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GCE JAN 2007 : (AS 1) Cell Biology

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Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education January 2007 Biology assessing Module 1: Cell Biology ASB11 Assessment Unit AS 1 [ASB11] TUESDAY 16 JANUARY, AFTERNOON 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 1.6 for use with Question 6 in this paper. Do not write your answer 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 ASB1W7 2339 Marks Section A Examiner Only Marks 1 Remark Read the following passage on recombinant DNA technology, and write the most appropriate word(s) in the blank spaces to complete the account. Gene selection begins when DNA is cut into shorter segments by the enzyme ______________________________. Each enzyme cuts DNA at specific recognition sites. Many of these enzymes produce staggered cuts, resulting in formation of ___________________________. Sections of DNA, with complementary staggered cuts, can be joined by the action of the enzyme ______________________________. An alternative approach to obtaining genes involves synthesising the desired gene from its template mRNA. The enzyme ______________________________ catalyses the production of a single strand of cDNA from mRNA. The enzyme ______________________________ synthesises a complementary second DNA strand to make a complete DNA copy of the gene. ASB1W7 2339 2 [4] [Turn over 2 The table below lists three polysaccharides and the isomers of glucose that may be used as monomers in their synthesis. Polysaccharide Glucose Examiner Only Marks Remark Glucose Starch Glycogen Cellulose (a) Complete the table by placing a tick ( ) if the isomer of glucose is the monomer involved in the polysaccharide synthesis and a cross ( ) if it is not involved. (Do not leave boxes blank.) [3] (b) State one similarity and one difference between the polysaccharides starch and glycogen. (Your answer should not include the monomers used in their synthesis.) Similar ity _________________________________________________ __________________________________________________________ _________________________________________________________ Difference _________________________________________________ _________________________________________________________ _______________________________________________________ [2] ASB1W7 2339 3 [Turn over 3 The table below illustrates three stages of the cell cycle in an animal cell. Complete the table by naming the stage illustrated, and briefly outlining one important event that takes place during the stage. Stage: ______________________________________________ Event: ______________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ Stage: ______________________________________________ Event: ______________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ Stage: ______________________________________________ Event: ______________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ Examiner Only Marks Remark [6] ASB1W7 2339 4 [Turn over 4 The diagram shows the arrangement of phospholipids in a cell membrane. Examiner Only Marks Remark (a) Describe the characteristics of phospholipid molecules that cause this arrangement. __________________________________________________________ _________________________________________________________ __________________________________________________________ _______________________________________________________ [2] The phospholipid molecules are able to move past each other within the membrane. This lateral diffusion within the membrane, also known as fluidity, is increased at higher temperatures. (b) Why does an increase in temperature make the membrane more fluid? __________________________________________________________ _______________________________________________________ [1] The tails of phospholipid molecules interact with each other, reducing the speed at which they can move. Cholesterol molecules, found within the phospholipid bilayer in animal cell membranes, interact with the phospholipid tails. (c) Explain the effect of cholesterol molecules on membrane fluidity. __________________________________________________________ _________________________________________________________ __________________________________________________________ _______________________________________________________ [2] ASB1W7 2339 5 [Turn over 5 (a) Enzymes are globular proteins which catalyse metabolic reactions and, as such, are influenced by pH. The diagram below shows the arrangement of the amino acids in an enzyme to which a substrate has attached. Examiner Only Marks Remark Using the diagram and your own understanding of enzyme action, explain the effect of variations in pH on the action of an enzyme. __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [3] (b) The effect of three temperatures (50 C, 60 C and 70 C) on enzyme action was investigated by incubating enzyme solutions, prior to mixing with the substrate, for different time periods (up to 1 hour). Following this heat treatment of the enzyme, the enzyme and substrate solutions were mixed and the rate of reaction measured. The results are shown in the graph opposite. ASB1W7 2339 6 [Turn over 50 C 100 Examiner Only Marks Remark Rate of reaction/arbitrary units 80 60 C 60 40 20 70 C 0 0 10 20 30 40 Incubation time/minutes 50 60 (i) From the graph, determine the rate of reaction when the enzyme was incubated for 40 minutes at 60 C . ____________________________________________________ [1] (ii) Identify trends shown in the graph above. ______________________________________________________ ______________________________________________________ ______________________________________________________ ____________________________________________________ [2] (iii) Suggest an explanation for the results. _____________________________________________________ ___________________________________________________ [1] ASB1W7 2339 7 [Turn over 6 Photograph 1.6 is an electronmicrograph of mammalian pancreatic cells. Examiner Only Marks Remark (a) Identify the structures labelled A to D. A __________________________ B __________________________ C __________________________ D __________________________ [4] (b) Using the scale bar on the photograph, calculate the diameter of the organelle along the axis indicated ( ). (Show your working.) Answer __________________ [3] ASB1W7 2339 8 [Turn over 7 Red blood cells have Na+ (sodium ion) pumps in their cell surface membranes. These pump Na+ out of the cell so that the concentration of Na+ in the plasma surrounding the cell is very high whilst the concentration of Na+ inside the cell is very low. Examiner Only Marks Remark high concentration of sodium ions A sample of blood cells (immersed in plasma) was treated with cyanide, a poison which inhibits the production of ATP. Within a few minutes all the red blood cells had burst (lysed). The plasma becomes red as haemoglobin is released. (a) What type of molecule forms the membrane pump? _______________________________________________________ [1] (b) Suggest what happened to the Na+ pumps when the red blood cells were treated with cyanide and explain why this happened. __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] (c) After cells have been treated with cyanide, what will happen to the concentration of Na+ inside the cells? _______________________________________________________ [1] (d) With reference to water potential, explain why the cyanide-treated cells then burst. __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ _______________________________________________________ [3] ASB1W7 2339 9 [Turn over (e) Haemoglobin is a protein that is both conjugated and quaternary in structure. Explain the terms l Examiner Only Marks Remark Conjugated ______________________________________________ __________________________________________________________ l Quaternary ______________________________________________ _______________________________________________________ [2] ASB1W7 2339 10 [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 structure of DNA and RNA and outline their functions. [10] DNA _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ASB1W7 2339 11 [Turn over RNA Examiner Only Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ASB1W7 2339 12 [Turn over THIS IS THE END OF THE QUESTION PAPER ASB1W7 2339 13 [Turn [Turn over ASB1W7 ASB1W7 2339 14 [Turn over ASB1W7 ASB1W7 2339 15 [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. S 3/06 2800 9-023-1 ASB1W7 2339 [Turn6over 1 [Turn over GCE Biology Advanced Subsidiary (AS) Assessment Unit AS 1 Module 1: Cell Biology January 2007 Photograph 1.6 (for use with Question 6) A B C D 1 m ASB1W7 Source: G. McCartney 2339.02 ASB11IN1

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Additional Info : Gce Biology January 2007 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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