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Date November 2019 Marks available 2 Reference code 19N.3.SL.TZ0.15
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
Command term Outline Question number 15 Adapted from N/A

Question

State the impact of environmental disturbance on biodiversity.

[1]
a.

State an example of an alien species.

[1]
b.i.

Outline the impact of alien species on endemic species in ecosystems.

[2]
b.ii.

Markscheme

changes/increases/decreases richness/biodiversity/evenness/the numbers of species ✔

a.

name of species and where it is invasive e.g. introduction of cane toads in Australia ✔

Accept common name of species but not general groups e.g. toads.

b.i.

a. ‹interspecific› competition with endemic/native species ✔ May be outlined using a specific example

b. may cause the extinction/reduction of endemic/native species
OR
reduces biodiversity
OR
becomes invasive ✔

c. does not have endemic / natural predators so may increase in numbers ✔

d. upsets the balance between predators and prey
OR
disrupts food chains ✔

b.ii.

Examiners report

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

Syllabus sections

Option C: Ecology and conservation » Option C: Ecology and conservation (Core topics) » C.3 Impacts of humans on ecosystems
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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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