18. Classification, biodiversity and conservation
A section of Biology, 9700
Listing 10 of 184 questions
The passage below outlines one method used by a student to estimate the population size of an animal species. Complete the passage by using the most appropriate scientific term or terms. A student estimated the population size of an animal species using the mark-release- technique. This can only be used for animals such as mice. The student caught a sample of mice using humane traps. The student then marked the mice in a way that did not them. For example, the mark did not make them more visible to potential . The student released the marked mice and left enough time for them to randomly with the population. The student then caught a second sample of mice and noted the numbers of marked and unmarked mice. The student estimated the population size by multiplying the number of mice in the first sample by the number in the second sample, then dividing by the number of mice in the second sample.
9700_s19_qp_43
THEORY
2019
Paper 4, Variant 3
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In 2014, scientists published a phylogenetic tree diagram showing how and when different groups of insects developed from ancestral groups. To construct the diagram, the scientists compared nucleotide and amino acid sequence data for 1478 genes from each of 103 different insect species. The 103 species represented all 32 orders of the class Insecta. The data were used to arrange the species in related groups according to their degree of molecular similarity and to track how sequences changed over time. Outline three ways in which the members of a species are similar. Organisms are classified in a hierarchical system of taxonomic units. Name the domain and kingdom to which insects belong. domain kingdom Explain why a phylogenetic tree diagram is useful for classifying insect species. For this study, new software for processing large quantities of data was developed. Calculate the total number of sequences that were compared, considering both the nucleotide and amino acid sequences for each gene. Explain why this study needs to make use of bioinformatic techniques.
9700_s21_qp_41
THEORY
2021
Paper 4, Variant 1
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One way to measure global biodiversity is to count the number of species of organisms. Table 3.1 shows estimates for 2009 of the number of species in some taxa of animals. The numbers in brackets are the numbers that were updated in 2019 from the International Union for Conservation of Nature and Natural Resources (IUCN) for three intensively studied taxa. Table 3.1 number of species in each taxon kingdom phylum class animals 1 438 805 arthropods 1 191 770 arachnids 102 248 crustaceans 47 000 myriapods 16 072 insects 1 024 945 other arthropod classes chordates 63 543 fish 31 269 amphibians 6515 (6722) birds 9990 (11 126) reptiles mammals 5487 (5692) molluscs 85 000 other animal phyla 98 492 List three features shared by animal species. Explain how the classification of species into a taxonomic hierarchy assists the work of conservation bodies such as the IUCN. Table 3.1 shows that the number of species of amphibians, birds and mammals has increased between 2009 and 2019. Discuss whether the increase in numbers means that these classes of chordate are being successfully conserved. With reference to Table 3.1, identify the class of animals that is most diverse then calculate the percentage of animal species that belongs to this class. Show your working and give your answer to two significant figures. answer = % An analysis in 2019 concluded that twice as many insect species have populations that are decreasing in size compared with chordate species. This analysis focused on developed countries that have large human populations. Outline two factors that may cause populations of insects to decrease in size in developed countries that have large human populations. Explain how the introduction of crops that are genetically modified to express the Bt toxin can benefit biodiversity.
9700_s21_qp_42
THEORY
2021
Paper 4, Variant 2
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Fruit flies of the genus Bactrocera are pests that damage fruit crops. Table 3.1 gives the names and geographical ranges of Bactrocera fruit flies that were classified as four separate species. Table 3.1 name geographical range B. dorsalis China, India, Thailand B. invadens Africa, India B. papayae Indonesia, Malaysia B. philippinensis Philippine Islands, Borneo In 2014, the classification of these flies was changed. All four species were recognised as belonging to a single species, B. dorsalis. Suggest reasons why the four species were originally classified as separate species. Some students decided to investigate whether the flies were members of one species or four separate species. Suggest a simple investigation that the students could carry out. Female B. dorsalis lay their eggs in different types of fruits, such as avocados, bananas, mangos and papayas. The eggs hatch into larvae that eat the fruit. The actions of the female flies and larvae allow microorganisms to enter the fruit. The microorganisms feed by secreting extracellular enzymes, causing the fruit to rot. Name two kingdoms that include organisms that could spoil fruit by secreting extracellular enzymes. Before the four Bactrocera species were reclassified as a single species in 2014, some governments in Asia banned fruit imports from African countries to avoid introducing B. invadens as an alien species. Explain why the introduction of alien species should be avoided. Suggest how reclassifying B. invadens as B. dorsalis will benefit fruit‑producing countries in Africa.
9700_s21_qp_43
THEORY
2021
Paper 4, Variant 3
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Two subspecies of reindeer, Rangifer tarandus, live in North America. Members of the different subspecies belong to the same species but have some morphological differences and are found in different geographical locations. shows a reindeer. Table 5.1 compares the features of the two North American reindeer subspecies. Table 5.1 feature woodland subspecies, R. tarandus caribou barren ground subspecies, R. tarandus groenlandicus habitat southern woodland northern tundra type of food tree leaves, grass lichens, moss summer and winter feeding grounds overlap yes no carry out long migrations no yes body size large small colour of fur dark light During the last ice age an ice sheet separated southern and northern populations of R. tarandus in North America. Explain how this ice sheet affected the evolution of R. tarandus to result in the two different subspecies. Assess the relative importance of natural selection and genetic drift in producing: the different colours of fur of the two subspecies of reindeer the different body sizes of the two subspecies of reindeer. Hybridisation has occurred between individuals of the two subspecies which now live in the area previously covered by the ice sheet. Comment on how the hybrid populations compare to the pure subspecies in terms of genetic variation and potential to adapt to climate change. Outline how practical techniques could be used to test the hypothesis that migratory behaviour in reindeer has a genetic basis.
9700_s22_qp_41
THEORY
2022
Paper 4, Variant 1
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Over the past 200 years, many species of animals and plants have become extinct. shows the changes between the years 1800 and 2000 in: • the number of species becoming extinct • the size of the world human population. 10 000 20 000 number of known extinct species world human population (×106) 40 000 30 000 Key number of species human population year It has been suggested that there is a correlation between the number of species becoming extinct and the size of the world human population. Suggest reasons for this possible correlation. Calculate the rate of species extinction per year between 1950 and 2000. Show your working. answer = Extinction of animal and plant species reduces biodiversity. Explain why it is important to maintain biodiversity.
9700_s22_qp_41
THEORY
2022
Paper 4, Variant 1
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The African penguin, Spheniscus demersus, lives along the coast of South Africa. shows two African penguins. One way of estimating the size of a population of African penguins is to use the mark-release- recapture method. Suggest three assumptions that must be made for the mark-release-recapture method to be valid. The International Union for the Conservation of Nature (IUCN) Red List of Threatened Species has categorised the African penguin as endangered and could become extinct. Suggest reasons why the African penguin has become endangered and could become extinct. shows the estimated numbers of African penguins in the years of 1800, 1900 and 2000. 1 000 000 2 000 000 estimated population size year 3 000 000 4 000 000 Calculate the mean yearly decrease in population size of the African penguin between 1900 and 2000. answer = yr –1 The African penguin is a member of the kingdom Animalia. Outline the characteristic features of the kingdom Animalia.
9700_s22_qp_42
THEORY
2022
Paper 4, Variant 2
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The Malayan tapir, Tapirus indicus, lives in the rainforest of South East Asia. shows a Malayan tapir and her calf. On the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species, the Malayan tapir is categorised as endangered and could become extinct. One problem is the illegal trade in the Malayan tapir. Apart from illegal trading, suggest and explain reasons why the Malayan tapir has become endangered and could become extinct. The trade in Malayan tapirs is regulated by the Convention on International Trade in Endangered Species (CITES). Suggest ways by which CITES attempts to regulate the trade in wild fauna and flora. Many endangered species, such as the Malayan tapir, are protected in zoos. Outline the role of zoos in the conservation of endangered species.
9700_s22_qp_43
THEORY
2022
Paper 4, Variant 3
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is a photograph taken at low tide in a mangrove swamp in Mozambique. The photograph shows a hermit crab surrounded by the pneumatophores (‘breathing roots’) of mangrove trees. The hermit crabs live inside the shells of dead molluscs. Large birds, such as Goliath herons, feed on the hermit crabs. The vertical pneumatophores are an adaptation to the soil in the swampy, coastal environment that contains very little oxygen. They are exposed to the air at low tide. The soil has a very high salt content as the sea often covers the area. Some bacteria are able to grow deep in the rich organic mud where the oxygen concentration is very low. Listed below are eight ecological terms that can be applied to the mangrove swamp and the organisms that live there. Use only the information given above to match each organism with the most appropriate term from the list. You may use each letter once, more than once or not at all. mangrove trees all the organisms in the mangrove swamp bacteria deep in the mud all the hermit crabs in the swamp A primary consumer B population C community D niche E secondary consumer F ecosystem G decomposer H producer Examiner’s Use Explain how the cells in the roots of mangrove trees obtain sufficient oxygen and water in this extreme environment. oxygen water
9700_w06_qp_2
THEORY
2006
Paper 2, Variant 0
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Questions Discovered
184