0610_s17_qp_41
A paper of Biology, 0610
Questions:
6
Year:
2017
Paper:
4
Variant:
1

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The giant quiver tree, Aloe pillansii, shown in , is an endangered species. These long-lived trees grow in harsh environments. Some populations of A. pillansii are found within the Richtersveld National Park, but one population is found just outside on a mountain called Cornell’s Kop in southern Africa. State the genus of the giant quiver tree. Explain why the A. pillansii trees on Cornell’s Kop represent a population. Suggest three reasons why the giant quiver tree is an endangered species. It was estimated in 2005 that the total number of giant quiver trees in the wild was less than 3000, which is considered to be very low compared with other tree species. Explain the risks to a plant species of having very small numbers. The population of A. pillansii trees on Cornell’s Kop was surveyed and photographed at four sites, A to D, from 1937 onwards. Researchers took photographs at all four sites in 2004 and compared them with the original photographs. The results are shown in Table 5.1. Table 5.1 site date of the original photograph number of living trees in the original photograph number of living trees in number of dead tree stumps average annual mortality rate / percentage of deaths per year A 1.0 B 0.9 C 2.1 D 5.6 Calculate the percentage decrease in the number of living trees at site B from 1953 to 2004. Show your working and give your answer to the nearest whole number. % Describe what the analysis of the photographs shows about the population of A. pillansii on Cornell’s Kop.
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Students investigated the effect of mineral ion deficiencies on the growth of radish plants. The seeds that were used in the experiment were from plants that had been self-pollinated for many generations and were therefore all genetically identical. Explain the advantage of using genetically identical radishes in this investigation. The radish seedlings were divided into four groups. Each group was grown in a different mineral ion solution as follows: complete solution containing all the major mineral ions solution with all the major mineral ions except nitrate ions solution with all the major mineral ions except magnesium ions solution with all the major mineral ions except phosphate ions The apparatus used to investigate the growth of the plants is shown in . solution inflow solution outflow mineral ion solution State three other environmental factors that could affect the growth of the seedlings. The results of the investigation are shown in Table 6.1. Table 6.1 group mineral ion solution number of plants total dry mass of all plants / mg mean dry mass of one plant / mg leaves roots total complete without nitrate ions without magnesium ions without phosphate ions Describe and explain the results for the radishes grown without nitrate ions (group 2). Describe the likely appearance of the radish plants grown in the solution without magnesium ions (group 3) and explain your answer. appearance explanation Phosphate ions are a component of DNA. Suggest why the radish plants in group 4 grew less than the radish plants in the complete solution (group 1).