| Date | May 2013 | Marks available | 2 | Reference code | 13M.3.HL.TZ1.1 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Discuss | Question number | 1 | Adapted from | N/A |
Question
Indigenous human populations living along riverbanks in the Amazon basin often rely heavily on fish as a major part of their diet. The data shown below come from a study that was carried out to investigate levels of mercury contamination in the Rio Negro basin in Brazil. Mercury concentration was measured in fish belonging to four different trophic levels and is shown in parts per billion (ppb).
Discuss how an understanding of biomagnification could help these human populations reduce their risk of mercury poisoning while maintaining their traditional diet.
Markscheme
a. (recognize that) some fish are more contaminated than others;
b. identify and eat fish that are close to the start of a food chain;
c. avoid eating piscivores/omnivores/highly polluted species;
d. eat only piscivores that feed close to the start of a food chain;
Examiners report
This was also a very popular option but not very high scoring in many cases.
Candidates often gave vague answers to this section and thus seldom were awarded more than 1 mark.
