Explain the causes and consequences of biomagnification with reference to a named example.

a. named example of chemical;
b. chemical absorbed by organism low in the food chain;
c. chemical not excreted/accumulates in body fat;
d. organism eaten by other organisms in higher trophic levels;
e. causing it to be much more concentrated at each trophic level;
f. substance accumulates in species at the highest trophic level;
g. may reach toxic levels;
h. named example of species at top of food chain;
i. harmful effect caused by the chemical;
Award [5 max] if specific name of chemical is not given or chemical does not bioaccumulate.

eg:
a. mercury;
b. absorbed by small fish;
c. (mercury) not excreted (by small fish) / accumulates in (small fish) tissues;
d. eaten by tuna;
e. (mercury) becomes more concentrated at each trophic level;
f. (mercury) accumulates in species at the highest trophic level;
g. may reach toxic levels;
h. humans may eat the tuna;
i. leads to brain damage / birth defects / mercury poisoning;

This question was relatively easy for the majority of candidates who used either DDT or mercury as example. Many answers nevertheless lacked detail needed for the "named example", and there were many other only partially correct statements. Candidates could describe the process in broad strokes, but failed to be able to explain it well in detail.