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
- SL
Exam analysis
Chance of appearing1%of analysed past papers
Latest appearanceMay 2017
Most common paperPaper3
Typical marks1
Common command terms
- Outline
- Describe
- State
Scoring notes
- Common mistake
- Saying higher temperature alone proves coral decline without acknowledging correlation limits.
Recent exam appearances
May 2017Paper3 ["SL"] · TZ113(c)[ 1 ]B4.1.5—Coral reef formation conditions
Practice this objective
Coverage 2017–2017 · 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.