3.2 Human impact on biodiversityIB Environmental Systems and Societies SL: Subtopic test

1. 1
   Burmese pythons (Python bivittatus), probably escaped or released pets, have bred in the Everglades of Florida since the 1980s. Stomach contents of captured pythons contain native mammals and birds, and surveys of the area have recorded steep declines in sightings of raccoons, opossums and bobcats since the pythons became established.

   (a)

   Which term best describes the Burmese python in the Everglades?

   [1 mark]

   • AEndemic species
   • BPioneer species
   • CInvasive alien species
   • DKeystone species

   (b)

   Pythons feeding on native mammals and birds is an example of which way that invasive species reduce biodiversity?

   [1 mark]

   • APredation
   • BCompetition for a limited resource
   • CIntroduction of a parasite
   • DHabitat fragmentation

   (c)

   Outline two ways in which invasive alien species can reduce local biodiversity.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   The Arabian oryx (Oryx leucoryx) was hunted until the last wild animals were killed in 1972. Animals bred in zoos and reserves were reintroduced to Oman from 1982 and later to other countries in the region, including the United Arab Emirates. The IUCN Red List now assesses the species as Vulnerable, having earlier listed it as Endangered.

   (a)

   Which organisation publishes the global conservation status of species as the Red List?

   [1 mark]

   • AConvention on International Trade in Endangered Species (CITES)
   • BWorld Trade Organization
   • CIntergovernmental Panel on Climate Change
   • DInternational Union for Conservation of Nature (IUCN)

   (b)

   What does the change from Endangered to Vulnerable show about the Arabian oryx?

   [1 mark]

   • AIt is no longer at any risk of extinction
   • BIts risk of extinction has fallen, but the species is still considered threatened
   • CIts risk of extinction has increased
   • DIt has become extinct in the wild

   (c)

   Explain why assigning a global conservation status to a species is useful.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A coastal lagoon in a developing country is open to any fisher, with no licences or catch limits. In 2000, 12 boats fished the lagoon and the total catch was 96 tonnes. In 2010, 25 boats caught a total of 150 tonnes. In 2020, 40 boats caught a total of 80 tonnes. Fishers say that each of them has to keep fishing harder just to earn the same income.

   (a)

   Calculate the percentage change in the catch per boat between 2000 and 2020.

   [3 marks]

   (b)

   Explain how the data illustrate the tragedy of the commons, and suggest one way it could be avoided.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   The Great Barrier Reef is a World Heritage Site off Queensland, Australia, and supports a very high diversity of corals, fish and other marine life. It is used by fishing fleets, tourism operators and shipping. Rivers draining farmland carry nutrients, sediments and pesticides to the reef, and warming seas have caused mass coral bleaching in several years, including 2016, 2017 and 2020. Large parts of the Marine Park are zoned as no-take areas where fishing is not allowed.

   (a)

   Explain, with reference to the Great Barrier Reef, how human activities have both direct and indirect effects on biodiversity.

   [6 marks]

   (b)

   To what extent does the tragedy of the commons explain the threats to the biodiversity of the Great Barrier Reef?

   [6 marks]

   Total for question 4: 12 marks

End of questions