B4.1.5—Coral reef formation conditions
Coral reef formation depends on warm, shallow, clear, sunlit, saline water and is limited by temperature, light, pH and carbon dioxide.
- Syllabus
- First assessment 2025
- Objective
- B4.1.5
- Level
- HL
Exam analysis
Chance of appearing2%of analysed past papers
Latest appearanceNovember 2016
Most common paperPaper2
Typical marks2
Common command terms
- Outline
- Describe
- State
Scoring notes
- Common mistake
- Saying higher temperature alone proves coral decline without acknowledging correlation limits.
Recent exam appearances
November 2016Paper2 ["HL"] · TZ01(b)[ 2 ]B4.1.5—Coral reef formation conditions
May 2016Paper3 ["HL"] · TZ01(c)[ 2 ]B4.1.5—Coral reef formation conditions
Practice this objective
Coverage 2016–2016 · Updated 15 Jul 2026
Concept essentials
- Reef-building corals need light because their zooxanthellae photosynthesise.
- Calcium carbonate skeleton formation is affected by pH and carbonate availability.
- High temperature can cause coral bleaching through loss of zooxanthellae.
- Temperature, light, salinity, carbon dioxide and pH can limit reef formation.