DP Biology (first assessment 2025)

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Question 22M.2.SL.TZ2.a

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Date May 2022 Marks available [Maximum mark: 5] Reference code 22M.2.SL.TZ2.a
Level SL Paper 2 Time zone TZ2
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 5]
22M.2.SL.TZ2.a

Outline energy flow through a community in a natural ecosystem.

[5]

Markscheme
  1. communities are made up of populations of different species;
  2. plants receive energy from the sun/light;
  3. convert it to chemical energy through photosynthesis;
  4. chemical energy is stored in organic/C-compounds;
  5. the energy is passed to other organisms through feeding / reference to food chain;
  6. respiration (of plants and animals) converts the chemical energy (of C-compounds) to other useful forms of energy;
  7. eventually the chemical energy is lost as heat energy;
  8. energy is non-recyclable/lost from a community/ecosystem;
  9. energy losses between trophic levels limit food chains/mass of top trophic levels/only about 10 % of energy is transferred;
Examiners report

This was well attempted with an average score of 3. The question was about energy, but weaker students also tended to include biomass. Fortunately, very few students failed to grasp the idea that the energy is lost from the ecosystem and not recycled.

Syllabus sections