9700_w09_qp_22
A paper of Biology, 9700
Questions:
6
Year:
2009
Paper:
2
Variant:
2
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1
Cell surface membranes are involved with the movement of substances into and out of cells. Calcium pumps in cell surface membranes maintain a concentration of calcium ions inside the cytoplasm that is a thousand times lower than outside the cell. shows the movement of calcium ions across a cell surface membrane. cytoplasm outside cell calcium ion With reference to , explain why calcium ions do not pass through the phospholipid bilayer; For Examiner’s Use name and describe the process by which calcium ions are moved across the membrane. name description Phagocytosis is the process by which bacteria are ingested by cells. Describe the role of the cell surface membrane during phagocytosis. Phagocytic cells contain many lysosomes. Describe the function of lysosomes in destroying ingested bacterial cells.
4. Cell membranes and transport  →  4.1. Fluid mosaic membranes
4. Cell membranes and transport  →  4.2. Movement into and out of cells
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2
For Examiner’s Use Sucrase is the enzyme that catalyses the hydrolysis of sucrose. A student investigated the effect of substrate concentration on the activity of this enzyme. Six test-tubes were set up each containing 10 cm3 of different concentrations of sucrose solutions. The test-tubes were left in a water bath at 30 °C for ten minutes. After ten minutes, 5 cm3 of a sucrase solution at 30 °C was added to each test-tube and the reaction mixtures were stirred. After a further five minutes, the temperature of the water-bath was raised to above 85 °C and the same volume of Benedict’s solution added to each test-tube in turn. The student recorded the time when a green colour first became visible in each test-tube. The concentrations used and the student’s results are shown in Table 2.1. Table 2.1 concentration of sucrose / g dm–3 time taken for green colour to appear / s Explain why the temperature of the water-bath was raised to above 85 °C. For Examiner’s Use Use the axes below to sketch a graph to show the effect of substrate concentration on the rate of hydrolysis of sucrose by sucrase. concentration of sucrose / g dm–3 rate of hydrolysis With reference to the student’s results, describe and explain the effect of increasing substrate concentration on the rate of hydrolysis of sucrose by sucrase.
2. Biological molecules  →  2.1. Testing for biological molecules
3. Enzymes  →  3.2. Factors that affect enzyme action
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3
For Examiner’s Use Explain why it is important that the daughter cells produced during a mitotic cell cycle in humans are genetically identical. Name two factors that increase the chance that a cancer cell will develop. shows a cancer cell in the process of cell division. With reference to , state the stage of cell division; For Examiner’s Use describe what is happening to the cell during this stage of cell division; describe how these cells develop into a tumour.
5. The mitotic cell cycle  →  5.1. Replication and division of nuclei and cells
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4
For Examiner’s Use A leafy twig was cut from a tree and the cut end immediately placed into water. The twig was then put into a potometer to measure the uptake of water. The potometer was placed on a balance to record changes in mass. shows the rate of water uptake and the rate of mass loss over a period of 24 hours. The graph also shows when it was light and when it was dark. time / h Key rate of mass loss rate of water uptake rate of water uptake / g h–1 rate of mass loss / g h–1 dark dark light For Examiner’s Use Explain how water was lost from the leaves of the leafy twig. With reference to , describe how the rates of water uptake and water loss change during the 24 hour period. Explain the mechanism by which water is transported in the xylem of the leafy twig while in the potometer.
4. Cell membranes and transport  →  4.2. Movement into and out of cells
7. Transport in plants  →  7.2. Transport mechanisms
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5
For Examiner’s Use Candida albicans is a yeast-like fungus that lives in human lungs. It is the causative agent of one of the opportunistic infections that may develop during AIDS. C. albicans is eukaryotic. shows its structure. L K J H Name H to L. H J K L State two ways in which the structure of a prokaryotic cell differs from that shown in . For Examiner’s Use C. albicans uses a transport protein, TMP1, to absorb sugar molecules from the inside of the mouth. TMP1 is encoded by a gene within the nucleus and is produced when sugars are present in the surroundings. Explain how the structures within the cell shown in , are involved with the production of functioning TMP1.
2. Biological molecules  →  2.2. Carbohydrates and lipids
1. Cell structure  →  1.2. Cells as the basic units of living organisms
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6
For Examiner’s Use Explain what is meant by the term community. shows the flow of energy through a woodland. All figures are in kJ m–2 per week. light energy absorbed by producers 65 800 primary consumers secondary consumers energy loss in respiration leaf litter energy trapped by producers and converted to biomass decomposers Calculate the energy trapped by the producers and converted to biomass as a percentage of the light energy absorbed. Express your answer to the nearest 0.1%. Show your working. Answer % For Examiner’s Use Suggest, in terms of energy flow, why there are no tertiary consumers in the woodland. Leaf litter is composed of dead leaves and twigs. The total energy in the leaf litter was 15 899 kJ m–2 but only 153 kJ m–2 per week is transferred to decomposers. When animal wastes rich in nitrogen were mixed with the leaf litter the energy flow to decomposers increased significantly. Suggest why the addition of animal wastes rich in nitrogen increased the energy flow to decomposers.
12. Energy and respiration  →  12.1. Energy
13. Photosynthesis  →  13.1. Photosynthesis as an energy transfer process
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