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Date November 2017 Marks available 2 Reference code 17N.3.HL.TZ0.14
Level Higher level Paper Paper 3 Time zone TZ0 / no time zone
Command term Identify Question number 14 Adapted from N/A

Question

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.]

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]

Identify how the pattern in mammals is different from reptiles and birds.

[1]
a.i.

Describe how invasive species such as F. silvestris can have a significant impact on native species.

[2]
a.ii.

Suggest a method to limit the impact of F. silvestris on native species.

[1]
a.iii.

State the role of an indicator species.

[1]
b.i.

Identify possible approaches to maintain the population of P. sandwichensis.

[2]
b.ii.

Markscheme

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]

a.i.

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]

a.ii.

a. control population/sterilization «of cats»/culling/hunting

b. keep household cats indoors

[Max 1 Mark]

a.iii.

a. early warning system

b. provide information on environmental conditions/ecosystem

OWTTE

[Max 1 Mark]

b.i.

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]

b.ii.

Examiners report

[N/A]
a.i.
[N/A]
a.ii.
[N/A]
a.iii.
[N/A]
b.i.
[N/A]
b.ii.

Syllabus sections

Option C: Ecology and conservation » Option C: Ecology and conservation (Core topics) » C.4 Conservation of biodiversity
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Option C: Ecology and conservation » Option C: Ecology and conservation (Core topics)
Option C: Ecology and conservation

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