18. Classification, biodiversity and conservation
A section of Biology, 9700
Listing 10 of 184 questions
Spartina alterniflora is a grass that grows in salt marshes. It spreads by means of seeds and by underground stems. On its native east coast of North America it prevents salt marshes from being eroded by the sea and provides a food source for a large number of different species of animals. Some time after its introduction to the west coast of North America in 1973, S. alterniflora hybridised with Californian cord grass, S. foliosa. The hybrid now outcompetes the native species. The hybrid differs from its parent species in a number of ways: • it is taller • it produces very large numbers of pollen grains which are dispersed by wind to the other species, producing yet more hybrid plants • it produces larger numbers of seeds capable of germination • it can self-pollinate. State the structural features that are characteristic of a wind-pollinated flower and explain how each feature contributes to successful pollination. Suggest how self-pollination could help the population of hybrid plants to increase. Suggest why the hybrid plant is not considered to be a new species of Spartina.
9700_s15_qp_42
THEORY
2015
Paper 4, Variant 2
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shows a water vole, Arvicola amphibius. This species is native to Great Britain. The numbers of water voles are estimated to have fallen by 94% in the last century. This is thought to be due to habitat fragmentation and also to extensive predation by mink, Neovison vison, shown in . Mink originated in North America but were brought to Great Britain for fur farming. Some escaped or were released into the wild, where their numbers rapidly increased. Name and describe a method for estimating the abundance of water voles in a local area. Both water voles and mink are classified as class Mammalia, phylum Chordata, kingdom Animalia. Outline two features of the cells of members of the kingdom Animalia that distinguish them from the cells of other multicellular eukaryotes. Discuss the reasons why alien species should be controlled. Suggest one way of controlling mink numbers in Great Britain.
9700_s16_qp_41
THEORY
2016
Paper 4, Variant 1
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shows a raccoon, Procyon lotor. This species is native to North America. Four individuals were released in Germany in 1934. There are now thought to be more than a million raccoons in Germany. Urban raccoons live in towns. Although they are nocturnal their large size means they may be noticed by humans. They may be found raiding bins containing food waste, or entering buildings. Describe a method for estimating the size of a raccoon population in a town. Raccoons are classified in the phylum Chordata of the kingdom Animalia. Name the domain to which raccoons belong. Outline three characteristic features of members of this domain. It has been suggested that raccoons may threaten biodiversity and pose a risk to human health in Germany. Explain how raccoons could cause problems for local biodiversity and for human health. local biodiversity human health
9700_s16_qp_42
THEORY
2016
Paper 4, Variant 2
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shows a water vole, Arvicola amphibius. This species is native to Great Britain. The numbers of water voles are estimated to have fallen by 94% in the last century. This is thought to be due to habitat fragmentation and also to extensive predation by mink, Neovison vison, shown in . Mink originated in North America but were brought to Great Britain for fur farming. Some escaped or were released into the wild, where their numbers rapidly increased. Name and describe a method for estimating the abundance of water voles in a local area. Both water voles and mink are classified as class Mammalia, phylum Chordata, kingdom Animalia. Outline two features of the cells of members of the kingdom Animalia that distinguish them from the cells of other multicellular eukaryotes. Discuss the reasons why alien species should be controlled. Suggest one way of controlling mink numbers in Great Britain.
9700_s16_qp_43
THEORY
2016
Paper 4, Variant 3
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There is considerable variation in the ecosystems that occur in the continent of North America. These include coniferous forest, prairie grassland, scrub and desert. Large areas of land that once contained natural ecosystems are now used for agriculture. Explain how the variation in ecosystems in North America contributes to biodiversity. The diversity of some beetle species that feed on animal dung was investigated at two types of grassland site in North America. The first type of grassland site was grazed by cattle and the second type of site was not grazed. Dung beetles were collected, identified and counted from two areas of the same total size. Some of the results are shown in Table 8.1. Table 8.1 beetle species number of dung beetles on grassland grazed by cattle number of dung beetles on grassland not grazed Onthophagus pennsylvanicus Canthon ebenus Canthon pilularius Onthophagus hecate total State the null hypothesis for a statistical test comparing the data from the two types of site. State how many genera and how many species of beetle are shown in Table 8.1. genera species Simpson’s Index of Diversity for the beetles on the grassland grazed by cattle was calculated as 0.521 using the formula: D = 1 – Σ n N 2 n = number of individuals of each species present in the sample N = the total number of all individuals of all species Calculate Simpson’s Index of Diversity for the beetles on the grassland that was not grazed. Complete Table 8.2 to show your working. Show all working to three decimal places. Write your final answer on the dotted line. Table 8.2 species number on grassland not grazed n N  n N Onthophagus pennsylvanicus Canthon ebenus Canthon pilularius Onthophagus hecate total Simpson’s Index of Diversity = Describe what the results in Table 8.1 and both figures for Simpson’s Index of Diversity show about the effect of grazing on the diversity of dung beetles.
9700_s17_qp_41
THEORY
2017
Paper 4, Variant 1
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An investigation was carried out in a temperate woodland that contained a number of areas with two different types of ground cover vegetation. • On higher ground where the soil was drier, the dominant ground cover plant was bracken, Pteridium aquilinum. • On lower ground where the soil was wetter, the dominant ground cover plant was bramble, Rubus fruticosus. Describe how the abundance of the two plant species at higher and lower ground sites could be measured. Soil from under bracken and under brambles was collected and placed in two funnels. A bright light was placed over each funnel so that small invertebrate animals moved down the funnels and were collected in two collecting vessels. The main groups of invertebrates present were identified and counted. Some of the results are shown in Table 8.1. Table 8.1 invertebrate group number present in soil under bracken number present in soil under brambles pseudoscorpion wireworm gamasid mite springtail total It was not possible to identify the invertebrates as far as genus or species level, and only the wireworm group could be classified as far as the taxonomic level above genus. Name the taxonomic level represented by the wireworm group. State the null hypothesis for a statistical test comparing the data from the two types of site. Simpson’s Index of Diversity for invertebrates from the soil under bracken was calculated as 0.663 using the formula: D = 1 – Σ n N 2 n = number of individuals of each species present in the sample N = the total number of all individuals of all species. Calculate Simpson’s Index of Diversity for the invertebrates from the soil under brambles. Complete Table 8.2 and use the space provided to show your working. Show all working to three decimal places. Write your final answer on the dotted line. Table 8.2 animal taxon number present in soil under brambles n N  n N pseudoscorpion wireworm gamasid mite springtail total Simpson’s Index of Diversity = Describe what Table 8.1 and the calculated figures for Simpson’s Index of Diversity show about the effect of bracken and bramble vegetation cover on the diversity and abundance of soil invertebrates in the woodland.
9700_s17_qp_42
THEORY
2017
Paper 4, Variant 2
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There is considerable variation in the ecosystems that occur in the continent of North America. These include coniferous forest, prairie grassland, scrub and desert. Large areas of land that once contained natural ecosystems are now used for agriculture. Explain how the variation in ecosystems in North America contributes to biodiversity. The diversity of some beetle species that feed on animal dung was investigated at two types of grassland site in North America. The first type of grassland site was grazed by cattle and the second type of site was not grazed. Dung beetles were collected, identified and counted from two areas of the same total size. Some of the results are shown in Table 8.1. Table 8.1 beetle species number of dung beetles on grassland grazed by cattle number of dung beetles on grassland not grazed Onthophagus pennsylvanicus Canthon ebenus Canthon pilularius Onthophagus hecate total State the null hypothesis for a statistical test comparing the data from the two types of site. State how many genera and how many species of beetle are shown in Table 8.1. genera species Simpson’s Index of Diversity for the beetles on the grassland grazed by cattle was calculated as 0.521 using the formula: D = 1 – Σ n N 2 n = number of individuals of each species present in the sample N = the total number of all individuals of all species Calculate Simpson’s Index of Diversity for the beetles on the grassland that was not grazed. Complete Table 8.2 to show your working. Show all working to three decimal places. Write your final answer on the dotted line. Table 8.2 species number on grassland not grazed n N  n N Onthophagus pennsylvanicus Canthon ebenus Canthon pilularius Onthophagus hecate total Simpson’s Index of Diversity = Describe what the results in Table 8.1 and both figures for Simpson’s Index of Diversity show about the effect of grazing on the diversity of dung beetles.
9700_s17_qp_43
THEORY
2017
Paper 4, Variant 3
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Questions Discovered
184