Explain why the batch reactor would be maintained at 40 C. ______________________________________________________ [1] Modern methods of juice extraction involve the immobilisation of the pectinase enzymes in a column reactor through which the fruit pulp flows. (c) State one possible method of immobilising pectinase. ______________________________________________________ [1] (d) State two possible advantages of the immobilised enzyme column reactor over the more traditional batch reactor. 1. _______________________________________________________ _________________________________________________________ 2. _______________________________________________________ ______________________________________________________ [2] ASB1S8 3309 8 [Turn over (e) Outline one way in which the rate of pectinase activity could be increased in the column reactor and describe how your method would bring about the increase in enzyme activity. Examiner Only Marks Remark _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] ASB1S8 3309 9 [Turn over 7 The enzyme, polygalacturonase (PG), is responsible for the softening of fruits such as tomatoes. To prolong the shelf life of tomatoes, scientists have genetically engineered tomato plants to create the Flavr Savr tomato that does not bruise during shipping and lasts longer on the shelf. To do this, the PG gene responsible for the production of the enzyme was first isolated. Scientists then used this isolated gene to create an anti or nonsense PG gene that was then introduced into tomato plants. This nonsense gene stops the translation of the original PG gene in the tomato plant and so stops enzyme production. The diagram below summarises the action of the introduced nonsense PG gene. Portion of original PG gene A T C G C G A T T A Portion of nonsense PG gene C G T A G C G C T A A T G C U G G U A G U A C original mRNA and nonsense mRNA G match up to produce double Process X A U C A Nonsense mRNA U Original mRNA C C A C G Original mRNA Nonsense mRNA C G A U Complementary bases of stranded RNA. Translation is prevented No polygalacturonase enzyme produced No softening of fruit ASB1S8 3309 10 [Turn over (a) Outline one way in which scientists could have isolated the original PG gene. Examiner Only Marks Remark _________________________________________________________ ______________________________________________________ [1] (b) Suggest how the nonsense PG gene could have been introduced into the tomato plant. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [3] (c) Name the process labelled X in the diagram. ______________________________________________________ [1] (d) Suggest two ways by which matching of the sense and nonsense mRNA would prevent translation and so inhibit the production of the polygalacturonase enzyme. 1. _______________________________________________________ _________________________________________________________ 2. _______________________________________________________ ______________________________________________________ [2] ASB1S8 3309 11 [Turn over Section B Examiner Only Marks Remark In this section you are expected to answer in continuous prose, supported, where appropriate, by diagrams. You are reminded that up to two marks in this question are awarded for the quality of written communication. [2] 8 Give an account of the distribution and role of carbohydrates, including monosaccharides, disaccharides and polysaccharides. [10] Monosaccharides _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ Disaccharides _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ASB1S8 3309 12 [Turn over Examiner Only _____________________________________________________________ Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ Polysaccharides _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ASB1S8 3309 13 [Turn over THIS IS THE END OF THE QUESTION PAPER S 3/07 3309 ASB1S8 530-048-1 16 [Turn over [Turn over GCE Biology Advanced Subsidiary (AS) Assessment Unit AS 1 Module 1: Cell Biology Summer 2008 Photograph 1.4 (For use with Question 4) A D B Source: M I Walker/Science Photo Library 30 m ASB1S8 3309.02 ASB11IN1 C

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Additional Info : Gce Biology June 2008 Assessment Unit AS 1 Module 1: Cell Biology
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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