| Date | November 2013 | Marks available | 2 | Reference code | 13N.2.HL.TZ0.3 |
| Level | Higher level | Paper | Paper 2 | Time zone | TZ0 |
| Command term | Distinguish | Question number | 3 | Adapted from | N/A |
Question
The table provides some information about organisms found in an Arctic environment.
(i) Label the diagram to complete the food web for the organisms in the table above.
(ii) Deduce the trophic level of Artic cod.
Distinguish between the movement of energy and nutrients in an ecosystem.
Markscheme
energy moves through/enters and leaves ecosystems / need a constant source of energy;
nutrients cycled between biotic and abiotic environment/in cycles such as C/N;
Examiners report
In (a) most were able to gain both marks for the food web, but only about half were able to deduce that the arctic cod was a secondary consumer. In part (b) most knew about the 10% passing to the next trophic level in a food chain, but did not apply this to the ecosystem – i.e. that it has to be continually replaced. The concept of ‘nutrients’ was poorly understood by many.
In (a) most were able to gain both marks for the food web, but only about half were able to deduce that the arctic cod was a secondary consumer. In part (b) most knew about the 10% passing to the next trophic level in a food chain, but did not apply this to the ecosystem – i.e. that it has to be continually replaced. The concept of ‘nutrients’ was poorly understood by many.
