18. Classification, biodiversity and conservation
A section of Biology, 9700
Listing 10 of 184 questions
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 name feeding habit percentage change in numbers between 1995 and 2005 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 Using the information in Table 1.1 suggest reasons for the changes in numbers of these birds. An ecosystem that has a wide range of species has a high biodiversity. Explain the benefits of maintaining biodiversity.
9700_w10_qp_42
THEORY
2010
Paper 4, Variant 2
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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. 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. 0.005 gene locus genetic diversity / arbitrary units Key: = teosinte 0.010 0.015 0.020 0.025 = cultivated maize Compare the genetic diversity of teosinte with that of cultivated maize. Suggest reasons for the differences in genetic diversity between teosinte and cultivated maize. Explain how these data support the idea that wild relatives of crop plants, such as maize, should be conserved. Most farmers today grow maize from seeds that have been produced by crossing two different homozygous parents. Explain why this is done.
9700_w13_qp_43
THEORY
2013
Paper 4, Variant 3
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List three reasons why it is important to conserve endangered plant species. 1. 2. 3. The tree Vatica guangxiensis is an endangered species. Only three wild populations exist, all in south-western China. Conservation of this species began in the 1980s. Conservation methods included attempts to preserve the habitat of the wild populations and the establishment of a fourth population in the Xishuangbanna Tropical Botanical Garden. In 2002, the genetic diversity of each of the four populations was assessed. This was done by testing samples of DNA from a number of individuals. • Twenty different regions of DNA were investigated, using electrophoresis. • For each population, the percentage of samples that showed differences in the DNA structure, shown by different bands on the DNA ‘fingerprint’, was calculated. • This figure was recorded as the percentage of polymorphic bands. The greater the percentage of polymorphic bands, the greater the genetic diversity in the population. Table 4.1 shows the results. Table 4.1 population number of individual plants sampled percentage of polymorphic bands wild population A 38.53 wild population B 31.60 wild population C 27.27 population in the botanic garden 30.74 With reference to Table 4.1, compare the genetic diversity of the population of V. guangxiensis in the botanic garden with the genetic diversity of the three wild populations. Suggest explanations for the relatively low percentage of polymorphic bands recorded in wild population C. Explain why high genetic diversity is important for a species. The Xishuangbanna Tropical Botanical Garden is located only tens of kilometres from the habitats of the wild populations of V. guangxiensis. Suggest how this may help with the long-term conservation of this species. Seed banks also have an important role in the conservation of endangered plant species. Explain why storing seeds may be a more successful method of conservation than maintaining a population of growing plants. Suggest why a sample of each type of seed stored in a seed bank is germinated every few years.
9700_w14_qp_41
THEORY
2014
Paper 4, Variant 1
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List three reasons why it is important to conserve endangered plant species. 1. 2. 3. The tree Vatica guangxiensis is an endangered species. Only three wild populations exist, all in south-western China. Conservation of this species began in the 1980s. Conservation methods included attempts to preserve the habitat of the wild populations and the establishment of a fourth population in the Xishuangbanna Tropical Botanical Garden. In 2002, the genetic diversity of each of the four populations was assessed. This was done by testing samples of DNA from a number of individuals. • Twenty different regions of DNA were investigated, using electrophoresis. • For each population, the percentage of samples that showed differences in the DNA structure, shown by different bands on the DNA ‘fingerprint’, was calculated. • This figure was recorded as the percentage of polymorphic bands. The greater the percentage of polymorphic bands, the greater the genetic diversity in the population. Table 4.1 shows the results. Table 4.1 population number of individual plants sampled percentage of polymorphic bands wild population A 38.53 wild population B 31.60 wild population C 27.27 population in the botanic garden 30.74 With reference to Table 4.1, compare the genetic diversity of the population of V. guangxiensis in the botanic garden with the genetic diversity of the three wild populations. Suggest explanations for the relatively low percentage of polymorphic bands recorded in wild population C. Explain why high genetic diversity is important for a species. The Xishuangbanna Tropical Botanical Garden is located only tens of kilometres from the habitats of the wild populations of V. guangxiensis. Suggest how this may help with the long-term conservation of this species. Seed banks also have an important role in the conservation of endangered plant species. Explain why storing seeds may be a more successful method of conservation than maintaining a population of growing plants. Suggest why a sample of each type of seed stored in a seed bank is germinated every few years.
9700_w14_qp_42
THEORY
2014
Paper 4, Variant 2
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Researchers measured insect biodiversity on Acacia trees in the African savannah using the following method: • insecticide was sprayed into each tree • this killed the insects, which fell onto a sheet below the tree • the dead insects were collected, identified and counted. The researchers considered each tree to be a small, distinct ecosystem. Discuss whether or not an individual tree can be described as a small, distinct ecosystem. Table 5.1 shows summary statistics for some of the trees sampled in this study. The leaf canopy area is a measure of the size of the tree and the extent of its leaf cover. Table 5.2 shows the diversity and abundance of some different taxonomic groups of insects in the study. Table 5.1 tree species number of trees sampled total leaf canopy area sampled / m2 number of insect species on the single tree with the smallest diversity on the single tree with the largest diversity mean for all trees sampled Acacia mellifera 6.28 Acacia nilotica 23.72 Acacia tortilis 4.00 Table 5.2 taxon number of species total number of individuals Coleoptera 113 2 197 Diptera 58 1 029 Formicidae 14 7 467 Hemiptera 121 11 875 Complete Table 5.1 by calculating the mean number of insect species for Acacia tortilis. Select, from Tables 5.1 and 5.2, a name to fit the following taxonomic groups: a genus a species Comment on the effects of sample size on the quality and accuracy of the data in Table 5.1. This study was carried out in Mkomazi Game Reserve in Tanzania. Suggest how research into insect diversity on Acacia trees is relevant to the conservation of bigger animals in the reserve, such as elephants.
9700_w16_qp_43
THEORY
2016
Paper 4, Variant 3
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The St. Lawrence river in Canada has been identified as an area with very high biodiversity. Explain how the term biodiversity can be considered at different levels. The St. Lawrence river is rich in species of aquatic mammals, especially whales. In spring, thousands of whales swim from the Atlantic ocean up the St. Lawrence river. Thirteen different species of whale have been recorded. One of these is the blue whale, Balaenoptera musculus. is a diagram of a blue whale. dorsal fin Photographs of blue whales are analysed by computer so that individual whales can be identified and population abundance can be estimated. Each blue whale is different in colour and in the shape of dorsal fin. Different whales also have different patterns of scarring. State the two sources of phenotypic variation in the blue whale population. Suggest one reason why it is difficult to measure the actual population size of the blue whale. The St. Lawrence river runs through very busy industrial areas. It has many ports for cargo ships, a good fishing trade and many whale-watching boat trips for tourists. Decades of whale hunting has caused a large decrease in whale population sizes. Since whale hunting was banned, whale populations have not recovered. Seven of the thirteen whale species in the St. Lawrence river have been rated as endangered species. Suggest two reasons why the populations of whales have not recovered since the ban on whale hunting. Fat samples from under the skin of individual whales of several different species were taken. These were analysed and the concentrations of the toxins DDT and PCBs were measured. Suggest why whales were found to have accumulated very high concentrations of DDT and PCBs in their fatty tissues. Algal blooms sometimes occur in the area of the Atlantic ocean near the St. Lawrence river. These result from rapid population growth of unicellular algae such as Alexandrium tamarense. A. tamarense produces saxitoxin, a neurotoxin that causes muscle paralysis by acting on voltage-gated sodium ion channels in neurones. Saxitoxin can kill whales. Suggest how saxitoxin results in the death of a whale. Algae, such as A. tamarense, used to belong to the kingdom Plantae but are now classified in the kingdom Protoctista. State one reason why A. tamarense is classified in the kingdom Protoctista and not in the kingdom Plantae.
9700_w17_qp_41
THEORY
2017
Paper 4, Variant 1
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shows a male red deer, Cervus elaphus. Red deer are herbivores, browsing on low vegetation in forests and on waste land. A history of wild red deer on the western European island of Ireland includes these facts: • Red deer have lived in Ireland for at least 12 000 years. • Originally red deer could cross from the neighbouring island of Great Britain to Ireland over a land connection. • A rise in sea levels at the end of the last Ice Age removed this land connection, separating the red deer on the two islands. • In the 1800s the number of red deer in Ireland decreased sharply after the main food crop for the human population failed for several consecutive years. • In the 1900s this decrease in the number of red deer continued as large areas of waste land were drained for agriculture. • By 1960 red deer were nearly extinct in Ireland, restricted to one population, A, of 60 individuals. • Since then protection has allowed population A to increase to over 600 red deer. • Several new red deer populations, B, C and D, have also been established in different parts of Ireland from individuals brought from Great Britain. Use the information given to identify two causes of extinction that may have threatened the survival of red deer in Ireland. Describe how the level of molecular similarity between the red deer in population A and population B can be investigated. Explain why some red deer in population A show unique molecular features that are not found in any of the red deer of populations B, C and D.
9700_w17_qp_42
THEORY
2017
Paper 4, Variant 2
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The St. Lawrence river in Canada has been identified as an area with very high biodiversity. Explain how the term biodiversity can be considered at different levels. The St. Lawrence river is rich in species of aquatic mammals, especially whales. In spring, thousands of whales swim from the Atlantic ocean up the St. Lawrence river. Thirteen different species of whale have been recorded. One of these is the blue whale, Balaenoptera musculus. is a diagram of a blue whale. dorsal fin Photographs of blue whales are analysed by computer so that individual whales can be identified and population abundance can be estimated. Each blue whale is different in colour and in the shape of dorsal fin. Different whales also have different patterns of scarring. State the two sources of phenotypic variation in the blue whale population. Suggest one reason why it is difficult to measure the actual population size of the blue whale. The St. Lawrence river runs through very busy industrial areas. It has many ports for cargo ships, a good fishing trade and many whale-watching boat trips for tourists. Decades of whale hunting has caused a large decrease in whale population sizes. Since whale hunting was banned, whale populations have not recovered. Seven of the thirteen whale species in the St. Lawrence river have been rated as endangered species. Suggest two reasons why the populations of whales have not recovered since the ban on whale hunting. Fat samples from under the skin of individual whales of several different species were taken. These were analysed and the concentrations of the toxins DDT and PCBs were measured. Suggest why whales were found to have accumulated very high concentrations of DDT and PCBs in their fatty tissues. Algal blooms sometimes occur in the area of the Atlantic ocean near the St. Lawrence river. These result from rapid population growth of unicellular algae such as Alexandrium tamarense. A. tamarense produces saxitoxin, a neurotoxin that causes muscle paralysis by acting on voltage-gated sodium ion channels in neurones. Saxitoxin can kill whales. Suggest how saxitoxin results in the death of a whale. Algae, such as A. tamarense, used to belong to the kingdom Plantae but are now classified in the kingdom Protoctista. State one reason why A. tamarense is classified in the kingdom Protoctista and not in the kingdom Plantae.
9700_w17_qp_43
THEORY
2017
Paper 4, Variant 3
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Questions Discovered
184