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Date May 2018 Marks available 3 Reference code 18M.3.HL.TZ1.16
Level Higher level Paper Paper 3 Time zone Time zone 1
Command term Discuss Question number 16 Adapted from N/A

Question

The graph shows the total number of alien species in marine ecosystems estimated by the European Environment Agency.

Define invasive alien species.

[1]
a.

Discuss the global impacts of invasive alien species.

[3]
b.

Using one example, outline biological control of an invasive alien species.

[2]
c.

The map shows an area of the Pacific Ocean characterized by exceptionally high concentrations of plastics and other debris that have been trapped by the currents of the North Pacific Gyre.

Outline one consequence of marine plastic pollution.

[1]
d.

Explain the consequences of biomagnification.

[2]
e.

Markscheme

organisms that are introduced (accidentally or deliberately) and negative environmental consequences

OWTTE

a.

a. inter-specific competition/alien species may out-compete native species 

b. lack of predators may allow alien species to thrive / reproduce more rapidly 

c. alien species may utilize areas/ resources that native species cannot 

d. predation by invasive species can cause loss of biodiversity 

e. can lead to species extinction 

f. alien species may introduce new diseases 

g. global shipping/air travel allows rapid transfer of alien species to new ecosystems

b.

a. specific name of invasive alien species to be controlled and where (in general) 

b. method of biological control with specific name of predator/parasite/pathogen

Examples must be verified.

a. rabbits introduced into Australia 

b. controlled by release of myxomavirus / myxomatosis (from South America)

c.

a. organisms may get tangled in plastic debris 

b. animals accidentally eat plastic mistaking it for food/feed plastic pieces to offspring 

c. (floating) plastic debris can block sunlight preventing photosynthesis

(allow any other reasonable example)

d.

a. chemicals (non-degradable) accumulate along the food chain becoming more concentrated at each successive trophic level 

b. negative effects of organisms high in food chain 

c. toxic effects/death/ thin egg shells/other valid example

Accept specific examples of chemicals.

e.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
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d.
[N/A]
e.

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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