Question 17N.3.HL.TZ0.14
| Date | November 2017 | Marks available | [Maximum mark: 7] | Reference code | 17N.3.HL.TZ0.14 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Describe, Identify, State, Suggest | Question number | 14 | Adapted from | N/A |
To assess the impact of introduced cats (Felis silvestris) that prey on native species, a study was carried out on 120 islands around the world. The graph shows the impact of F. silvestris on reptiles, birds and mammals.
[Source: A global review of the impacts of invasive cats on island endangered vertebrates, F. M. Medina et al. (2011) Global Change Biology, 17, pp. 3503–3510. Reproduced with permission from John Wiley and Sons.]
Identify how the pattern in mammals is different from reptiles and birds.
[1]
a. more extinct than endangered «in mammals as opposed to reptiles and birds»
b. total percentage extinct plus endangered mammals lower than reptiles and birds
[Max 1 Mark]
Describe how invasive species such as F. silvestris can have a significant impact on native species.
[2]
a. cats/invasive species compete with native species for food/habitat/resources
OWTTE
b. invasive species/cats may reduce/endanger native populations
c. invasive species/cats may change the structure/balance of the food web/chain
[Max 2 Marks]
Suggest a method to limit the impact of F. silvestris on native species.
[1]
a. control population/sterilization «of cats»/culling/hunting
b. keep household cats indoors
[Max 1 Mark]
The ‘Ua‘u petrel (Pterodroma sandwichensis) is considered to be an indicator species in the Hawaiian Islands.
[Source: https://commons.wikimedia.org/wiki/File:Oestrelata_phaeopygia_AvesHawaiienses00Wils_0382.jpg]
State the role of an indicator species.
[1]
a. early warning system
b. provide information on environmental conditions/ecosystem
OWTTE
[Max 1 Mark]
Identify possible approaches to maintain the population of P. sandwichensis.
[2]
a. ex-situ/zoos/captive breeding
b. control predators
c. in-situ/management of natural reserves/breeding habitats/parks/resources/clean-up pollution
d. education
OR
government legislation
Accept any other valid answer
[Max 2 Marks]