2 Section A For Examiner’s Use Answer all the questions. 1 The Great Lakes, in North America, lie between the USA and Canada. A survey of birds of the Lake Ontario area has shown the relative abundance of birds between 1995 and 2005. Table 1.1 shows the feeding habits and the relative change in numbers of some of the birds in the survey. Table 1.1 percentage change in numbers between 1995 and 2005 name feeding habit mallard Anas platyrhynchos amphibia, plants +10.0 tree swallow Tachycineta bicolor flying insects – 6.2 blue-winged teal Anas discors aquatic insects, molluscs, plants –12.3 pied-billed grebe Podilymbus podiceps amphibia, aquatic insects, fish –15.9 black tern Chlidonias niger aquatic insects, fish, flying insects –18.7 (a) Using the information in Table 1.1 suggest reasons for the changes in numbers of these birds. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [4] © UCLES 2010 9700/41/O/N/10 3 (b) An ecosystem that has a wide range of species has a high biodiversity. For Examiner’s Use Explain the benefits of maintaining biodiversity. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [4] [Total: 8] © UCLES 2010 9700/41/O/N/10 [Turn over 22 Section B For Examiner’s Use Answer one question. 9 (a) Outline the behaviour of chromosomes during meiosis. [9] (b) Describe the ways by which gene mutations can occur. [6] [Total: 15] 10 (a) Outline the need for energy in living organisms using named examples. [9] (b) Explain the different energy values of carbohydrate, lipid and protein as respiratory substrates. 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The percentage decrease in the number of marine animal species between 1950 and 2000 is shown in Fig. 1.1. 0 10 percentage decrease in the number of 20 marine animal species between 1950 and 2000 30 40 1950 1960 1970 1980 1990 2000 year Fig. 1.1 Suggest explanations for the decrease in the number of marine animal species between 1950 and 2000. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [3] © UCLES 2010 9700/43/O/N/10 3 (b) Explain what is meant by the term biodiversity. .......................................................................................................................................... For Examiner’s Use .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [2] (c) Discuss the benefits of maintaining the biodiversity of a marine ecosystem, such as that in the coastal waters of Canada. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [3] [Total: 8] © UCLES 2010 9700/43/O/N/10 [Turn over 15 6 From 1975 to 1977 one of the Galapagos Islands, Daphne Major, experienced a severe drought. A ground finch, Geospiza fortis, feeds on seeds on Daphne Major. For Examiner’s Use Fig. 6.1 shows the ground finch, G. fortis. Fig. 6.1 • • • • One of the few plants that survived the drought produced large seeds inside tough fruits. Many G. fortis died during the drought and the population declined from 1400 in 1975 to 190 in 1977. The mean beak depth of those G. fortis that died was 10.68 mm and the mean beak depth of those that survived was 11.07 mm. The mean beak depth of G. fortis before the drought was 10.86 mm. (a) Calculate the percentage decrease in population size between the years 1975 and 1977. Show all the steps in your calculation and give your answer to the nearest whole number. Answer ............................................ % [2] (b) Suggest why some G. fortis were able to survive the drought while others died. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [3] © UCLES 2010 9700/43/O/N/10 [Turn over 16 (c) Natural selection was taking place on Daphne Major. State the type of natural selection operating on G. fortis during the drought and explain your answer. type of natural selection ................................................................................................... explanation ...................................................................................................................... .................................................................................................................................... [2] [Total: 7] © UCLES 2010 9700/43/O/N/10 For Examiner’s Use 20 Section B For Examiner’s Use Answer one question. 9 (a) Explain how meiosis and fertilisation may result in genetic variation in offspring. [7] (b) Explain, using examples, how the environment may affect the phenotype of an organism. [8] [Total: 15] 10 (a) Describe the structure of ATP and the role of ATP as the energy currency in all living organisms. [8] (b) Outline anaerobic respiration in mammalian cells and describe how it differs from anaerobic respiration in yeast cells. 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......................................................................................................................................................... ......................................................................................................................................................... ......................................................................................................................................................... ......................................................................................................................................................... ......................................................................................................................................................... © UCLES 2010 9700/43/O/N/10 For Examiner’s Use 2 Section A Answer all the questions. 1 The Ethiopian wolf, Canis simensis, is a member of the Canidae family of carnivores. Fig. 1.1 shows an Ethiopian wolf. Fig. 1.1 (a) Ethiopian wolves evolved from an ancestor similar to the grey wolf that crossed into Northern Africa from Europe about 100 000 years ago. They live in the alpine grasslands and heathlands at, or above, 3000 m altitude in Ethiopia. State the most likely type of speciation that led to the evolution of the Ethiopian wolf. ...................................................................................................................................... [1] (b) A population of Ethiopian wolves is called a pack. Heterozygosity has been found to be low in all of the packs of Ethiopian wolves that have been studied. Suggest why the heterozygosity may be low in Ethiopian wolf packs. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [2] © UCLES 2011 9700/41/O/N/11 For Examiner’s Use 3 (c) The Ethiopian wolf is classified as an endangered species by the International Union for the Conservation of Nature and Natural Resources (IUCN). It publishes an annual list of endangered species called the Red List. For Examiner’s Use Complete Table 1.1 to summarise four of the main reasons, with further explanation, as to why the Ethiopian wolf has become an endangered species. Table 1.1 reason explanation an activity that accompanies human expansion and reduces the size of the wolf habitat rabies, a lethal viral disease of wolves a human activity to control wolves, considered to be pests the result of wolves breeding with domestic dogs [4] (d) According to the Red List, the number of endangered mammal species in 2007 was 349 and in 2008 was 448. Calculate the percentage increase in endangered mammal species between 2007 and 2008. Give your answer to the nearest whole number. Show your working. answer ............................................. .% [2] [Total: 9] © UCLES 2011 9700/41/O/N/11 [Turn over 2 Section A For Examiner’s Use Answer all the questions. 1 The Bengal Tiger, Panthera tigris tigris, is an endangered mammalian species of Southern Asia. It lives mostly in a forest habitat. Fig. 1.1 shows a Bengal Tiger. Fig. 1.1 (a) Table 1.1 shows the relationship between available forest habitat and Bengal Tiger numbers between 1970 and 2010. Table 1.1 © UCLES 2011 year forest habitat remaining compared to 1970 (%) Bengal Tiger numbers 1970 100 37 000 1980 79 27 000 1990 42 12 000 2000 26 3 600 2010 18 1 400 9700/43/O/N/11 3 Calculate the percentage decrease in the number of Bengal Tigers between 1970 and 2010. Give your answer to the nearest whole number. For Examiner’s Use answer ............................................. % [2] (b) Suggest methods to conserve the Bengal Tiger. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [4] (c) The Bengal Tiger belongs to the kingdom Animalia. State two differences between members of the kingdom Animalia and the kingdom Plantae. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [2] [Total: 8] © UCLES 2011 9700/43/O/N/11 [Turn over 18 7 Corals are simple marine animals and usually exist in colonies of thousands of individuals. Fig. 7.1 shows a coral colony. Fig. 7.1 Corals absorb calcium carbonate from the sea to build their skeletons, which help to form large coral reefs. Coral reefs provide a home for about 25% of known fish species and have the highest biodiversity of any marine ecosystem. (a) Corals, although they are animals, are sometimes mistaken for members of the plant kingdom. State two ways in which corals differ from plants. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [2] (b) Outline what is meant by the term ecosystem. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [2] © UCLES 2012 9700/42/O/N/12 For Examiner’s Use 19 (c) Coral reefs are at risk of damage due to human activities. All the coral reefs in three regions were classified as being at low, medium or high risk of damage. For Examiner’s Use Table 7.1 shows the areas of coral reef at risk of damage in these three regions. Table 7.1 area of coral reef at risk of damage / 1000 km2 low medium high percentage of coral reef at high risk of damage Caribbean Sea 9 8 7 29 Indian Ocean 20 15 10 Pacific Ocean 60 30 9 region (i) Complete Table 7.1, giving your answers to the nearest whole number. (ii) Suggest how human activities could damage coral reefs. 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[3] [Total: 8] © UCLES 2012 9700/42/O/N/12 [Turn over 5 2 Mammoths are extinct mammals related to elephants. About three million years ago, the ancestors of mammoths migrated from Africa into Europe and Asia. There, about 1.7 million years ago, the steppe mammoth evolved and became adapted to the cooler conditions. Then, about 700 000 years ago, as the climate changed and the Arctic became much colder, the woolly mammoth evolved. For Examiner’s Use Woolly mammoths showed a number of obvious adaptations to reduce heat loss, including thick fur, small ears and small tails. (a) Explain how variation and natural selection may have brought about the evolution of the woolly mammoth from the steppe mammoth. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [5] (b) A frozen, 43 000 year old woolly mammoth was found in Siberia. Its DNA was extracted and sequenced. The sequences of the genes coding for the α and β chains of haemoglobin were compared with those of modern Asian elephants. The results suggested that, when compared with Asian elephants: • • there was only one different amino acid in the woolly mammoth’s α chains there were three different amino acids in the woolly mammoth’s β chains. Explain the likely effect of these differences on a molecule of mammoth haemoglobin. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [3] © UCLES 2013 9700/42/O/N/13 [Turn over 6 (c) Scientists synthesised woolly mammoth haemoglobin in order to investigate whether or not the different haemoglobin was part of the mammoth’s adaptation to a cold climate. The affinity of haemoglobin for oxygen is affected by the changes in temperature that can occur in mammals, for example in active muscle tissue or close to the skin surface. It is advantageous for Arctic mammals to have haemoglobin whose affinity for oxygen is only slightly affected by changes in temperature. This is often achieved by using substances called ‘red cell effectors’, which bind to haemoglobin. Fig. 2.1 compares the effect of temperature on the affinity for oxygen of woolly mammoth and Asian elephant haemoglobin, with and without red cell effectors. Key woolly mammoth Asian elephant effect of temperature on the affinity of haemoglobin for oxygen haemoglobin haemoglobin plus red cell effectors Fig. 2.1 (i) Suggest why it is advantageous for Arctic mammals to have haemoglobin whose affinity for oxygen is only slightly affected by changes in temperature. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [2] © UCLES 2013 9700/42/O/N/13 For Examiner’s Use 7 (ii) Explain whether or not Fig. 2.1 provides evidence that woolly mammoth haemoglobin is better adapted for a cold climate than Asian elephant haemoglobin. 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[4] [Total: 14] © UCLES 2013 9700/42/O/N/13 [Turn over 13 5 (a) Maize originated in the Americas, and 55% of the world’s maize production is from this part of the world. For Examiner’s Use Fig. 5.1 shows the mean yields of maize in the USA between 1860 and 2010. 11 10 9 8 7 grain 6 yield / tonnes per hectare 5 4 3 2 1 0 1860 1880 1900 1920 1940 year 1960 1980 2000 2020 Fig. 5.1 Describe the changes in grain yield between 1860 and 2010. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [3] © UCLES 2013 9700/42/O/N/13 [Turn over 14 (b) The greatest improvement in maize yields came after growers realised that maize hybrids have a much greater yield than inbred lines. Between 1860 and the 1930s, maize was allowed to pollinate naturally in the field. From the 1930s onward, maize seed was produced using ‘double-cross’ hybrids. To produce a double-cross hybrid: • two different maize plants, A and B, are crossed to produce a hybrid, C • two other maize plants, X and Y, are crossed to produce a hybrid, Z • the hybrid C is then crossed with the hybrid Z, to produce the double-cross hybrid. From 1960 onwards, maize seed was produced using ‘single-cross’ hybrids. This involves crossing one inbred (entirely homozygous) plant with a different inbred plant. Explain why single-cross hybrids are genetically uniform, but double-cross hybrids are not. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [3] © UCLES 2013 9700/42/O/N/13 For Examiner’s Use 15 (c) An experiment was carried out in 1996–1997 to investigate the relative effects of genotype and environment on the yield of maize. For Examiner’s Use Maize seeds with different ‘inbreeding coefficients’ were used. The greater the inbreeding coefficient, the greater the degree of homozygosity in the maize plants. Maize seeds with different inbreeding coefficients were planted in two different areas in 1996, and in the same two areas in 1997. Fig. 5.2 shows the results. 9 1996 site 1 1996 site 2 1997 site 1 1997 site 2 8 7 grain 6 yield / tonnes per 5 hectare 4 3 2 0.0 0.2 0.4 0.6 0.8 1.0 inbreeding coefficient Fig. 5.2 (i) Inbreeding depression is a reduction in vigour that results from inbreeding. Explain how the results in Fig. 5.2 demonstrate inbreeding depression in maize. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [2] (ii) Explain how the results in Fig. 5.2 show that the environment affects maize yields. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [2] [Total: 10] © UCLES 2013 9700/42/O/N/13 [Turn over 20 8 (a) The tiger, Panthera tigris, is classified as an endangered species by the International Union for the Conservation of Nature and Natural Resources (IUCN). The IUCN publishes an annual list of endangered species called the Red List. Fig. 8.1 shows the number of tigers in the wild between 1900 and 2010. 100 000 90 000 80 000 70 000 60 000 number of tigers in the wild 50 000 40 000 30 000 20 000 10 000 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 year Fig. 8.1 Calculate the overall rate of decrease in number of tigers between 1900 and 2010. Give your answer to the nearest whole number. answer ........................ tigers per year [2] © UCLES 2013 9700/42/O/N/13 For Examiner’s Use 21 (b) Describe the reasons why a named species has become endangered. .......................................................................................................................................... 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[4] [Total: 6] © UCLES 2013 9700/42/O/N/13 [Turn over 23 Section B For Examiner’s Use Answer one question. 10 (a) Explain what is meant by a gene mutation and outline the possible consequences of a gene mutation for an organism. [9] (b) Explain how faulty CFTR proteins in cell surface membranes can lead to the symptoms of cystic fibrosis. [6] [Total: 15] 11 (a) Describe the main features of an organism belonging to the plant kingdom. [7] (b) Describe the structure of a mitochondrion and outline its function in a plant cell. 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Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. © UCLES 2013 9700/42/O/N/13 4 2 The evolutionary origin of the four-legged amphibians (such as frogs and toads) from fish has been the subject of much debate for many years. Among living fish, the rarely-caught coelacanth and the lungfish are thought to be most closely related to these amphibians. Samples of blood were taken from two coelacanths that were captured recently near Comoros. The amino acid sequences of the α and β chains of coelacanth and lungfish haemoglobin were compared with the known sequences of amphibian adults and their aquatic larvae (tadpoles). Organisms with more matches in the amino acid sequence of a polypeptide chain share a more recent common ancestor than those with fewer matches. The comparisons with three species of amphibians, Xenopus laevis (Xl), X. tropicana (Xt) and Rana catesbeiana (Rc) are shown in Table 2.1. Table 2.1 percentage of matches of amino acid sequence species of amphibian adults fish species α chains β chains (a) (i) species of amphibian larvae (tadpoles) Xl Xt Rc Xl Xt Rc coelacanth 42.0 47.5 no data 45.4 42.6 48.2 lungfish 40.4 42.1 no data 40.7 39.0 37.9 coelacanth 42.1 43.2 40.7 52.1 52.1 58.2 lungfish 44.1 45.9 41.4 47.3 45.9 48.6 Explain whether or not the information in Table 2.1 supports the suggestion that coelacanths and amphibians share a more recent common ancestor than do lungfish and amphibians. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [4] © UCLES 2013 9700/43/O/N/13 For Examiner’s Use 5 (ii) Suggest why adults and tadpoles of the same species of amphibian have different amino acid sequences in their haemoglobin. For Examiner’s Use .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [2] (b) Coelacanth haemoglobin has a very high affinity for oxygen, suggesting that coelacanths, which have been captured at depths of between 200 m and 400 m, live in water that has a low concentration of oxygen. Explain how an environmental factor, such as the low concentration of oxygen in deep water, can act: (i) as a stabilising force in natural selection .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [3] (ii) as an evolutionary force in natural selection. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [3] © UCLES 2013 9700/43/O/N/13 [Turn over 6 (c) Explain the role of isolating mechanisms in the evolution of new species. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [3] [Total: 15] © UCLES 2013 9700/43/O/N/13 For Examiner’s Use 12 5 Maize was developed from a wild plant called teosinte, which grows from Mexico south to Argentina. It is thought that cultivated maize was derived from teosinte only once. Maize has been found at archaeological sites dated to 5500 years ago. (a) Fig. 5.1 shows the genetic diversity at ten gene loci in teosinte and in cultivated maize. This was determined by sequencing the DNA base pairs at each locus, and calculating how much each of these base sequences varied. The gene loci are numbered in order of the degree of diversity in teosinte. 0.025 Key: = teosinte = cultivated maize 0.020 genetic diversity / arbitrary units 0.015 0.010 0.005 0 1 2 3 4 5 6 7 8 9 10 gene locus Fig. 5.1 (i) Compare the genetic diversity of teosinte with that of cultivated maize. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [2] © UCLES 2013 9700/43/O/N/13 For Examiner’s Use 13 (ii) Suggest reasons for the differences in genetic diversity between teosinte and cultivated maize. For Examiner’s Use .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [3] (iii) Explain how these data support the idea that wild relatives of crop plants, such as maize, should be conserved. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [2] (b) Most farmers today grow maize from seeds that have been produced by crossing two different homozygous parents. Explain why this is done. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [3] [Total: 10] © UCLES 2013 9700/43/O/N/13 [Turn over 18 8 The Atlantic cod, Gadus morhua, is fished for food. (a) Fig. 8.1 shows the size of the stocks of Atlantic cod between 1968 and 2000. 300 280 260 240 220 200 180 160 size of Atlantic cod stocks / thousand tonnes 140 120 100 80 60 40 20 0 1968 1972 1976 1980 1984 1988 1992 1996 2000 year Fig. 8.1 Calculate the overall rate of decrease in size of the stocks of Atlantic cod between 1968 and 2000. answer ...................... tonnes per year [2] © UCLES 2013 9700/43/O/N/13 For Examiner’s Use 19 (b) Suggest how the stocks of Atlantic cod may be increased. .......................................................................................................................................... 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[3] [Total: 5] © UCLES 2013 9700/43/O/N/13 [Turn over
