| Date | May 2017 | Marks available | 2 | Reference code | 17M.3.SL.TZ2.16 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Compare and contrast | 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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