DP Biology (last assessment 2024)

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Question 23M.3.HL.TZ2.20a

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Date May 2023 Marks available [Maximum mark: 3] Reference code 23M.3.HL.TZ2.20a
Level HL Paper 3 Time zone TZ2
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 3]
23M.3.HL.TZ2.20a
(a)

Outline the effect of nitrogen compounds from agricultural land leaching into a lake.

[3]

Markscheme
  1. excess nutrients/eutrophication;
  2. excessive growth of algae/algal blooms;
  3. blocking of sun prevents photosynthesis;
  4. increased decomposition of algae/organisms;
  5. increased biochemical oxygen demand/BOD;
  6. other organisms/fish die due to lack of oxygen;
Examiners report

Most candidates provided partial answers as they all seem to have basic knowledge of eutrophication and algal blooms, but most do not seem to understand about BOD and the process that leads to this situation.

Syllabus sections