9700_w10_qp_21 - revisedeck

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For Examiner’s Use Complete the passage with the most appropriate term. Within each ecosystem there is a of organisms that interact with each other and with their environment. Each species fills a particular within the ecosystem. Feeding relationships in food webs are an example of the interactions species have with each other. In old field ecosystems in North America, producers, such as blue grass, provide energy for grazing animals. These animals form the in the food chain. Very little of the energy consumed by grazing animals is available to carnivores. State two reasons why this is so. 1. 2.

18. Classification, biodiversity and conservation → 18.2. Biodiversity

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For Examiner’s Use Table 2.1 shows some of the structures in different parts of the gas exchange system. Complete Table 2.1 by indicating with a tick (✓) if the structure is present in each part of the gas exchange system or a cross (✗) if it is not. Table 2.1 structure trachea bronchus bronchiole alveolus ciliated epithelium goblet cells cartilage smooth muscle An exercise physiologist investigated aspects of breathing in an athlete. The minute volume is the volume of air breathed in during one minute. The data recorded is in Table 2.2. Table 2.2 vital capacity / dm3 breathing rate at rest / breaths min–1 minute volume / dm3 5.8 5.5 Explain how the physiologist would determine the vital capacity of the athlete. Calculate the athlete’s tidal volume. Answer = For Examiner’s Use shows a cross section of a coronary artery partially blocked by plaque causing atherosclerosis. Explain why atherosclerosis in coronary arteries may limit the ability of people to take vigorous exercise. For Examiner’s Use Describe the effects of nicotine and carbon monoxide in cigarette smoke on the cardiovascular system. nicotine carbon monoxide

9. Gas exchange → 9.1. The gas exchange system

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For Examiner’s Use Red blood cells are suspended in plasma which has a concentration equivalent to that of 0.9% sodium chloride (NaCl ) solution. A student investigated what happens to red blood cells when placed into sodium chloride solutions of different concentration. A small drop of blood was added to 10 cm3 of each sodium chloride solution. Samples were taken from each mixture and observed under the microscope. The number of red blood cells remaining in each sample was calculated as a percentage of the number in the 0.9% solution. The results are shown in . 0.0 0.5 1.0 concentration of NaCl / % percentage of cells remaining 1.5 With reference to , describe the student’s results. For Examiner’s Use The student also measured the cell volumes of the red blood cells in three of the sodium chloride solutions. The results are shown in Table 3.1. Table 3.1 concentration of sodium chloride / % mean red cell volume / µm3 0.7 0.9 1.5 shows the appearance of some red blood cells removed from the 1.5% sodium chloride solution. Explain the results shown in , Table 3.1 and , in terms of water potential. 0% NaCl solution 0.7% NaCl solution 1.5% NaCl solution For Examiner’s Use Red blood cells each contain about 240 million molecules of haemoglobin that transport oxygen and carbon dioxide. Describe the role of haemoglobin in the transport of oxygen and carbon dioxide. oxygen carbon dioxide The haematocrit is the proportion of the blood that is composed of red blood cells. Samples of blood were taken from an athlete who lived at sea level since birth and moved to live and train at an altitude of 5000 m for three weeks. The haematocrit and the number of red blood cells per mm3 were determined before moving to high altitude and after three weeks at that altitude. The results are shown in Table 3.2. Table 3.2 altitude haematocrit number of red blood cells × 106 per mm3 sea level 0.45 6.1 5000 m (after three weeks) 0.53 7.3 Calculate the percentage increase in the number of red blood cells per mm3 after three weeks at 5000 m. Show your working. Answer = % For Examiner’s Use Explain why the haematocrit increases at altitude.

8. Transport in mammals → 8.1. The circulatory system

8. Transport in mammals → 8.2. Transport of oxygen and carbon dioxide

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For Examiner’s Use Cholera bacteria release the enzyme neuraminidase which alters some of the surface proteins on the membranes of epithelial cells in the small intestine. These surface molecules become receptors for the toxin, choleragen, released by cholera bacteria. The toxin stimulates the cells to secrete large quantities of chloride ions into the lumen of the small intestine. Sodium ions and water follow the loss of chloride ions. Name the pathogen that causes cholera. Suggest how chloride ions are moved from the epithelial cells into the lumen of the small intestine. Explain how cholera bacteria are transmitted from one person to another. A potential vaccine for choleragen was trialled on volunteers. shows the concentration of antibodies against choleragen in the blood of a volunteer who received a first injection at week 0, followed by a booster injection at week 15. injection injection time / weeks antibody concentration For Examiner’s Use Using the information in , explain the differences between the responses to the first injection and the booster injection. Discuss the problems involved in preventing the spread of cholera.

10. Infectious diseases → 10.1. Infectious diseases

11. Immunity → 11.2. Antibodies and vaccination

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For Examiner’s Use Cellulose is a polysaccharide. shows three sub-units from a molecule of cellulose. CH2OH C C C O C C H OH H H H OH H CH2OH C C C O C C H OH H H H OH H CH2OH C C C O O C C H OH H H H OH H O O Name the sub-unit molecule of cellulose. Name the bonds that attach the sub-unit molecules together within cellulose. Cellulose has high mechanical strength which makes it suitable for the cell walls of plants. Explain how cellulose has such a high mechanical strength making it suitable for the cell walls of plants. For Examiner’s Use Plant cell walls consist of cellulose that is embedded in a matrix of compounds, such as pectins and proteins. Cell wall material is synthesised inside the cell and transported to the cell surface membrane as shown in the drawing made from an electron micrograph in . A L K J H G F E D C B Locate the parts of the cell labelled in which apply to each of the following statements. You must only give one letter in each case. You may use each letter once, more than once or not at all. The first answer has been completed for you. statement letter from organelle that contains DNA H transports cell wall material to the cell surface membrane site of transcription site of ribosome synthesis site of photosynthesis For Examiner’s Use Enzymes known as expansins are found in the matrix of cell walls to help the growth of cells. Use the information in to describe how proteins made by the ribosomes reach the matrix of the cell wall.

2. Biological molecules → 2.2. Carbohydrates and lipids

1. Cell structure → 1.2. Cells as the basic units of living organisms

7. Transport in plants → 7.2. Transport mechanisms

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