| Date | November 2009 | Marks available | 2 | Reference code | 09N.3.HL.TZ0.10 |
| Level | Higher level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Outline | Question number | 10 | Adapted from | N/A |
Question
A colony of a marine diving bird, Brunnich’s guillemot (Uria lomvia), lives on the southern limits of the Arctic on Coats Island. Brunnich’s guillemots feed principally on Arctic cod (Arctogadus glacialis) which are characteristic of Arctic waters.
The graph shows the changes in ice cover on Coats Island over a period of 19 years.
At Coats Island, chick mass at 14 days was measured in most years between 1988 and 2002. The scattergraph below shows the results, plotted against proportion of ice cover.
Outline the changes in ice cover shown in the data above.
Suggest one reason for the changes in ice cover.
Outline the relationship between ice cover and the mass of 14-day-old chicks on Coats Island.
Suggest reasons for the relationship.
Predict, with a reason, the change in the mass of chicks in the years ahead.
Markscheme
downward trend / decreasing slightly;
the data show much variability/fluctuates;
warmer air/atmosphere/water temperatures/global warming (bringing about more ice melt)
increase in summer ice cover has a positive effect on mass increase;
high proportion of ice cover has little effect / (slightly) negative effect on chick mass/growth;
changes in (water) temperature/climate change influence fish populations/ food available for chick growth;
changes in habitat affect chick growth / rearing of chicks;
mass may go down as proportion of ice cover has decreased;
mass may increase as most recent data shown in (bar) graph shows increasing proportion of ice area;
Examiners report
Almost all candidates stated a decreasing trend although few mentioned the fluctuation in the data seen. There were some candidates simply restating data and this gained no marks.
All candidates made reference to global warming being the reason for the reduction in ice cover.
Many candidates gave good trend here suggesting that the mass of chicks did increase with increasing ice cover, up to a certain point and following this, the mass decreased, thus gaining 2 marks. This showed good data interpretation skills even if it may go against their logic.
The best candidates had clearly read the information given at the start of the question about the Brunnich`s guillemots feeding on Arctic cod, characteristic of Arctic waters. The best candidates did answer that if there was less ice (due to global warming) that there may be less cod, so less food, so decrease in chick mass, which was very pleasing to see. Others did suggest some good logical answers concerning changes to habits, but these answers did not really include all the data given, although marks could be awarded if they did made sense.
Many candidates successfully suggested that with global warming there would be a decrease in chick mass (due to less cod). This meant that these candidates were really using the data given.
