| Date | November 2015 | Marks available | 2 | Reference code | 15N.3.SL.TZ0.19 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Discuss | Question number | 19 | Adapted from | N/A |
Question
The distributions of many terrestrial organisms are currently shifting in latitude in response to changing climate. The graph shows the latitudinal shifts of the northern range boundaries of species within two taxonomic groups that were observed over 25 years in Britain. Positive latitudinal shifts indicate that a species now inhabits areas further to the north than it did before and negative shifts indicate that the northern edge of the range has moved south.
State which taxonomic group shows the greatest median shift.
Calculate the percentage of ground beetles that are below the zero shift.
Compare the changes in the range of ground beetles with the changes in the range of spiders.
Spiders and ground beetles are both predators. Discuss possible effects on other species resulting from the latitudinal shift of the predators.
Markscheme
spider
16.75(%)
Accept answer in the range of 16.5 (%) to 17(%).
a. both taxonomic groups showed movement to the north;
b. slightly more spiders moved north;
c. spiders shows the furthest northern shift;
d. range of ground beetles extends further south (than spiders);
e. the spiders' biggest movement is 75 to 100 km to the north and the ground beetles' biggest movement is 50 to 75 km to the north;
f. overall spiders have a broader range;
a. competition for resources/food/space/other resource;
b. change in predation/number of other species;
c. change/decrease/increase in biodiversity;
d. food webs may change;
Examiners report
A popular option choice with most candidates scoring well on the interpretation of the data.
A popular option choice with most candidates scoring well on the interpretation of the data.
A popular option choice with most candidates scoring well on the interpretation of the data.
A popular option choice with most candidates scoring well on the interpretation of the data.
