| Date | May 2017 | Marks available | 1 | Reference code | 17M.3.SL.TZ1.13 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | State | Question number | 13 | Adapted from | N/A |
Question
Reef-building corals are an association between two organisms: coral polyps and Zooxanthellae.
State the relationship between Zooxanthellae and coral reef species.
[1]
a.
Describe the exchange of materials between the coral’s polyps and Zooxanthellae.
[2]
b.
State one limiting factor on Zooxanthellae which affects coral reef formation.
[1]
c.
Markscheme
mutualism
a.
a. polyp is a source of carbon dioxide for the Zooxanthellae
OR
polyp is a source of ammonia/nitrogen for the Zooxanthellae
b. Zooxanthellae provide oxygen to the polyp
OR
Zooxanthellae provide sugars/glucose/glycerol/lipids/amino acids to the polyp
b.
light / temperature / salinity / carbon dioxide / pH
c.
Examiners report
[N/A]
a.
[N/A]
b.
[N/A]
c.
Syllabus sections
Option C: Ecology and conservation » Option C: Ecology and conservation (Core topics) » C.1 Species and communities
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