| Date | May 2017 | Marks available | 2 | Reference code | 17M.3.SL.TZ1.15 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Outline | Question number | 15 | Adapted from | N/A |
Question
After their introduction cane toads (Rhinella marina) have become a serious pest in many parts of Australia. In an attempt to control them scientists set traps to which they added toxins produced by native species of toad to capture cane toad tadpoles. The toad toxin attracts the cane toad tadpoles without killing them.
Outline one consequence of introducing an alien species into an ecosystem.
State the origin of cane toads.
Evaluate the use of traps containing toxin as a means of cane toad control.
Markscheme
a. uncontrolled increase of numbers «in alien species»
OR
become invasive
OR
have no «natural» predators
b. outcompetes native species / reduces biodiversity
OR
carries disease
OR
preys on local species decreasing population size
OR
disrupts food chains/webs
Central/South/Latin America
a. the baited traps catch a lot more tadpoles than the unbaited traps / traps with bait are more effective than those without
b. baited traps are almost 20 times more effective
c. traps without toxin reach capacity sooner than those with toxin
d. there may be environmental/health/safety problems with the toad toxin used
e. there is no information on how toads are controlled since the toxin does not kill the tadpoles
