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Date May 2017 Marks available 1 Reference code 17M.3.SL.TZ2.16
Level Standard level Paper Paper 3 Time zone Time zone 2
Command term Outline Question number 16 Adapted from N/A

Question

The pyramid of biomass obtained from a pine forest stream includes the parasite biomass. Parasites are fungi, worms and other organisms that live on a host.

Estimate the approximate amount of biomass represented by parasites in this ecosystem.

[1]
a.

Compare and contrast the biomass in the different trophic levels.

[2]
b.

Outline the reason that parasite biomass occurs in both tertiary consumers and secondary consumers.

[1]
c.

Markscheme

any value between 15 kg and 22 kg

a.

a. biomass decreases going up the trophic levels ✓

b. autotrophs have greatest biomass «around 40 040 kg»
OR
tertiary consumers have the least biomass ✓

c. greatest loss of biomass is from autotrophs to primary consumers

b.

parasites feed on secondary and primary consumers

c.

Examiners report

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

Syllabus sections

Option C: Ecology and conservation » Option C: Ecology and conservation (Core topics) » C.2 Communities and ecosystems
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