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Date November 2020 Marks available 4 Reference code 20N.3.SL.TZ0.15
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
Command term Explain Question number 15 Adapted from N/A

Question

Explain what information a pyramid of energy provides about an ecological community.

Markscheme

a. shows the amount of energy at each trophic level (of a food chain/web);

b. (energy) measured over a period of time/year
OR
units are energy per area per time/kJ m–2 year–1;

c. the width/size of each bar represents the amount of energy;

d. the bottom level represent the producers;

e. subsequent levels represent consumers;

f. each level should be roughly one tenth of the size/10 % of the preceding level;
OR
organisms at the top of the food chain are shown to have much less energy available to them;

g. the energy that enters a community is ultimately lost as heat/in respiration

Some answers may be displayed in a diagram.

Examiners report

The better candidates performed well in this question while weaker candidates are still confused by pyramids of energy. Many referred to numbers, or biomass at each trophic level. Very few candidates stated that the measurements were taken over a period of time.

Syllabus sections

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