1. 1
   A large area of tropical rainforest is cleared to make way for a palm oil plantation, removing the natural habitat of hundreds of different species of plants, insects, birds and mammals that previously lived there. Conservationists are concerned about the long-term effect of this land-use change on the variety of life in the region.

   (a)

   Which term best describes the variety of living organisms found within an area such as this rainforest?

   [1 mark]

   • ABiodiversity
   • BPopulation
   • CCommunity
   • DTrophic level

   (b)

   The clearing of rainforest for the palm oil plantation removes the natural living space of many species entirely. Which of the following best describes this cause of biodiversity loss?

   [1 mark]

   • AOverexploitation
   • BHabitat destruction
   • CInvasive species
   • DEutrophication

   (c)

   Explain why the loss of biodiversity caused by clearing this area of rainforest could be harmful, both for the stability of the local ecosystem and for human wellbeing.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A farmer applies large amounts of nitrate fertiliser to his fields to increase crop growth. Heavy rain washes some of this excess fertiliser into a nearby river, causing a sudden increase in the concentration of nitrate ions in the water, which environmental scientists monitor because of its effects on the river's plant and animal life.

   (a)

   What is the term for this type of pollution entering a water body?

   [1 mark]

   • ABioaccumulation
   • BEutrophication
   • CNutrient runoff
   • DDenitrification

   (b)

   Following the fertiliser runoff, algae in the river grow rapidly, forming a dense layer on the water's surface that blocks sunlight from reaching plants below. When the algae die, decomposing bacteria multiply and use up large amounts of oxygen from the water. What is the term for this whole process, from nutrient enrichment to oxygen depletion?

   [1 mark]

   • ANitrification
   • BTranspiration
   • CFossilisation
   • DEutrophication

   (c)

   Describe the full sequence of events in the river following the fertiliser runoff, explaining why fish and other aquatic animals in the river are likely to die as a result.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A group of ecology students investigates biodiversity along a rocky coastline. They place a one-metre-square quadrat at regular intervals along a line (a transect) running from the top of the shore down to the water's edge, and record every species found within each quadrat, in order to study how species distribution and diversity change across the shore, including monitoring for signs of water pollution.

   (a)

   Describe this sampling method and explain why placing quadrats at regular intervals along such a line gives useful information about how species distribution changes across the shore.

   [3 marks]

   (b)

   In one quadrat near the water's edge, the students find only two species of small invertebrate, both of which are known to tolerate low oxygen levels and are commonly found in polluted water; in a quadrat further along the transect, away from a nearby stream outflow, they find eight different invertebrate species, most of which require clean, well-oxygenated water to survive. Explain how this difference in species richness between the two quadrats, together with the known tolerances of the species found, can be used as evidence of water pollution near the stream outflow.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Large-scale cattle farming to meet global demand for beef and dairy products releases significant amounts of methane, produced by digestion in cattle, and carbon dioxide, released from fertiliser use, transport and land clearance for pasture. Scientists have linked rising atmospheric concentrations of these gases to an enhanced greenhouse effect, global climate change, and knock-on effects on biodiversity worldwide.

   (a)

   Explain how carbon dioxide and methane contribute to the greenhouse effect and global warming, and describe how the resulting climate change could affect ecosystems and biodiversity worldwide.

   [6 marks]

   (b)

   As global demand for beef continues to rise, several conservation organisations are separately working to protect an endangered species of wild cattle relative that is losing its natural grassland habitat to farmland expansion. One organisation is establishing a captive breeding programme to raise individuals in zoos before reintroducing them to protected reserves, while another is creating a seed bank to preserve the genetic diversity of the native grassland plants the species depends on. Evaluate the effectiveness of captive breeding programmes and seed banks as conservation methods for protecting this endangered species and its habitat, including at least one limitation of each method.

   [6 marks]

   Total for question 4: 12 marks

End of questions