IB ESS HL · Unit 2 of 8

Unit 2: Ecology

Unit 2 of IB Environmental Systems and Societies covers Ecology. This unit contains 8 topics and 31 sub-topics. Below you'll find free study notes, flashcards, and exam preparation resources for every topic in this unit.

8 topics31 sub-topics

ESS Flashcards Exam technique guide

What Unit 2 covers

HL Unit 2 extends ecological principles with more detailed quantitative analysis of energy flows, productivity calculations, complex nutrient cycling models, and deeper evaluation of human impacts. Students must interpret larger datasets and demonstrate more sophisticated ecological reasoning.

Topics in Unit 2

2.1

Species, populations

3 sub-topics

2.2

Communities and ecosystems

3 sub-topics

2.3

Habitat, niche and interactions

2 sub-topics

2.4

Food chains & webs and trophic levels

2 sub-topics

2.5

Flows of energy and matter

4 sub-topics

2.6

Human impacts

8 sub-topics

2.7

Biogeochemical cycles

6 sub-topics

2.8

Biomes, zonation, succession

3 sub-topics

Study tip: Work through the topics in order — each builds on concepts from the one before. Start with notes, then reinforce with flashcards and practice questions.

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Unit 1 Unit 3