Question 18N.3.SL.TZ0.15
| Date | November 2018 | Marks available | [Maximum mark: 5] | Reference code | 18N.3.SL.TZ0.15 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Deduce, State | Question number | 15 | Adapted from | N/A |
When water rises above a certain temperature, coral bleaching may occur. The coral expels Zooxanthellae algae living in its tissues, leaving the coral a white colour. The graph shows how the water temperature is changing in the coral reefs surrounding the Cayman Islands.
State the trend in temperatures from 1982 to 2014.
[1]
«overall» water temperature increasing
OR
the range of fluctuations increases ✔
Do not accept the trend is fluctuating
Deduce the effect of bleaching on corals.
[4]
a. the coral and the algae have a symbiotic/mutualistic relationship
OR
two different organisms live together and depend on each other ✔
b. algae expelled from coral/relationship broken ✔
c. coral produces carbon dioxide from respiration ✔
d. the algae use the carbon dioxide to carry out photosynthesis/produce nutrients ✔
e. without the nutrients from the algae the coral are liable to starve ✔
f. coral dies/is susceptible to disease ✔
Do not accept effects on species other than coral
