Question 19M.3.SL.TZ1.c
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.3.SL.TZ1.c |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Outline | Question number | c | Adapted from | N/A |
Torre Guaceto is a marine protected area which covers over 22 km2 of the Adriatic Sea in south-eastern Italy. The diagram shows a food chain within this area.
The data refers to the numbers of these three species inside the marine protected area, where fishing is limited, and outside the marine protected area, where fishing is allowed.
[Source: data provided by The Science of Marine Reserves Project (PISCO), based on Guidetti 2006 Ecological Applications]
With respect to this food chain, outline what is meant by a keystone species.
[3]
a. keystone species have a disproportionate effect on the biological community ✔
b. removal of the sea bream «due to fishing» ✔
c. results in more sea urchins ✔
d. which significantly reduce the producers/seagrass ✔
Do not accept first trophic level for mpd
The syllabus definition of a keystone species was not often given, so alternative wording had to be judged on merit. The keystone species was not always recognized as the sea bream, but if it was, three marks were easily achieved.
