EdExcel-O-Level-Biology-Paper-1-May-2007

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Centre No. Paper Reference Surname Initial(s) Candidate No. 7 0 4 0 0 2 Signature Paper Reference(s) 7040/02 Examiner s use only London Examinations GCE Team Leader... s use only Biology Ordinary Level Paper 2 Wednesday 9 May 2007 – Afternoon Time: 2 hours Materials required for examination Items included with question papers Nil Nil Instructions to Candidates The paper is arranged in three sections, A, B and C In Section A, answer ALL questions in the spaces provided in this book In Section B, answer any TWO questions in the spaces provided in this book In Section C, answer any TWO questions in the spaces provided in this book In the boxes above, write your centre number, candidate number, your surname, initial(s) and signature Indicate which question you are answering by marking the box ( ) If you change your mind, put a line through the box ( ) and then indicate your new question with a cross ( ) Information for Candidates Calculators may be used The total mark for this paper is 100 The mark allocation is indicated at the end of each question The marks for parts of questions are shown in round brackets: e g (2) This paper has 12 questions Any blank pages are indicated Advice to Candidates Write your answers neatly and in good English In calculations, show all the steps in your working This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2007 Edexcel Limited. Turn over A25935A W850/U7040/57570 4/6/4/2/2/1 SECTION A Answer ALL questions in this section 1. Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Athletes and their respiration Leave blank Adam is an athlete. When he starts to run quickly, his muscles contract and stores of available energy in his muscle cells are used up. In order to continue using his muscles, Adam must release more energy as fast as he requires it. This energy is released by aerobic respiration. How fast the energy is released depends upon how 5 fast his muscles are supplied with oxygen. A fit athlete can absorb about 4 dm3 (litres) of oxygen per minute and release about 80 kJ of energy. However, only about 20% of this energy is available for movement. The energy released by using the 4 dm3 of oxygen would enable a fit athlete to run at a speed of about 20 km per hour. If this athlete could keep up this speed for over 10 two hours, he would have a good chance of winning a medal in an Olympic marathon race. To win a short sprint event, however, he would need to run nearly twice as fast. He obtains the energy for this extra speed from anaerobic respiration. This more than doubles the energy available to the athlete, but anaerobic respiration cannot continue at this rate for more than a short time. 15 In a 100 m race, most of the energy required is released by anaerobic respiration. The same is true of jumping and throwing events. In middle distance races, such as the 800 m and 1500 m, athletes obtain about half the energy they require from aerobic respiration and the other half from anaerobic respiration. A good middle distance runner judges his speed so that the combined energy supplied by aerobic and 20 anaerobic respiration is enough to get him to the finish before the build up of lactic acid affects his muscles. After an event involving anaerobic respiration, the athlete continues to breathe heavily so that he can obtain oxygen to convert lactic acid to harmless products. This extra amount of oxygen is called the ‘oxygen debt’. The maximum oxygen debt that an 25 athlete can build up is about 17 dm3. It may take an athlete up to 45 minutes to repay this debt and his breathing to return to normal. (a) Which substance found in muscle cells acts as an energy store? ....................................................................................................................................... (1) (b) What is the oxygen required for? (line 5) ....................................................................................................................................... (1) .......................................................................................continued.................................................................................. [Show More]

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