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GCE JUN 2007 : (AS 2) Physiology and Ecology

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Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education 2007 Biology assessing Module 2: Physiology and Ecology ASB21 Assessment Unit AS 2 [ASB21] TUESDAY 19 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. 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. For Examiner s use only Question Number 1 2 3 4 5 6 7 8 Total Marks ASB2S7 2478 Marks BLANK PAGE ASB2S7 2478 2 [Turn over Section A Examiner Only Marks 1 Remark Identify the plant cells or tissues that are described by each of the following statements. (a) A type of supporting cell with an unevenly thickened cellulose wall, often at the corners. _______________________________________________________ [1] (b) A layer of specialised cells, one cell thick, that lies between the cortex and the vascular tissue in roots and containing a Casparian strip in their radial walls. _______________________________________________________ [1] (c) A type of supporting cell with thick, lignified walls and which is not involved in the transport of water. _______________________________________________________ [1] (d) A specialised cell associated with a sieve-tube and which facilitates the movement of materials into and out of the sieve tube. _______________________________________________________ [1] ASB2S7 2478 3 [Turn over 2 The diagram below shows a sectional view of the mammalian heart with the valves labelled. Examiner Only Marks Remark semilunar valves atrioventricular valves (a) With reference to blood pressure and heart structure, explain why blood does not flow back into the atria when the ventricles contract. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] (b) The atrioventricular valves are part of a sheet of insulating tissue, that prevents the excitation wave passing directly from the atria to the ventricles. (i) Briefly explain how the excitation wave passes into the ventricles. _____________________________________________________ ___________________________________________________ [1] (ii) What is the advantage of the delay caused by this arrangement? _____________________________________________________ ___________________________________________________ [1] ASB2S7 2478 4 [Turn over (c) With reference to blood pressure and structures involved, explain why blood does not flow back into the ventricles when they relax. Examiner Only Marks Remark _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] ASB2S7 2478 5 [Turn over 3 In photosynthesis, light is absorbed by different pigments including chlorophyll a, chlorophyll b and carotenoids. Chlorophyll a is the most abundant pigment and is of universal occurrence in all photosynthesising plants. Examiner Only Marks Remark The graph below shows the absorption spectrum of each of the different pigments. Relative absorption of light chlorophyll b chlorophyll a carotenoids Violet 400 Blue Green 500 Yellow 600 Light wavelength/nm Orange Red 700 Colour of light (a) Chlorophyll a and chlorophyll b are green in colour, while carotenoids are orange. Use the information in the graph to explain the colour of the carotenoids. _________________________________________________________ _______________________________________________________ [1] (b) Explain the advantage to the process of photosynthesis of light being absorbed by a number of different pigments, and not just chlorophyll a. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] ASB2S7 2478 6 [Turn over (c) What is meant by the term action spectrum ? Examiner Only Marks Remark _________________________________________________________ _______________________________________________________ [1] ASB2S7 2478 7 [Turn over 4 Different bird species feeding in the mudflats around the coastline of Northern Ireland have different beak lengths. The diagram below shows four such bird species along with the deepest prey that each might reach. Turnstone Shelduck Crabs and Hydrobia snails Oystercatcher Examiner Only Marks Remark Curlew Cockles Tellin Lugworm Source: New Perspectives in Advanced Biology, Martin Hanson, Hodder and Stoughton, 1999 (a) Suggest how having a different beak length would influence competition between the four bird species. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] ASB2S7 2478 8 [Turn over In certain areas of the coastline cockles are harvested for human consumption. Such harvesting can affect the numbers of both Turnstone and Shelduck. Examiner Only Marks Remark (b) State what would happen to the populations of both Turnstone and Shelduck, and suggest explanations for these changes. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] ASB2S7 2478 9 [Turn over 5 The diagram below represents a section through part of the ileum and shows a villus with a magnified view of some cells in the epithelium. epithelium of villus A columnar epithelium of villus columnar epithelial cell B capillary network lacteal thin layer of smooth muscle (muscularis mucosa) extends into the villus crypt of Lieberk hn Paneth cell muscularis mucosa Source: Adapted from Advanced Biology Principles and Applications, C J Clegg with D G Maclean, John Murray, 1994 ASB2S7 2478 10 [Turn over (a) State the role of each of the following. Examiner Only Marks Remark Lacteal ___________________________________________________ _________________________________________________________ Paneth cells _______________________________________________ _________________________________________________________ Muscularis mucosa _________________________________________ _______________________________________________________ [3] (b) Name the cell structure labelled A and the cell labelled B. In each case, describe their function within the ileum. Cell structure A Name __________________________ Function _________________________________________________ _________________________________________________________ Cell B Name __________________________ Function _________________________________________________ _______________________________________________________ [4] ASB2S7 2478 11 [Turn over 6 The diagram below shows tissues involved in the movement of water through a leaf and the eventual loss of water by transpiration through an open stoma. xylem vessel cell wall cytoplasm vacuole substomatal air space stomatal transpiration Source: Adapted from Biological Science Vol 2, Green, Stout, Taylor (ed. Soper), Cambridge, 1990 Examiner Only Marks Remark (a) Using the diagram above, describe the sequence of events in the leaf that result from the loss of water through open stomata. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] ASB2S7 2478 12 [Turn over The rate of water flowing through a branch of a tree and the tree trunk was measured over a 24-hour period. The results are shown in the graph below. Examiner Only Marks Remark 8 7 Rate of water flow/m h 1 6 5 Branch Trunk 4 3 2 1 0 4 am 8 am Noon Time of day 4 pm 8 pm (b) Using your understanding of the cohesion tension theory (i) describe and explain the changes in the rate of water flow in the branch over the 24-hour period; _____________________________________________________ _____________________________________________________ _____________________________________________________ _____________________________________________________ _____________________________________________________ ___________________________________________________ [3] (ii) describe and explain the difference in the rate of water flow in the branch and in the tree trunk. _____________________________________________________ _____________________________________________________ ___________________________________________________ [2] ASB2S7 2478 13 [Turn over 7 The table below shows the blood flow to various organs while a person is at rest and during strenuous exercise. Organ Skeletal muscle Blood flow at rest /cm3 min 1 Examiner Only Marks Remark Blood flow during strenuous exercise /cm3 min 1 1200 12 500 500 1900 Kidneys 1100 600 Intestine 1400 600 Other 1600 1900 Total 5800 17 500 Skin (a) Calculate the percentage increase in the blood flow to the skeletal muscle as a result of strenuous exercise. (Show your working.) Answer _____________ [2] (b) With reference to the functioning of arteries, explain how blood flow to organs such as the kidneys is decreased during strenuous exercise. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] ASB2S7 2478 14 [Turn over (c) Suggest explanations for the pattern of changes in the blood flow to the organs during strenuous exercise. Examiner Only Marks Remark _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] (d) The skeletal muscle respires much more rapidly during strenuous exercise. Explain, as fully as possible, how this results in oxyhaemoglobin unloading (dissociating) more oxygen to the tissue. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] ASB2S7 2478 15 [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 flow of energy from the sun through ecosystems. In your account you should describe the efficiency of energy transfer from the sun to producers energy transfer through the trophic levels [10] Energy transfer from the sun to producers ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ASB2S7 2478 16 [Turn over Examiner Only Marks Remark ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ Energy transfer through the trophic levels ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ASB2S7 2478 17 [Turn over THIS IS THE END OF THE QUESTION PAPER ASB2S7 2478 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. S 3/06 7-129-1 [Turn over

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Additional Info : Gce Biology June 2007 Assessment Unit AS 2 Module 2: Physiology and Ecology
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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