Discuss the impact of alien species on the environment.

a. (interspecific) competition with native species;

b. does not have natural predators so may survive more;

c. can be a predator difficult to control;

d. reproduce faster/more;

e. may cause the extinction of native species;

f. most are benign/some may be beneficial (e.g. honeybee introduced to the Americas from Europe in the 1600s);

Many candidates gave specific examples of alien species rather than discussing the impact of these on the environment. While describing examples however, candidates tended to touch on their impact and get 2 or 3 marks.