28 9 Gilbert’s potoroo is one of the most critically endangered species in the world. Gilbert’s potoroo was thought to be extinct until one was found in 1994. It is thought that there are only 70 individuals. The photograph shows a potoroo and its pouched baby feeding on berries. The map shows the only part of Australia where Gilbert’s potoroo is found. Turn over 29 The diet of Gilbert’s potoroo is about 90% fungi. Analysis has shown that the fungal spores are spread in the faeces of the potoroos. These spores then germinate. (a) Explain the advantage to the ecosystem of fungal spores being spread by potoroos. 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(b) In 1994, there were only 20 Gilbert’s potoroo individuals, 12 of which were in a captive colony. A captive breeding programme was set up using: • four adult females and one young female • one adult male, two young males and one young male still in its mother’s pouch. (i) Explain why allele frequencies may cause problems in this population of potoroos. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 30 (ii) Foxes and feral cats, which are predators of potoroos, were introduced into Australia by settlers. The photograph shows a feral cat with its prey. The Australian government is using poisoned sausages in an attempt to kill 2 million feral cats by 2020. The sausages contain chunks of kangaroo meat combined with chicken fat, herbs, spices and a poison. The content of the sausages was based on flavours irresistible to cats. The poison used is produced by the Swan River pea plant that is found in Western Australia.  Other Australian plants that contain the poison are: Acacia, Wedge Peas and Nemcia. This poison is a natural toxin that biodegrades rapidly and the native wildlife in Australia has evolved natural resistance to it. A group of 160 000 people in Australia have signed a petition against the plan to poison feral cats. Discuss whether the plan to poison feral cats is justified. 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(Total for Question 9 = 14 marks)