9700_s08_qp_4
A paper of Biology, 9700
Questions:
10
Year:
2008
Paper:
4
Variant:
0
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1
shows the relationship between annual deforestation rates and annual human population growth for six countries. percentage annual deforestation rate percentage annual human population growth V B N P I Z B – Burundi P – Philippines N – Nigeria I – Indonesia Z – Zimbabwe V – Vietnam Describe the relationship shown in . For Examiner’s Use Over half of the species of plants and animals comprising the biodiversity of the Earth are thought to exist in tropical rainforests. Explain the meaning of the term biodiversity. Explain the economic reasons for maintaining biodiversity.
18. Classification, biodiversity and conservation  →  18.3. Conservation
18. Classification, biodiversity and conservation  →  18.2. Biodiversity
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2
For Examiner’s Use is a light micrograph of a small part of the pancreas. Name structures A and B. A B With reference to , explain why the pancreas is an endocrine gland. For Examiner’s Use Insulin and glucagon are involved in the control of blood glucose concentration. When blood glucose concentration rises, secretion of insulin increases. Outline two ways in which insulin affects the activity of cells in the liver. 1. 2. Some forms of diabetes are caused by an inability to secrete insulin and can be controlled by regular injections of insulin. Most of this insulin is now produced using genetically modified Escherichia coli. Explain the advantages of using this type of insulin, rather than insulin obtained from animal sources.
14. Homeostasis  →  14.1. Homeostasis in mammals
15. Control and coordination  →  15.1. Control and coordination in mammals
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3
For Examiner’s Use shows the male and female flowers of maize. With reference to , describe how the flowering habit of maize encourages wind-pollination. In a maize plant, the anthers normally ripen before the stigmas are mature and ready to receive pollen. This encourages cross-pollination. Explain the potential advantages of cross-pollination to a plant species. For Examiner’s Use Cultivated maize is related to a wild Mexican grass, teosinte. Teosinte looks very different from maize. In particular, teosinte has a very hard layer surrounding the fruit, making it impossible to use as an edible grain. Archaeological excavations have found that maize in its edible form dates back at least 4000 years. It has been argued that the structural differences between teosinte and maize grains are so great that it is unlikely that maize could have been bred from teosinte so long ago. Investigations have been carried out into the genetic differences between teosinte and maize. A gene on chromosome 4, tga 1, containing 1042 base pairs, was found to be responsible for all of the structural differences between teosinte and maize. shows the DNA base sequence of the only part of tga 1 that always differs between teosinte and maize. teosinte GAT TGG GAT CTC AAG GCG GCG GGC GCG TGG maize GAT TGG GAT CTC AAC GCG GCG GGC GCG TGG Outline the principles of electrophoresis as used in sequencing this DNA. For Examiner’s Use Suggest how the difference in the base sequence of the tga 1 gene shown in could cause large differences in phenotype between teosinte and maize. With reference to , explain how these results support the suggestion that it would have been relatively easy for early farmers in Mexico to have bred maize from teosinte.
17. Selection and evolution  →  17.2. Natural and artificial selection
17. Selection and evolution  →  17.3. Evolution
16. Inheritance  →  16.2. The roles of genes in determining the phenotype
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4
For Examiner’s Use Outline the role of calcium ions in the transmission of nerve impulses. It has been suggested that during maturation of a sperm, the uptake of calcium ions is necessary to produce the vigorous movements of the sperm’s flagellum that allow it to penetrate the zona pellucida of an oocyte. Uptake of calcium ions can be measured by staining the sperm with a non-toxic fluorescent stain. Fluorescence increases as the concentration of calcium ions inside the sperm increases. Sperm from two types of mice were investigated: • wild-type mice, whose sperm have a particular protein, P. P is an ion channel found in the plasma (cell surface) membrane. • mutant mice whose sperm did not have protein P. The results of the investigation are shown in . sperm head sperm flagellum sperm from wild-type mice sperm from mutant mice mean percentage increase in fluorescence key: For Examiner’s Use With reference to , describe and explain the different mean percentage increases in fluorescence of sperm from wild-type and mutant mice, sperm heads and flagella. For Examiner’s Use The ability of sperm from wild-type and mutant mice to penetrate oocytes was tested using in-vitro fertilisation (IVF) of oocytes with and without a zona pellucida. The results are shown in . oocytes with zona pellucida oocytes without zona pellucida sperm from wild-type mice key: sperm from mutant mice percentage of oocytes penetrated by sperm Explain what is meant by in-vitro fertilisation. With reference to , explain the differences in the ability of sperm from wild- type and mutant mice to penetrate oocytes in IVF.
16. Inheritance  →  16.1. Passage of information from parents to offspring
15. Control and coordination  →  15.1. Control and coordination in mammals
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5
For Examiner’s Use A significant quantity of the metallic copper produced in some countries is obtained using the chemoautotrophic bacterium, Thiobacillus ferro-oxidans, which is present in rocks in many countries. The process, known as bioleaching, is shown in . Acidified water is pumped onto large heaps of waste material, containing iron and copper sulfides, left from conventional mining. Thiobacillus ferro-oxidans oxidises iron (sulfide to iron (sulfate. The iron (ions oxidise copper sulfide to soluble copper sulfate. The solution is collected in shallow ponds. step 1 step 2 step 3 step 4 Scrap iron is put into the ponds and the following reaction allows metallic copper to be precipated onto the iron: Cu2+ + Fe Cu + Fe2+ Metallic copper is scraped off the surface of the scrap iron and refined. Suggest the benefit to the bacterium of step 2. For Examiner’s Use State two environmental disadvantages of extracting metals by bioleaching. 1. 2. Explain why the production of metallic copper by bioleaching can be cheaper than using conventional mining methods.
3. Enzymes  →  3.2. Factors that affect enzyme action
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6
For Examiner’s Use Colour blindness is a condition characterised by the inability of the brain to perceive certain colours accurately. • The most common form is termed red-green colour blindness (RGC). • RGC results from a recessive allele. • 0.6% of females worldwide have RGC. • 8.0% of males worldwide have RGC. shows the occurrence of RGC in one family. = male = female = male with RGC Explain the meaning of the terms allele and recessive. allele recessive Explain why females are less likely than males to have RGC. With reference to , and using the symbols R for the dominant allele and r for the recessive allele, state the genotypes of the individuals 1, 4, 6 and 7.
16. Inheritance  →  16.2. The roles of genes in determining the phenotype
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7
An absorption spectrum is a graph of the absorption of different wavelengths of light by a photosynthetic pigment. An action spectrum is a graph of the rate of photosynthesis at different wavelengths of light. shows the absorption spectra of chlorophyll a and chlorophyll b as well as an action spectrum. wavelength of light / nm rate of photosynthesis percentage light absorption action spectrum chlorophyll b chlorophyll a With reference to , compare the absorption spectra of chlorophyll a and chlorophyll b, For Examiner’s Use For Examiner’s Use explain the shape of the action spectrum, explain why plants appear green . is an electron micrograph showing a section through part of a chloroplast. On , draw label lines and use the letters W and Y to identify the following structures: • W where the light-independent reactions occur • Y where chlorophyll is found For Examiner’s Use Explain why increasing the concentration of carbon dioxide may increase the rate of production of carbohydrates at high light intensities.
13. Photosynthesis  →  13.1. Photosynthesis as an energy transfer process
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8
For Examiner’s Use The Atlantic herring, Clupea harengus, lives in large populations called shoals and may grow up to 40 cm long. shows the appearance of C. harengus. The length of C. harengus shows wide variation. shows the numbers of fish of different lengths in a population of C. harengus. The arrows show the selection pressures, P and S. length of fish / cm number of fish selection pressure P selection pressure S For Examiner’s Use Sketch a graph on the axes below to show the distribution of length of C. harengus, when selection pressures P and S operate for a few years. length of fish / cm number of fish Name this type of natural selection Sketch a graph on the axes below to show the distribution of length of C. harengus, when selection pressure S alone operates for a few years. length of fish / cm number of fish Name this type of natural selection Suggest two examples of selection pressure S. 1. 2.
17. Selection and evolution  →  17.2. Natural and artificial selection
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