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IB Biology HL B4.1.5 Coral Reef Formation Conditions Questions

Practise reading coral-cover data and ocean-temperature trends to assess how warming may affect reef-building corals in IB Biology HL B4.1.5.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Calculate percentage-point change in coral cover between dates from a graph.
  • Interpret coral-cover and temperature trends, noting correlation does not prove causation.

IB Biology HL B4.1.5 Coral Reef Formation Conditions Questions question 1

[Maximum number: 3]

Coral reefs are among the most spectacular ecosystems on Earth. They support a rich diversity of life and provide economic benefits to the people who use them. In Papua New Guinea in the Pacific Ocean north of Australia the following data were collected. Coral cover is the percentage of the reef surface covered by live hard coral.

Dual-axis line graph for 1994–2004: dashed line gives live coral cover on the left percentage axis, 0–80%; grey solid line gives mean annual ocean temperature on the right axis, 24.30–24.70°C.

Question (a)

(a)

Calculate the difference in coral cover in 1996 and 2002. No working required.
……%

[ 1 ]

Question (b)

(b)

Describe the evidence that the ocean temperature has an effect on coral cover.

[ 2 ]
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